METHOD FOR DETECTING AN UN BALANCING AND CALIBRATION OF A MULTIPORT AMPLIFIER OF A TELECOMMUNICATION

专利摘要:
The method of detecting an imbalance of a multiport amplifier (MPA) intended to be embedded on a satellite (SAT), the multiport amplifier comprising a plurality of paths, each path being configurable in gain and in phase, said method comprising A transmission of a first spread spectrum modulated test signal (SE1) from the first transmitting station (STE1) to the first channel (V1), the first test signal being generated in at least the useful band of the first lane (V1); Reception by the second receiver station (STS2) configured in frequency to receive signals transmitted by the second antenna (Tx2) connected to the second channel (V2) of the multiport amplifier (MPA), said signals being capable of comprising a replica of the first test signal (SE1); Detecting and measuring at least one received signal power (SS2) corresponding to a replica of the first test signal (SS2) having leaked at the output of the second output port (PS2); A calculation of at least one unbalance value of the MPA from the measurement of the power of the replica of the test signal (SS2) received in the second terrestrial station (STS2).
公开号:FR3018407A1
申请号:FR1451739
申请日:2014-03-04
公开日:2015-09-11
发明作者:Antonio Arcidiacono；Daniele Vito Finicchiaro；Pera Alessandro Le；Yan Brand
申请人:Eutelsat SA；
IPC主号:

专利说明:

[0001] METHOD FOR DETECTING AN UN BALANCING AND CALIBRATION OF A MULTIPORT AMPLIFIER OF A TELECOMMUNICATIONS SATELLITE.
[0002] FIELD The field of the invention relates to the methods for detecting the unbalance and calibration of a multiport amplifier of a telecommunications satellite. The field of the invention applies to the tests and calibrations of a multiport amplifier comprising a plurality of amplification channels for decomposing, amplifying and recomposing signals between at least one input port and one output port. The field applies to the unbalance measurements and calibrations of a multiport amplifier called MPA as much when the satellite is in the testing phase prior to final orbiting in an operational phase at any time during its lifetime. The field of the invention relates to tests that can be performed without service interruption while minimizing the effects of interference from neighboring systems or interference that may be caused by its own system. STATE OF THE ART 25 When a telecommunications satellite is launched into its operational orbit, a certain number of tests must be carried out to ensure that all the functionalities are validated before it is brought into operational state. It also happens that a number of tests must be conducted during the operational phase of the satellite. These tests must preferably be conducted without service interruption, in particular vis-à-vis the operators operating broadcast channels passing through the satellite. Telecommunication satellites generally perform a repeater function, that is to say they retransmit in a predefined area a signal sent to the satellite for example for a broadcast application Tv.
[0003] The satellite comprises a set of equipment forming, for example, a system for controlling, processing, amplifying, addressing and broadcasting signals. Particularly sensitive equipment is the amplification chain which may include one or more amplifier channels corresponding to a reduction in the satellite capacity. These channels are called "paths" when they allow to decompose and recompose signals arriving at the input ports of the MPA. The MPA comprises components including a so-called "Butler" matrix for amplifying and phase shifting components divided by an input block and to redial them by an output block to the output ports. Each transmission channel is allocated to an input port and an output port. The signals of a channel can therefore be, at the input of the MPA, decomposed in different paths and recomposed after amplification at the output to be routed to a transmitting antenna of said channel. Currently, different repeater solutions integrate a multiport amplifier onboard a telecommunications satellite. An amplification path of a satellite repeater generally comprises a traveling wave amplification tube. This is a broadband amplifier with very low background noise. Generally, a telecommunications satellite includes an MPA for processing multiple paths for amplifying signal components from different channels of a certain frequency bandwidth. Each channel can be "rented" or used by broadcasters or operators. It is therefore important that each path amplifying and phase shifting the components of an input signal of the MPA be calibrated so as to provide an orthogonality function between the divided components in the different paths of the MPA. Multiport amplifiers are particularly used for missions requiring the coverage of a plurality of spots, each designating a land station. The satellite makes it possible to transmit a plurality of downlink beams generated from a power management adapted to each channel and to manage the allocation of input and output ports and the routing of the signals to the antennas of the channel. satellite. These solutions allow flexibility in allocating the power required on each output port of a multiport amplifier. Multiport amplifiers are commonly called in the state of the art an "MPA", whose acronym in the English terminology means "Multi-Port Amplifier". Generally, an MPA comprises for each of its paths a traveling wave tube, better known by the acronym TWTA. We recall that the TWTA is a vacuum tube used in microwave frequencies to make amplifiers of low, medium or high power. It allows for broadband amplifiers with very low background noise. It is particularly suitable for communication satellite amplifiers. In addition, an MPA includes a beamforming network for developing one or more beams (x) transmitted with a given power, phase, and direction. An example of such a commonly used network is a Butler matrix having N inputs and N outputs and a specific configuration of paths comprising amplifiers and phase shifters and allowing to obtain a phase shift and amplification configuration of the signal components. at the input of the MPA which are divided to obtain one or more desired MPA output signal (s). In nominal operation, if a channel is defined between the input port # 1 and the output port # 1, then a signal routed to the input port # 1 is only present on the output port No. 1. The peculiarity of an MPA is that the signals of the same channel are out of phase in each of the paths in a plane defining the phase shifts from one path to another. In each path, the phase-shifted signals are amplified a TWTA-type amplifier. In practice, a selected design of a beam formation and recomposition network can be provided by a Butler matrix. The latter performs a function called "unitary function". The unit function contributes to the formation of a beam recomposed to an output of the matrix and potentially to the formation of N beams recomposed at each of the outputs. One advantage is that each active TWTA contributes to the amplification of signals of different channels. If a plurality of frequency-separated signals are routed to the different inputs of a matrix, each TWTA amplifies the signals of each channel. When an MPA is properly calibrated, signals routed to a first input port of a channel are only present at the output of a first output port. A problem occurs when the calibration between the different paths of the MPA is not performed properly. Indeed, a drift in phase and / or in amplitude of the components between the different paths can lead to make resultants of non-zero MPA output signal components while a configuration of the MPA predict that the latter should be substantially zero in output from other output ports. This results from a functionality of a Butler matrix as detailed in FIG. 2 which makes it possible to cancel signal components in phase opposition at the output of the MPA. This problem is usually called imbalance of the MPA.
[0004] An unbalance of an MPA can cause different consequences including: ^ the reduction of the power of a main signal at the output of a port of the matrix because the summation of the components in phase are slightly out of phase; reducing the power of a main signal at the output of a port of the matrix caused by a difference in gain between different paths of an MPA; the creation of significant levels of signals, called leaks, outputs of some ports because of a drift phase shift that no longer makes a resultant components summed together in phase opposition substantially zero. A commonly accepted limit is that the power of the leaks should be of the order of a power of 25dB less than the power of the main signal on the same channel. One way today of solving the problem of unbalancing an MPA is to parameterize the phases and amplitudes of each TWTA channel. But a problem related to the de-calibration or the unbalance of the channels remains present with the aging of the TWTA modules or the aging of the inputs and outputs of a Butler matrix or other components. Another disadvantage of this solution is that when a TWTA fails and a second TWTA is chosen to replace it, it is not previously calibrated in amplitude and phase vis-à-vis the other TWTA MPA. It is therefore imperative to measure the amplitude and phase imbalances of a path of the MPA vis-à-vis other amplification paths to correct the calibration dynamically. Finally, one of the major problems encountered is to perform measurements and a re-calibration without disturbing the current communications of the MPA on each of the other channels. A first known solution consists of measurements carried out on board the satellite and transmitted to the ground in an architecture called "open loop". In this solution the calibration of a path of the MPA is performed by taking measurements on the output signals of the matrix. In-line RF detectors are then used which are connected by means of one or more couplers to ports not used by the relayed transmissions in the satellite. RF detectors measure power levels of output signals from unused ports. The measurements are performed on each port independently of each other. The measurements are then transmitted to a ground station using the telemetry link. For example, an increase in the RF level measured at the output of one of the ports vis-à-vis the level injected reflects degradation of the calibration of the MPA. A problem of this solution is that it depends on the operational configuration chosen, in particular on the choice of the input levels of the emitted test signals. Measurements sent to a ground station may not be usable or exploitable to deduce a recalibration to be performed. The major disadvantage of this solution is the dependence of the test on the chosen operational configuration. A second solution consists of measurements made on board the satellite and transmitted to the ground in a so-called "closed loop" architecture. One or more test signals are / are generated on board by means of a DSP and are / are injected into one or more input ports of the matrix. The output signals of the output ports are collected via a calibrated coupler (s). The input signals are also injected by means of a calibrated coupler on the input ports of the matrix. The outputs of the matrix can be looped back to the DSP so that the DSP adjusts the phase shifts and amplitude differences of the signal generated at the input of the matrix. Such a system has the disadvantage of being expensive. In addition, it is necessary to embark a complex architecture aboard the satellite in particular by providing a DSP specifically designed to perform these calibration tests. As a result, the components engage additional weight on board the satellite.
[0005] A third solution is to directly receive the signals transmitted on the channels to be tested / calibrated in a plurality of ground stations. The frequency band and the directivity of the antennas are then chosen so as to allow these transmissions from the satellite. An example of an implementation consists, for example, in choosing a main terrestrial station on which a main signal is emitted from the satellite. The antenna and the corresponding channel of the satellite are configured to transmit this main signal on a predefined station. Furthermore, a plurality of spots geographically distinct from the main station are chosen, each corresponding to the transmission on one channel of the MPA. This method consists in measuring the losses of lines of the main channel on at least one other channel by measuring in each of the spots the received power corresponding to the signals of the main channel. For this, the RF levels on each channel are measured on the ground in each spot. After signal reconstitution, with attenuation of the antenna close, it is possible to deduce the line losses caused by the MPA. Comparisons of the received signals make it possible to deduce and isolate the losses caused by an unbalance of one or more channels of the MPA. A major disadvantage of this solution is that it disrupts the on-going telecommunications of the satellite when in an operational operating configuration.
[0006] In conclusion, today's solutions to measure MPA unbalance and correct these imbalances are costly, difficult to implement, and disruptive to ongoing operational communications when the satellite is operational. SUMMARY OF THE INVENTION The invention solves the aforementioned drawbacks.
[0007] An object of the invention relates to a method for detecting an imbalance of a multiport amplifier MPA intended to be embedded on a satellite, the multiport amplifier comprising a plurality of paths, each path being configurable in gain and in phase, multiport MPA amplifier comprising a plurality of input ports and a plurality of output ports, each input port being associated with an output port to form a transmission channel called "channel", each output port being connected to a satellite antenna. A first channel is configured in frequency in a transmission channel defining a first band useful for receiving signals from a transmitting station on the ground and retransmitting them after amplification in the multiport amplifier MPA to a first ground station of a first geographical zone, a second output port of a second channel being configured to transmit via a second antenna to a second earth station of a second geographical area.
[0008] The method comprises: - transmitting a first spread spectrum modulated test signal from the first transmitting station to the first channel of the multiport amplifier, the first test signal being generated in at least the useful band of the first channel, a reception by the second receiver station configured in frequency to receive signals transmitted by the second antenna connected to the second channel of the multiport amplifier, said signals being capable of comprising a replica of the first test signal; detecting and measuring at least one power of received signals corresponding to a replica of the first test signal having leaked at the output of the second output port; a calculation of at least one unbalance value of the MPA from the measurement of the power of the replica of the first test signal received in the second terrestrial station. Advantageously, the MPA comprises a Butler matrix comprising: an input module making it possible, from the first test signal, to generate a plurality of components that are out of phase and of the same amplitude to a plurality of paths connecting the input module to a module; Release; a plurality of paths each comprising at least one signal amplifier; an output module for dividing and recomposing the out-of-phase and amplified incoming components so as to deliver: in a given output port, an amplified non-zero signal corresponding to the first input signal to be transmitted to the first terrestrial station and; o in the other ports, the resultants of the components of the first test signal substantially zero to calibration errors.
[0009] Advantageously, the first test signal is a radio frequency signal modulated by a sequence of data bits encoded by a baseband PN pseudo noise sequence, the PN sequence comprising an N symbol size and a TSymbol encoding rate.
[0010] Advantageously, the PN pseudo noise sequence is chosen from a family of codes each having an orthogonality property. Advantageously, the orthogonality of a sequence corresponds to the result of an autocorrelation of two same sequences, one of which is temporally offset with the other by at least the duration of a symbol, the result of the autocorrelation presenting a substantially obtained level in the noise level.
[0011] Advantageously, the length N of the pseudo noise sequence PN is calculated so as to obtain an encoding gain greater than a minimum threshold, the encoding gain being defined by the ratio between the coding rate of a symbol of a PN pseudo noise sequence and the encoding rate of a data bit of a sequence of data bits.
[0012] Advantageously, the peak of the autocorrelation of a pseudo noise sequence is of a normed value of 1 and, outside the correlation peak, the value of the autocorrelation function is of the order of 1 / N.
[0013] Advantageously, the pseudo noise sequence PN is chosen from the following list: {a code of the type Gold codes, a code of type "Maximum Lengh Sequence", a code of the type Walsh-Hadamard codes}. According to a second embodiment, a first isolation threshold value between the first antenna of the first channel and the second antenna of the second channel is respected so that the power received from the signals of the first antenna at the second station of reception is considered negligible with respect to the power of the signals received by the second receiving station from the second antenna. In this second embodiment, at least two receiver stations are used to receive the signals. An advantage of this embodiment is to overcome the implementation of a self-timer in one of the satellite channels. On the other hand, it is necessary to ensure a certain level of isolation of the signals received in a station coming from an antenna of the satellite vis-à-vis the signals emitted from the other antennas. Advantageously, the power difference between the signals received by the second station from the first antenna and the signals received by the second station from the second antenna is greater than a predefined threshold. Advantageously, the first isolation threshold value is defined by comparing the powers received in a receiver of the second station between the signals originating on the one hand from the first antenna and on the other hand from the second antenna.
[0014] Advantageously, the signals at the output of at least two antennas (Tx1, Tx2) of the MPA are polarized with different polarizations so as to introduce additional insulation between the two corresponding antennas.
[0015] According to a second embodiment: a delay at the output of one of the channels of the MPA is introduced so as to delay the output signals of the output port (Psi, Ps2) of the corresponding channel; a single earth station is used to receive the output signals of each output port, the orientation of the first and second antennas for receiving the signals of the first and second channels at the land station. An advantage of this second embodiment is to enable the signals to be recovered in the same receiving station. Advantageously, the duration of the delay generated on the transmitted signals is greater than a minimum duration corresponding to the period of a symbol of the PN sequence of the first test signal. Advantageously, the delay is introduced by a retarder at the output of one of the channels of the MPA. Advantageously, the retarder is a delay line whose length is sized to introduce a desired delay. Advantageously, one of the channels of the MPA is connected to a telemetry antenna or a horn antenna and that at least one retarder is arranged between the channel and the telemetry or horn antenna. Advantageously, a delay is generated by means of a configuration of a beamforming network coupled with the output ports of the MPA so as to assign for each output port signals having a predefined phase shift.
[0016] Advantageously, the receiver of the first terrestrial station performs an autocorrelation function of the signals received from each of the channels over a predefined time window so as to discriminate the presence of each of the PN sequences in reception, the discrimination of the two sequences resulting from an insulation obtained thanks to the delay injected into one of the channels of the satellite. Advantageously, the first test signal is transmitted on a channel in the same frequency band as useful telecommunications signals. Advantageously, the steps are successively repeated between different paths of the MPA.
[0017] Another subject of the invention concerns a method for calibrating a multiport MPA amplifier of a satellite. The method comprises: measuring a power level of the replica of the first test signal on a receiver of a terrestrial station using the method of detecting an imbalance of a multiport MPA amplifier of the invention; a generation of at least one calibration setpoint deduced from the signal power measurements comprising the replica of the first test signal; a transmission of said at least one calibration setpoint to the satellite. Advantageously, at least one calibration setpoint comprises at least one phase shift setpoint and / or a gain setpoint. Advantageously, the receiver of the receiving station, measuring the power of a signal corresponding to a replica of the first test signal at the output of a second channel, transmits to a control station the power data collected so as to the control station transmits a control signal to the satellite for reconfiguring the MPA with the generated gain and / or phase shift instructions. An advantage of this calibration method is to be compatible with an operational operation of the satellite. Operator transmissions can be uninterrupted during the calibration process. One advantage is that the emission of the test signal does not disturb the operational transmissions. Calibration can be performed by the telemetry antenna, so operational transmissions are not disturbed by the calibration signal.
[0018] BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will emerge on reading the detailed description which follows, with reference to the appended figures, which illustrate: FIG. 1: different responses to autocorrelation functions based on different lengths pseudo-noise sequences; FIG. 2: an example of a Butler matrix used to implement an MPA; FIG. 3A: a block diagram of the means to be used for transmitting a signal from a first transmitting station to the satellite in order to carry out the method of the invention; FIG. 3B: an example of an MPA comprising at least two main channels; FIG. 4: power curves of the signals received by stations corresponding to the example of FIG. 3B terrestrial according to their respective positions with regard to the pointing of the antennas of the different channels; FIG. 5: an embodiment of the invention comprising a line retarder on one of the channels of an MPA, for example that represented in FIG. 3A.
[0019] DESCRIPTION In the present description, the term "signal leakage" of a channel to another channel of an MPA, signals normally transmitted on a main channel through a first port of entry found to be amplified by another way and resulting in directing signals to another MPA output port than the one intended to receive them. Leaks are linked to poor path isolation of an MPA, which means that amplifiers or phase shifters introduce phase shift differences or unmaintained amplification differences at the output of the MPA. There is thus differentiated "a path" of an MPA which can be configured by a variable gain and a phase-shifter and which takes a signal significance from the point of view of the processed signal in said path, of a "path" which includes a port of input and an output port and which is associated with a receiving antenna and a transmitting antenna. Butler / MPA matrix. Fig. 2 shows an MPA comprising a Butler matrix comprising 8 CH paths; connecting an input block, called IBM "Input Butler Matrix" in the English terminology, to an output block, called OBM meaning "Output Butler Matrix" in the English terminology. The IBM input block includes PE; input ports. Each SEi signal entering an input port of the IBM input block is divided into 8 equal amplitude components. According to other embodiments, the number of input ports and paths of the Butler matrix can be adapted according to the case treated. The division of the input signal introduces a phase shift Acpi between each component of the divided signal. Each component of the input signal SEi constitutes a replica of the incoming signal which is out of phase with each other according to a pre-established phase shift plan. The Butler matrix comprises CH paths; to join the IBM input block and the OBM output block, each of the CH paths; comprising an amplifier for amplifying each component of the same gain. The OBM output block makes it possible to divide each s of the incoming amplified components into 8 other sub-components of equivalent amplitudes with a new phase shift. A total of 64 signals from the input signal SEi are generated in total. The OBM output block is set to obtain the resultant of any combination of previously divided components at one of its output ports of the OBM output block. It is therefore possible to obtain cancellations of phase-shifted signals by summation so that a given resultant is zero or amplifications of signals of the same phase shift. Figure 2 shows 8 outputs 10, 11, 12, 13, 14, 15, 16 and is BM (SE1) of the Butler matrix. In this example, the Butler matrix is configured such that summed summaries of the components at the outputs 10, 11, 12, 13, 14, 15 and 16 are zero or virtually zero. By way of example, the output 10 represents two summed components having an opposite phase shift which leads mathematically to a zero resultant. The output BM (SE1) corresponds to a summation of the components in phase, that is to say including the same phase shift, the resultant of the summed components is therefore non-zero. It will be understood from the light of FIG. 2 that a drift of an amplifier or phase-shifter of one of the Butler matrix paths may lead to non-zero summings at certain outputs while the configuration of the matrix is set to cancel the summation of the components. These drifts can occur with aging components of the Butler matrix. The invention therefore allows a re-calibration of the MPA by compensating the drift of phases and / or amplitudes that may occur throughout the life of the MPA. These compensations can be applied to the MPA paths, and / or the Butler matrix input and output blocks. The invention therefore aims to solve the problem related to the isolation of the channels of the MPA caused by a drift phase shifters and amplifiers of the Butler matrix. In the present application, therefore, a "channel" is defined as the set formed by: the input port of an MPA, the different paths used to phase out and amplify the incoming signals and; ^ the output port in which the signals are recomposed. A leak is found when incoming signals in a given input port are found on an output port not belonging to the port associated with the input port. Main track / secondary track. For the purpose of a better understanding of the invention, one of the ways of the so-called "main" MPA is distinguished from a "secondary track". The "main channel" is defined as the channel intended to transmit and relay test signals to measure the unbalance of the MPA. The test signals thus transmitted are received at the main input port PE1. In the present description and the examples described, the main channel corresponds to the first channel V1 which connects the input port PE1 to the output port Psi. We speak indifferently of a first SEi test signal or first SEI test signals. A "secondary channel" is called for the incoming signals in the main port of the main channel, a channel in which components of the wanted signals have been amplified and summed with a phase or amplitude difference which introduces significant leaks. at the exit of a port of a secondary road. By convention, the V1 channel is the main channel receiving the test signals for the recalibration of the MPA and the other channels are secondary channels. The method of the invention makes it possible to measure the leakage at the output of these secondary channels due to a bad calibration or a drift of a previous calibration. In the present description, the V2 channel is used to describe in detail the mechanisms for measuring leakage levels according to the method of the invention. The secondary channel corresponds to the second channel V2 which connects the input port PE2 to the output port Pst. When an MPA is properly calibrated, the main signal leaks generated at the output of a secondary port should be minimized as much as possible. In the case of optimized calibration, the leakage becomes negligible from the point of view of the power generated parasitizing the useful signals transiting on the secondary channel. When leaks are caused by a drift of the initial calibration of the MPA, phase and / or amplitude differences in the Butler matrix cause the formation of signals from the components of the main signal at the output of a port other than the main exit port. Operational configuration. The method of the invention comprises a first step of transmitting a first spread spectrum modulated signal SEi from a first transmitting station STE on the ground to a first port PE1 of a main channel, called first channel V1 of the first channel. multi-port MPA amplifier of the satellite. The first channel V1 is understood as the channel carrying the useful signal SEi from a first input port PE1 to a first output port Ps1. A configuration of the MPA allows to route the components of the useful signals in the Butler matrix which will be summed in phase at the output of the first output port Psi of the MPA. The other channels are theoretically configured so as to produce a zero resultant at the output of the other output ports Psk with respect to the routing of the first signal SEi. The useful signal SEi produces, at the input of the MPA, different components of the signal which are out of phase and amplified in different paths of the MPA and which are recomposed at the output port Psi. The method of the invention makes it possible in particular to transmit the test signal SEi in the useful band of the first channel V. Thus the spread spectrum modulated signal SEi can be transmitted for the purposes of calibration tests at the same time as a signal useful telecommunication transiting in the same way Vi for example by another transmitter without harming the latter transmission. The first test signal SEi may comprise a data sequence encoding a digital identification information. The latter is modulated for example by a pseudo noise sequence PN as detailed below. The transmitter E1 based on a terrestrial station STE1 emits a signal, denoted SEI, modulated by a modulator mod spread spectrum direct sequence s, known by the acronym DSSS meaning in the English terminology: "Direct Sequence Spread Spectrum ". The signal is therefore emitted at low power and disturbs little neighboring communications and communications transmitted on the same main channel. The method of the invention makes it possible to measure at the output of each secondary port Psk the part of the signal SEi which has produced leaks on the other channels. The transmitted signal SEi allows according to the method of the invention to evaluate the unbalance between two channels and therefore the unbalance of the MPA by comparing the output of two different output ports Psi and Psk of the MPA the amplitudes of the signals from the components. summed from the first SEI signal. The level of the leakage of the signal SEi on a Psk output port whose results of the components of the input signal SEi should be substantially zero allow to deduce recalibration parameters paths of the MPA. The method of the invention makes it possible to measure the imbalances between the channels V1 and V2 in particular by the deduction of phase shift parameter and path gain of the MPA. The method of the invention makes it possible to measure the level of leakage at the downlink of the satellite to one or more receiving earth stations from which the signal level measurements are made. The method of the invention thus makes it possible to measure and quantify the power of a signal SS1 emitted by the satellite to a terrestrial station and to compare it with the powers of the leaks also emitted by the same satellite towards a terrestrial station. According to the different embodiments of the invention, the earth stations receiving the SS1 test signal having been relayed by the satellite and the leaks may be the same receivers or receivers of different earth stations. Measurements can be derived from signals received at receiving earth stations such as STS1 and ST52 stations shown in Figure 3A. According to the embodiments of the invention, the stations may be different and far enough apart to provide isolation between a main channel and a secondary channel; be identical when the method discriminates the signals from each channel independently of each other. The measurements are made from: firstly, context data such as the positions of the earth stations and the signal attenuation pattern according to the position of the satellite and; on the other hand, data specific to the received signals such as their power and the correlations of the spread spectrum modulated signal. Spread spectrum modulation. The method of the invention makes it possible to define a particularly advantageous spectrum spreading modulation by means of PN pseudo noise sequences. The pseudo noise sequences PN make it possible to generate a test signal SEi which can be embedded in terms of the power in a power received by the satellite of a useful signal transmitted simultaneously on the same channel V1. The properties of a modulation of a signal by a PN pseudo noise sequence makes it possible to discriminate the signal SEi on reception by an appropriate demodulation. Indeed, one of the advantages of the use of the direct sequence spread spectrum modulated signals and that they do not disturb the current transmissions made by the satellite, including transmissions of operators and content broadcasters defining operational communications. . Interference between the wanted signals and the SEi signals is, therefore, limited by the nature of the spread spectrum modulated signals. There is therefore no deterioration in the quality of service of communications in progress during a measurement of an unbalance of an MPA according to the method of the invention and during the calibration procedure of the MPA. The channel V1 which is tested by the method of the invention can therefore be used jointly by an operator transmitting data signals intended for example for Tv broadcasting. As previously stated, an example of a signal generated by spread spectrum A direct signal of particular interest in the method of the invention is a PN sequence type signal, the acronym of which means "Pseudo Noise" which can be understood as a pseudo noise sequence in French terminology. A first advantage of the PN sequence is that it can be detected by a receiver which demodulates the signal received from the main channel V1 or the secondary channel V2. By applying the decoding of the received data sequence over a given period of time, the PN sequence being known, an autocorrelation function makes it possible to detect the presence or absence of a sequence contained in the signal. One of the problems solved by the invention is in particular to discriminate a receiving PN sequence from a main channel from that contained in leak signals from a secondary channel. Introduction of the two embodiments. According to the embodiments, the receiving PN sequence at a land station can be detected in different ways to solve this problem. The invention proposes two main embodiments of the method of the invention based on the same inventive concept using: in a first mode, the method makes it possible to introduce a delay generated on one of the secondary channels so as to discriminate on the ground: o a PN sequence received from the main channel V1 which is not delayed; a replica of a PN sequence included in leak signals at the output of a secondary port. - 20 - - in a second mode, by providing a sufficient isolation between a main channel and a secondary channel and more particularly antennas connected to these channels, the isolation making it possible to discriminate on the ground: o a PN sequence received from the channel principal that is not delayed; a replica of a PN sequence included in leak signals at the output of a secondary port.
[0020] In the present description we mean a discrimination of a PN sequence by a PN sequence modulated by the data bits. It is of course understood that a demodulation operation makes it possible, from a carrier or signal carriers, to extract the modulated data in baseband.
[0021] First mode: Self-timer. Consider first the first embodiment. When the method of the invention comprises the generation of a delay on a secondary channel, the method makes it possible to size this delay by adapting the ratio between the size of the PN sequence; - the self-timer on the satellite. PN sequence / coding, PG.
[0022] Let's study first, the choice of the PN sequence, its size, and its type of code. The size of the PN sequence is defined by a coding rate, noted Tsymboi. The Tsymboi coding rate may be expressed: either as the number of symbols generated per second that can be coded and transmitted or; or in number of symbols encoding a data bit, the data bits being transmitted at a bit rate per second, denoted Tbit. The encoding gain of a bit is introduced by a sequence PN by the function PG: 21 - PG = 10 log (Tsymbol / Tbit) If for example the PN sequence has 10 symbols for the coding of a bit, then PG = 10 dB. Figure 1 shows different PN sequences of different sizes, it is a code called "Gold code". An advantage of using PN sequences is the orthogonality of the generated sequences. Indeed, the product / correlation of a PN sequence with any sequence is close to zero in the sense that the average value obtained is close to zero, whereas the autocorrelation of a PN sequence with itself gives a maximum as illustrated in FIG. 1 by different results of the autocorrelation function of a PN function. It can be seen that the longer the PN sequence, the greater is the criterion of orthogonality of the sequences. The maximum of the peak of the autocorrelation function makes it possible to obtain high peaks. This is a first advantage in the detection of the PN sequence which can be more easily found in the received signal. Another advantage can be obtained in the light of FIG. 1, which shows that an offset of at least one symbol between two same self-correlated sequences makes it possible to obtain a level of the autocorrelation product in the level of the noise. The use of a long PN sequence, that is to say having a high Tsymbol encoding rate, makes it possible to obtain a virtually zero product of the autocorrelation function of two PN sequences which are shifted by at least one symbol duration Dsymboi or more. Thus the introduction of a delay on a secondary path of a duration of at least equal to or greater than that of a symbol Dsymboi allows in reception to dissociate the two PN sequences from the main track and a secondary path when there are signal leaks. The method of the invention therefore makes it possible to adapt a PN sequence having a high Tsymboi encoding rate so as to reduce the stress on the self-timer on the satellite. Indeed, when the retarder is a delay line, its length is proportional to the delay that it is desired to introduce. Let us consider an example case in which the following configuration is given: a 72MHZ channel in the Ku band; - a carrier frequency down to 11GHz - the wavelength is then (3109) / (11.108) = 2.72 cm - an SSSD sequence with an encoding rate of 50 Mchip / s - a roll-off factor of 6 = 0.4 We assume PG = 60 dB on the amplification chain which corresponds to a bit coding rate of 50 bits / s. The period of a symbol is therefore 2Ons in this example. This gives us, for a delay line technology, a length of the line of the order of 6 meters for a wavelength of 220À. It is thus understood that the higher the PG, the shorter the length of the delay line will be, which reduces the space requirement in the satellite. PN sequence / Code type. Many code sequences may be used with the method of the invention such as the following known sequences: Gold codes, "Maximum Lengh Sequences", Walsh-Hadamard codes and other sequences. In the embodiment of injecting a delay on one of the secondary channels, the method of the invention thus makes it possible to limit the delay to a Dsymbol or more symbol duration while benefiting from the orthogonality properties of the PN sequences. These properties allow in reception to discriminate a PN sequence from a main channel of the same PN sequence from a secondary channel. The method of the invention may therefore include optimizing the value of the PG encoding gain by decreasing the transmission rate of a data bit. The method of the invention uses the generation of such a PN sequence in a transmitted signal SEi from a transmitting station STE1 transmitting the signal to a satellite SAT. In the embodiment involving the generation of a delay, the latter will be introduced out of the output port PS2 of the MPA by convention with regard to the example illustrated in FIG. 3A. At the receivers located in each earth station, the signals are detected, demodulated, possibly time stamped. The amplitudes of the signals and powers are calculated. The main signal is designated as that taking the transmission path provided for this purpose, that is to say the channel V1 connecting the port between PE1 to the output port Psi, by following the different paths of the MPA after decomposition and recomposition of the received signal at the input port PE1. The replicas contained in the leaks present on at least one other port are designated as the signals coming from the main signal but whose recompositions at the output of another port did not generate zero or substantially zero signals in accordance with the calibration of the MPA. .
[0023] In the embodiment generating a delay at the output of the channel V2, the PN sequence at the output of a secondary port is shifted by at least one Dsymbol symbol time to discriminate on reception of this sequence of the PN sequence of the main channel . By temporally shifting the replica of the main sequence by injecting a delay, it is possible to detect the replica unambiguously at the receiver of the earth station, when the two sequences are received by the same receiver for example. Another way to proceed and use a decoding algorithm of the main PN sequence and useful data of the main channel V1. Once these data are demodulated, they can be used to deduce the presence of the same PN sequence from a secondary channel in the received signal by correlating the received signal with the PN sequence modulated by the data bits. But this method requires a specific software implementation for decoding. Implementation of the delay. Let us detail this first embodiment on reading FIG. 5 which represents a retarder 22 on a secondary channel. In this first embodiment, a first variant consists in placing on the V2 channel or at the output of a secondary channel of the MPA a retarder making it possible to introduce a line delay. The latter makes it possible to delay the signals at the output of the output port PS2.
[0024] By way of example, each MPA output port could be equipped with delay lines, which are filters capable of providing the envisaged phase delay. A practical way is to use a waveguide technology. It is then necessary that the deteriorations associated with these filters must be less than 0.1 dB. This makes it possible not to degrade the output power too much. For this purpose, a retarder 22 may be arranged at the output of the output port PS2 of the MPA as illustrated in Figure 5. Several retarders.
[0025] According to other embodiments, retarders are present at the output of each channel. These deniers as detailed previously allow in reception to make signal leakage power measurements in a secondary path of the MPA. In this case, each self-timer can have its own delay to isolate in reception a replica of the sequence originally transmitted on the main channel and leaking to other paths. An advantage of defining a different delay on each channel is to allow uniquely adjusting each channel to a reference channel. This makes it possible to perform the tests that one wishes without disturbing the useful data links transiting while the method of the invention is carried out. There is therefore no service interruption of the MPA during the calibration phase and the preliminary phase to deduce the calibration values of the MPA. Consequently, the part of the components of the main signal forming leaks on a secondary output port, for example of the channel V2, are delayed by a delay defined between the channel V1 and the channel V2: ATV2N1. One self-timer According to another variant, only one channel is equipped with a retarder and all the calibration measurements are made by comparing the measurements of a channel with that being equipped with the retarder. In this case, it is best to put the self-timer on a main channel to delay the main signals and not delay the leaks. According to this first embodiment, the receiver STS2 receives two signals from the satellite whose power can be isolated by taking into account the delay. The measured power relative to the part of the received signal 10 corresponding to the leaks makes it possible to deduce values of calibration setpoints in phase and in amplitude to be applied to the MPA. Delay with beam network. According to a second embodiment using no delay on the channels, it is possible to benefit from a configuration making it possible to generate delays on each channel of the MPA by using a beam forming network allocated to a specific configuration of the ports. MPA outputs. For example, when a beamforming network is advantageously coupled with the output ports of the MPA and different covers of each antenna according to a given phase shift configuration of the signals transmitted on each channel of the MPA. This configuration makes it possible to phase out the signals of a given delay on each channel so that each target earth station receives a phase-shifted signal, for example a multiple of a delay To. If a delay of To is introduced between the first channel V1 and the second channel V2, each delay introduced in the other channels of an MPA may be, for example, a multiple of the delay To. Then, for the channel V3, there is a delay of 2.T0, for the channel V4 3.To. 30 Delay with output port not used by the MPA. Finally, a third variant for generating delays on each of the MPA channels consists of the use of an output port not used by the MPA communications. This output port can then be configured with a low power delay line which is connected to a horn antenna which is for example used for the telemetry link or the transmission of a Beacon signal. The replica of the sequence that is delayed is received at a terrestrial station providing the telemetry link.
[0026] In this solution, each signal leakage power difference measurement is performed between the main channel being tested and the channel connected to the port connected to the delay line and the horn antenna. Calibration values of the MPA are then deduced. Each channel can then be calibrated with respect to the same test channel using the horn antenna.
[0027] This solution has the advantage of requiring only a few hardware modifications, except for the delay line to be integrated in the unused port. According to the cases, a configuration for activating a delay at the output of a PS2 output port of a secondary channel V2 can be triggered according to the test procedures initiated at given periods and predefined durations. Thus, it is not necessary for example in the last variant using the horn that the delay line does not generate a delay permanently on all the signals transiting on this channel.
[0028] The solution to use an unused MPA output port for the purpose of introducing a delay provides an effective solution. This output port may be the second port Ps2. In this case, the antenna Tx2 is a horn antenna in this example. In this way, the signal corresponding to the amplified leaks and emitted by the horn antenna TX2 via the unused port PS2, is noted SS2. The main sequence replica is time-shifted by the necessary time that has been configured in the self-timer function. The signal SS2 is transmitted to a terrestrial station intended to receive the telemetry signals for example.
[0029] If the MPA is not properly calibrated, then the receiver of the earth station is able to detect a power of received signals. It is then able to deduce the presence of a replica of the same PN sequence transmitted on the main channel thanks to the introduction of the delay on the secondary path and thanks to the implementation of an autocorrelation function. . One of the preferred solutions used in the case of communication passing through the main channel is that of introducing a delay at the output of the port PS2 and of using an output port of the MPA not used by the operational communications. We then use Tx2 which is a horn antenna as detailed in this third variant. The introduction of delay allows us to overcome the level of isolation between the channels. Indeed, an insulation of at least 40dB between the power received on the ground of each channel is minimally necessary. This constraint imposes to receive the signals in two different stations and sufficiently distant to reach the necessary isolation constraints. The delay can be generated by means for example of a delay line, such as a low power coaxial cable output from the output port PS2. The delayed signal can be attenuated by the self-timer and the gain of the telemetry antenna, also called "horn antenna", which is smaller than the gain of a radio communication antenna connected to the MPA such as the Tx1 antenna. The gain of the telemetry antenna is less than the gain of the Tx1 antenna, approximately 20 to 30db lower. As a result, the power difference between the main sequence transmitted by Tx1 and the replica transmitted by Tx2 on reception in the ground station STS2 may be 20dB + 20dB = 40dB. In order for the autocorrelation function to remain efficient under these conditions, it is then necessary to size the size N of the pseudo-noise sequence PN so as to maximize its detection by the receiver STS2. Analysis of the signals in reception. A third advantage of the method using the introduction of a delay is that it does not necessarily decode the signals, the autocorrelation function applied to the signals received over a given window of time allows: to detect the presence of the PN sequence received and transmitted by the main channel; Detection of the presence of the same replicated PN sequence from a secondary path when leakage has occurred on at least one secondary port Pk. These detections can be deduced from the result of the autocorrelation functions without decoding the sequences. There is therefore no need to use a decoding algorithm which makes it possible to avoid a data analysis step in reception. Only the power of the received signal can be measured and the results of the autocorrelation functions. The analysis of the power of the received signal comprising a replica of the sequence resulting from a secondary channel makes it possible to deduce MPA rebalancing parameters. The method of the invention can be applied to each secondary channel by comparing the received signals between a secondary channel and a main channel. The deviations of the phase shift parameters and the gain difference (s) of the amplifiers of the MPA are obtained by analyzing the power levels of the leaks at the output of each channel and therefore on the ground after reception of the signals emitted by the satellite. SAT. A calculation step makes it possible to deduce the rebalancing parameters that must be applied to the MPA according to a calibration method. A calibration of the MPA can then be initiated when the detection method makes it possible to deduce leakage values at the outputs of each channel. 2nd mode. According to another embodiment, a delay is not necessarily introduced in a secondary channel to discriminate the part of the signal corresponding to the main signal of the leaks. As already introduced previously, a problem encountered in this case is the isolation of earth stations from each other vis-à-vis the signals that are not intended for them. In this second embodiment, the method of the invention makes it possible to solve this problem. This embodiment requires receiving the signals from the main channel and the signals of a secondary channel including leaks in two terrestrial stations sufficiently isolated from each other in frequencies. The signals received at each station each having the same PN sequence modulated by the data bits can therefore be received simultaneously and be analyzed a posteriori: either by performing a decoding, a level measurement and a comparison of the demodulated data; or by an autocorrelation function applied to the two received and time-stamped signals and by analyzing the peak of correlation.
[0030] FIG. 3A represents an emitter E1 of a land station STEi. A signal SEi is modulated by a PN sequence; pseudo-noise and transmitted to the satellite via an uplink. A second channel V2 connected to an output port PS2 is then considered. The first channel V1 is connected to an output port Psi.
[0031] Each output antenna Tx1 and TX2 is oriented according to a diffusion configuration. FIG. 3B proposes an exemplary configuration making it possible to better understand this second embodiment based on good insulation of the main track with a secondary track. For example, the output antenna Tx1 connected to the first port Psi is directed to broadcast on a zone in France FR while the output antenna Tx2 connected to the second port Ps2 is directed to broadcast a German zone DE. The output signal of the antenna Tx1 is denoted SS1 and the output signal of the antenna Tx2 is denoted SS2. The example of the French and German zone coverage will be taken to detail a case study to better understand the invention, but the method of the invention applies when two receiving stations provides sufficient insulation between them. The satellite SAT receives the signal SEi on an antenna ANTE1 of reception. The antenna delivers the received signal to a first port PE1 of the MPA. When the MPA is not calibrated, signals recomposed at the output of secondary ports may generate leaks which include a trace of the PN sequence; modulated by the data bits. The leaks are generated according to the principles explained with reference to FIG. 2 during the recomposition of signal components summed in theory in phase opposition.
[0032] The measurement of the leakage powers comprising the PM sequence can be performed by analyzing the power received on the STS2 station. This analysis makes it possible to deduce from it unbalance values and therefore to deduce calibration instructions from the MPA in the same way as in the first embodiment.
[0033] In the example illustrated in FIG. 3B, when one is located on a reception zone in Germany, FIG. 3B illustrates that a part SS1 'of the signals transmitted by the antenna TX1 of the signals SS1 arrives at the receiver STS2 in the area in Germany DE. This is due to a 100% non-isolation between blanket areas that are not totally disjoined due to the geographical proximity of the zones. For example, border towns between Germany and France will be more prone to the consequences of insufficient insulation by receiving signals from both antennas. In Germany, when no signal is injected on the input port PE2, the receiver STS2 thus receives the sum of: ^ the signals transmitted by the first antenna Tx1 and having been attenuated by the distance and the inclination between the satellite Tx1 antenna and receiver located in Germany; signals fleeing from the first channel V1 to the second channel V2. Figure 4 illustrates the signal levels received at each earth station. The power received at the terrestrial station STS2 therefore comprises: a first portion SRsTs2 (A) amplified by the antenna Tx1 but isolated partially geographically and; a second part SRsTs2 (B) amplified by the antenna Tx2 resulting from the leakage of the MPA caused by an unbalance of the latter. Curve 41 represents the power of the signal from the Tx1 antenna which is intended to cover the area located in France. It can be seen that the power is actually maximum in the FR coverage area and that this power is decreasing in the neighboring zones including the DE zone located in Germany. Identically, the curve 42 represents the power of the signal from the antenna Tx2 intended to cover the area located in Germany. It can be seen that the power is effectively maximum in the coverage area DE and that this power decreases in the neighboring areas including the FR zone located in France. From the point of view of a receiver STS2, located in Germany in zone DE, it receives the sum of the power of the signals coming from the two antennas of which Tx1 and Tx2.
[0034] In order to better understand the curves of FIG. 4, the gain FR-rxi is called: the gain of the signals at the output of the antenna Tx1 and arriving at the receiver STS1 and; the gain FR-rx12: the gain of the signals at the output of the antenna Tx1 and arriving at the receiver STS2 these signals are denoted SS1 'and; the gain DE-rx22: the gain of the antenna connected to the second channel V2 ensuring the coverage of the German zone and therefore of the receiver STS2, the received power SRsTs2: the power of the signals received at the receiver STS2, leaks SSv1, v2 at the output of the antenna Tx2 from the non-zero recomposition of components of the signal SEi on a secondary channel.
[0035] We obtain: SRsTs2 = SRsTs2 (A) + SRsTs2 (B), with: o SRSTS2 (A) = (SS1 'FR-D (12) o SRSTS2 (B) = (SSV1-> V2 DETX22) -32- When the MPA is calibrated perfectly, that is to say that there is no leak of the channel V1 on the output port PS2, in theory we must have: ^ SSvi, v2r-, 0 and therefore SRsTs2 (B) = -. 0 s In this case, the receiver STS2 located in the German zone in the same example as above, receives only the signal SS1 'coming from the antenna Tx1 and therefore the power called SRsTs2 (A) It is specified that the signals SS1 and SS1 'are identical, only the gain in reception of these signals differs from one terrestrial station to another depending on the pointing direction of the antenna and the isolation of the antenna. When the MPA is unbalanced, signals transmitted by a secondary channel including the PN sequence modulated by the data bits are found at the output of a secondary port PS 2. The leaks, denoted SSv1, v2, are non-zero and have a power that is to be measured at an isolated terrestrial station of the station receiving signals from the main channel V1. In the same example as above, the receiver located in the zone in Germany receives a part of the signal coming from the antenna Tx1 which provides the coverage of the zone in France and a portion of signals amplified by the amplifiers of the channel V2 coming from from track V1. FIG. 4 represents the two parts of the power received from the signals SS1 'and SS2 by the receiver STS2. When no useful signal is transmitted on the channel V2, we have: SS2 = SSV1-> V2 Indeed, only the leakage of the out of phase components of the signal SEi summed at the output of the MPA are emitted in this case by the antenna The method of the invention makes it possible to measure the only part of the signal received at the STS2 receiver resulting from the components of the main signal of the channel V1 which have recomposed at the output of a secondary port and thus forming leaks on the PS2 output port. The measurement of these leaks makes it possible to deduce an unbalance value of the MPA. The same measurements can be applied to each channel taking for each measurement a main reference channel, in our case we have taken V1 and the port PE1 as the port receiving the main test signal for the measurement of the MPA unbalance. . This second embodiment requires the choice of an isolation threshold between the two antennas Tx1 and Tx2 and thus a configuration of the antennas Tx1 and Tx2 and their orientation pointing two earth stations far enough apart. When the isolation of the signals emitted between the two channels is sufficient, the received power of the signals amplified by the main channel V1 and received in the receiver STS2 are negligible with regard to the power of the signals coming from the signal leaks of the channel V1 on the PS2 output port. Concretely, the ratio 43 can be appreciated with reference to FIG. 4. When the power of the signal received by the station STS2 is maximum, the power of the signal SS1 'coming from the antenna TX1 is negligible. This second embodiment sets out to define a solution that aims to control the isolation between the transmit antennas Tx1 and Tx2 of the satellite. By choosing stations from each sufficiently distant zone, for example "Brest" for France and "Berlin" for Germany, the signals leaving the Psi port bound for Brest in the France zone will not disturb the signals received in a very small area. station located in Berlin in the zone Germany. The signal strength received in Berlin by the Tx2 antenna will be much higher than the power of the signals emitted by Tx1 and received in Berlin which will be considered of negligible power. It is considered that the attenuations are sufficiently strong and thus the covers in these cities sufficiently disjointed to consider the signal power SS1 'as negligible in reception of the STS2 receiver located in Berlin. The method of the invention makes it possible to measure an imbalance of the MPA, in particular by comparing the power of the leaks from one channel to the other. In our example case, the signal strength received in Berlin, ie the STS2 station, from the channel V1 and the port Psi and therefore from the antenna Tx1 must be negligible with respect to the power of the signals coming from the channel V2 and the port PS2, thus from the antenna Tx2 corresponding to the leakage of the signals of the channel V1 towards the channel V2. In this example, it is assumed that no signal is injected into the input port PE2 of the channel V2 intended to transmit on the antenna Tx2. The only signals present at the output port PS2 will be the leakage of signals injected at the input of the input port PE1 intended to be transmitted alive the antenna Tx1. Consider an example case in which the unbalance of the MPA is 20dB. If the isolation between the antennas Tx1 and Tx2 makes it possible to have a difference of more than 20dB between them, then the power of the signal SS1 'in reception at the station STS2 will be negligible vis-à-vis the power received from the leaks due the imbalance of the MPA. The choice of the STS1 and STS2 ground stations taken as sufficiently distant from each other therefore contribute to isolating the two antennas Tx1 and Tx2 from each other. At the ground station STS2 two cases can occur: ^ Either no signal is detected and the MPA set then calibrated, that is to say that the unbalance of the MPA is below an acceptable threshold; ^ Either a signal is detected and the spread spectrum sequence is received. The power of the received signal can be detected and measured. In this case, the knowledge of the gain of the antenna Tx2 and the knowledge of the insulation makes it possible to deduce therefrom the unbalance of the MPA. In one embodiment, several coverage areas can be reached with the Tx2 antenna. The received power measurements can then be recorded at different geographical points, ie at different stations. The results can then be consolidated by comparing the powers received in different earth stations. This makes it possible to validate and verify with greater certainty the unbalance levels of the MPA. The isolation between the two antennas Tx1 and Tx2 can also be improved by assigning signals of a certain polarization to the antenna Tx1 and another polarization to the antenna Tx2. It may be for example inverse or orthogonal polarizations. This solution makes it possible to minimize the powers received from the signals received at the station ST2 coming from the antenna Tx1. An advantage of this method is that it does not require any hardware modification of the satellite.
[0036] One of the major advantages of using a spread spectrum signal is that it is compatible with operational operation to perform these tests while maintaining continuity of service for telecommunication operators. Indeed, the spread spectrum sequences do not disturb the useful signals passing through the MPA. One advantage is that at the receiver of the terrestrial station STS2, the useful communications can be easily processed so as to retain only the spread spectrum received sequence. This property does not prevent the method of the invention from being compatible in a mode in which useful communications are transiting on the V2 path. In this case, the MPA processes incoming signals in the PE2 input port and routes them to the PS2 output port. Taking again, the previous example with a 20dB isolation between the two antennas at the ground stations, the value of the unbalance which is detectable at the STS2 station is 20dB. Calibration of the MPA. Different methods of the invention make it possible to measure the presence or absence of an imbalance of the MPA. When an unbalance of the 30 MPA is detected in a test procedure, a calibration value is deduced. The calibration for example of the different paths of the MPA can be performed. A calibration of a path consists for example in: introducing a phase shift of a variable phase-shifter so as to obtain a predefined phase plane between each path and; Adjusting a variable gain of an amplifier of each path of the MPA. Identical calibration of IBM input modules and OBM output can be calibrated according to the components that are concerned. s The phase and / or the amplitude of each path of the MPA can therefore be adjusted according to one or more instructions. The change of phase or amplitude of a path is likely to impact generally all channels of the MPA (link of an input port with an output port). To perform the calibration of the MPA, calibration instructions 10 in phase and / or amplitude must be transmitted to the satellite. A control station is used to generate the calibration instructions to the satellite from the power measurements taken in an STS2 station. These instructions can be addressed by means of control commands for example through the telemetry link.
[0037] The calibration instructions can be applied for each path of the MPA or the IBM input and OBM output modules. Each path can be calibrated one after the other according to an iteration of the parameters assigned to each component, including phase shifters and amplifiers.
[0038] 20 The calibration makes it possible to correct the imbalances of the MPA. The imbalance of the MPA may have been caused by the redundant use of a TWTA tube amplifier of an MPA path or a change of response time of a TWTA amplifier or the drift of some passive components of the different paths of the amplifier. MPA.
[0039] A MPA unbalance measurement test plan may be conducted to generate a calibration plan. The calibration can then be tested again according to the same process and readjusted if necessary by an iteration of the calibration procedure. The method of the invention can be applied to all MPAs including those present in broadcast satellites and including geostationary satellites. The method of the invention nevertheless applies to any type of satellite comprising an MPA.

权利要求:
Claims (24)
[0001]
REVENDICATIONS1. A method of detecting an imbalance of a multi-port amplifier (MPA) for satellite navigation (SAT), the multiport amplifier comprising a plurality of paths, each path being configurable in gain and in phase, the amplifier multiport (MPA) comprising a plurality of input ports (PE1, PE2) and a plurality of output ports (Psi, Ps2), each input port being associated with an output port to form a transmission channel called "Channel", each output port being connected to an antenna of the satellite (Txi, Tx2), characterized in that a first channel (V1) is frequency-configured in a transmission channel defining a first band useful for receiving signals from a transmitting station (STE1) on the ground and retransmitting them after amplification in the multiport amplifier (MPA) to a first terrestrial station (STS1) of a first geographical area, a second output port (Ps2) a second channel (V2) being configured to transmit via a second antenna (Tx2) to a second terrestrial station (STS2) 20 of a second geographical area, said method comprising: - a transmission of a first signal spectrum of the first transmitting station (STE1) to the first channel (V1) of the multiport amplifier (MPA), the first test signal being generated in at least the useful band of the first way (Vi); a reception by the second receiving station (STS2) configured in frequency to receive signals emitted by the second antenna (Tx2) connected to the second channel (V2) of the multiport amplifier (MPA), said signals being able to comprise a replica of the first test signal (SEI); detecting and measuring at least one received signal power (SS2) corresponding to a replica of the first test signal (SEI) having leaked at the output of the second output port (Ps2); at least one unbalance value of the MPA from the measurement of the power of the replica of the first test signal (SEI) received in the second earth station (STS2).
[0002]
2. A method of detecting an imbalance of a multiport amplifier (MPA) according to claim 1, characterized in that the MPA comprises a Butler matrix comprising: - an input module (IBM) allowing from the first signal test device (SEI) for generating a plurality of out of phase and equal amplitude components to a plurality of paths connecting the input module (IBM) to an output module (OBM); a plurality of paths each comprising at least one signal amplifier; an output module (OBM) for dividing and recomposing the out-of-phase and amplified incoming components so as to deliver: in a given output port (PE1), an amplified non-zero signal (BM (SE1)) corresponding to the first signal input (SEI) to be transmitted to the first ground station (STS1) and; o in the other ports, results of the components of the first test signal (SEI) substantially zero calibration errors close.
[0003]
A method for detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 1 to 2, characterized in that the first test signal (SEI) is a radio frequency signal modulated by a sequence of bits. encoded by a baseband PN pseudo noise sequence, the PN sequence comprising an N symbol size and a TSymbol encoding rate.
[0004]
4. The method of detecting unbalance of a multiport amplifier (MPA) according to claim 3, characterized in that the PN pseudo noise sequence is selected from a family of codes each having an orthogonality property.
[0005]
5. A method of detecting an imbalance of a multiport amplifier (MPA) according to claim 4, characterized in that the orthogonality of a sequence corresponds to the result of an autocorrelation of two same sequences, one of which is shifted temporally with the other of at least the duration of a symbol, the result of the autocorrelation having a substantially obtained level in the noise level.
[0006]
6. A method of detecting an imbalance of a multiport amplifier (MPA) according to claim 5, characterized in that the length N of the pseudo noise sequence PN is calculated so as to obtain an encoding gain (PG). greater than a minimum threshold, the encoding gain (PG) being defined by the ratio between the encoding rate of a symbol (Tsymbol) of a pseudo noise sequence PN and the coding rate (Tbit) of a data bit of a sequence of data bits.
[0007]
7. A method of detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 3 to 6, characterized in that the peak of the autocorrelation of a pseudo noise sequence is of value standardized of 1 and that outside the correlation peak the value of the autocorrelation function is of the order of 1 / N.
[0008]
8. A method for detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 3 to 7, characterized in that the PN pseudo noise sequence is chosen from the following list: {a type code Gold codes, a code of type "Maximum Lengh Sequences", a code of type Walsh-Hadamard codes}.
[0009]
9. A method for detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 1 to 8, characterized in that a first isolation threshold value between the first antenna (Txi) of the first channel (V1) and the second antenna (Tx2) of the second channel (V2) is satisfied so that the received power of the signals of the first antenna (Tx1) at the second reception station (STS2) is considered negligible vis-à-vis the power of the signals received by the second receiving station (STS2) (STS2) from the second antenna (Tx2).
[0010]
10. A method of detecting an imbalance of a multiport amplifier (MPA) according to claim 9, characterized in that the power difference between the signals received by the second station (STS2) from the first antenna (Tx1) ) and the signals received by the second station (STS2) from the second antenna (Tx2) is greater than a predefined threshold.
[0011]
11. A method for detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 9 to 10, characterized in that the first isolation threshold value is defined by comparing the powers received in a receiver of the second station (STS2) between the signals coming from the first antenna (Tx1) and the second antenna (Tx2).
[0012]
12. A method for detecting an imbalance of a multiport amplifier (MPA) according to any one of the preceding claims, characterized in that the signals (SS1, SS2) output from at least two antennas (Tx1, Tx2). MPA are polarized with different polarizations so as to introduce between the two corresponding antennas additional insulation.
[0013]
13. A method of detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 1 to 8, characterized in that: a delay at the output of one of the channels (V1, V2) the MPA is introduced so as to delay the output signals of the output port (Psi, Ps2) of the corresponding channel (V1, V2); a single terrestrial station (STS1, STS2) makes it possible to receive the signals at the output of each output port (Psi, Ps2), the orientation of the first and second antennas (Txi, Tx2) allowing the reception of the signals ( SS1, SS2) of the first and second channels (V1, V2) at the land station (STS1, STS2).
[0014]
A method for detecting unbalance of a multiport amplifier (MPA) according to claim 13, characterized in that the duration of the delay generated on the transmitted signals is greater than a minimum duration corresponding to the period of a symbol ( Dsymbol) of the PN sequence of the first test signal (SEI).
[0015]
15. A method for detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 13 to 14, characterized in that the delay is introduced by a retarder (22) at the output of one of the channels ( Vi, V2) of the MPA.
[0016]
16. The method of detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 13 to 15, characterized in that the retarder is a delay line whose length is sized to introduce a desired delay.
[0017]
17. A method for detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 13 to 16, characterized in that one of the channels (Vi, V2) of the MPA is connected to an antenna of telemetry or horn antenna and that at least one retarder is arranged between the channel and the telemetry or horn antenna.
[0018]
18. A method for detecting an unbalance of a multiport amplifier (MPA) according to any one of claims 13 to 14, characterized in that a delay is generated by means of a configuration of a training network. beams coupled with the output ports of the MPA so as to assign for each output port signals having a predefined phase shift.
[0019]
19. A method of detecting an imbalance of a multiport amplifier (MPA) according to any one of claims 13 to 18, characterized in that the receiver of the first terrestrial station (STS1, STS2) performs a autocorrelation function of the signals received from each of the channels (SS1, SS2) over a predefined time window so as to discriminate the presence of each of the PN sequences in reception, the discrimination of the two sequences resulting from an isolation obtained thanks to the delay injected into one of the satellite channels.
[0020]
20. A method of detecting unbalance of a multiport amplifier (MPA) according to any one of the preceding claims, characterized in that the first test signal (SEI) is transmitted on a channel (V1) in the same band. frequency than useful telecommunications signals.
[0021]
21. A method of detecting an unbalanced multi-carrier amplifier (MPA) according to any one of the preceding claims, characterized in that the steps are successively repeated between different paths of the MPA.
[0022]
22. A method for calibrating a multiport amplifier (MPA) of a satellite (SAT), characterized in that it comprises: a measurement of a power level of the replica of the first test signal on a receiver of a terrestrial station (STS2) by the method of detecting a multiport amplifier (MPA) unbalance according to any one of claims 1 to 21; a generation of at least one calibration setpoint deduced from the signal power measurements comprising the replica of the first test signal (SEI); a transmission of said at least one calibration setpoint to the satellite.
[0023]
23. A method for calibrating a multiport amplifier (MPA) of a satellite (SAT) according to claim 22, characterized in that the at least one calibration setpoint comprises at least one phase shift setpoint and / or a setpoint. of gain.
[0024]
24. A method for calibrating a multiport amplifier (MPA) of a satellite (SAT) according to claim 23, characterized in that the receiver of the receiving station (STS2), measuring the power of a signal (SS2) corresponding to a replica of the first test signal at the output of a second channel (V2), transmits to a control station the power data collected so that the control station transmits a control signal to the satellite (SAT) aimed at reconfigure the MPA with the generated gain and / or phase shift instructions.

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同族专利:

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公开号 | 公开日

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US20150256134A1|2015-09-10|

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EP2916470A1|2015-09-09|

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US9641135B2|2017-05-02|

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EP2916470B1|2016-11-02|

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ES2613520T3|2017-05-24|

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FR3018407B1|2016-04-01|

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CA2884055A1|2015-09-04|

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PL2916470T3|2017-06-30|

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法律状态:
2015-03-19| PLFP| Fee payment|Year of fee payment: 2 |

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优先权:

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申请号 | 申请日 | 专利标题

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FR1451739A|FR3018407B1|2014-03-04|2014-03-04|METHOD FOR DETECTING AN UN BALANCING AND CALIBRATION OF A MULTIPORT AMPLIFIER OF A TELECOMMUNICATIONS SATELLITE.|FR1451739A| FR3018407B1|2014-03-04|2014-03-04|METHOD FOR DETECTING AN UN BALANCING AND CALIBRATION OF A MULTIPORT AMPLIFIER OF A TELECOMMUNICATIONS SATELLITE.|

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ES15157474.6T| ES2613520T3|2014-03-04|2015-03-03|Procedure for detecting an imbalance and calibration of a multi-port amplifier of a telecommunications satellite|

---

EP15157474.6A| EP2916470B1|2014-03-04|2015-03-03|Method for detecting an imbalance and for calibrating a multiport amplifier of a telecommunications satellite|

---

PL15157474T| PL2916470T3|2014-03-04|2015-03-03|Method for detecting an imbalance and for calibrating a multiport amplifier of a telecommunications satellite|

---

CA2884055A| CA2884055A1|2014-03-04|2015-03-04|Process used for the detection of imbalances and the calibration of a multiport amplifier for a telecommunications satellite|

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US14/638,276| US9641135B2|2014-03-04|2015-03-04|Method for detecting an unbalance and for calibrating a multi-port amplifier of a telecommunications satellite|