SYSTEM AND METHOD FOR MANAGING THE OPERATION OF A TRAVELLING WAVE TUBE AMPLIFIER

Abstract

A satellite system includes a radio frequency signal amplifier device comprising a control and supply module and a plurality of travelling wave tubes. The module is configured to apply to at least one of the tubes an anode voltage operating value, generating a cathode current in response. The module is moreover configured to measure at least one sum of the cathode currents that is associated with the plurality of tubes, the at least one measurement of the sum of the cathode currents being implemented on the basis of a single measuring circuit, and to determine at least one corrected anode voltage operating value, associated with the at least one of the tubes, on the basis of the at least one measurement of the sum of the cathode currents.

Claims

1. A satellite system comprising a radio frequency signal amplifier device, the amplifier device comprising a control and supply module and a plurality N of travelling wave tubes, the control and supply module being configured to apply, for at least one of said tubes, an anode voltage operating value Va0.sub.n, the tube generating a cathode current Ik in response to application of said anode voltage operating value Va0.sub.n, wherein the control and supply module is configured to measure at least one sum of the cathode currents M?Ik that is associated with said plurality N of travelling wave tubes, said at least one measurement of the sum of the cathode currents being implemented on the basis of a single measuring circuit, the control and supply module being configured to determine at least one corrected anode voltage operating value associated with said at least one of said tubes on the basis of said at least one measurement of the sum of the cathode currents, the control and supply module being moreover configured to apply said at least one associated corrected anode voltage operating value to said at least one of said tubes.

2. The system according to claim 1, wherein each tube is associated with a given operating point PF.sub.n associated with a cathode current setpoint value CIk.sub.n and an anode voltage setpoint value CVa0.sub.n, the control and supply module being configured to apply said anode voltage setpoint value (CVa0.sub.n) to each tube, and wherein the control and supply module is configured to activate a correction mode and to perform, during said correction mode: a single measurement of the sum of the cathode currents (M?Ik) that is associated with said plurality N of travelling wave tubes at the operating points (PF.sub.n), for each tube, a determination of a corrected anode voltage value DVa0.sub.n on the basis of said single measured sum of the cathode currents M?Ik, said cathode current setpoint value CIk.sub.n and said anode voltage setpoint value CVa0.sub.n, the control and supply module being moreover configured to apply, during said correction mode, said associated corrected anode voltage value DVa0.sub.n to each tube.

3. The system according to claim 2, wherein the determination, for each tube, of said corrected anode voltage value DVa0.sub.n is performed on the basis of an estimated perveance value DG.sub.n and said cathode current setpoint value CIk.sub.n, said corrected anode voltage value DVa0.sub.n being defined by: $\mathrm{DVa}{0}_n={\left(\frac{{\mathrm{CIK}}_n}{{\mathrm{DG}}_n}\right)}^{+2/3}.$

4. The system according to claim 2, wherein the determination, for each tube, of said corrected anode voltage value DVa0.sub.n of the travelling wave tube is performed on the basis of a derivative formula for the cathode current with respect to the anode voltage of the tube at the operating point PF.sub.n.

5. The system according to claim 2, wherein the control and supply module is configured to moreover perform, during said correction mode, a determination of a drift ratio Q?IK on the basis of said single measured sum of the cathode currents M?Ik and a sum of said cathode current setpoint values CIk.sub.n of said plurality N of tubes.

6. The system according to claim 2, wherein application, during said correction mode, of the corrected anode voltage value DVa0.sub.n to the tube is performed in response to a detection of a performance drift of at least one tube from said plurality N of travelling wave tubes.

7. The system according to claim 6, wherein the control and supply module comprises a data set comprising the stored operating points PF.sub.n, and wherein said performance drift is determined on the basis of a comparison of at least one estimated perveance value DG.sub.n with a perveance setpoint value CG.sub.n included in said data set.

8. The system according to claim 5, wherein the control and supply module comprises a data set comprising the PF.sub.n stored operating points, and wherein said performance drift is determined on the basis of a comparison of the drift ratio Q?IK with a drift threshold included in said data set.

9. The system according to claim 6, wherein said performance drift is determined on the basis of a comparison, for at least one of said tubes, of said corrected anode voltage value DVa0.sub.n with said associated anode voltage setpoint value CVa0.sub.n.

10. The system according to claim 2, wherein the control and supply module comprises an internal clock and wherein the correction mode is activated in response to a detection of a predefined time stamp.

11. The system according to claim 2, wherein the control and supply module comprises an internal clock and a data set comprising the stored operating points PF.sub.n, the control and supply module being configured to store in a calibration table and to associate a time stamp with said corrected anode voltage value DVa0.sub.n and/or said estimated perveance value DG.sub.n, and to store, each time the correction mode is activated, said corrected anode voltage value DVa0.sub.n and/or said estimated perveance value DG.sub.n in said data set, and wherein the control and supply module is moreover configured to calculate, for at least one tube from said plurality N of travelling wave tubes, a trend curve on the basis of said data set, and to estimate at least one predicted anode voltage value PVa0.sub.n and/or a predicted perveance value PG.sub.n, associated with a predefined subsequent time stamp value.

12. The system according to claim 1, wherein each tube is associated with a given operating point PF.sub.n associated with an anode voltage setpoint value CVa0.sub.n and a cathode current setpoint value CIk.sub.n, and wherein the control and supply module is configured to activate a calibration mode and to perform, during said calibration mode: for a single tube from said plurality N of travelling wave tubes, an application of a first anode voltage value to the tube, a first measurement of the sum of the calibration cathode currents M?Ik.sup.1 that is associated with said plurality N of travelling wave tubes, for said single tube, an application of a given second anode voltage value BVa0.sub.n to the tube, a second measurement of the sum of the calibration cathode currents M?Ik.sup.2 that is associated with said plurality N of travelling wave tubes, a comparison of said first and second measurements of the sum of the calibration cathode currents M?Ik.sup.1 and M?Ik.sup.2; the control and supply module being moreover configured to perform an update of said anode voltage setpoint value CVa0.sub.n on the basis of said given second anode voltage value BVa0.sub.n and according to said comparison.

13. The system according to claim 12, wherein said first anode voltage value is an anode voltage reference value RVa0.sub.n associated with a cathode current reference value RIk.sub.n, and wherein, for said single tube, said comparison is moreover performed on the basis of a calibration accuracy setpoint ?, said cathode current setpoint value CIk.sub.n and said cathode current reference value RIk.sub.n, such that
|M?Ik.sup.2?M?Ik.sup.1?CIk.sub.n+RIk.sub.n|<?.

14. The system according to claim 12, wherein the calibration mode is activated in response to detection of a performance drift.

15. A method for controlling and supplying power to a plurality of N travelling wave tubes, the method being implemented in a satellite system comprising said travelling wave tubes, the method comprising an initial step of applying an anode voltage operating value Va0.sub.n to at least one of said tubes, the tube generating a cathode current Ik in response to application of said anode voltage operating value Va0.sub.n, wherein the method comprises the steps of: measuring at least one sum of the cathode currents that is associated with said plurality N of travelling wave tubes, said at least one measurement of the sum of the cathode currents being implemented on the basis of a single measuring circuit, determining at least one corrected anode voltage operating value associated with said at least one of said tubes on the basis of said at least one measurement of the sum of the cathode currents, applying said at least one associated corrected anode voltage operating value to said at least one of said tubes.

Description

DESCRIPTION OF THE DRAWINGS

[0042] Other features, details and advantages of the invention will become apparent on reading the description provided with reference to the appended drawings, which are given by way of example.

[0043] FIG. 1 is a diagram showing a travelling wave tube according to the prior art.

[0044] FIG. 2 is a diagram showing a radio frequency signal amplifier according to embodiments of the invention.

[0045] FIG. 3 is a graph showing the evolution of the anode voltage to be applied as a function of a drift ratio, according to embodiments of the invention.

[0046] FIG. 4 is a flowchart showing steps of the method for managing the operation of travelling wave tubes, according to embodiments of the invention.

[0047] FIG. 5 is a flowchart showing steps of the method for managing the operation of travelling wave tubes, according to embodiments of the invention.

[0048] Identical references are used in the figures to denote identical or similar elements. For the sake of clarity, the elements that are shown are not to scale.

DETAILED DESCRIPTION

[0049] FIG. 2 diagrammatically shows a device 100 comprising a plurality of N travelling wave tubes 1020-n and a control and supply module 1040, according to embodiments of the invention.

[0050] The index n is used to designate the nth tube among the various travelling wave tubes, and is thus between 1 and N. The number N is greater than 1. For example and without limitation, the number N may be equal to 4 or to 8.

[0051] The device 100 is a travelling wave tube amplifier, also called a TWTA. In an example of application of the invention to the satellite field, the device 100 may be aboard a satellite system 10 and used to generate and transmit high-power radio frequency signals towards the ground, for example a telecommunication satellite.

[0052] The radio frequency signal amplifier device 100 may deliver a few hundred watts, for example, and operate at high frequency (or microwave frequency). In particular, the amplifier device 100 may reach frequencies up to the W band of 100 GHz, for example.

[0053] A travelling wave tube 1020-n, also called a TWT, is an elongated vacuum tube used in the device 100 to produce low-, medium- or high-power microwave amplifiers.

[0054] In a number of embodiments, the device 100 may be a TWTA having multiple TWTs. In these embodiments, one or more travelling wave tubes 1020-n may comprise a housing incorporating M travelling wave tubes (not shown in the figures).

[0055] The device 100 moreover comprises one or more high-voltage cables 1060-n connecting one or more tubes 1020-n to the control and supply module 1040. A high-voltage cable can be used to supply high voltage to at least one travelling wave tube. The control and supply module 1040 comprises a high-voltage power supply or an electronic power conditioner, called an EPC, configured to transform a low-voltage supply voltage into multiple high voltages used to supply power to the N travelling wave tubes 1020-n. The control and supply module 1040 may comprise one or more DC-DC power converters supplied with energy by a power bus (or primary bus) 202 connected to an electrical supply source 200 of the satellite 10.

[0056] Each tube 1020-n is associated with one or more specific and/or optimum operating points denoted PF.sub.nj. The index j is used to designate a j-th operating point of a travelling wave tube 1020-n among the various operating points of the tube 1020-n, and is thus between 1 and J, J being greater than or equal to 1. Each specific and/or optimum operating point PF.sub.nj of a travelling wave tube 1020-n is associated with a cathode current setpoint value (denoted CIk.sub.n), and with an anode voltage setpoint value (also called anode zero voltage setpoint value and denoted CVa0.sub.n). The remainder of the description will be provided with reference to a value of J equal to 1, an operating point of a travelling wave tube 1020-n then being denoted PF.sub.n.

[0057] The control and supply module 1040 is configured to apply an anode current setpoint value CVa0.sub.n, to each tube 1020-n.

[0058] For a travelling wave tube 1020-n, in response to application of the anode voltage setpoint value CVa0.sub.n, the cathode 1022 generates an electron beam 1024 characterized by a specific cathode current value, denoted Ik.sub.n.

[0059] In a number of embodiments, the operating points PF.sub.n (or PF.sub.nj) and the associated specific cathode current values and the associated anode voltage setpoint values may be stored in a data set, for example in a storage unit 1042 internal to the control and supply module 1040 and/or in a unit 300 external to the amplifier device 100. The external unit 300 may be, for example, programming equipment or the on-board computer, denoted OBC, of the satellite 10. The remainder of the description will be provided with reference to a data set shown in the form of a calibration table, by way of non-limiting example. The external unit 300 may also receive instructions from a ground centre.

[0060] As illustrated in FIG. 2, the control and supply module 1040 comprises a measuring unit 1044 configured to measure the value of the sum of the specific cathode current values Ik.sub.n associated with all N travelling wave tubes 1020-n of the radio frequency signal amplifier device 100. This value is hereinafter also called the sum of the cathode currents and denoted M?Ik.

[0061] It should be noted that, for one or more tubes 1020-n, the specific value Ik.sub.n of the cathode current, generated in response to application of the anode voltage setpoint value CVa0.sub.n, may be different from the cathode current setpoint value, denoted CIk.sub.n, associated with this anode voltage setpoint value CVa0.sub.n. A difference between the specific value Ik.sub.n of the generated cathode current and the cathode current setpoint value CIk.sub.n results from a variation in emissivity of the cathode 1022.

[0062] Thus, to maintain the performance of each of the travelling wave tubes 1020-n of the satellite 10, the control and supply module 1040 may be configured to activate a correction mode and to perform, during the correction mode:

[0063] a measurement of the sum of the cathode currents M?Ik, and

[0064] for each tube 1020-n, a determination of a corrected anode voltage value (also called corrected anode zero voltage value), denoted DVa0.sub.n.

[0065] The control and supply module 1040 is moreover configured to apply, during the correction mode and to each tube 1020-n, the corrected anode voltage value DVa0.sub.n.

[0066] The corrected anode voltage value DVa0.sub.n may be estimated, for example via a determination unit 1046 internal to the control and supply module 1040, on the basis of the measured sum M?Ik of the cathode currents, the cathode current setpoint value CIk.sub.n and the anode voltage setpoint value CVa0.sub.n.

[0067] In a first variant of the invention, the corrected anode voltage value DVa0.sub.n may be determined using a formula for defining the perveance G.sub.n of a travelling wave tube 1020-n according to the cathode current and the anode voltage. The formula for the perveance G.sub.n may be defined using the following equation (01):

[00002]$\begin{array}{cc}{G}_n=\frac{{\mathrm{Ik}}_n}{{\left(\mathrm{Va}{0}_n\right)}^{3/2}}& \left(01\right)\end{array}$

[0068] It should be noted that the perveance G.sub.n of a travelling wave tube 1020-n is specific to this tube 1020-n and is an image of the emissivity of the cathode. Thus, the perveance G.sub.n of the travelling wave tube 1020-n varies with the life of the tube 1020-n and may be associated with the specific and/or optimum operating points of the tube 1020-n.

[0069] In a number of embodiments, the determination unit 1046 may be configured to estimate, for each tube 1020-n, the corrected anode voltage value DVa0.sub.n on the basis of a perveance value, denoted DG.sub.n, estimated according to the cathode current setpoint value CIk.sub.n of the tube 1020-n, as defined by the following equation (02):

[00003]$\begin{array}{cc}\mathrm{DVa}{0}_n={\left(\frac{{\mathrm{CIK}}_n}{{\mathrm{DG}}_n}\right)}^{+2/3}& \left(02\right)\end{array}$

[0070] In addition, the estimated perveance value DG.sub.n of a tube 1020-n may be estimated on the basis of an estimated cathode current value, denoted DIK.sub.n, and the anode voltage setpoint value CVa0.sub.n, as defined by the following equation (03):

[00004]$\begin{array}{cc}{\mathrm{DG}}_n=\frac{{\mathrm{DIK}}_n}{{\left(\mathrm{CVa}{0}_n\right)}^{3/2}}& \left(03\right)\end{array}$

[0071] The estimated cathode current value DIK.sub.n is in particular estimated on the basis of the measured sum M?IK of the cathode currents.

[0072] In a number of embodiments, the estimated cathode current value DIK.sub.n of the tube 1020-n may be defined on the basis of the cathode current setpoint value CIk.sub.n and a drift ratio, denoted Q?IK, as defined by the following equation (04):

DIK.sub.n=CIK.sub.n?Q?IK (04)

[0073] In equation (04), the drift ratio Q?IK may be defined as the ratio of the measured sum M?IK of the cathode currents to a sum ?.sub.n CIK.sub.n of the cathode current setpoint values CIk.sub.n on all tubes 1020-n. Thus, the drift ratio Q?IK may be expressed using the following equation (05):

[00005]$\begin{array}{cc}Q?\mathrm{IK}=\frac{M?\mathrm{IK}}{{?}_n{\mathrm{CIK}}_n}& \left(05\right)\end{array}$

[0074] The expression of the corrected anode voltage value DVa0.sub.n to be applied for each tube 1020-n may thus be simplified by combining the previous equations (02), (03), (04) and (05). In particular, the expression of the corrected anode voltage value DVa0.sub.n may be simplified using the following equations (06) or (07):

[00006]$\begin{array}{cc}\mathrm{DVa}{0}_n=\mathrm{CVa}{0}_n?{\left(\frac{1}{Q?\mathrm{IK}}\right)}^{+2/3}& \left(06\right)\\ \mathrm{DVa}{0}_n=\mathrm{CVa}{0}_n?{\left(\frac{{?}_n{\mathrm{CIK}}_n}{M?\mathrm{IK}}\right)}^{+2/3}& \left(07\right)\end{array}$

[0075] In a second variant of the invention, the corrected anode voltage value DVa0.sub.n may be obtained by using a derivative formula for the cathode current with respect to the anode voltage of the tube 1020-n at the operating point PF.sub.n. In particular, the corrected anode voltage value DVa0.sub.n may be obtained on the basis of the following equation (08):

[00007]$\begin{array}{cc}\mathrm{DVa}{0}_n=\mathrm{CVa}{0}_n?\left(1-\frac{2}{3}?\left(Q?\mathrm{IK}-1\right)\right)& \left(08\right)\\ \mathrm{DVa}{0}_n=\mathrm{CVa}{0}_n?\left(1+\frac{2}{3}?\left(1-\frac{M?\mathrm{IK}}{{?}_n{\mathrm{CIK}}_n}\right)\right)& \left(09\right)\end{array}$

[0076] According to equations (07) and (09), the corrected anode voltage value DVa0.sub.n is estimated on the basis of the measured sum M?Ik of the cathode currents, the cathode current setpoint value CIk.sub.n and the anode voltage setpoint value CVa0.sub.n.

[0077] FIG. 3 is a graph showing the evolution of the corrected anode voltage value DVa0.sub.n to be applied as a function of the drift ratio Q?IK, obtained on the basis of equations (06) and (08), according to the first and second variants of the invention. As illustrated in FIG. 3, the two variants of the invention are equivalent for a drift ratio Q?IK very close to 1, and up to 0.6% for an error of ?10% between the measured sum M?IK of the cathode currents and the sum ?.sub.n CIK.sub.n of the cathode current setpoint values on all tubes 1020-n.

[0078] Advantageously, the determination unit 1046 may be configured to estimate, for each tube 1020-n, the estimated perveance value DG.sub.n the estimated cathode current value DIK.sub.n and/or the drift ratio Q?IK.

[0079] Moreover, the storage unit 1042 may be configured to store the corrected anode voltage value DVa0.sub.n, and also the estimated perveance value DG.sub.n and/or the estimated cathode current value DIK.sub.n, associated with the tube 1020-n in the calibration table. The storage unit 1042 may also be configured to store the drift ratio Q?IK.

[0080] Advantageously, the control and supply module 1040 may comprise an internal clock (not shown in the figures), and the storage unit 1042 may be configured to store and associate with each of the stored values (estimated perveance value DG.sub.n, estimated cathode current value DIK.sub.n, and/or drift ratio Q?IK) a time stamp value defined by the internal clock. This time stamp value may be defined when measuring the sum of the cathode currents M?Ik in the correction mode.

[0081] In some embodiments, application of the corrected anode voltage values DVa0.sub.n may be performed in response to detection of a performance drift. For example and without limitation, a performance drift may be determined on the basis of the comparison of one or more estimated cathode current values DIK.sub.n with a predefined cathode current value threshold. A performance drift may also be determined on the basis of the comparison of the corrected anode voltage values DVa0.sub.n with the anode voltage setpoint values CVa0.sub.n, the comparison of the estimated perveance values DG.sub.n with perveance setpoint values, denoted CG.sub.n (defined using equation (01) on the basis of the anode voltage setpoint values CIk.sub.n and the cathode current setpoint values CIk.sub.n) and/or the comparison of the drift ratio Q?IK with a predefined drift threshold.

[0082] Each tube 1020-n may also be associated with a reference operating point, denoted PF.sub.n0. Each reference operating point PF.sub.n0 of a travelling wave tube 1020-n is associated with a cathode current reference value, denoted RIk.sub.n, and with an anode voltage reference value (also called anode zero voltage reference value), denoted RVa0.sub.n.

[0083] Advantageously, the control and supply module 1040 may be configured to activate a calibration mode and to perform, during the calibration mode:

[0084] for a single tube 1020-n to be calibrated, application of the anode voltage reference value RVa0n to the tube 1020-n,

[0085] a first measurement of the sum of the calibration cathode currents M?Ik.sup.1,

[0086] for this single tube 1020-n to be calibrated, application of a given anode voltage value (also called given anode zero voltage value), denoted BVa0.sub.n,

[0087] a second measurement of the sum of the calibration cathode currents M?Ik.sup.2,

[0088] a comparison of the first and second measurements of the sum of the calibration cathode currents M?Ik.sup.1 and M?Ik.sup.2, and

[0089] an update of the anode voltage setpoint value CVa0.sub.n in the calibration table on the basis of the given anode voltage value BVa0.sub.n and according to the comparison of the first and second sum measurements.

[0090] In a number of embodiments, the comparison performed during the calibration mode may moreover be defined on the basis of the cathode current setpoint value CIk.sub.n, the cathode current reference value RIk.sub.n, and a predefined calibration accuracy setpoint value, denoted ?. For example, the comparison performed during the calibration mode may be defined using the following equation (10):

|M?Ik.sup.2?M?Ik.sup.1?CIk.sub.n+RIk.sub.n|<?(10)

[0091] Thus, if equation (10) is verified, the anode voltage setpoint value CVa0.sub.n in the calibration table may be replaced by the given anode voltage value BVa0.sub.n applied to the tube 1020-n. If identity (10) is not verified, another given anode voltage value BVa0.sub.n is chosen and then applied to the tube 1020-n and the calibration mode continues, taking a new second measurement of the sum of the calibration cathode currents M?Ik.sup.2, and a new comparison of the first measurement of the sum of the calibration cathode currents M?Ik.sup.1 with the new second measurement of the sum of the calibration cathode currents M?Ik.sup.2.

[0092] The given anode voltage value BVa0.sub.n may be chosen (that is to say sought) using successive approximation methods, for example.

[0093] According to some embodiments, the control and supply module 1040 may be configured to, before the calibration mode, cut off the supply of voltage to N?1 tubes and to apply the calibration mode of a single tube 1020-n that is then supplied with power so as to generate the electron beam 1024 of the tube 1020-n. In this case, the control and supply module 1040 may be configured to perform, during the calibration mode:

[0094] for this single tube 1020-n, application of a given anode voltage value BVa0.sub.n,

[0095] a single measurement of the sum of the calibration cathode currents M?Ik.sup.0,

[0096] a comparison of the measured sum M?Ik.sup.0 of the calibration cathode currents with the cathode current setpoint value CIk.sub.n, using the following identity (11):

M?Ik.sup.0=CIk.sub.n (11),

and

[0097] an update of the anode voltage setpoint value CVa0.sub.n in the calibration table on the basis of the given anode voltage value BVa0.sub.n and according to the comparison.

[0098] Thus, if equation (11) is verified, the anode voltage setpoint value CVa0.sub.n in the calibration table may be replaced by the given anode voltage value BVa0.sub.n applied to the tube 1020-n. If identity (11) is not verified, another given anode voltage value BVa0.sub.n is chosen and then applied to the tube 1020-n and the calibration mode continues, taking a new single measurement of the sum of the calibration cathode currents M?Ik.sup.0 and a new comparison of the cathode current setpoint value CIk.sub.n with the new single measurement of the sum of the calibration cathode currents M?Ik.sup.0.

[0099] The control and supply module 1040 may be configured to repeat application of the calibration mode to one or more other operating points PF.sub.nj of the same tube 1020-n, and/or to another tube 1020-n, to multiple tubes 1020-n, or to all the tubes 1020-n of the system 10. Repeating application of the calibration mode allows a complete or partial update of the calibration table. The control and supply module 1040 may also be configured to repeat application of the calibration mode by cutting off the supply of power to the previously controlled single tube 1020-n to be calibrated and by supplying power to another single tube 1020-n to be calibrated.

[0100] In a number of embodiments, the correction mode and/or the calibration mode may be triggered following the supply of power to one or more tubes 1020-n, in response to a change of operating point of a tube and/or in response to detection of a performance drift. In other embodiments, the correction mode and/or the calibration mode may also be triggered in response to a command from the module 1040 or from the external unit 300 of the amplifier device 100. This control for triggering the correction mode and/or the calibration mode may be programmed and/or induced by a ground centre.

[0101] Advantageously, in the embodiments where the control and supply module 1040 comprises an internal clock, the correction mode and/or the calibration mode may be triggered in response to detection of a predefined time stamp (for example via a programmed trigger command), for example periodically. For example and without limitation, the correction mode may be triggered every second whereas the calibration mode may be triggered every 3 to 6 months, for a certain number of years from the launch of the satellite 10, and then annually.

[0102] Thus, the control and supply module 1040 may comprise a learning unit 1048 configured to calculate, for one or more tubes 1020-n, a trend curve, on the basis of the values stored in the calibration table and the associated time stamp values. The learning unit 1048 may thus be configured to predict (i.e. estimate), on the basis of the trend curve, using an equation adapted for the trend curve, for example, one or more predicted anode voltage values (also called predicted anode zero voltage values), denoted PVa0.sub.n and/or one or more predicted perveance values, denoted PG.sub.n, for one or more predefined time stamp values.

[0103] In these embodiments, the control and supply module 1040 may be configured to determine detection of a performance drift on the basis of the predicted anode voltage values PVa0.sub.n and/or the predicted perveance values PG.sub.n. The control and supply module 1040 may also be configured to apply the predicted anode voltage value(s) PVa0.sub.n. This embodiment has the advantage of compensating for the ageing of the tube 1020-n by reducing the number of measurements to be taken (i.e. frequency of correction modes to be activated) and the frequency of calibration modes to be activated.

[0104] Moreover, the control and supply module 1040 comprises one or more specific integrated circuits (not shown in the figures) and/or a digital circuit. For example and without limitation, a digital circuit may be any microcontroller. The various units (and the correction and control modes) may be implemented using one or more of these circuits. In particular, the measuring unit 1044 may be implemented on the basis of a single measuring circuit.

[0105] The various embodiments of the invention have the advantage of facilitating the adjustment of the operating point of the various travelling wave tubes of the satellite and thus of allowing control of the dispersion of the perveance of each of the tubes of the system due to their ageing and variations in temperature. The activation and implementation of the calibration mode have the advantage of requiring very little or no external manual intervention, and of being able to be carried out quickly, for a few hundred milliseconds or so, with limited impact on radio frequency signal traffic from the satellite 10.

[0106] Moreover, the various embodiments of the invention have the advantage of minimizing the wiring and the number of measuring circuits, and thus also reducing its cost.

[0107] FIG. 4 and FIG. 5 are flowcharts describing the method, implemented by a satellite system 10 and in particular by a modular radio frequency signal amplifier device 100, for controlling operation and the adjustment of the high-voltage power supply vis-?-vis travelling wave tubes, according to embodiments of the invention.

[0108] In step 400, the correction mode is activated while each tube 1020-n is used according to an operating point PF.sub.n.

[0109] In step 420, for each tube 1020-n, the cathode current setpoint value CIk.sub.n and the anode voltage setpoint value Va0.sub.n, which are associated with the operating point PF.sub.n, are received.

[0110] In step 440, in response to activation of the correction mode, the value of the sum of the cathode currents M?Ik of the tubes 1020-n is measured by the control and supply module 1040.

[0111] A person skilled in the art will readily understand that steps 400, 420 and 440 may be carried out simultaneously and/or in a different order, for example a given order defined by the module 1040.

[0112] In step 460, for each tube 1020-n, the corrected anode voltage value DVa0.sub.n is determined on the basis of the value of the measured sum M?Ik of the cathode currents, the cathode current setpoint value CIk.sub.n and the anode voltage setpoint value CVa0.sub.n.

[0113] In step 480, for each tube 1020-n, the corrected anode voltage value DVa0.sub.n is applied to the tube 1020-n.

[0114] In step 500, the calibration mode is activated.

[0115] In step 502, in response to activation of the calibration mode, the anode voltage reference value RVa0.sub.n is applied to a single tube 1020-n to be calibrated.

[0116] In step 504, a first value of the sum of the calibration cathode currents M?Ik.sup.1 is measured.

[0117] In step 506, a given anode voltage value BVa0.sub.n is applied to this single tube 1020-n to be calibrated.

[0118] In step 508, a second value of the sum of the calibration cathode currents M?Ik.sup.2 is measured.

[0119] In step 510, a comparison is made between the calibration accuracy setpoint ? and a function defined on the basis of the second value of the measured sum M?Ik.sup.2 of the calibration cathode currents, the first value of the measured sum M?Ik.sup.1 of the calibration cathode currents, the cathode current setpoint value CIk.sub.n and the cathode current reference value RIk.sub.n.

[0120] In step 512, an update of the calibration table is performed according to the comparison.

[0121] A person skilled in the art will understand that the system and the method according to the embodiments of the invention or sub-elements of this system may be implemented in various ways by hardware, software, or a combination of hardware and software, in particular in the form of program code that may be distributed as a program product, in various forms.

[0122] The invention is not limited to the embodiments described above by way of non-limiting example. It encompasses all variant embodiments that might be envisaged by a person skilled in the art. In particular, a person skilled in the art will understand that the invention is not limited to the various modules and units of the system and in particular to the various variants of the invention for determining the corrected anode voltage value that have been described by way of non-limiting example.