JP2005295092A - Communication system, master station and slave station communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a communication system, a master station and a slave station communication apparatus capable of correcting a frequency error in communication via a non-geostationary satellite.
In a master station, a control signal is transmitted on an outbound line with a transmission frequency in which a satellite Doppler shift amount is corrected. In a slave station communication device, a frequency shift amount of a control signal received on the outbound line is The transmission frequency of the inbound line 6 is set based on a satellite Doppler shift value, a shift amount of the satellite Doppler shift value, and an amount of correction due to an error from that of the master station at the reference frequency of the slave station communication device.
[Selection] Figure 1

Description

  The present invention relates to a communication system, a master station, and a slave station communication apparatus that correct a frequency error generated in a carrier wave in communication via a non-geostationary satellite.

  Japanese Patent Laid-Open No. 3-286628 describes a frequency error correction technique in a communication system via a conventional satellite. According to Japanese Patent Laid-Open No. 3-286628, a pilot station is provided for frequency correction, and the pilot station detects a frequency error of a carrier wave generated between the pilot station and the satellite by returning the pilot signal to the satellite, The reception frequency is shifted by the corresponding amount so that the earth station can receive without error, and the correction frequency is distributed to each earth station by the pilot signal, so that the frequency of the transmission signal is also corrected at the earth station.

JP-A-3-286628

  In the conventional technique described in Patent Document 1, a dedicated pilot station is provided for frequency correction and a pilot signal is constantly transmitted. However, a dedicated transmission facility is provided for the constant transmission of such a pilot signal. There is a problem that it becomes necessary and causes an increase in the size of communication equipment, and a dedicated frequency band is required for the pilot signal, and there is also a problem from the viewpoint of effective frequency utilization. In this conventional technology, only the frequency correction value between the pilot station and the satellite detected by the pilot station is distributed to each earth station. If the satellite is a non-stationary satellite, the Doppler accompanying the satellite movement is used. Since the shift amount varies depending on the distance between the pilot station and each earth station, there is a problem in that correction for this amount cannot be performed. Further, when the earth station moves at a high speed, a Doppler shift occurs in the carrier frequency, but there is a problem that the amount of Doppler shift cannot be corrected.

  The present invention has been made to solve the above-described problems, and is a communication system capable of correcting a frequency error in communication via a non-stationary satellite without causing an increase in the size of communication equipment. An object is to obtain a station and a slave station communication device.

  A communication system according to a first aspect of the present invention is a communication system in which a control signal is transmitted and received between a master station and a slave station communication device through an outbound line and an inbound line via a non-stationary satellite. The satellite Doppler shift value is detected by transmission / reception of the loopback, the transmission frequency of the outbound line is corrected based on the satellite Doppler shift value, the control station transmits the control signal through the outbound line, and the control signal received through the outbound line And a slave station communication device that detects a frequency shift amount and transmits a transmission signal through an inbound line at a transmission frequency corrected based on the frequency shift amount.

  According to a second aspect of the present invention, there is provided a demodulator for detecting a satellite Doppler shift value by transmission / reception by returning to a non-stationary satellite via a control signal transmitted / received to / from a slave station communication device; A modem control unit that commands the transmission frequency of the outbound line based on the satellite Doppler shift value, a transmission frequency setting unit that converts the reference signal to a carrier frequency in response to a command from the modem control unit, and a transmission frequency setting unit And a modulator that modulates a control signal using a carrier wave and transmits the modulated signal using an outbound line.

  A slave station communication device according to a third aspect of the invention comprises a demodulator that demodulates a control signal transmitted from a master station via an outbound line and detects a frequency shift amount at the time of reception, and a correction amount based on the frequency shift amount A modem control unit for correcting and instructing the transmission frequency of the inbound line based on the command, a transmission frequency setting unit for converting the reference signal into a carrier frequency in response to a command from the modem control unit, and a carrier wave from the transmission frequency setting unit And a modulator that modulates the control signal and transmits it through an inbound line.

  According to a fourth aspect of the present invention, there is provided a demodulator for detecting a satellite Doppler shift value by transmission / reception by returning to a non-stationary satellite via a control signal transmitted / received to / from a slave station communication device; A modem control unit that corrects and instructs the transmission frequency of the outbound line based on the satellite Doppler shift value, a transmission frequency setting unit that converts the reference signal to a carrier frequency according to a command from the modem control unit, and the transmission frequency setting And a modulator that modulates a control signal with a carrier wave from a unit and transmits the modulated signal through an outbound line, and the satellite Doppler shift value is placed on the control signal.

  A slave station communication device according to a fifth aspect of the invention includes a demodulator that demodulates a control signal transmitted from a master station through an outbound line, and an inbound line based on a correction amount based on a satellite Doppler shift value carried on the control signal. The modem control unit that corrects and instructs the transmission frequency of the transmitter, the transmission frequency setting unit that converts the reference signal to the carrier frequency by the command from the modem control unit, and the control signal is modulated by the carrier wave from the transmission frequency setting unit And a modulator for transmitting via an inbound line.

  A master station according to a sixth aspect of the invention is the master station according to the fourth aspect of the invention, in which a reception beam number and satellite position information are further added to the control signal.

  A slave station communication device according to a seventh aspect of the present invention is the slave station communication device according to the fifth aspect of the invention, wherein the modem control unit is configured to determine the position of the local station obtained from the received beam number included in the control signal; The amount of deviation of the satellite Doppler shift value is calculated from the satellite position information included in the control signal, and the transmission frequency of the inbound line is determined based on the correction amount obtained by adding the amount of deviation to the satellite Doppler shift value. It is corrected and commanded.

  A slave station communication device according to an eighth aspect of the invention demodulates a control signal transmitted from a master station via an outbound line and detects a frequency shift amount at the time of reception, and the demodulator is mounted on the control signal. A shift amount of the satellite Doppler shift is calculated based on the position of the local station obtained from the received beam number and the satellite position information included in the control signal, and the local station is calculated from the shift amount of the satellite Doppler shift and the frequency shift amount. And an error in the reference frequency between the master station and the inbound line based on a satellite Doppler shift value carried in the control signal, a correction amount based on the error in the reference frequency, and a shift amount in the satellite Doppler shift. Modem control unit that corrects and instructs the transmission frequency of the transmitter, and a transmission frequency setting unit that converts the reference signal to the carrier frequency by the command from the modem control unit , In which a modulator for transmitting the inbound line by modulating a control signal by a carrier wave from the transmission frequency setting unit.

  A slave station communication device according to a ninth aspect of the invention is the slave station communication device according to the third, fifth, seventh, or eighth aspect of the invention, and further between the slave side slave station communication device. A modulator that modulates a transmission signal in a communication line to be transmitted and received with a carrier wave; and a transmission frequency setting unit that generates a carrier wave input to the modulator by frequency-converting a reference signal according to a command from the modem control unit. The modem controller corrects and instructs the transmission frequency of the communication line based on the correction amount.

  A communication system according to a tenth aspect of the present invention is a communication system that transmits and receives control signals between a master station and a slave station communication device through an outbound line and an inbound line via a non-stationary satellite. A master station that detects a satellite Doppler shift value by sending and receiving by turning back, corrects the transmission frequency of the outbound line based on the satellite Doppler shift value, and transmits a control signal carrying the satellite Doppler shift value through the outbound line; The amount of frequency deviation of the control signal received through the outbound line is detected, and the transmission signal is transmitted through the inbound line with a transmission frequency corrected based on this amount of frequency deviation and the satellite Doppler shift value included in the received control signal. A slave station communication device.

  A slave station communication device according to an invention of claim 11 demodulates a control signal transmitted from a master station through an outbound line, detects a frequency shift amount at the time of reception, the frequency shift amount, A modem control unit that corrects and instructs the transmission frequency of the outbound line based on the correction amount based on the satellite Doppler shift value included in the control signal, and converts the reference signal to the carrier frequency according to the command from the modem control unit A transmission frequency setting unit and a modulator that modulates a control signal with a carrier wave from the transmission frequency setting unit and transmits the modulated control signal through an inbound line are provided.

  A slave station communication device according to a twelfth aspect of the invention is a slave station communication device according to the eleventh aspect of the invention, wherein the transmission signal on the communication line for transmission / reception with the counterpart slave station communication device is modulated by a carrier wave. And a transmission frequency setting unit that generates a carrier wave input to the modulator by frequency-converting a reference signal according to a command from the modem control unit, and the modem control unit communicates based on the correction amount. It is a command that corrects the transmission frequency of the line.

  According to the first to eighth aspects of the present invention, in the master station, the control signal is transmitted on the outbound line with the transmission frequency corrected for the satellite Doppler shift amount, and in the slave station communication device, the control signal is received on the outbound line. Because the transmission frequency of the inbound line is set based on the amount of control signal frequency deviation, satellite Doppler shift value, satellite Doppler shift value deviation amount, and correction amount due to error from the master station at the reference frequency of the slave station communication device It is possible to transmit / receive data on the outbound line and the inbound line by correcting the frequency shift of the reference signal of the slave station communication apparatus and the Doppler shift caused by the progression of the non-stationary satellite.

  According to the ninth aspect of the present invention, the slave station communication device has a frequency shift amount of the control signal received on the outbound line, a satellite Doppler shift value, a shift amount of the satellite Doppler shift value, and a master frequency at the reference frequency of the slave station communication device. Since the transmission frequency in the communication line is set based on the correction amount due to the error from that of the station, in the communication line between the slave station communication devices, the frequency shift of the reference signal of the slave station communication device or the progress of the non-stationary satellite It is possible to transmit / receive data while correcting the Doppler shift caused by the above.

  According to the invention of claim 10 or claim 11, in the master station, the control signal is transmitted on the outbound line with the transmission frequency corrected for the satellite Doppler shift amount, and in the slave station communication device, the control signal is received on the outbound line. Since the transmission frequency of the inbound line is set based on the amount of control signal frequency deviation and the amount of correction based on the satellite Doppler shift value, the Doppler shift caused by the movement of the slave station communication device and the Doppler shift caused by the movement of the non-stationary satellite are corrected. Can be transmitted and received on the outbound line and the inbound line.

  According to the twelfth aspect of the present invention, the slave station communication device sets the transmission frequency in the communication line based on the frequency shift amount of the control signal received in the outbound line and the correction amount by the satellite Doppler shift value. In a communication line between station communication devices, Doppler shift caused by movement of a slave station communication device or Doppler shift caused by the progress of a non-stationary satellite can be corrected and transmitted / received.

Embodiment 1

  A communication system, a master station, and a slave station communication apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 is a block diagram of a communication system according to Embodiment 1 of the present invention. In FIG. 1, 1 is a master station, 2 is a non-stationary satellite, 3 is a slave station communication device mounted on a vehicle or the like moving on the ground, and 4 is a slave station communication device mounted on an aircraft or the like moving at high speed in the air. It is. Reference numeral 5 denotes an outbound line for transmitting a control signal from the master station 1 to the slave station communication apparatus 3 or the slave station communication apparatus 4, and reference numeral 6 denotes the slave station communication apparatus 3 or the slave station communication apparatus 4 to the master station 1. On the other hand, an inbound line for transmitting a control signal, 7 is a communication line for communication between each slave station communication device. The non-geostationary satellite 2 represents an orbiting satellite group that orbits in a low orbit, and a quasi-zenith satellite group that provides communication by sequentially flying in the zenith direction of the master station 1 and the slave station communication devices 3 and 4. For example, the quasi-zenith satellite is composed of a group of three satellites and navigates an orbit that perturbs from north to south across the equator while revolving the earth at a speed that approximately matches the rotation of the earth. By navigating a group of satellites in such an orbit, three satellites fly in sequence over Japan (in the quasi-zenith direction) located in the northern hemisphere, so the master station 1 and the slave station communication devices 3 and 4 are generally It is possible to always communicate via a satellite located in the zenith direction.

  When a non-geostationary satellite is used as a satellite, a Doppler shift is added to the carrier frequency due to the Doppler effect accompanying the movement of the satellite in the transmission frequency on each line. The master station 1 can detect the Doppler shift amount of the carrier frequency due to the satellite movement by receiving the control signal transmitted through the outbound line 5 via the satellite 2 and transmit the signal so as to cancel the Doppler shift of the satellite. Correct the frequency. In this case, the master station 1 receives the control signal transmitted by a line other than the outbound line, detects the carrier frequency Doppler shift amount due to satellite movement, and corrects the transmission frequency so as to cancel the satellite Doppler shift. You can also

  FIG. 2 is a schematic diagram showing the geographical arrangement of the beams transmitted from the satellite in the first embodiment of the present invention. In FIG. 2, the master station 1 is located within one beam # 3 of multibeams # 1 to #N by a plurality of satellite communications from the satellite, and the slave station communication device 3 is separated from the master station 1 It is assumed that it is located within the beam #K. The coordinate table shown in FIG. 2 represents the coordinate position of the beam center corresponding to the beam number assigned to each beam. The master station 1 transmits a control signal by the out-band line 5 for each beam via the satellite, and the slave station communication device 3 receives the control signal and detects the beam number from the received signal. Recognize the approximate position coordinates of the station. When the position of the local station is known in this way, the slave station communication device 3 calculates an approximate frequency shift amount of the satellite Doppler shift value in the beam that is in the area with respect to the satellite Doppler shift value in the beam to which the master station 1 belongs. can do. By providing a coordinate table as shown in FIG. 2 in the slave station communication apparatus 3, even if the slave station communication apparatus 3 freely moves between the beams of the multi-beams # 1 to #N, the outband line 5 If the beam number information transmitted from the master station is received and detected, it is possible to know its own approximate current position and to calculate the frequency shift amount of the satellite Doppler shift value. If the coordinate table in the slave station communication device 3 is in a writable state, the coordinate table is corrected when the multi-beam is rearranged, and the current position of the multi-beam is transmitted from the master station 1 to the out-band. It is also possible to rewrite the coordinate table in the slave station communication device 3 that has been distributed via the line 5 and has received it.

  FIG. 3 is a block diagram showing the configuration of the master station according to Embodiment 1 of the present invention. In FIG. 3, 8 is a control signal input terminal, 9 is a modulator that modulates the control signal with a carrier wave, and 10 is a transmitter that transmits the outbound line 5. Reference numeral 11 is a reference frequency oscillator that oscillates a reference frequency signal in the master station 1, and 12 is a transmission frequency setting unit that converts the reference signal from the reference frequency oscillator 11 to the carrier frequency of the outbound line 5. A carrier wave output from the frequency setting unit 12 is input to the modulator 9. Reference numeral 13 denotes a receiver that receives the inbound line 6, reference numeral 14 denotes a demodulator that mixes a received signal from the receiver with a carrier wave and converts the low frequency, and reference numeral 15 denotes an output terminal of the demodulated received signal. Reference numeral 16 denotes a reception frequency setting unit that converts the reference signal from the reference frequency oscillator 11 to the carrier frequency of the inbound line 6. The carrier wave output from the reception frequency setting unit 16 is input to the demodulator 14. A modem control unit 17 calculates correction values for the transmission frequency and the reception frequency based on various values, and instructs the transmission frequency setting unit 12 and the reception frequency setting unit 16 to set the set values of the respective carriers. is there.

  FIG. 4 is a block diagram showing a configuration of the slave station communication apparatus according to Embodiment 1 of the present invention. In FIG. 4, 18 is a control signal input terminal, 19 is a modulator that modulates the control signal with a carrier wave, and 20 is a transmitter that transmits the inbound line 6. Reference numeral 21 denotes a reference frequency oscillator that oscillates a reference frequency signal in the slave station communication device 3, and 22 denotes a transmission frequency setting unit that converts the reference signal from the reference frequency oscillator 21 to the carrier frequency of the inbound line 6, The carrier wave output from the transmission frequency setting unit 22 is input to the modulator 19. Reference numeral 23 denotes a receiver that receives the outbound line 5, reference numeral 24 denotes a demodulator that mixes a received signal from the receiver 23 with a carrier wave, and converts it to a low frequency, and reference numeral 25 denotes an output terminal of the demodulated received signal. A reception frequency setting unit 26 converts the reference signal from the reference frequency oscillator 21 to the carrier frequency of the outbound line 5, and inputs the carrier wave output from the reception frequency setting unit 26 to the demodulator 24. A modem control unit 27 calculates correction values for the transmission frequency and the reception frequency based on various values, and instructs the transmission frequency setting unit 22 and the reception frequency setting unit 26 to set the set value of each carrier to be set. It is. Reference numeral 28 denotes an input terminal for a transmission signal in the communication line 7, reference numeral 29 denotes a modulator that modulates the transmission signal by a carrier wave, and reference numeral 30 denotes a transmitter that transmits the communication line 7. Reference numeral 31 denotes a transmission frequency setting unit that converts the reference signal from the reference frequency oscillator 21 to the transmission carrier frequency of the communication line 7, and the carrier wave output from the transmission frequency setting unit 31 is input to the modulator 29. 32 is a receiver that receives the communication line 7, 33 is a demodulator that mixes the received signal from the receiver 32 with a carrier wave and converts it to low frequency, and 34 is an output terminal for the demodulated received signal. Reference numeral 35 denotes a reception frequency setting unit that converts the reference signal from the reference frequency oscillator 21 to the reception carrier frequency of the communication line 7. The carrier wave output from the reception frequency setting unit 35 is input to the demodulator 33. The modem control unit 27 also calculates correction values for the transmission frequency and the reception frequency based on various values for the transmission frequency setting unit 31 and the reception frequency setting unit 35, and instructs the setting value of each carrier to be set. To do.

  Next, frequency error correction processing in the communication system, the master station, and the slave station communication apparatus according to Embodiment 1 of the present invention will be described. FIG. 5 is a schematic diagram for explaining frequency error correction processing in the communication system, the master station, and the slave station communication apparatus according to Embodiment 1 of the present invention. In FIG. 5A, the master station 1 itself receives a control signal transmitted through the outbound line 5 and detects a satellite Doppler shift Δfsat accompanying the progression of the non-stationary satellite 2. In detecting the satellite Doppler shift, the demodulator 14 detects a frequency shift of the received control signal with respect to the frequency of the outbound line commanded from the modem control unit 17 to the reception frequency setting unit 16. This frequency shift amount is a satellite Doppler shift value that accompanies the progression of the non-geostationary satellite 2, and the satellite Doppler shift value detected in this way is input to the modem control unit 17.

  In FIG. 5A, the master station 1 transmits a control signal 36 while shifting the frequency by −Δfsat from the center of the transmission channel of the outbound line 5. This is set by a command from the modem control unit 17 to the transmission frequency setting unit 12. The difference in position between the master station 1 and the slave station communication device 3 causes a shift in the satellite Doppler shift Δfsat. The slave station communication device 3 receives the control signal 37 at a frequency shifted by Δfpos from the channel center of the outbound line 5. Will do. Here, since the frequency of the reference signal generated by the reference frequency oscillator 21 in the slave station communication device 3 and the frequency of the reference signal generated by the reference frequency oscillator 11 in the master station 1 are actually different, The reception frequency of the outbound line 5 set in the reception frequency setting unit 26 in the slave station communication device 3 based on the reference signal generated by the reference frequency oscillator 21 in the communication device 3 and the frequency at the center of the transmission channel of the master station 1 If the error is Δfmt, the slave station communication device 3 detects the (Δfmt−Δfpos) value as a reception frequency deviation in the demodulator 24. In the slave station communication device 3 according to the first embodiment of the present invention, the modem control unit 27 may use the detected value (Δfmt−Δfpos) as the correction amount.

  The master station 1 puts the reception beam number, satellite position information, and satellite Doppler shift Δfsat on the control signal and transmits it via the outbound line. The slave station communication device 3 receives these received beams from the received signal received on the outbound line 5. The number, satellite position information, and satellite Doppler shift Δfsat are detected. The modem control unit 27 of the slave station communication device 3 reads the approximate position of the own station from the detected reception beam number from the coordinate table shown in FIG. 2, and calculates Δfpos from this position and satellite position information. The modem control unit 27 of the slave station communication device 3 calculates Δfmt from the Δfpos value and the (Δfmt−Δfpos) value detected as described above. In the slave station communication device 3 according to Embodiment 1 of the present invention, the modem control unit 27 may use the detected Δfsat as a correction amount, or may use the (Δfsat + Δfpos) value as a correction amount. .

  In FIG. 5B, the modem control unit 27 of the slave station communication device 3 uses the detected and calculated correction amounts by Δfsat, Δfpos, Δfmt, and Δf′sat, Δf′pos, Δf, which are transmission band errors. The transmission frequency of the inbound line 6 converted into 'mt and corrected by these is instructed to the transmission frequency setting unit 22, and the transmission signal 38 is transmitted. The transmission signal 38 passes through the satellite 2, and the master station 1 can receive the transmission signal 39 at the channel center of the inbound line 6. As shown in the above description, the (Δfmt−Δfpos) value, Δfsat value, and (Δfsat + Δfpos) value may be used as correction amounts. Similarly, based on these correction amounts, an error in the transmission band may occur. It can be converted into a certain Δf′sat, Δf′pos, Δf′mt, and the transmission frequency of the inbound line 6 corrected by these is instructed to the transmission frequency setting unit 22, and the transmission signal 38 can be transmitted. Can receive the transmission signal 39 near the center of the channel of the inbound line 6. Further, the modem control unit 27 of the slave station communication device 3 corrects the transmission frequency on the inbound line 6 by Δf′pos and Δf′mt, instructs the transmission frequency setting unit 22, and transmits the transmission signal 40. May be. At this time, the transmission signal 40 passes through the satellite 2, and the master station 1 receives the transmission signal 41, but the modem control unit 17 of the master station 1 has already detected the satellite Doppler shift Δf'sat, and the inbound line It is also possible to receive six received channels after correcting them by Δf′sat.

  In FIG. 5 (b), the slave station communication device 3 can perform the same correction when transmitting to the other party slave station communication device 3 (or 4) through the communication line 7. That is, the modem control unit 27 in the transmission side slave station communication device 3 transmits the corrected frequency of Δf′sat, Δf′pos, Δf′mt from the center of the transmission channel (communication line 7) of the slave station communication device. Thus, the transmission frequency setting unit 31 is instructed to transmit a transmission signal 38, and the counterpart slave station communication device 3 on the receiving side receives the transmission signal 39 via the satellite 2. Similarly to the above, the modem control unit 27 of the transmitting-side slave station communication device 3 may use the (Δfmt−Δfpos) value, the Δfsat value, and the (Δfsat + Δfpos) value as the correction amounts. Based on this, it is converted into Δf′sat, Δf′pos, Δf′mt which are errors in the transmission band, and the transmission frequency of the inbound line 6 corrected by these is instructed to the transmission frequency setting unit 22, and the transmission signal 38 is transmitted. You can also However, Δf′pos calculated in the modem control unit 27 in the transmitting-side slave station communication device 3 is a correction amount of the satellite Doppler shift caused by the position between the slave station communication device 3 and the master station 1. As a result, a satellite Doppler shift shift corresponding to the position with the counterpart slave station communication device 3 has occurred, and the transmission signal 39 is received at the offset frequency position by the counterpart slave station communication device 3. The Actually, the channel center position shift of the communication line 7 of the partner side slave station communication device 3 (the offset due to the frequency shift of the reference frequency signal generated by the reference frequency oscillator of the partner side slave station communication device 3). ) Is added, the counterpart side slave station communication device 3 receives the communication line.

  If the position of the receiving side slave station communication device 3 is transmitted by the control signal of the outbound line 5 from the master station and the location can be detected in the transmitting side slave station communication device 3, In the modem control unit 27 of the slave station device 3, Δf′pos can be calculated based on the satellite Doppler shift amount calculated based on the relationship between the position of the local station and the partner station and the satellite position, and the transmission signal can be corrected.

  As described above, in the communication system, the master station, and the slave station communication apparatus according to Embodiment 1 of the present invention, the positional relationship between the master station and the slave station communication apparatus and the slave station communication apparatus Since the correction is performed based on the positional relationship between them, it is possible to correct the frequency deviation more accurately and perform communication on the inbound line, the outbound line, and the communication line.

Embodiment 2

  A communication system, a master station, and a slave station communication apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. Although the block configurations of the master station and slave station communication apparatuses according to Embodiment 2 of the present invention are the same as those shown in FIGS. 3 and 4, it is assumed that the processing described below can be performed. FIG. 6 is a schematic diagram illustrating frequency error correction processing in the communication system, the master station, and the slave station communication apparatus according to Embodiment 2 of the present invention. When the communication system, the master station, and the slave station communication device in the second embodiment are moving at high speed like the slave station communication device 4, the Doppler shift accompanying the high speed movement is corrected with the satellite 2. The process is performed.

  In FIG. 6A, the master station 1 itself receives the control signal transmitted through the outbound line 5 and detects the satellite Doppler shift Δfsat accompanying the progress of the non-stationary satellite 2. In the detection of the satellite Doppler shift, the demodulator 14 detects the frequency shift of the received control signal with respect to the frequency of the outbound line 6 instructed from the modem control unit 17 to the reception frequency setting unit 16, and the detected satellite Doppler shift is detected. The value is input to the modem control unit 17.

  In FIG. 6A, the master station 1 transmits a control signal 42 while shifting the frequency by −Δfsat from the center of the transmission channel of the outbound line 5. This is set by a command from the modem control unit 17 to the transmission frequency setting unit 12. The control signal 42 is received by the slave station communication device 4 via the satellite 2. The frequency shift of the control signal 43 received by the slave station communication device 4 is the difference Δfpos caused in the satellite Doppler shift Δfsat due to the difference in position between the master station 1 and the slave station communication device 4, and the high speed movement of the slave station communication device 4 Δfdpl generated with the satellite 2 due to the above. That is, the slave station communication device 4 receives the control signal 43 at a frequency shifted by (Δfpos + Δfdpl) from the channel center of the outbound line 5, and the demodulator 24 detects this (Δfpos + Δfdpl) value as a reception frequency deviation. . Here, it is assumed that the reference frequency oscillator 21 included in the slave station communication device 4 is of high accuracy and the frequency deviation of the generated reference signal is small. At this time, Δfmt considered in the first embodiment need not be considered.

  The master station 1 puts the reception beam number, satellite position information, and satellite Doppler shift Δfsat on the control signal and transmits them via the outbound line. The slave station communication device 4 receives these received beams from the received signal received on the outbound line 5. The number, satellite position information, and satellite Doppler shift Δfsat are detected. The modem control unit 27 of the slave station communication device 4 reads the approximate position of the own station from the detected reception beam number from the coordinate table shown in FIG. 2, and calculates Δfpos from this position and satellite position information. The modem control unit 27 of the slave station communication device 4 calculates Δfdpl from the Δfpos value and the value detected as described above (Δfpos + Δfdpl).

  In FIG. 6B, the modem control unit 27 of the slave station communication device 4 uses the detected and calculated Δfsat, Δfpos, Δfdpl correction amounts Δf′sat, Δf′pos, Δf ′ as transmission band errors. The transmission frequency of the inbound line 6 converted to dpl and corrected by these correction amounts is instructed to the transmission frequency setting unit 22, and the transmission signal 44 is transmitted. The transmission signal 44 passes through the satellite 2, and the master station 1 can receive the transmission signal 45 at the channel center of the inbound line 6. The modem control unit 27 of the slave station communication device 4 corrects the transmission frequency on the inbound line 6 with Δf′pos and Δf′dpl and instructs the transmission frequency setting unit 22 to transmit the transmission signal 46. Also good. At this time, the transmission signal 46 passes through the satellite 2, and the master station 1 receives the transmission signal 47, but the modem control unit 17 of the master station 1 has already detected the satellite Doppler shift Δf'sat, and the inbound line It is also possible to receive six received channels after correcting them by Δf′sat.

  In FIG. 6B, the same correction can be performed when the slave station communication device 4 transmits data to the partner slave station communication device 4 (or 3) via the communication line 7. That is, the modem control unit 27 in the transmission side slave station communication device 4 transmits from the center of the transmission channel (communication line 7) of the slave station communication device at a frequency corrected by Δf′sat, Δf′pos, Δf′dpl. The transmission frequency setting unit 31 is instructed to transmit the transmission signal 44, and the receiving side slave station communication device 4 receives the transmission signal 45 via the satellite 2. However, Δf′pos calculated by the modem control unit 27 in the transmitting-side slave station communication device 4 is a correction amount of the satellite Doppler shift caused by the position between the slave station communication device 4 and the master station 1. As a result, a satellite Doppler shift shift corresponding to the position with the counterpart slave station communication device 4 has occurred, and the transmission signal 45 is received at the offset frequency position by the counterpart slave station communication device 4. The Actually, the channel center position shift of the communication line 7 of the partner side slave station communication device 3 (the offset due to the frequency shift of the reference frequency signal generated by the reference frequency oscillator of the partner side slave station communication device 3). ) Is added, the counterpart side slave station communication device 3 receives the communication line. When the other party is the slave station communication device 4, the accuracy of the reference frequency oscillator 21 in the slave station communication device 4 is high, and the shift of the channel center position of the communication line 7 can be almost ignored. However, when the other party is the slave station communication apparatus 4, the other party slave station communication apparatus is equivalent to the satellite Doppler shift deviation (Δdpl) that occurs with the satellite 2 due to the high speed movement of the counterpart slave station communication apparatus 4. 4, the frequency of the transmission signal 45 received is shifted.

  If the position of the receiving side slave station communication device 3 is transmitted by the control signal of the outbound line 5 from the master station and the location can be detected in the transmitting side slave station communication device 3, The modem control unit 27 of the slave station communication device 3 can also correct the transmission signal by calculating Δf′pos based on the satellite Doppler shift amount calculated from the relationship between the position of the local station and the partner station and the satellite position. .

  As described above, in the communication system, the master station, and the slave station communication device according to the second embodiment of the present invention, the Doppler shift amount of the non-stationary satellite that accompanies the high-speed movement of the slave station communication device is set to the communication between the master station and the slave station. Since correction is performed based on the positional relationship between the devices and the positional relationship between the slave stations, it is possible to correct the frequency deviation more accurately and perform communication on the inbound line, the outbound line, and the communication line.

It is a block diagram of the communication system which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the geographical arrangement | positioning of the beam transmitted from a satellite in Embodiment 1 of this invention. It is a block diagram which shows the structure of the main | base station which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the subunit | mobile_unit communication apparatus which concerns on Embodiment 1 of this invention. It is a schematic diagram explaining the frequency error correction process in the communication system, the master station, and the slave station communication apparatus according to Embodiment 1 of the present invention. It is a schematic diagram explaining the process of the frequency error correction | amendment in the communication system which concerns on Embodiment 2 of this invention, a master station, and a slave station communication apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master station 2 Non-stationary satellite 3, 4 Slave station communication apparatus 5 Outbound line 6 Inbound line 7 Communication line 9 Modulator 12 Transmission frequency setting part 14 Demodulator 17 Modem controller 19, 29 Modulator 21 Reference frequency oscillator 22, 31 Transmission frequency setting unit 24, 33 Demodulator 27 Modem controller

Claims (12)

In a communication system that transmits and receives control signals between a master station and a slave station communication device via an outbound line and an inbound line via a non-geostationary satellite, the satellite Doppler shift value is detected by transmission and reception by returning to the non-geostationary satellite. The transmission frequency of the outbound line is corrected based on the satellite Doppler shift value, and the frequency deviation between the master station that transmits the control signal through the outbound line and the control signal received through the outbound line is detected. And a slave station communication device that transmits a transmission signal through an inbound line at a transmission frequency corrected based on the communication system. A demodulator that detects a satellite Doppler shift value by transmitting / receiving to a non-geostationary satellite via a control signal transmission / reception with a slave station communication device, and an outbound line transmission based on the satellite Doppler shift value A modem control unit for instructing a frequency, a transmission frequency setting unit for converting a reference signal to a carrier frequency in response to a command from the modem control unit, and a control signal is modulated by a carrier wave from the transmission frequency setting unit, and an outbound line is used. A master station comprising a modulator for transmission. Demodulate the control signal transmitted from the master station by the outbound line, detect the frequency deviation at the time of reception, and correct the transmission frequency of the inbound line based on the correction amount by the frequency deviation amount A modem control unit, a transmission frequency setting unit that converts a reference signal to a carrier frequency according to a command from the modem control unit, and a modulation that modulates the control signal using a carrier wave from the transmission frequency setting unit and transmits the modulated signal through an inbound line And a slave station communication device. A demodulator that detects a satellite Doppler shift value by transmitting / receiving to a non-geostationary satellite via a control signal transmission / reception with a slave station communication device, and an outbound line transmission based on the satellite Doppler shift value A modem control unit that corrects and commands the frequency, a transmission frequency setting unit that converts the reference signal to a carrier frequency in response to a command from the modem control unit, and a control signal that is modulated by the carrier wave from the transmission frequency setting unit And a modulator for transmitting via an outbound line, and the satellite Doppler shift value is placed on the control signal. A demodulator that demodulates the control signal transmitted from the master station by the outbound line, and a modem control unit that corrects and commands the transmission frequency of the inbound line based on the correction amount by the satellite Doppler shift value carried on the control signal; A transmission frequency setting unit that converts the reference signal into a carrier frequency according to a command from the modem control unit, and a modulator that modulates the control signal using the carrier wave from the transmission frequency setting unit and transmits the modulated signal through an inbound line. A slave station communication device. 5. The master station according to claim 4, wherein a reception beam number and satellite position information are further included in the control signal. The modem control unit calculates a shift amount of the satellite Doppler shift value from the position of the local station obtained from the received beam number carried in the control signal and the satellite position information carried in the control signal, 6. The slave station communication apparatus according to claim 5, wherein a command is performed by correcting the transmission frequency of the inbound line based on a correction amount obtained by adding the shift amount to the Doppler shift value. A demodulator that demodulates the control signal transmitted from the master station via the outbound line and detects the amount of frequency deviation at the time of reception, the position of the own station obtained from the received beam number carried on the control signal, and the control signal The satellite Doppler shift shift amount is calculated based on the satellite position information placed on the satellite position information, and the reference frequency error between the own station and the master station is calculated from the satellite Doppler shift shift amount and the frequency shift amount. A modem control unit for calculating and instructing the transmission frequency of the inbound line based on a correction amount based on a satellite Doppler shift value carried on the control signal, an error of the reference frequency, and a shift amount of the satellite Doppler shift; A transmission frequency setting unit that converts the reference signal to a carrier frequency according to a command from the modem control unit, and a carrier wave from the transmission frequency setting unit. Slave station communication apparatus characterized by comprising a modulator for transmitting the inbound line by modulating a more control signals. The slave station communication apparatus according to claim 3, 5, 7, or 8, wherein the modulation further modulates the transmission signal on the communication line for transmission / reception with the counterpart slave station communication apparatus by the carrier wave. And a transmission frequency setting unit that generates a carrier wave input to the modulator by frequency-converting a reference signal according to a command from the modem control unit, and the modem control unit communicates based on the correction amount. A slave station communication apparatus characterized by correcting and transmitting a transmission frequency of a line. In a communication system that transmits and receives control signals between a master station and a slave station communication device via an outbound line and an inbound line via a non-geostationary satellite, the satellite Doppler shift value is detected by transmission and reception by returning to the non-geostationary satellite. Then, the transmission frequency of the outbound line is corrected based on the satellite Doppler shift value, and the frequency deviation between the master station that transmits the control signal carrying the satellite Doppler shift value through the outbound line and the control signal received through the outbound line And a slave station communication device that transmits a transmission signal through an inbound line at a transmission frequency corrected based on the amount of frequency deviation and the satellite Doppler shift value carried on the received control signal. A featured communication system. A demodulator that demodulates the control signal transmitted from the master station through the outbound line and detects the frequency shift amount at the time of reception, correction by the frequency shift amount, and the satellite Doppler shift value carried on the control signal A modem control unit that corrects and instructs the transmission frequency of the outbound line based on the amount, a transmission frequency setting unit that converts the reference signal to a carrier frequency in accordance with a command from the modem control unit, and a transmission frequency setting unit A slave station communication device comprising: a modulator that modulates a control signal with a carrier wave and transmits the modulated signal through an inbound line. In the slave station communication device according to the invention of claim 11, further, a modulator for modulating a transmission signal in a communication line for transmission / reception with a counterpart slave station communication device by a carrier wave, and a carrier wave input to the modulator, A transmission frequency setting unit that generates a frequency-converted reference signal according to a command from the modem control unit, and the modem control unit corrects and instructs the transmission frequency of the communication line based on the correction amount. A slave station communication device.

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