JPS609381B2 - SCPC antenna tracking receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antenna tracking reception system for a station that requires antenna tracking, such as an earth station for satellite communication.

Conventionally, as a tracking method for a satellite communication earth station, when tracking a direction where the satellite is almost stationary, such as a stationary satellite, for example, as shown in Japanese Patent Application No. 52-26218, the tracking method is to move in the direction where the reception level is maximum. A method of tracking and controlling the antenna is used.

Among such antenna tracking systems, FIG. 1 is a block diagram of a commonly used system. In the figure, an input signal is transmitted to an antenna device 1, a low noise amplification device 2, a directional coupler 4, a power distribution device 3, reception frequency conversion devices 11 to 12, and demodulation devices 21 to 22. A signal branched from the antenna is sent out by a tracking receiver 5, and a driving device 6 drives a mechanical device of the antenna to perform tracking. Here, up to the power distribution device 3 operates at a microwave band frequency, and this band can transmit the entire frequency band of the satellite (for example, 500 MHz). The next reception frequency conversion devices 11 to 12 perform necessary band restriction on a desired reception frequency among all the frequency bands, convert it to an intermediate frequency (for example, 70 MHZ), and send it to the next demodulation device. In this method, the satellite peakon signal is generally used, so a portion of the signal power is extracted by a microwave band directional coupler and converted to a predetermined frequency by a receiving frequency converter dedicated to the peakon in the tracking receiver. Then, the received power of this peak signal is detected.

The drive device is controlled so that the DC signal of this received signal becomes maximum, thereby driving the mechanical device of the antenna and performing tracking control. The signal-to-noise ratio of this peakon signal is
Since this is usually not very good, it is necessary to detect the amplitude of the received signal by a synchronous detection method as a method of detecting the received power, and the receiving circuit configuration for this purpose has become complicated. Although this method achieves high tracking accuracy, it requires an expensive tracking receiver because of its complicated configuration.
Furthermore, in stations that do not require much precision, such as recent small earth stations, the system shown in the block diagram of FIG. 2 is widely used.

In this figure, the same components as in FIG. 1 are indicated by the same number. In addition, the received signal that has passed through the frequency converter 12 is passed through a directional coupler 7 in the intermediate frequency band, passes through a simple tracking receiving device 8 different from that shown in FIG. It consists of The feature of this method is that the received modulated signal wave is directly used and one of the received modulated signal waves is extracted by the directional coupler 7 in the intermediate frequency band.
A dedicated reception frequency converter used in the tracking receiver 5 of FIG. 1 is omitted. Additionally, if this received signal is frequency modulated, the amplitude of the carrier wave changes depending on the frequency shift, so a method that detects the total power within the transmission band is required as a method for detecting the received power. It is. The signal-to-noise ratio in this case is good to some extent because a modulated signal wave for reception is used, and therefore the reception level can be detected extremely easily using a rectification detection method using a diode. In this way, this method realizes a very simple and low-cost antenna tracking system, but there are problems such as tracking accuracy and reliability due to the use of the signal waves of the other earth station. . In the method shown in Figure 2, there is no problem when a signal is always present, such as in frequency division multiplexed frequency modulators (hereinafter referred to as FDM-FM waves) widely used in satellite communications, but in recent years, small General transmission single signal wave (Single Channel) that is being put into practical use at earth stations
1PerCanier (hereinafter referred to as SCPC wave) has a problem in that it is essentially unusable.

FIGS. 3a and 3b are frequency allocation diagrams within a receiving band in satellite communication, showing the entire band of received waves and the SCPC wave region.

It is assumed that there are several FDM-FM waves and one SCPC wave in this entire band. Each earth station prepares a receiving frequency conversion device for the desired carrier wave, and in the case of SCPC waves, there are many modulated carrier waves within the band, as shown in the detailed diagram in Figure 3b. . This S
A feature of the CPC system is that each carrier wave is intermittent depending on the presence or absence of a modulated signal (that is, a system that aims to utilize power effectively by transmitting a modulated carrier wave only when a modulated signal is present). Therefore, the power of each carrier wave and the total power within the transmission band are constantly changing. Therefore, a station receiving only SCPC waves cannot use the method shown in FIG. 2 because there is no signal wave with constant power. Furthermore, it is not a good idea to provide such a small station with an expensive dedicated tracking receiver. SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a tracking reception system that has an extremely simple configuration and is highly accurate and reliable even in stations receiving SCPC waves.

The present invention will be explained in detail below with reference to the drawings. FIG. 4 is a block diagram of an embodiment of the present invention, and the same numbers as in FIG. 1 indicate the same components.

In the figure, an SCPC wave converted into an intermediate frequency band by a frequency converter 12 passes through a pilot receiving device 9, is branched by an intermediate frequency band power distribution device 10, and is connected to each demodulator 31-32. Further, the tracking system is constructed by simply connecting part of the information obtained by the pilot receiving device 9 directly to the driving device. Next, the pilot receiving device 9, which plays an important role in this system, will be explained.

As shown in Figure 3b, the SCPC method inserts an unmodulated pilot signal within the normal band, and uses the received signal wave to correct fluctuations in frequency and received power that occur within the satellite and at each earth station for each station. It is used as. This pilot signal is also used as a monitoring signal for the entire SCPC system. In this SCPC system, it is essential to correct fluctuations in frequency and received power, and a pilot receiver 9 is always provided for this purpose. FIG. 5 shows a specific configuration diagram of the pilot receiving device used in the present invention, IEICE communication system study group material CS75-121 (Vol.
75, No. 142, pp. 103-110).

In this SCPC device, a received intermediate frequency (IF) signal A (70±1 MHZ) is mixed with the output of VC064 constituting an automatic phase adjustment circuit in a mixer 51 to become an intermediate frequency signal (116±18 MH2), It is amplified by an amplifier 52. This amplified intermediate frequency signal B is 48MH
The signal is mixed by a Z reference signal oscillator 53 and a mixer 54, and extracted by a band filter 55 as a pilot reception signal (70 MHZ). This pilot reception signal is transmitted to the demodulation circuit 6
5 to detect the pilot signal. Further, the phase of the received pilot signal is compared with the output of the reference oscillator 56 of 70 MHz, passes through the filter 62, and drives the VC064 to form an automatic phase control circuit. The 70 MHZ reference signal that has passed through the phase/2 phase shifter 57 is also phase-compared with the pilot reception signal by a phase comparator 58, filtered by a filter 59, and held by a hold circuit 60.
The AGC voltage C is supplied to the intermediate frequency amplifier 52 through the AGC voltage C, forming an automatic gain control circuit. In this circuit,
Since the AGC voltage C of the received pilot signal is detected in proportion to the received power, it can be used as a tracking signal for the antenna.

By branching out this AGC voltage and connecting it to the antenna driver, there is no need to add any other receiving equipment.
An antenna tracking system can be configured. Furthermore, since this pilot receiving apparatus has the automatic phase control circuit as described above, the synchronous detection method is used in the example of FIG. 5 as a method of detecting received power. In this case, it is clear that the tracking receiver has a function completely equivalent to that of the tracking receiver described in the system shown in FIG. 1, and extremely accurate tracking characteristics can be obtained. Furthermore, since the pilot signal used here has a very important role in the SCPC system, it is processed to be sufficiently reliable compared to other modulation signals. Therefore, it can be said that the tracking method according to the present invention that utilizes such a signal has sufficient reliability. As explained above, for satellite communication earth stations that receive SCPC waves, the configuration of an antenna tracking system using a pilot receiver is more advantageous than conventional methods in terms of cost, accuracy, and reliability. be.

[Brief explanation of drawings]

1 and 2 are block diagrams of a conventional antenna tracking system, FIGS. 3a and 3b are frequency allocation diagrams within the receiving band, FIG. 4 is a block diagram of an embodiment of the antenna tracking system according to the present invention, and FIG. The figure is number 4
FIG. 2 is a configuration diagram of the pilot receiving device shown in FIG. In the figure, 1...Antenna device, 2...Low noise amplifier, 3...Microwave band power distribution device, 4...Microwave band directional coupling Vessel, 5...
... Tracking receiving device, 6... Drive device, 7.
...Intermediate frequency band directional coupler, 8...Simple tracking receiver, 9...Pilot receiver, 10...Intermediate frequency band power distribution device , 11
~12...Receiving frequency converter, 21-22, 31
~32... Demodulator, 51, 54... Mixer, 52... Intermediate frequency amplifier, 53, 56...
...Reference oscillator, 55...Band filter, 5
7... Phase shifter, 58, 61... Phase comparator, 59... Filter, 60, 63...
・Hold circuit, 62...Limiting filter, 64...
VC○, 65... Pilot demodulation circuit.
Festival illustration 2 illustrations younger brother J illustration 4th illustration Tsutomu J illustration

Claims (1)

[Claims] 1 An antenna means for receiving a signal wave of a general transmission single signal (hereinafter referred to as SCPC) communication system, an antenna driving means for controlling the pointing direction of the antenna means in response to the voltage of a control signal, and a signal wave receiving by the antenna means. S comprising automatic gain control and automatic frequency control means for extracting a pilot signal from the signal wave and performing automatic gain control and automatic frequency control, respectively.
An antenna tracking receiver for CPC, characterized in that an automatic gain control voltage of the automatic gain control means is supplied to the antenna driving means as the voltage of the control signal.
C antenna tracking receiver.