JP2964758B2 - Antenna angle tracking receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna angle tracking receiver, and more particularly to a tracking receiver employing a cross-correlation method.

[0002]

2. Description of the Related Art Conventionally, a two-phase PSK wave or a four-phase PSK wave in which no carrier remains is received and an antenna angle error for automatically controlling an antenna in a radio wave arrival direction is detected. A cross-relation system for synchronously detecting a signal with this reference signal has been employed.

[0003]

The operation threshold level of this system is determined by the S / N of the sum signal, and
The limit is about 10 dB. This is A by envelope detection.
This is because the sum of the signal power and the noise power becomes constant by the operation of the GC loop. When C / N = 0 dB, the signal power and the noise power are equal, and the signal power is suppressed by 3 dB. Therefore, if the difference signal is detected based on the sum signal, the detection sensitivity of the angle error signal is rapidly reduced, and stable acquisition and tracking of the signal cannot be performed. Therefore, the satellite EIR
It is necessary to make P larger than a value necessary for data demodulation, and there is a problem that a load on a satellite is large. SUMMARY OF THE INVENTION It is an object of the present invention to provide a tracking receiver capable of lowering a detection threshold level of an angle error signal, enabling automatic tracking to a low level, and reducing a burden on a satellite.

[0004]

SUMMARY OF THE INVENTION A tracking receiver according to the present invention comprises a multiplier for recovering a carrier of a received wave, a phase-locked loop for tracking the phase of the recovered carrier, and detecting a recovered carrier signal level to detect the level. An AGC loop for controlling to a constant level, a memory circuit for outputting gain control information corresponding to an AGC voltage generated in the AGC loop, and a variable amplifier for controlling a gain of an angle error signal level based on the gain control information. Prepare. The memory circuit stores the AGC voltage generated in the AGC loop and control information for correcting the signal suppression level in advance in association with each other, and outputs level correction information according to the input AGC voltage.

[0005]

According to the present invention, information for correcting a decrease in the angle error signal is obtained by detecting the amount of suppression of the reproduced carrier level. Based on this correction information, the detection threshold level of the angle error signal is lowered, and the automatic tracking is reduced to a low level. Make it possible.

[0006]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of one embodiment of the present invention. A in the figure
The section is an angle error detection circuit of a cross-relation type. That is, the sum signal 1 and the difference signal 2 are connected to the low noise amplifiers 3 and 3, respectively.
The signal is amplified at 11 and frequency-converted at frequency converters 4 and 12. Further, after being subjected to AGC amplification by the AGC amplifiers 5 and 13, the signals pass through the bandpass filters 6 and 14. The sum signal is detected by a detector 15 and passed through an AGC loop filter 16 to generate an AGC1 voltage, which is supplied to the AGC amplifiers 5 and 13. The sum signal and the difference signal passed through the phase shifter 7 and the sum signal and the difference signal passed through the π / 2 phase shifter 8 are synchronously detected by synchronous phase detectors 9 and 10, respectively. Are output to the variable gain DC amplifiers 30 and 31.

On the other hand, part B in the figure is a threshold level improving circuit according to the present invention, which reproduces a carrier in an N-multiplier 17 and mixes it with a mixer 19, a bandpass filter 20, a synchronous phase detector 21, a loop filter 22, The phase of the reproduced carrier is tracked by a phase locked loop composed of the VCO 23. The recovered carrier level is detected by detecting the output of the bandpass filter 20 in the phase locked loop and the reference signal of the phase locked loop passed through the π / 2 phase shifter 24 in the synchronous detector 25. This detection signal is converted into an AGC2 voltage through an AGC loop filter 26, and is fed back to the AGC amplifier 18 to form an AGC loop for controlling the level of the reproduced carrier wave to be constant. The AGC2 voltage contains information on signal level suppression due to C / N deterioration.

The AGC2 voltage is converted to digital information by an A / D converter 27 and input to a memory circuit 28. The AGC2 voltage and control information for correcting the signal suppression level are stored in advance in the memory circuit 28 in association with each other, and when the AGC2 voltage is input, the corresponding level correction information is output. This level correction information is converted into analog information by a D / A converter 29 and input to the variable gain DC amplifiers 30 and 31, respectively. Therefore, each of the DC amplifiers 30 and 31 corrects the angle error signal level based on the level correction information. This lowers the detection threshold level of the angle error signal.

[0009]

As described above, according to the present invention, by detecting the amount of suppression of the reproduced carrier level, the amount by which the decrease in the angle error signal is corrected is known, and the detection threshold level of the angle error signal is determined based on this information. Can be lowered. As a result, the deviation of the angle of arrival of the radio wave can be detected, and the automatic tracking can be performed to a low level, so that the burden on the satellite can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a tracking receiving apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 sum signal 2 difference signal 17 multiplier 18 AGC amplifier 21, 25 synchronous detector 23 VCO 27 A / D converter 28 memory circuit 29 D / A converter 30, 31 variable gain DC amplifier

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01S 3/00-3/74 H04B 1/08 H04B 1/18 H04L 27/22

Claims (2)

(57) [Claims] 1. A tracking receiver for receiving a two-phase or four-phase PSK wave and detecting an antenna angle error signal in the direction of an incoming radio wave, a multiplier for reproducing a carrier of a received wave, and phase-tracking the reproduced carrier. A phase locked loop and an AGC for detecting a reproduced carrier signal level and controlling it to a constant level
A loop, a memory circuit for outputting gain control information corresponding to the AGC voltage generated in the AGC loop, and a variable amplifier for controlling the gain of the angle error signal level based on the gain control information. Antenna angle tracking receiver. 2. The memory circuit according to claim 1, wherein an AGC voltage generated in the AGC loop and control information for correcting the signal suppression level are stored in association with each other in advance, and the level correction information is output according to the input AGC voltage. Item 1. The antenna angle tracking receiver according to Item 1.