CN112769432B - Method and generator for generating 10MHz frequency standard of relay satellite SMA downlink signal without pilot frequency - Google Patents

Abstract

The invention relates to a method for generating a downlink 10MHz frequency standard signal of a relay satellite SMA without a pilot frequency. In-phase quadrature phase-locked loop, the VCO voltage-controlled oscillator outputs the locked telemetry carrier signal; S2, the telemetry carrier signal output by the VCO voltage-controlled oscillator is divided by decimals and integers to form a 10MHz frequency standard signal, which is sent to the relay satellite. Ground station SMA receiver. The method of the invention saves the frequency resources of the relay satellite transponder, does not need an additional pilot signal (about 20 MHz of bandwidth), is simple to implement and consumes less resources.

Description

Method and generator for generating 10MHz frequency standard of relay satellite SMA downlink signal without pilot frequency

technical field

The invention relates to a method and a generator for generating a 10MHz frequency standard of a relay satellite SMA downlink signal.

Background technique

In the relay satellite system (TDRSS), in order to improve its ability to serve multiple targets, it is necessary to increase the S-band phased array multiple access (SMA) equipment. In relay satellite SMA signal transmission, in order to reduce the demodulation loss of the downlink signal, it is required to use the satellite-ground coherent local oscillator to demodulate the downlink signal. In the existing relay satellite SMA system, a dedicated pilot signal is set for the ground SMA receiving equipment to restore the 10MHz coherent signal during demodulation, and then generate the different combined frequency signals required by each unit of SMA ground receiving. The disadvantage of this method is that it occupies extra bandwidth of the relay satellite transponder (generally about 20MHz), which reduces the application efficiency of the relay satellite.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problem that the SMA downlink signal of the existing relay satellite uses a dedicated pilot channel to occupy the bandwidth of the transponder, and uses the characteristics that the relay satellite S-band and Ka-band transponders have full coherence. The method and generator of the satellite-ground coherent 10MHz frequency standard for the demodulation performance requirements of ground SMA receiving equipment and saving frequency resources.

The technical scheme adopted by the present invention is: a method for generating a downlink 10MHz frequency standard signal of a relay satellite SMA without a pilot frequency, comprising the following steps:

S1, the relay satellite ground station receives the relay satellite Ka-band telemetry signal, and after output by the low noise amplifier, it is sent to the in-phase quadrature phase-locked loop, and the VCO voltage-controlled oscillator outputs the locked telemetry carrier signal;

The specific method of S1 is:

S11, multiply the relay satellite Ka-band telemetry signal and the VCO voltage-controlled oscillator output signal, and the output signal obtains the Q-channel signal y _q (t) after passing through the Q-channel second-order low-pass filter; t is the time;

S12, multiply the telemetry signal of the relay satellite Ka-band with the 90° phase-shifted output signal of the VCO voltage-controlled oscillator, and the output signal obtains the signal y _i (t) of the channel I after passing through the second-order low-pass filter of channel I;

S13, multiply the Q-channel signal y _q (t) by the I-channel signal y _i (t), and the output signal passes through the loop filter to generate the error control voltage signal of the VCO voltage-controlled oscillator, and control the output of the VCO voltage-controlled oscillator Telemetry carrier signal.

S2, the telemetry carrier signal output by the VCO voltage-controlled oscillator is divided into a 10MHz frequency standard signal by fractional and integer frequency division, and sent to the SMA receiver of the relay satellite ground station.

A relay satellite SMA downlink 10MHz frequency standard signal generator without pilot frequency, including VCO voltage-controlled oscillator, Q-channel second-order low-pass filter, I-channel second-order low-pass filter, loop filter, decimal and Integer frequency divider, the output signal of the VCO voltage-controlled oscillator is multiplied by the Ka-band telemetry signal of the relay satellite, and the output signal is passed through the Q-channel second-order low-pass filter to obtain the Q-channel signal y _q (t); VCO voltage-controlled oscillator The 90° phase-shifted output signal is multiplied by the relay satellite Ka-band telemetry signal, and the output signal passes through the I-channel second-order low-pass filter to obtain the I-channel signal y _i (t); the Q-channel signal y _q (t) and I The channel signals y _i (t) are multiplied, and the output signal passes through the loop filter to generate the error control voltage signal of the VCO voltage-controlled oscillator, and control the VCO voltage-controlled oscillator to output the telemetry carrier signal;

The telemetry carrier signal output by the VCO voltage-controlled oscillator is divided by decimal and integer to form a 10MHz frequency standard signal, which is sent to the SMA receiver of the relay satellite ground station;

t is time.

Compared with the prior art, the present invention has the following beneficial effects:

According to the frequency syntheses of the relay satellites S and Ka frequency band repeaters, the present invention has the characteristic of full coherence, uses in-phase quadrature phase-locked loop (Costa loop), integer and fractional frequency dividers, and transmits telemetry through the relay satellite Ka frequency band. The signal recovers the satellite-ground coherent 10MHz frequency standard signal at the ground station. In the case of no pilot signal, this frequency standard is used to provide satellite-ground coherence 10MHz for the S-band multiple access (SMA) component of the relay satellite ground station. frequency source. The newly generated satellite-ground coherent 10MHz frequency source meets the application requirements of the relay satellite ground equipment, and the phase noise at 10Hz offset from the carrier is about -112.5dBc/Hz. The invention can save the bandwidth of the relay satellite transponder by about 20MHz, and has the advantages of novel design and simple use. In the field of relay satellite S-band phased array multiple access (SMA) link transmission, the method of the invention does not require pilot signals to use relay satellite telemetry signals to generate satellite-ground coherent 10MHz frequency signals, thereby saving relay satellite transponders Frequency resources, no additional pilot signal (about 20MHz bandwidth) is required, and the implementation is simple and the resource consumption is small.

Description of drawings

Figure 1 is a schematic block diagram of the generation of a 10MHz satellite-ground coherent frequency standard signal downlink by a relay satellite SMA without a pilot frequency;

Figure 2 is a block diagram of the downlink connection of the ground station SMA equipment based on the satellite-ground coherent frequency standard.

Detailed ways

The invention utilizes the full coherence characteristics of the frequency synthesis of the relay satellite S-band and Ka-band repeaters, and restores the satellite-ground coherent 10MHz frequency standard signal at the ground station through the relay satellite telemetry signal. In the next step, this frequency standard is used to provide a satellite-ground coherent 10MHz frequency source for each component of the ground station SMA. The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Example:

A method for generating a 10MHz satellite-ground coherent frequency standard signal downlinking a relay satellite SMA without a pilot frequency, the principle block diagram of which is shown in Figure 1, and specifically includes the following steps:

S1, the relay satellite ground station receives the relay satellite Ka-band telemetry signal, and after output by the low noise amplifier (LNA), it is sent to the in-phase quadrature phase-locked loop (Costa loop), and the VCO voltage controlled oscillator outputs the locked telemetry carrier signal ;

S11, the relay satellite Ka-band telemetry signal is multiplied by the VCO voltage-controlled oscillator output signal, and the output signal is passed through the Q-channel second-order low-pass filter to obtain the Q-channel signal y _q (t);

S12, the Ka-band telemetry signal of the relay satellite is multiplied by the 90° phase-shifted output signal of the VCO voltage-controlled oscillation, and the output signal is passed through the I-channel second-order low-pass filter to obtain the I-channel signal y _i (t);

S13, the Q-channel signal y _q (t) is multiplied by the I-channel signal y _i (t), the output signal passes through the loop filter to generate the error control voltage signal of the VCO voltage-controlled oscillator, and controls the VCO voltage-controlled oscillator to output telemetry carrier signal.

S2, the telemetry carrier signal output by the VCO voltage-controlled oscillator is divided into 10MHz satellite-to-ground coherent frequency standard signal after fractional and integer frequency division, and sent to each component of the ground station SMA receiver, as shown in Figure 2, including Ka/L Downconverter, 30-channel FDM separation unit, L/IF downconverter, digital beamforming (DBF) terminal and SMA data transmission terminal. In the SMA receiver of the relay satellite ground station, the Ka/L downconverter, the 30-channel FDM separation unit, the L/IF downconverter, the digital beamforming terminal and the S-band multiple access data transmission terminal use the 10MHz frequency standard signal.

For the in-phase quadrature loop, when the loop is locked, the received demodulation telemetry data is directly extracted from the low-pass filter output y _i (t) of the in-phase branch, and the judgment of the in-phase and quadrature branch is no longer required. , which overcomes the 180° phase uncertainty problem.

Theoretical analysis shows that if the Ka/L downconverter in the SMA link does not use the satellite-to-ground phase reference frequency standard signal, but directly uses the ground station time system, the frequency deviation is about ^10-6 Hz, which is in the engineering error. Within the allowable range, the ground station Ka/L downconverter can also be designed uniformly.

In the SMA downlink component of the ground station, the return (downlink) calibration terminal is required to have an internal 10MHz frequency source and the ability to receive an external 10MHz reference source provided by the ground station, but should not use satellite-ground coherence. 10MHz reference source. The return calibration terminal feeds back the 30-way return amplitude and phase detection results to the DBF to complete the compensation for the inconsistency of the amplitude and phase.

Using the method of the present invention, a relay satellite SMA downlink 10MHz frequency standard signal generator without pilot frequency is designed, which includes a VCO voltage-controlled oscillator, a Q-channel second-order low-pass filter, and an I-channel second-order low-pass filter. , loop filter, decimal and integer frequency dividers, the output signal of the VCO voltage-controlled oscillator is multiplied by the Ka-band telemetry signal of the relay satellite, and the output signal is passed through the second-order low-pass filter of the Q-channel to obtain the Q-channel signal y _q ( t); The 90° phase-shifted output signal of the VCO voltage-controlled oscillator is multiplied by the Ka-band telemetry signal of the relay satellite, and the output signal passes through the I-channel second-order low-pass filter to obtain the I-channel signal y _i (t); Q-channel The signal y _q (t) is multiplied by the I-channel signal y _i (t), and the output signal passes through the loop filter to generate the error control voltage signal of the VCO voltage-controlled oscillator, which controls the VCO voltage-controlled oscillator to output the telemetry carrier signal; VCO The telemetry carrier signal output by the voltage-controlled oscillator is divided into 10MHz frequency standard signal by fractional and integer frequency, which is sent to the SMA receiver of the relay satellite ground station. The VCO adopts HMC738 (oscillation frequency is in the Ka band), and uses the relay satellite telemetry signal to restore the satellite-ground coherent 10MHz frequency standard signal at the ground station. After testing, the phase noise is about -112.5dBc/Hz at 10Hz deviating from the carrier. , the measured results meet the application requirements of relay satellite ground equipment.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can use the methods and technical contents disclosed above to improve the present invention without departing from the spirit and scope of the present invention. The technical solutions are subject to possible changes and modifications. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention belong to the technical solutions of the present invention. protected range.

Claims (2)

1. a relay satellite SMA downlink 10MHz frequency standard signal generation method without pilot frequency, is characterized in that, comprises the steps: S1, the relay satellite ground station receives the relay satellite Ka-band telemetry signal, and after output by the low noise amplifier, it is sent to the in-phase quadrature phase-locked loop, and the VCO voltage-controlled oscillator outputs the locked telemetry carrier signal; S2, the telemetry carrier signal output by the VCO voltage-controlled oscillator is divided by decimal and integer to form a 10MHz frequency standard signal, and sent to the SMA receiver of the relay satellite ground station; The specific method of S1 is: S11, multiply the relay satellite Ka-band telemetry signal and the VCO voltage-controlled oscillator output signal, and the output signal obtains the Q-channel signal y _q (t) after passing through the Q-channel second-order low-pass filter; t is the time; S12, multiply the telemetry signal of the relay satellite Ka-band with the 90° phase-shifted output signal of the VCO voltage-controlled oscillator, and the output signal obtains the signal y _i (t) of the channel I after passing through the second-order low-pass filter of channel I; S13, multiply the Q-channel signal y _q (t) by the I-channel signal y _i (t), and the output signal passes through the loop filter to generate the error control voltage signal of the VCO voltage-controlled oscillator, and control the output of the VCO voltage-controlled oscillator Telemetry carrier signal. 2. a relay satellite SMA downlink 10MHz frequency standard signal generator without pilot frequency, is characterized in that, comprises VCO voltage-controlled oscillator, Q road second-order low-pass filter, I road second-order low-pass filter, loop channel filter, fractional and integer frequency dividers, the output signal of the VCO voltage controlled oscillator is multiplied by the Ka-band telemetry signal of the relay satellite, and the output signal is passed through the Q channel second-order low-pass filter to obtain the Q channel signal y _q (t) ; The 90° phase-shifted output signal of the VCO voltage-controlled oscillator is multiplied by the Ka-band telemetry signal of the relay satellite, and the output signal is passed through the I-channel second-order low-pass filter to obtain the I-channel signal y _i (t); the Q-channel signal y _q (t) is multiplied by the I channel signal y _i (t), the output signal passes through the loop filter to generate the error control voltage signal of the VCO voltage-controlled oscillator, and controls the VCO voltage-controlled oscillator to output the telemetry carrier signal; t is the time ; The telemetry carrier signal output by the VCO voltage-controlled oscillator is divided by decimal and integer to form a 10MHz frequency standard signal, which is sent to the SMA receiver of the relay satellite ground station.

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