JPH08201496A - Tracking receiver - Google Patents

Abstract

PURPOSE: To reduce in size, weight and power consumption a receiver and to prevent the deterioration of tracking error detecting characteristics caused by a crosstalk by processing a sum signal and a difference signal by one frequency converter, an AGC amplifier, etc. CONSTITUTION: An RF sum signal and an AM-modulated RF difference signal are combined by a multiplexer 4, a multiplexed signal is frequency-converted by one frequency converter 5, and branched after passing a band pass filter 7 and an AGC amplifier 8. One of them is suppressed in the difference signal and generated with a sum signal by a limiter amplifier 11, and the other is phase-converted by a 90 deg.-phase converter 12, and product detected by a product detector 13 to obtain an error signal output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking receiver, and more particularly to a tracking receiver used for automatically controlling tracking of an antenna for receiving radio waves in a high frequency region such as a microwave frequency band to a desired target. Regarding

[0002]

2. Description of the Related Art An example of a conventional product detection type tracking receiver of this type is shown in FIG. The RF sum signal and the RF difference signal are input to the input terminal 1 and the input terminal 2, respectively, from the antenna part (not shown). The RF difference signal is AM-modulated by the modulator 3 by the clock signal of the low frequency oscillator 17, and the RF difference signal and the RF sum signal are IF-converted by the local oscillation signal output from the local oscillator 6 in the frequency converters 5A and 5B, respectively.
Frequency converted to signal. These IF signals are band-limited by the bandpass filters 7A and 7B, and the AGC amplifier 8
It is amplified in A and 8B. This AGC amplifier 8A,
The output of 8B is an envelope detector 9 and an AGC loop filter 1
0 is fed back to each amplifier 8A, 8B,
GC amplification is performed.

Of the outputs of the AGC amplifiers 8A and 8B, the output of the AGC amplifier 8B which is a difference signal is 90
The phase is shifted by 90 ° through the phase shifter 12, and then the product detector 13 detects the sum signal and the product, and outputs the baseband difference signal. This baseband difference signal is synchronously detected by the synchronous detector 14 with the clock signal of the low frequency oscillator 17, and an error signal is detected by this, and this error signal is passed through the low-pass filter 15 to generate a DC error component. Is extracted, a desired DC gain is extracted by the DC amplifier 16, and this is output to the output terminal 18 as a DC error signal.

[0004]

In such a conventional tracking receiver, a frequency converter, a bandpass filter, and an AGC amplifier are provided in each of the signal systems of the sum signal and the difference signal. Therefore, there are problems that the number of components is large, the receiver becomes heavy and large, and the power consumption is large. Further, if each signal system is provided with an independent frequency converter or AGC amplifier, the phase characteristics between the sum signal and the difference signal are changed due to temperature fluctuations due to the difference in temperature characteristics and frequency characteristics in these devices. However, there is a problem that crosstalk occurs between output error signals in the product detector, and the tracking error detection characteristic is deteriorated.

In addition to the above, for example, Japanese Patent Laid-Open No. 5-2
Also in the tracking receivers described in Japanese Patent Laid-Open No. 7001 and Japanese Patent Laid-Open No. 3-204010, since a frequency converter, an AGC amplifier, etc. are similarly provided in each system of the sum signal and the difference signal, the above description is made. Such problems will be latent.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to process a sum signal and a difference signal with a single frequency converter, an AGC amplifier, etc., thereby reducing the size, weight and power consumption of the receiver. Another object of the present invention is to provide a tracking receiver capable of preventing deterioration of tracking error detection characteristics due to crosstalk in an output error signal.

[0007]

The tracking receiver of the present invention comprises:
A multiplexer for synthesizing the RF sum signal and the AM-modulated RF difference signal, a frequency converter for frequency-converting the multiplexed signal, and a frequency-converted signal are branched and provided in one of the paths. It is provided with a limiter amplifier, a 90 ° phase shifter provided on the other path, and a product detector which inputs the outputs of the limiter amplifier and the 90 ° phase shifter, respectively.

Here, a band-pass filter for limiting the band of the frequency-converted multiplexed signal and an AGC amplifier for AGC-amplifying the filtered signal are provided, and the product-detected signal is synchronized. It is preferable to provide a synchronous detector for detecting, a low-pass filter and a DC amplifier connected to the output side thereof. Further, the AM modulator for AM modulation and the synchronous detector are operated by the signals of the same signal source.

[0009]

In this tracking receiver, the RF sum signal and the RF difference signal are combined and frequency-converted at the same time, and the AM modulation difference signal is suppressed by the limiter amplifier to generate the sum signal component. The self-multiplication detection between the sum and the difference is possible with the signal component and the combined signal, and a desired error signal can be obtained.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a tracking receiver of the present invention. The RF sum signal input terminal 1 and the RF difference signal input terminal 2 are connected to the RF sum signal and the RF sum signal from the antenna part (not shown), respectively.
The difference signal is input. The RF sum signal input terminal 1 is connected to one input end of the multiplexer 4. The RF difference signal input terminal 2 is input to the modulator 3, and the output of the modulator 3 is connected to the other input end of the multiplexer 4. The modulator 3 is configured to AM-modulate the RF difference signal based on the clock signal generated by the low frequency oscillator 17.

A local oscillator 6 is provided at the output terminal of the multiplexer 4.
A frequency converter 5 for frequency-converting the output of the multiplexer 4 into an IF signal according to the local oscillation signal output from is connected. Further, the band-pass filter 7 that limits the band of the frequency-converted IF signal is connected to the AGC amplifier. The AGC amplifier 8 includes an envelope detector 9 for detecting the output of the AGC amplifier 8 to extract a predetermined low frequency component, and an AGC loop filter for feeding back the extracted signal to the AGC amplifier 8 as an AGC control voltage. 10 are connected.

Further, at the output terminal of the AGC amplifier, as will be described later, a limiter amplifier 11 for transmitting only the sum signal component of the combined signal output from the AGC amplifier,
A π / 2 phase shifter 12 for shifting the phase of the combined signal by 90 ° is connected in parallel. A product detector 13 that multiplies the output of the limiter amplifier 11 and each output of the π / 2 phase shifter 12 is connected.

Further, at the output end of the product detector 13,
A synchronous detector 14 for synchronously detecting the output of the product detector 13 by the clock signal of the low-frequency oscillator 17, a low-pass filter 15, and a DC amplifier 16 are connected, and an error signal is output from an error signal output terminal 18. It is configured to output.

According to this configuration, the RF sum signal is input from the input terminal 1 to the multiplexer 4, while the RF difference signal is input from the input terminal 2 and then AM modulated by the clock signal from the low frequency oscillator 17. Then, it is input to the multiplexer 4.
Therefore, the multiplexer 4 outputs the combined signal, that is, the "sum signal + AM modulation difference signal". This combined signal is converted into an IF signal in the frequency converter 5, band-limited in the bandpass filter 7, and then amplified to a predetermined signal level in the AGC amplifier.

This amplified signal is branched into two, one of which removes the "AM modulation difference signal" of the combined signal by the limiter amplifier 11 to generate only the "sum signal" component. On the other hand, the combined signal is 9 by the π / 2 phase shifter 12.
The phase is shifted by 0 °. A baseband difference signal is obtained by performing a product detection in the product detector 13 using these signals. Further, the baseband difference signal is synchronously detected by the synchronous detector 14 by the clock signal from the low frequency oscillator 17, whereby an error signal is obtained.

Thereafter, the low-pass filter 15 extracts the DC error signal component from the error signal, and the DC amplifier 1
By extracting the desired DC gain at 6, a DC error signal is output from the error signal output terminal 18. It goes without saying that tracking control of the antenna part is performed by using this DC error signal.

Therefore, in this tracking receiver, the RF sum signal and the RF difference signal are multiplexed and then processed by one system. However, by providing the limiter amplifier 11, the "AM modulation difference signal" is obtained. Since the sum signal component is suppressed by generating the sum signal component, it is possible to perform a self product detection between the sum signal and the difference signal and obtain a desired error signal. .

As a result, the frequency converter, the bandpass filter,
The AGC amplifier only needs to be provided in one system, and the number thereof can be reduced to 1/2 as compared with the conventional receiver. As a result, the size and weight of the receiver can be reduced, and the power consumption can be reduced. Further, since the frequency converter and the AGC amplifier are provided in only one system, even if these characteristic fluctuations occur due to temperature fluctuations or the like, there is no fluctuation in the phase characteristics between the sum signal and the difference signal. It is possible to prevent the occurrence of crosstalk due to, and to prevent the deterioration of the tracking error detection characteristic.

[0019]

As described above, according to the present invention, the RF sum signal and the AM-modulated RF difference signal are combined in a combiner, the combined signal is frequency-converted, and then branched. One is passed through the limiter amplifier, the other is passed through the 90 ° phase shifter, and the product detection is performed by each output, so at least one frequency converter should be provided in one system, and the number of frequency converters can be reduced. It is possible to reduce the size and weight of the receiver, reduce power consumption, eliminate the effects of temperature fluctuations in the two systems, and prevent degradation of tracking error detection characteristics due to crosstalk in the output error signal. Can be realized.

Further, a band filter for limiting the band of the frequency-converted multiplexed signal and an AGC amplifier for AGC-amplifying the filtered signal are sufficient for one system, and the receiver can be miniaturized by reducing these components. It is possible to further reduce the size, reduce the weight, and reduce the power consumption.

Furthermore, by providing a synchronous detector for synchronously detecting the product-multiplied detected signal, and a low-pass filter and a DC amplifier connected to the output side thereof, two phase tracking error signals are converted into DC voltage. Can be output.

An AM modulator for performing AM modulation,
By configuring the synchronous detector and the signal from the same signal source to operate respectively, AM modulation and synchronous detection are preferably performed, and the configuration of the signal source can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a tracking receiver of the present invention.

FIG. 2 is a block diagram of an example of a conventional tracking receiver.

[Explanation of symbols]

 1 RF sum signal input terminal 2 RF difference signal input terminal 3 Modulator 4 Combiner 5 Frequency converter 6 Local oscillator 7 Bandpass filter 8 AGC amplifier 9 Detector 10 AGC loop filter 11 Limiter amplifier 12 90 ° phaser 13 Multiplier detector 14 Synchronous detector 15 Low-pass filter 16 DC amplifier 17 Low-frequency oscillator 18 Error signal output terminal

Claims (4)

[Claims] 1. An RF sum signal and an AM-modulated RF difference signal are frequency-converted, their phases are shifted by 90 °, product detection is performed, and two phase tracking error signals are detected from the demodulated signal. In the tracking receiver, the RF sum signal and AM
A multiplexer for synthesizing the modulated RF difference signal, a frequency converter for converting the frequency of the combined signal, a limiter amplifier for branching the frequency-converted signal, and provided on one path thereof, and another A tracking receiver comprising: a 90 ° phase shifter provided in the path; and a product detector that inputs the outputs of the limiter amplifier and the 90 ° phase shifter, respectively. 2. A bandpass filter for limiting the band of a frequency-converted multiplexed signal, and an A for amplifying the filtered signal by AGC.
The tracking receiver of claim 1 comprising a GC amplifier. 3. The tracking receiver according to claim 2, further comprising a synchronous detector for synchronously detecting the product-multiplied detected signal, and a low-pass filter and a DC amplifier connected to the output side of the synchronous detector. 4. A tracking receiver according to claim 3, wherein the AM modulator for AM modulation and the synchronous detector are operated by signals from the same signal source.