JPH11177348A - Frequency converting device and monitoring method for local oscillation signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frequency converting device which monitors a local oscillation signal wave without providing an additional means and an additional part that occupy useless space and this monitoring method for the local oscillation signal. SOLUTION: The frequency converting device which inputs a high frequency signal of a 1st frequency from an input terminal 3a of a frequency conversion circuit 3, inputs a local oscillation signal from an input terminal 3c and outputs a high frequency signal of a 2nd frequency which is the sum/difference of the 1st frequency and the local oscillation frequency from an output terminal 3b inputs the local oscillation signal to a terminal 2a of a circulator that makes a signal pass from the terminal 2a to a terminal 2b and also makes a signal pass from the terminal 2b to a terminal 2c, connects the terminal 2b of the circulator and the terminal 3c of the device 3 with a prescribed reflection coefficient and monitors a part of the local oscillation signal that is outputted from the terminal 2c of the circulator. Also, it terminates a test before an operation and the terminal 2c of the circulator after adjustment with a terminating device 4 of a prescribed impedance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a frequency converter mounted on, for example, a communication satellite or a broadcasting satellite and used as an up-converter or a down-converter, and a method of monitoring a local oscillation signal in the frequency converter.

[0002]

2. Description of the Related Art DBM (Double Balanced Modulato)
r: a frequency converter using a double balanced modulator) or the like, in order to improve the S / N (Signal / Noise) ratio and secure frequency stability, a local oscillation signal wave (hereinafter referred to as a local oscillator signal as needed). Emission or local emission)
May be monitored.

FIG. 2 is a block diagram showing a configuration example of such a conventional frequency converter with a local oscillation signal monitor terminal. In FIG. 2, a local oscillation signal output from a local oscillation signal generation circuit 51 is supplied to a local oscillation signal input terminal 53 c of a frequency conversion circuit 53 via an isolator 55. This isolator 55 is inserted for impedance matching between the local oscillation signal generation circuit 51 and the frequency conversion circuit 53.

The frequency conversion circuit 53 has a DMB
The high-frequency signal input to the signal input terminal 53a is mixed with the local oscillation signal, frequency-converted, and output from the signal output terminal 53b.

That is, when the frequency converter with a local oscillation signal monitor terminal is used as a receiver or a down converter, an RF (Radio Frequency) signal is input to the signal input terminal 53a.
ncy: a high frequency, generally indicating a transmission / reception frequency) signal is input, and an IF (Intermediate F
requency (intermediate frequency) signal is output.

On the other hand, when the frequency converter with a local oscillation signal monitor terminal is used as an up-converter or the like, an IF signal is input to a signal input terminal 53a, and an RF signal is output from a signal output terminal 53b.

Conventionally, a directional coupler 54 is inserted between the local signal generation circuit 51 and the isolator 55. The local oscillation signal is monitored by measuring the high-frequency signal output from the coupling terminal 54a of the directional coupler 54.

FIG. 3 is a block diagram showing a configuration example of a receiver mounted on an artificial satellite to which a conventional frequency converter with a local oscillation signal monitor terminal is applied. In FIG. 3, parts corresponding to the respective parts shown in FIG. 2 are given the same reference numerals, and descriptions thereof will be omitted.

In FIG. 3, reference numeral 56 denotes a low noise amplifier circuit,
Reference numeral 7 denotes an IF signal amplifier circuit. Reference numeral 58 denotes a primary power supply voltage supplied from the satellite main body on which the receiver is mounted, and a secondary power supply voltage suitable for the operation of the local signal generation circuit 51, the low noise amplification circuit 56, or the IF signal amplification circuit 57. This is a voltage conversion circuit for converting the voltage into a voltage.

In the example shown in FIG. 1, a received signal input to an RF signal input terminal 101 of a receiver is amplified by a low-noise amplifier circuit 56, then frequency-converted by a frequency converter circuit 53, and further amplified by an IF signal amplifier circuit. After being amplified by 57, it is output as an intermediate frequency signal from the IF signal output terminal 102 of the receiver.

[0011]

The receiver shown in FIG.
In order to evaluate its characteristics, various items are tested before being incorporated into the artificial satellite body. The test items include phase noise and phase shift characteristics of the local oscillation signal, and group delay characteristics. Among the test items, for the phase noise of the local signal, a part of the local signal was extracted and the spectrum and
Measure with an analyzer.

The phase shift characteristic and the group delay characteristic are obtained, for example, by using an RF signal input to a receiver as a reference signal, and using an output IF signal as a measurement signal, and measuring a phase change with respect to the reference signal using a vector network analyzer. Measured by

At the time of such a test or adjustment, since the reference signal and the measurement signal need to have the same frequency, frequency conversion is performed using an external mixer or the like so that the frequency of the reference signal becomes equal to the frequency of the measurement signal. I do. The local oscillator signal supplied to the external mixer needs to have a correlation with the local oscillator signal in the receiver. Therefore, a part of the local oscillation signal of the receiver is usually used also in this case.

As described above, in order to measure the phase noise, the phase shift transmission characteristic, the group delay characteristic, etc. of the local oscillation signal of the receiver, the frequency conversion device constituting the receiver includes the local oscillation signal in advance. It is necessary to provide a configuration for taking out a part.

For the above reasons, in the conventional frequency converter, the directional coupler 54 is inserted between the local signal generation circuit 51 and the isolator 55 as shown in FIG. 2 or FIG. A part of the local oscillation signal is extracted from the local oscillation signal monitoring terminal 54a of the directional coupler 54. The local oscillation signal monitor terminal 54a is terminated by a terminator (not shown) when the receiver is installed in the artificial satellite body.

Here, consider the power level of the local oscillation signal output from the local oscillation signal monitoring terminal 54a in the prior art. The power level of the local oscillation signal output from the local oscillation signal generation circuit 51 is about several tens [dBm (value based on 1 mW)].

Incidentally, the degree of coupling of the directional coupler 54 must be set so that the coupling loss of the local signal power can be ignored. For example, a coupling loss of 0.05 [d
B], it is necessary to set the degree of coupling to about 20 [dB].

In such a case, the power level of the local oscillation signal output from the local oscillation signal monitoring terminal 54a is -number [d
Bm]. Therefore, when the directional coupler 54 as described above is used as a means for outputting a local oscillation signal of an external mixer for measuring phase shift characteristics, group delay characteristics, and the like, an auxiliary amplifier having a gain of 10 to 20 [dB] is inserted. There is a need to.

The above-described monitor output is necessary only for testing and adjustment on the ground, and is not necessary for the operation of the receiver in orbit. However, conventionally, such a directional coupler 54 had to be incorporated in the frequency converter. For this reason, there have been problems such as an increase in size and weight of the receiver.

As an example, a C band (6/4 [GHz] band) or Ku band (14/12 [GHz] band) receiver used for a geostationary communication satellite 2
With a local signal of [GHz], a microstrip line directional coupler that requires a coupling length of approximately 1/4 wavelength requires a space of about 25 [mm] × 15 [mm] including a mounting portion. In some cases. Of course, this space is essentially unnecessary for operation of the receiver in satellite orbit.

The present invention has been made under such a background, and a frequency converter and a local oscillator capable of monitoring a local oscillation signal wave without providing an additional device or an additional component occupying a useless space. It is intended to provide a signal monitoring method.

[0022]

In order to solve the above-mentioned problem, according to the first aspect of the present invention, an input high-frequency signal of a first frequency is converted into a signal having a frequency different from the first frequency. A frequency converter for converting a local oscillation signal having a frequency difference between the first frequency and the second frequency into a high frequency signal having a frequency of 2 A circulator having a third terminal for passing the local oscillation signal in a predetermined direction with respect to the first to third terminals, a local oscillation signal passing through the circulator, and a high-frequency signal of the first frequency; And mixing means for mixing. Also,
In the invention according to claim 2, in the frequency conversion device according to claim 1, the circulator allows a signal to pass from the first terminal to the second terminal and causes the signal to pass through the second terminal. Passing a signal from the terminal to the third terminal, the local oscillator means being connected to a first terminal of the circulator, the mixing means being connected to a second terminal of the circulator, 3
And a part of the local oscillation signal is output from the terminal. In the invention according to claim 3,
In the frequency converter according to claim 2, the mixing means includes: a first input terminal to which a high-frequency signal of the first frequency is input; a second input terminal to which the local oscillation signal is input; An output terminal from which the high-frequency signal of the second frequency is output, wherein the second input terminal and the second terminal of the circulator are connected with a predetermined reflection coefficient. Further, in the invention according to claim 4, in the frequency conversion device according to any one of claims 2 and 3, the third terminal of the circulator is connected to a predetermined terminal after a test before operation and after the adjustment is completed. It is characterized by having a terminating means for terminating with impedance. Further, in the invention described in claim 5, claim 1 or claim 4 is provided.
In the frequency conversion device according to any one of the above, the mixing unit outputs a high-frequency signal of a second frequency that is a sum of the first frequency and a local oscillation frequency.
Also, in the invention according to claim 6, in the frequency conversion device according to any one of claims 1 to 4, the mixing means uses the difference between the first frequency and the local oscillation frequency. A high frequency signal of a certain second frequency is output. In the invention according to claim 7, a high-frequency signal of a first frequency is input from a first input terminal of the mixing means, a local oscillation signal is input from a second input terminal, and the local oscillation signal is input from an output terminal. A method for monitoring a local oscillation signal in a frequency converter that outputs a high-frequency signal having a second frequency, which is a sum or difference frequency between the frequency 1 and the local oscillation frequency, comprising: A local oscillation signal is input to the first terminal of the circulator that allows a signal to pass in the direction and passes the signal from the second terminal to the third terminal; and a second terminal of the circulator and the mixing means. And a second input terminal having a predetermined reflection coefficient, and monitoring a part of the local oscillation signal output from a third terminal of the circulator. Further, according to the invention described in claim 8, according to claim 7
In the method for monitoring a local oscillation signal described in (1), the third terminal of the circulator is terminated by a terminator having a predetermined impedance after a test or adjustment before operation.

[0023]

DETAILED DESCRIPTION OF THE INVENTION Configuration The present invention will be described below. FIG. 1 is a block diagram illustrating a configuration of a frequency conversion device according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a local oscillation signal generating circuit for generating a local oscillation signal for frequency conversion. Artificial satellites used for communication satellites and broadcasting satellites generally transmit and receive microwave band radio waves. In such a case, an element that oscillates a microwave is used for the local signal generation circuit.

Reference numeral 2 denotes a circulator. The circulator 2 is generally used for switching between transmission and reception of microwave charged waves (shared transmission and reception). The circulator 2 has three terminals 2a, 2b and 2c, and allows an electromagnetic wave (high-frequency current) to pass in the direction of the arrow in the figure. That is, the electromagnetic wave input from the terminal 2a is output in the direction of the terminals 2b and 2c. Reference numeral 4 denotes a terminator such as a terminating resistor or a terminating line connected to the terminal 2c of the circulator 2.

Reference numeral 3 denotes a frequency conversion circuit composed of a DBM or the like as an example. The frequency conversion circuit 3 has two input terminals (3a, 3c) and one output terminal (3b), and outputs a signal having a sum or difference frequency between the two input signals. .

In this embodiment, the local oscillation signal output from the local oscillation signal generation circuit 1 is supplied to the terminal 2a of the circulator 2
Is input to The local oscillation signal output from the terminal 2 b of the circulator 2 is input to an input terminal 3 c of the frequency conversion circuit 3.

On the other hand, a reception signal (transmission signal) whose frequency is to be converted is input to an input terminal 3a of the frequency conversion circuit 3. Thereby, the output terminal 3 of the frequency conversion circuit 3
b outputs a frequency-converted reception signal (transmission signal).

B. Operation The local oscillation signal output from the local oscillation signal generation circuit 1 is input to the terminal 2a of the circulator 2. Here, a case where a predetermined measuring instrument is connected without connecting the terminator 4 to the terminal 2c of the circulator 2 will be described. Here, the power level of the local oscillation signal output from the local oscillation signal generation circuit 1 is set to about several [dBm].

As described above, the signal input to the terminal 2a of the circulator 2 passes from the terminal 2a to the terminal 2b. In the present embodiment, the terminal 2 of the circulator 2
The local oscillation signal input to a is output from the terminal 2b after receiving a passing loss of about 0.5 [dB].

The local oscillation signal output from the terminal 2 b of the circulator 2 is input to an input terminal 3 c of the frequency conversion circuit 3. In the present embodiment, a predetermined mismatch is provided between the impedance of the terminal 2b of the circulator 2 and the impedance of the input terminal 3c of the frequency conversion circuit 3. The degree of the impedance mismatch is set as several [dB] or about 10 [dB] in terms of reflection loss.

As described above, the terminal 2b of the circulator 2
Since there is an impedance mismatch between the frequency conversion circuit 3 and the input terminal 3c of the frequency conversion circuit 3, most of the local oscillation signal power is input to the input terminal 3c of the frequency conversion circuit 3, but part of the power is reflected. In this case, the power level of the reflected local oscillation signal is about several [dBm] to about 10 [dBm] based on the value of the reflection loss at the input terminal 3c.

The local oscillation signal reflected by the input terminal 3c of the frequency conversion circuit 3 is input again to the terminal 2b of the circulator 2. As described above, the signal input to the terminal 2b of the circulator 2 passes from the terminal 2b to the terminal 2c.

In this embodiment, the local oscillation signal input to the terminal 2b of the circulator 2 is output from the terminal 2c after receiving a passing loss of about 0.5 [dB].
That is, the power level of the local oscillation signal output from the terminal 2c of the circulator 2 is approximately several dBm or 10 dBm.
[DBm].

The local oscillation signal output from the terminal 2c of the circulator 2 can be used not only for measuring phase noise but also for measuring phase shift characteristics and group delay characteristics as a local oscillation signal of an external mixer. That is, the terminal 2c of the circulator 2 functions as a monitor terminal for monitoring the local oscillation signal.

It should be noted that the terminal 2c of the circulator 2 in the present embodiment is terminated by the connection of the terminator 4 after the performance test or the adjustment is completed. When the circulator 2 terminates the terminal 2c, it functions as an isolator in which the passage from the terminal 2a to the terminal 2b is in the forward direction and the passage from the terminal 2b to the terminal 2a is in the reverse direction.

That is, in the frequency converter of the present embodiment,
By terminating the terminal 2c of the circulator 2 after the performance test or the adjustment on the ground is completed, there is no adverse effect on the operation of the artificial satellite equipped with the frequency conversion device on orbit during launch.

[0037]

As described above, according to the present invention, the high frequency signal of the first frequency is input from the first input terminal of the mixing means, the local oscillation signal is input from the second input terminal, and the output terminal is provided. A frequency converter that outputs a high-frequency signal of a second frequency, which is the sum or difference frequency of the first frequency and the local oscillation frequency, from the first terminal to the second terminal, A local oscillation signal is input to a first terminal of a circulator that passes a signal from the second terminal to a third terminal, and a predetermined reflection is made between the second terminal of the circulator and the second input terminal of the mixing means. It is connected by a coefficient and monitors a part of the local oscillation signal output from the third terminal of the circulator. In addition, since the third terminal of the circulator is terminated by a predetermined impedance terminating means after the test or adjustment before operation, the local oscillation signal wave can be monitored without providing an additional device or an additional component that occupies unnecessary space. And a method of monitoring a local oscillation signal that can be realized.

That is, according to the present invention, since the local oscillation signal can be monitored without using a directional coupler, the receiver, down converter, up converter, etc. mounted on an artificial satellite can be used without impairing the function. The size and weight can be reduced.

According to the present invention, the power level of the local oscillation signal output from the monitor terminal of the circulator is several [dB].
m] to 10 [dBm], depending on the external mixer, can be directly extracted as a local oscillation signal without using an auxiliary amplifier. Therefore, there is an advantage that measurement of the phase shift characteristic, the group delay characteristic, and the like is facilitated.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a frequency conversion device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a conventional frequency conversion device with a local oscillation signal monitoring terminal.

FIG. 3 is a block diagram showing an example of the configuration of a receiver mounted on an artificial satellite to which a conventional frequency converter with a local oscillation signal monitor terminal is applied.

[Explanation of symbols]

 Reference Signs List 1 local oscillation signal generation circuit (local oscillation means) 2a terminal (first terminal) 2b terminal (second terminal) 2c terminal (third terminal) 3 frequency conversion circuit (mixing means) 3a input terminal (first terminal) Input terminal 3c Input terminal (second input terminal) 3b Output terminal 4 Terminator (terminating means) 51 Local signal generation circuit 53 Frequency conversion circuit 53a Signal input terminal 53b Signal output terminal 53c Local signal input terminal 54 Directivity Coupling device 54a Coupling terminal 55 Isolator 56 Low noise amplification circuit 57 IF signal amplification circuit 58 Voltage conversion circuit 101 RF signal input terminal 102 IF signal output terminal

Claims (8)

[Claims] 1. A frequency conversion device for converting an input high-frequency signal of a first frequency into a high-frequency signal of a second frequency different from the first frequency, wherein the first frequency and the second frequency Local oscillation means (1) for oscillating a local oscillation signal having a frequency different from that of the first and second terminals, and first, second, and third terminals (2a, 2b, 2c). A circulator (2) for passing the local oscillation signal in a predetermined direction with respect to
A local oscillation signal passing through the circulator;
And a mixing means (3) for mixing the high frequency signal with a high frequency signal of the frequency conversion device. 2. The local oscillation circuit according to claim 1, wherein the circulator allows a signal to pass from the first terminal to the second terminal, and allows a signal to pass from the second terminal to the third terminal. The means is connected to a first terminal of the circulator, the mixing means is connected to a second terminal of the circulator, and a part of the local oscillation signal is output from a third terminal of the circulator. The frequency conversion device according to claim 1, wherein 3. The mixing means includes: a first input terminal (3a) to which the high frequency signal of the first frequency is input; and a second input terminal (3c) to which the local oscillation signal is input.
And an output terminal (3b) from which a high-frequency signal of the second frequency is output, wherein the second input terminal and the second terminal of the circulator are connected with a predetermined reflection coefficient. The frequency conversion device according to claim 2, wherein 4. Termination means (4) for terminating a third terminal of the circulator with a predetermined impedance after a test or adjustment before operation is completed.
Alternatively, the frequency conversion device according to claim 3. 5. The apparatus according to claim 1, wherein the mixing unit outputs a high-frequency signal having a second frequency that is a sum of the first frequency and a local oscillation frequency. The frequency converter according to any one of the preceding claims. 6. The apparatus according to claim 1, wherein the mixing unit outputs a high-frequency signal having a second frequency that is a difference between the first frequency and a local oscillation frequency. The frequency converter according to any one of the preceding claims. 7. A high-frequency signal having a first frequency is input from a first input terminal of the mixing means, a local oscillation signal is input from a second input terminal, and a difference between the first frequency and the local oscillation frequency is output from an output terminal. A method of monitoring a local oscillation signal in a frequency converter that outputs a high-frequency signal having a second frequency that is a sum or difference frequency, the method including: passing a signal from a first terminal to a second terminal; A local oscillation signal is input to the first terminal of the circulator that passes a signal from the second terminal to the third terminal, and the second terminal of the circulator and the second terminal of the mixing unit are input to the first terminal of the circulator.
A local reflection signal connected to the circulator with a predetermined reflection coefficient, and monitoring a part of the local oscillation signal output from a third terminal of the circulator. 8. The local oscillation signal monitoring method according to claim 7, wherein the third terminal of the circulator is terminated by a terminator having a predetermined impedance after a test or adjustment before operation.