JPH011336A - microwave transmission equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave transmission device that converts the frequency of a transmission IF (intermediate frequency) into a transmission microwave.

1. Prior Art] Conventionally, when converting a microwave local oscillator into a synthesizer, a reference signal source for a phase-locked loop used to stabilize the frequency of the microwave local oscillator has been developed in consideration of cost and simplicity of H3 construction. As a method, a specific axial low frequency frequency synthesizer oscillator is used. Additionally, recently, the microwave frequencies used have tended to become higher.

On the other hand, in small capacity systems, a comparatively low F frequency is often adopted, so in such cases a double conversion method in which frequency conversion is performed twice is generally adopted. It is.

[Problems to be Solved] In the conventional configuration described above, the purpose is to easily convert a microwave local oscillator into a frequency synthesizer, and the voltage controlled oscillator (hereinafter referred to as , abbreviated as VCO) is -/f
It has a fairly wide band voltage tuning characteristic. Therefore, it is susceptible to external mechanical vibrations, shocks, etc., and its frequency tends to fluctuate. Therefore, the output frequency of a microwave oscillator whose phase is synchronized using this frequency synthesizer as a reference source also fluctuates due to mechanical vibrations and shocks. As a result, there was a problem in that FM modulation was applied.

This is particularly a serious problem when applied to small-capacity digital communications, and in the worst case, there is a possibility that the frame synchronization of the entire system will be out of sync.

To solve this problem, conventional vibration isolation structures have been used to protect against vibrations caused by mechanical shock and sound pressure, but this complicates the mechanical structure of the entire device.
The price was also high, and it was not a desirable method.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a microwave transmission device that is simple in structure and is not adversely affected by mechanical vibrations or shocks.

Means for Solving Problem L] The present invention provides a voltage-controlled first local oscillator and a first frequency mixer for converting the frequency of a first IF multiplied signal and a second IF multiplied signal; a second local oscillator and a second frequency mixer for converting the IF multiplied signal into a microwave signal; and a phase-locked loop for frequency stabilization of the second local oscillator using a frequency synthesizer as a reference signal source. In the microwave transmission device, the oscillation frequencies of the first and second local oscillators are different from the first and second local oscillators.
The polarity of the two frequency conversion operations in the frequency mixer is set to an oscillation frequency with opposite characteristics to each other, and a part of the feedback voltage of the phase-locked loop is branched, and only the alternating current component is sent to the frequency mixer. The control voltage is applied to the control voltage application terminal of the first local oscillator.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings.

The drawing is a block circuit diagram of an apparatus according to an embodiment of the present invention.

In the same figure, □ indicates that the device of this embodiment adopts a double conversion method in order to support a comparatively small capacity digital communication system conducted in a comparatively high microwave frequency band (near the quasi-millimeter wave band). are doing.

For this purpose, a first frequency mixer 2 generates a second IF multiplied signal by frequency mixing the first IF multiplied signal from the IF signal input terminal 1 and the oscillation frequency of the first local oscillator 3; It has a second frequency mixer 6 that mixes the frequency of this second IF multiplied signal and the oscillation frequency of the second local oscillator 7.

Here, the first local oscillator 3 is usually one in the IF band, and a fixed frequency one such as a crystal oscillator is used for -1u, but it has a control voltage application terminal for fine adjustment of the oscillation frequency. ing.

Said 1st. A low-pass filter 4 and a first amplifier 5 are provided between the second frequency mixers 2 and 6.

Furthermore, a bandpass filter 8 and a second amplifier 9 are provided downstream of the second frequency mixer 6 to pass only a required microwave signal, and a microwave signal output terminal 10 is provided.
The output is now obtained.

Here, as a characteristic configuration of the apparatus of this embodiment, the above-mentioned first.
The oscillation frequency of the second local oscillator 3.7 is the same as that of the first local oscillator 3.7. The polarities of the two frequency conversion operations in the second frequency mixers 2 and 6 are set to oscillation frequencies with opposite characteristics.

Further, the second local oscillator 7 uses the output signal of the frequency synthesizer 11 with a specific axial low frequency as a reference signal source, and configures a phase loop with a phase ratio calibrator 12 and a loop amplifier 13. The 4F6i voltage signal of the loop branched at the branch terminal 14 provided at the capacitor 15
The DC component is cut by the first local oscillator 3.
Only the alternating current component is applied to the oscillation frequency control voltage application terminal of the oscillation frequency control voltage application terminal.

The operation of the device configured as above will be explained.

Due to the mechanical vibrations applied to the frequency synthesizer 11, the output signal of the frequency synthesizer 11 is subjected to FM modulation in accordance with the vibrations. Therefore, the output signal of the second local oscillator 7, which is phase-synchronized with this, also has an FM frequency.
There will be some modulation. This means that the phase loop follows mechanical vibration, so a voltage corresponding to this vibration is detected at the branch terminal 14 in the loop.
By applying only this AC component to the control voltage terminal of the first local oscillator 3, the first local oscillator 3 is also subjected to FM modulation in accordance with the mechanical vibration.

Here, the first. During the second frequency conversion, the FM modulation component can be equivalently canceled by reversing the vertical relationship of the local oscillation frequency with respect to the signal.

Therefore, in this embodiment, it is not necessary to take any mechanical anti-vibration measures against vibrations caused by external mechanical vibrations, shocks, sound pressure, etc. This makes it possible to simplify the physical structure (the physical structure) and, in turn, to reduce the price of the device.

In this way, the device of this embodiment utilizes the fact that the frequency fluctuation signal due to mechanical vibration etc. can be detected by the phase-locked loop configured to stabilize the frequency of the second local oscillator 7. is applied to the voltage control terminal of the first local oscillator 3, and a fluctuation signal is also given to the first local oscillator 3. In the first frequency conversion and the second frequency conversion, by reversing the vertical relationship of the local oscillation frequency with respect to the signal, the first frequency conversion due to the fluctuation signal is performed.
By making the polarities of the FM modulation characteristics of the second local oscillators 3 and 7 equivalently opposite characteristics, this fluctuation signal can be canceled in the final output.

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Effects of the Invention] As explained above, according to the present invention, it is possible to electrically take measures against vibrations caused by external mechanical vibrations, shocks, sound pressure, etc., and mechanical improvements as vibration-proofing measures can be taken. Since this is not necessary, the mechanism of the device can be simplified and the cost of the device can be reduced.

[Brief explanation of drawings]

The drawing is a block circuit diagram of an apparatus according to an embodiment of the present invention. 2; first frequency stabilization; 3; first local oscillator; 6; second frequency mixer; 7; second local oscillator; Agent: Patent Attorney Kihei Watanabe

Claims (1)

[Claims] a voltage-controlled first local oscillator and a first frequency mixer for frequency converting a first IF signal into a second IF signal; and a voltage-controlled first local oscillator and a first frequency mixer for converting the second IF signal into a microwave signal. A microwave transmission device comprising a second local oscillator, a second frequency mixer, and a phase-locked loop for frequency stabilization of the second local oscillator using a frequency synthesizer as a reference signal source, The oscillation frequencies of the first and second local oscillators are set to oscillation frequencies such that the polarities of the two frequency conversion operations in the first and second frequency mixers have opposite characteristics, and the phase A microwave transmission device characterized in that a part of the feedback voltage of the synchronous loop is branched, and only the alternating current component thereof is applied to the control voltage application terminal of the first local oscillator.