JPS6167315A - Automatic frequency controlling system - Google Patents

Abstract

PURPOSE:To eliminate the influence of the frequency variation of the local oscillator of a transmitting and receiving system, by extracting a pilot signal inserted at the transmitting side at the receiving side and automatically controlling the frequency. CONSTITUTION:A pilot signal of a frequency f0 inserted from a synthesizer 11 becomes to have a frequency of f0+DELTAf at the output of a frequency converter 20 due to the frequency variation of the oscillator 3 at the transmitting station and oscillator 9 at the receiving station. The pilot signal is extracted by a pilot detecting filter 14 and FM detector 15 and converted into a voltage. The converted voltage is supplied to an error detecting circuit 17 and an error voltage corresponding to the frequency variation DELTAf is outputted. The error voltage is inputted in a voltage controlling type oscillator 19 after noises are removed from the error voltage at an LPF18. Therefore, the frequency of the pilot signal always becomes f0 at the output of the frequency converter 20 and the influence of the frequency variation of the oscillators at the transmitting and receiving stations can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control formula that automatically corrects the influence of frequency fluctuations of a local oscillator included in a wireless device.

[Conventional technology]

FIG. 1 is a block diagram showing an example of the configuration of a conventional wireless device, in which 1 is a modulator, 2 is a transmission frequency converter, 3 is a transmission local oscillator, 4 is a transmission amplifier, 5 is a transmission antenna, Reference numeral 6 represents a receiving antenna, 7 a receiving amplifier, 8 a receiving frequency converter, 9 a receiving local oscillator, and 10 a demodulator.

The stability of the conventional mless device, as shown in the Pt51 diagram, is
As is clear from this figure, it depends on the frequency stability of the transmitting and receiving local oscillators.

[Problem that the invention seeks to solve]

In the above-mentioned m'f-free device, for example, the frequency stability of the local oscillator in the 20 GHz band is ±1 × 10'/ΔT.
(ΔT is the operating temperature range), a frequency fluctuation of ±2 MHz will occur.

Therefore, in the conventional system, in order to ensure stability, the local oscillator must be made of a complex and sophisticated device with little frequency fluctuation, which reduces the economic efficiency of the device. There was a point.

On the other hand, in the normal h1 configuration, due to such frequency fluctuations, the radio channel 11'! Since it is necessary to increase the spacing, there is a disadvantage that the frequency utilization efficiency decreases; in the case of the synchronous detection method, the PLL loop bandwidth has to be widened, which has the disadvantage of increasing reproduced carrier noise. .

In order to solve these drawbacks, the present invention inserts a biloft signal on the transmitting side, detects the frequency fluctuation of the pilot signal with an FM detector on the receiving side, and uses this detection output to generate a local oscillator of the frequency converter. This is intended to automatically control the oscillation frequency of the voltage-controlled keepsake oscillator to suppress the influence of frequency WL fluctuations of the local oscillators of the transmitting device and the receiving device.

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be described in detail based on the drawing of an Example.

[First Embodiment] FIG. 2 is a block diagram showing one embodiment of the present invention,
1 is a modulator, 2 is a transmission frequency converter, 3 is a transmission oscillator, 4 is a transmission amplifier, 5 is a transmission antenna, 6 is a reception antenna, 7 is a reception amplifier, 8 is a reception frequency converter, 9 is a reception Local oscillator, 10 is a demodulator, 11 is a synthesizer, 12 is a slotted oscillator, 13 is a distributor, 14 is a biloft detection filter, 15 is an FM detector, 16 is a base voltage input terminal, 17 is an error detector , 18 is a low-pass filter, 19
2 represents a voltage-controlled keepsake, and 20 represents a frequency converter.

In FIG. 2, the biloft signal of oscillation frequency f0 inserted from the synthesizer 11 has a frequency of f0+Δf at the output of the frequency rlL converter 20 due to frequency fluctuations of the transmitting local oscillator 3 and the receiving local oscillator 9.

This pilot signal passes through a pyroft detection filter 14 (bandpass filter) with a center frequency f0, and FM detection i! 315, it is converted to a voltage of ■18. By supplying the voltage V to the reference voltage input terminal 16, the error detector 17 outputs an error voltage {circle around (2)} corresponding to the frequency rlL variation Δf1.

The error voltage is further removed from noise by a low-pass filter 18, and then inputted to a voltage-controlled vibrator 191.

As mentioned above, from the divider 13 in FIG.
Since a feedback loop is formed up to 0,
At the output of the frequency converter 20, the frequency aWL of the biloft signal
is always r. Therefore, the influence of frequency fluctuations of the transmitting and receiving local oscillators can be removed.

〔Effect of the invention〕

As explained above, according to the method of the present invention, the transmitting/receiving system extracts the viroft signal inserted in the transmitting (J system) on the receiving side and automatically controls the frequency to maintain a predetermined value. Since the influence of the frequency fluctuation of the local 86 oscillator is corrected, the local oscillator of the device can be a simple and inexpensive one1, which has the advantage that the device can be realized economically. Since a stable signal that is not affected by local oscillator frequency fluctuations can be expected, it is possible to make the IllwS of the wireless channel as easy as possible, and in the case of a synchronous detection method, the PLL loop bandwidth can be reduced. This has the advantage of reducing reproduced carrier noise by narrowing the carrier.

[Brief explanation of the drawing]

ttS1 diagram shows an example of the configuration of a conventional wireless device.
Figure 2 is a professional diagram showing one embodiment of the present invention.
? , 7. . 1...Modulator, 2...Transmission frequency converter, 3...Transmission local oscillator, 4...
...Transmission amplifier, 5 ...Transmission antenna,
6...Receiving antenna, 7...
Receiver (d amplifier, 8... Receive frequency transformer S,
9...Reception local oscillator, 10...
・Avenger, IX...... combination! Vessel, X2...
...Pyro 7) Oscillator, 13 ...Distributor, 14 ...Pyro no lj! output filter,
15...1-do-M detector, 16...
Reference voltage input terminal 17...Error detector,
18...Low pass filter, 19...
...Voltage controlled oscillator, 20... Frequency converter agent Patent attorney Takashi Honma

Claims (1)

[Claims] In a wireless transmission/reception system that performs communication in opposite directions, the transmitting system is provided with a synthesizer for inserting a pilot signal into the transmitted signal, and the receiving system is provided with a frequency converter having a voltage-controlled oscillator as a local oscillator, and the frequency converter is provided with a frequency converter having a voltage-controlled oscillator as a local oscillator. means for extracting a pilot signal from the output of the oscillator, and means for outputting a frequency deviation of the extracted pilot signal as a corresponding DC voltage, and applying the DC voltage to the voltage controlled oscillator to oscillate it. An automatic frequency control method that controls the frequency of a received pilot signal to maintain a predetermined value by automatically adjusting the frequency.