JPS63110842A - Reception control system - Google Patents

Abstract

PURPOSE:To control an AFC circuit without its own station identification signal and to correctly receive a signal with a frequency allocated to its own station by providing a radio transmitter-receiver with the AFC and a digital processor with a discrimination part discriminating a station identification signal inserted into a reception signal. CONSTITUTION:The radio transmitter-receiver 1 separately connected to the digital processor 2 in a reception control system is provided with the AFC circuit made up of a frequency converter 6, a demodulator 7 and a partial oscillator 3. A synchronizing circuit 8 in the processor 2 outputs the station identification signal inserted into the reception signal, and a decision part 4 decides whether the signal is to identify its own station. If not, the oscillation frequency of the partial oscillator 3 is controlled. A control signal that the decision part 4 identifies is inputted to a control circuit 20 and a switch circuit 19. A control voltage applied to a voltage controlled oscillator 18 as a 2nd frequency partial oscillator is changed to automatically receive the signal of the frequency allocated to its own station.

Description

[Detailed Description of the Invention] [Summary] In a digital wireless communication system, a wireless transmitting/receiving device is placed on the antenna side and a digital processing device is placed separately on the indoor side, etc., and the digital processing device converts received signals into Extracts the included station identification signal and determines whether it is the own station identification signal, and if it is not the own station identification signal, automatically controls the receiving local oscillation frequency of the wireless transmitter/receiver to follow the received signal frequency. It controls the automatic frequency control circuit and performs a re-locking operation so that it can receive the signal in which the own station identification signal is inserted.

[Industrial application field]

The present invention provides a reception control system in which a radio transmitting/receiving device and a digital processing device are placed separately in a digital wireless communication system in which frequency intervals are set to be relatively narrow, so that signals to the own station can be correctly received. It is related to the method.

In order to make effective use of frequencies, frequencies are allocated at narrow intervals, and an automatic frequency control circuit is installed in the receiving system of wireless transmitting and receiving equipment to eliminate errors in the transmitting side frequency and the receiving side local oscillation frequency. A configuration for correcting this is adopted. In such a case, it is necessary to be able to reliably receive the signal of the frequency assigned to the own station.

[Conventional technology]

A wireless communication system that performs digital wireless communication between a plurality of opposing stations has, for example, the configuration shown in FIG. 3. In the same figure, 31.36.41.46 are digital processing units (DU), 32, 35, 42.45
is a wireless transmitter/receiver (TA), 33, 34.43.44
is an antenna. Wireless transmitting/receiving device 32, 35.42.
45 includes a transmitting section including a modulator, a frequency converter, etc., and a receiving section including a frequency converter, a demodulator, an automatic frequency control circuit, etc. Each wireless transmitter/receiver 32°35.42
．． Digital processing devices 31, 36, 4 connected to 45
1.46 adds a frame synchronization signal to transmission data of a predetermined length and transfers it to the wireless transmitting/receiving devices 32.35, 42.45, and also performs frame synchronization of the received signal from the wireless transmitting/receiving devices 32, 35, 42.45. and processes the received data.

The automatic frequency control circuits of the radio transmitting/receiving devices 32, 35, 42, and 45 are for correcting errors in the transmission frequency on the transmitting side and the receiving local oscillation frequency on the receiving side. It is something that you have. In the same figure, 5
1 is a frequency converter, 52 is a voltage controlled oscillator as a local oscillator, 53 is a band pass filter, 54 is a demodulator, 5
5 is an amplifier, and 56 is a low-pass filter.

A received high frequency signal or a received intermediate frequency signal is applied to a frequency converter 51, mixed with a local oscillation signal from a voltage controlled oscillator 52, converted to an intermediate frequency signal, and added to a demodulator 54 via a bandpass filter 53. The demodulated data is transferred to a digital processing device. Further, the signal indicating the frequency difference from the demodulator 54 is amplified by the amplifier 55 and becomes the control voltage of the voltage controlled oscillator 52 via the low-pass filter 56, which converts the received high frequency signal or received intermediate frequency signal input to the frequency converter 51. The frequency of the local oscillation signal is controlled to follow the frequency.

In addition, in order to make effective use of frequencies, frequency allocation is relatively narrow, but the local oscillation frequency is adjusted by the automatic frequency control circuit mentioned above so that the local oscillation frequency can be received by the frequency signal assigned to the own station. Automatically controlled.

Frequencies in the tens of GHz band have come to be used, and for example, when communicating using a frequency of 20 GHz or higher, it is necessary to separate the antennas 33, 34, 43° 44 and the radio transmitting/receiving device 32, 35, 42, 45. If the antennas 33, 34, 43, 44 and the wireless transmitter/receiver bag W
A configuration that integrates 32°, 35.42.45 is adopted. In that case, the digital processing section 31.36.41
．． 46 is placed indoors due to power consumption and connection with other devices. That is, the wireless transmitting/receiving devices 32, 35, 42
．． 45 and the digital processing units 31, 36, 41, and 46 are arranged separately.

[Problem that the invention seeks to solve]

By providing an automatic frequency control circuit, even if the transmission frequency on the transmitting side fluctuates somewhat, the receiving side can track the fluctuation and perform reception processing. However, in a small-capacity wireless communication system, the frequency bandwidth becomes narrower, so the frequency allocation interval also becomes narrower. For example, as shown in Fig. 5, if we consider the assigned frequency fo of our own station as the center, the frequencies of other stations will be fLl + fL2 + at intervals of 8f.
f141+fH2, . . . In that case, if Δf is 5 MHz and the bandwidth centered on the frequency fo is 5 MHz, it will overlap with adjacent frequencies of other stations. Also, due to a difference in the transmission frequency on the transmitting side or a difference in the reception local oscillation frequency of the own station, the 6th
As shown in the figure, the frequency f of the own station. If a shift of αf occurs around , the frequency interval between adjacent frequencies fLI+fHI becomes even narrower.

In such frequency allocation and reception conditions, if the reception level of the allocated frequency fo of the own station decreases due to fading etc. and the reception level of the adjacent frequency fLI+fMl is high, the signal of the adjacent frequency fLl+fMl is A pseudo pull-in phenomenon may occur in which the automatic frequency control circuit operates in a manner similar to that of a receiver. Therefore, in a wireless communication system as shown in FIG.
Countermeasures were taken, such as changing the orientation of 4.43.44 to prevent parallel wireless lines from forming.
It was not possible to demonstrate sufficient effectiveness.

It is also possible to apply a method of adding an identification signal for route identification, but as mentioned above, the wireless transmitter/receiver 3
2, 35, 42. 45, antenna 3 installed on the roof ring
3.34.43.44, and the digital processing devices 31.36, 41.46 are placed indoors, the wireless transmitting/receiving devices 32, 35, 42.45 are equipped with identification signal extraction, discrimination, etc. It would be nearly impossible to provide such a processing function. Therefore, it has been difficult to detect pseudo entrainment.

An object of the present invention is to detect such pseudo-retraction, perform a re-retraction operation, and perform control so that a correct signal can be received.

[Means for solving problems]

The reception control system of the present invention detects pseudo pull-in by an automatic frequency control circuit using a station identification signal and performs a re-lock-in operation, which will be explained with reference to FIG. A wireless transmitting/receiving device 1 is placed on the antenna 5 side, and a digital processing device 2
is placed indoors, etc., and the wireless transmitting/receiving device 1 controls the oscillation frequency of the local oscillator 3, which applies a local oscillation signal to the frequency converter 6, using a signal corresponding to the deviation from the center frequency by the demodulator 7. The digital processing bag R2 has a synchronization circuit 8 to perform frame synchronization, a decoder 9 to decode and output data, and extracts a station identification signal, which is the own station identification signal. It includes a determination unit 4 that determines whether or not there is.

When the determination unit 4 of the digital processing unit 2 determines that the station identification signal is not the own station identification signal, it applies a control signal to the radio transmitting/receiving device 1 to control the automatic frequency control circuit and to control the local oscillator 3. It sweeps the oscillation frequency, temporarily stops frequency conversion, etc., and starts the re-pulling operation.

[Effect]

The wireless transmitting/receiving device 1, which is integrated with or placed close to the antenna 5, is equipped with an automatic frequency control circuit, has a function of converting a received high frequency signal into an intermediate frequency signal, and demodulating the intermediate frequency signal, and This does not include a function to determine whether or not a signal of the assigned frequency is being received. On the other hand, the digital processing unit 2 extracts the station identification signal and determines whether or not it is the own station identification signal in the determining unit 4. If it is determined that it is not the own station identification signal, the digital processing unit 2 extracts the station identification signal and determines whether or not it is the own station identification signal. Therefore, the control signal is applied to the wireless transmitting/receiving device 1, the automatic frequency control circuit is controlled, the re-locking operation is started, and the process is repeated until it is determined that the own station identification signal has been received. , the correct signal can be received and processed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of main parts of an embodiment of the present invention, and 11
is the first frequency converter, 12 is the first local oscillator, 13
is a bandpass filter, 14 is a second frequency converter, 1
5 is an AGC amplifier, 16 is a bandpass filter, 17 is a demodulator, 18 is a voltage controlled oscillator as a second local oscillator, 19 is a switch circuit, 20 is a control circuit such as a kickoff circuit, and double super heterodyne reception. The main parts of the wireless transmitting/receiving apparatus of this system are shown, and the digital processing apparatus to which demodulated received data is added and outputs a control signal based on the determination result of the station identification signal is not shown.

A received high frequency signal from an antenna (not shown) is applied to a first frequency converter 11, converted into a first intermediate frequency signal by a local oscillation signal from a first local oscillator 12, and passed through a bandpass filter 13. via the second frequency converter 14.

A local oscillation signal from a voltage controlled oscillator 18 as a second local oscillator is applied to the second frequency converter 14 via a switch circuit 19, and the first intermediate frequency signal is applied to the second intermediate frequency signal. The received data is amplified to a constant signal level by the AGC amplifier 15, and applied to the demodulator 17 via the bandpass filter 16. The demodulated received data is transferred to a digital processing device (not shown). Ru.

The control circuit 20 also includes an amplifier, a low-pass filter, etc., and has the function of sweeping the local oscillation frequency by changing the magnitude of the control voltage applied to the voltage-controlled oscillator 18 when a control signal is applied. . When no control signal is applied, a control voltage corresponding to the detection signal from the demodulator 17 is formed to control the voltage controlled oscillator 18, and the local oscillation frequency is automatically controlled in accordance with the received frequency. It is something.

The received data of the demodulated output includes a synchronization signal, two station identification signals, and data.The frame synchronization in which the synchronization signal is detected is performed by known means, and the station identification signal is extracted and predetermined. It is determined whether or not the own station identification signal is the own station identification signal. When it is determined that the signal is the own station identification signal, no control signal is output, so the automatic frequency control circuit controls the oscillation frequency of the voltage controlled oscillator 18 to follow the fluctuations in the reception signal frequency.

Also, if a pseudo pull-in is performed in the automatic frequency control circuit so that signals of adjacent allocated frequencies can be received,
You will receive a signal containing the station identification signal of another station,
Since it is determined that this station identification signal is not the own station identification signal, a control signal is output. That is, pseudo-retraction detection is performed. This control signal is applied to either or both of the switch circuit 19 and the control circuit 2o. The illustrated state shows a case in which it is connected so that it can be added to both.

For example, when the switch circuit 19 is controlled to be turned off by a control signal and turned on after a predetermined period of time has passed, the local oscillation signal is no longer applied to the frequency converter 14 because the switch circuit 19 is turned off, and the frequency No conversion will be performed. Therefore, the automatic frequency control circuit escapes from the pseudo-pull state. Then, when the switch circuit 19 is turned on, frequency conversion is started, a pull-in operation in the automatic frequency control circuit is started, and control is performed so that the local oscillation frequency corresponds to the received signal frequency.

When in a pseudo pull-in state, the above-mentioned operation is repeated until it determines that it has received its own station identification signal, and by determining that it has received its own station identification signal, the local oscillation frequency becomes the one that corresponds to the received signal frequency at that time. Controlled by automatic frequency control circuit so that the correct signal can be received and processed.

In addition, in a configuration in which only the control circuit 20 is controlled by the control signal and the switch circuit 19 is in the on state or omitted, when the control signal is applied, the voltage controlled oscillator 1
The control voltage of No. 8 is greatly changed to escape the pseudo-retracted state and start the re-retracting operation. Thereby, the signal of the frequency assigned to the own station can be correctly received.

In the above embodiment, a case is shown in which the automatic control circuit including the voltage controlled oscillator 18 as the second local oscillator is controlled in response to the reception determination result of the station identification signal.
It is also possible to configure an automatic frequency control circuit using the first local oscillator 12 as a voltage controlled oscillator and control it using the above-mentioned control signal. Of course, the present invention can also be applied to a single super heterologin system.

〔Effect of the invention〕

As explained above, in the present invention, the wireless transmitting/receiving device 1 having an automatic frequency control circuit and the digital processing device 2 are arranged separately, the intervals between allocated frequencies are narrow, and the automatic frequency control circuit is used to control the allocation of other stations. Even if the signal is pulled into the frequency, the determination unit 4 in the digital processing device 2 determines whether or not it is the own station identification signal, and if it is not the own station identification signal, the automatic frequency control circuit is controlled. Even if a pseudo-retraction state occurs when the power is turned on or due to deterioration of the S/N of the wireless line, it will be detected and the re-retraction operation will be started. This has the advantage of being able to receive the correct signal on the own station's assigned frequency.

[Brief Description of the Drawings] Figure 1 is a principle block diagram of the present invention, Figure 2 is a block diagram of main parts of an embodiment of the present invention, Figure 3 is an explanatory diagram of a wireless communication system, and Figure 4 is an automatic frequency Block diagram of control circuit, 5th
The figure is an explanatory diagram of frequency allocation, and FIG. 6 is an explanatory diagram of frequency fluctuation. 2 is a radio transmitting/receiving device, 2 is a digital processing device, 3 is a local oscillator, 4 is a determining section, 5 is an antenna, 6 is a frequency converter, 7 is a demodulator, 8 is a synchronization circuit, and 9 is a decoding section.

Claims (1)

[Claims] A wireless transmitting/receiving device (1) and a digital processing device (2) are arranged separately, and the wireless transmitting/receiving device (1) converts the oscillation frequency of a receiving local oscillator (3) into a received signal. The digital processing device (
2) includes a determination unit (4) that extracts the station identification signal inserted into the received signal and determines whether it is the own station identification signal; When determining that the signal is not a self-station identification signal, the wireless transmitting/receiving device (1)
A reception control method, characterized in that the automatic frequency control circuit is controlled to perform a re-pulling operation.