JP3219786B2 - Squelch control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squelch control method, and more particularly to a squelch control method in a microwave digital radio system.

[0002]

2. Description of the Related Art A conventional transmitting apparatus and receiving apparatus of a microwave digital radio system have a configuration shown in FIG. 3, and a part of the output of a main intermediate frequency amplifier 3 in the receiving apparatus is detected by a detector 7. In addition to obtaining a signal detection voltage, a gain control voltage is generated by a gain control amplifier (AGC) 4 based on the signal detection voltage, and the gain control voltage and a reference voltage for setting a squelch level are compared with a comparator (COMP). ) 5
The squelch point is detected by comparing with.

[0003]

In this conventional squelch control method, since squelch detection is performed only with a gain control voltage within a reception frequency band, an interference wave having a squelch level or higher is received in a no-signal state. Even in such a case, there is a problem that the squelch operation is not performed when there is a signal.

An object of the present invention is to provide a squelch control method which eliminates a squelch malfunction caused by reception of an interference wave in a no-signal state.

[0005]

A squelch control method according to the present invention is provided by a digital radio system.
A squelch control that prevents interference with its own system,
For identification in the transmission device, the control signal identifies the signal of the own system and the transmission device can be identified for each line.
First means for adding and transmitting a code, and an identification code for reading the identification code from a received signal in a receiving device.
A reader for reading the identification code,
The same code as the identification code added by the first means.
A second means including a code comparing unit for outputting a comparison result, and the code comparing unit determining whether the code matches the identification code.
And a third means for causing the receiving device to perform a squelch operation when detection is not possible .

[0006]

[0007]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the embodiment shown in FIG. 1, a transmitting panel 1 adds an identification signal for identifying that the signal is a self-system signal to an analog control signal, and transmits the analog control signal from a transmitting antenna. The high-frequency signal received from the receiving antenna is transmitted to the receiving high-frequency board (R
XRF) 2 to be converted into an intermediate frequency signal, and input to the main intermediate frequency amplifier 3. A part of the output of the main intermediate frequency amplifier 3 is input to an identification signal detector (DET) 8 to determine the presence or absence of an identification signal. In the identification signal detector (DET) 8
Demodulates the control signal from the input signal,
The identification signal is detected by the control signal. Identification signal detected
If not, the signal received by the receiver
Judge that there is. If the received wave is an interference wave, the squelch control unit (SQL) 6 determines that a squelch point has been detected, and the squelch operation can be performed even if the detector 8, AGC 4, and COMP 5 do not detect the squelch point. Becomes

Therefore, when an interference wave having a squelch level or higher is received in a no-signal state, the identification signal cannot be detected .
Therefore , it is determined that the received radio wave is an interference wave, and squelch malfunction is prevented.

[0010] By the way, the transmission and reception of the same system unit and its
And paired receiver, for example, there is a case where the direction is used for each line of the two different routes. In the embodiment of FIG. 1 described above, it is determined whether a received radio wave is a received signal of the own line or an interference wave based on the presence or absence of an identification signal for identifying a signal of the own system . In some cases, it is not possible to distinguish an interference wave from another line of the same system from a reception signal of the own line, and in this case, a correct squelch operation cannot be performed due to the interference wave. FIG. 2 shows a second squelch operation that can be performed correctly even in such a case.
FIG. 4 is a block diagram of an embodiment of FIG.

In the embodiment shown in FIG. 2, a transmitting board (TX) 1 adds an identification code to an analog control signal and transmits the analog control signal from a transmitting antenna. This identification code is a code composed of a plurality of bits that can be used to identify the device of each line of the system for each line. The high-frequency signal received from the receiving antenna is converted into an intermediate frequency signal by the RXRF 2 and is input to the main intermediate frequency amplifier 3. A part of the output of the main intermediate frequency amplifier 3 is used as an identification code detector (DET) 8A
And read the identification code. By comparing the read code with the same identification code set in the TX 1 by the code comparison unit (COMP) 9, it is determined whether the received radio wave is a signal of the own line of the own system or an interference wave. In the case of an interference wave, the squelch point is detected in SQL6 and the squelch operation can be performed.

Therefore, even if an interference wave from another line of the same system is received in a no-signal state, the identification code detected from the received radio wave is compared with the identification code set in the receiving panel to obtain the received radio wave. Is determined to be a signal of its own line or an interference wave, and a malfunction of the squelch control can be eliminated.

[0013]

As described above, according to the present invention, the identification signal added to the control signal in the transmitting device is detected in the receiving device, and if it cannot be detected, the received signal is determined to be an interference wave, and the squelch point is determined. By detecting it,
There is an effect that a squelch malfunction in waiting for reception of an interference wave can be eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram of a second embodiment of the present invention.

FIG. 3 is a block diagram of a conventional squelch control method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission board 2 Reception high frequency board 3 Main intermediate frequency amplifier 4 Gain control amplifier 5 Comparator 6 Squelch control part 7 Detector 8 Identification signal detector 8A Identification code detection part 9 Identification code comparison part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-109439 (JP, A) JP-A-58-172098 (JP, A) JP-A-60-103832 (JP, A) 57730 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/10-1/14 H04B 1/04 H04B 1/16 H04B 1/38-1/58 H04B 7/14 -7/22

Claims (1)

(57) [Claims] (1)Other systems in digital wireless systems
With squelch control to prevent interference from the system to the own system
So,  The transmitting device automatically receives the control signal.systemSignal
And identifyFor identification and transmission equipment that can be identified for each line
the codeFirst means for adding and transmitting; andRead identification code
An identification code reading unit for reading the identification code;
Code with the identification code added by the first means.
Code comparison unit that compares the same code and outputs the comparison result.
IncludingA second means;The code comparing section detects a match with the identification code.
When you can not A second step of causing the receiving device to perform a squelch operation.
3. A squelch control method comprising: