JPS6035846A - Receiver - Google Patents

Abstract

PURPOSE:To detect the interference quantity of radio wave frequency with a simple constitution by receiving a composite signal of a voice signal and a digital signal, detecting the jitter quantity of the digital signal and detecting an interference value related to a prescribed function by the input of the jitter quantity. CONSTITUTION:A voice signal and a digital signal having different frequency bands are inputted to input terminals 11, 12 respectively and composed by a composing circuit 13 and the composite signal is transmitted from a transmitter 14. A receiving circuit 31 receives the composite signal of the voice and digital signals and an HPF32 and a LPF34 select the voice signal and the digital signal respectively. The digital signal is inputted to a data signal deciding circuit 35 and a received data signal is outputted from a terminal. The digital signal is also inputted to a jitter measuring circuit 37 and the jitter quantity detected by the circuit 37 is inputted to a data conversion circuit 38. The circuit 38 outputs the interference quantity of radio wave frequency having the relation of a fixed function to the jitter quantity from a terminal 39.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiver, particularly a radiotelephone receiver having the ability to detect interference at radio frequencies. In communications, interference is a problem when a limited frequency channel is shared by a large number of users, such as in mobile radio communications. That is, if a certain channel is being used regularly and another user uses the same channel, interference will occur in the radio frequency band, making it impossible for both parties to communicate. Accurately checking the usage status of this channel before starting communication will reduce the chance of such interference, but with mobile radio, etc., the lines are unstable, so this method is also insufficient. isn't it. A receiver having a function of detecting interference is of practical significance because it can detect this interference at an early stage while the amount of interference is small and can take measures such as switching to another channel.

Conventionally, as a method for detecting interference, for example, literature (1)
(Kokai, Ishikawa, "Study of co-frequency interference detection method in land mobile communications," Proceedings of the 1985 National Conference of the Institute of Electronics and Communication Engineers, 42176) is known. However, this method has the disadvantage that the circuit configuration becomes complicated.

An object of the present invention is to provide a reception Ia having an interference detection device with a simple circuit configuration.

In the present invention, a signal transmitted by combining an audio signal and a digital signal is received, the jitter of the digital signal is detected, and this jitter amount is input ξ to obtain a value determined by a predetermined functional relationship. Detected as an amount of interference.

The present invention will be described in detail below using the drawings.

FIG. 1 is a block diagram of a transmitter for the receiver of the present invention to communicate with koji. Dachi terminals 11 and 12
The audio signal and digital signal respectively inputted from the synthesizer circuit 13) are synthesized, and then transmitted by the transmitting circuit 14. FIG. 2 is a conceptual diagram of a transmission baseband signal spectrum. The frequencies of the audio signal spectrum 22 and the digital signal spectrum 21 are separated so that they do not overlap. Since it is usually sufficient for audio signals to be transmitted in a band of up to 300 KHz, digital signals can be inserted above or below this frequency band. In the embodiment of the present invention, the case is shown in which it is inserted on the lower side. In this way, there have been numerous attempts to simultaneously transmit digital signals by inserting digital signals into the lower band of the audio signal. "Study of Busy Signal Transmission in Communications", Proceedings of the 1985 National Conference of the Institute of Electronics and Communication Engineers, A 2201). The results show that transmission at a transmission rate of about 50 bits/second can be carried out satisfactorily. By transmitting the data signal at the same time as the audio signal, it is possible to have a high level of control over which channel to switch to when interference occurs.

FIG. 3 is a block diagram for explaining an example of a receiver using the present invention. The transmitted signal is received by the receiving circuit 31. The way it comes out is divided into two branches, - 10,000 is a high pass filter 3
24, the exclamation signal is sent to the output terminal 33.
I can get this. The other signal is input to the low-pass filter 34 to obtain a digital signal. The obtained digital signal is branched into two, one of which is input to the data signal determination circuit 35/, and output to the output terminal 36.
A received data signal is obtained. The other branched signal of the digital signal is input to the jitter measurement circuit 37, and its output is input to the data conversion 1/1 path 38.
The amount of interference is detected at the output terminal 39. Data conversion circuit 3
8 inputs the amount of jitter and outputs the amount of interference. For example, as shown in FIG. 7, there is a one-to-one functional relationship between the amount of jitter and the amount of interference. Naturally, as the amount of interference increases, the error rate increases. This functional relationship is almost determined once the transmitter/receiver circuit to be actually used is determined. However, as the amount of noise increases, variations occur in the functional relationship and the accuracy of detecting the amount of interference deteriorates, which is unavoidable as in the conventional method of detecting the amount of interference. The data conversion circuit 38 that determines the functional relationship can be easily implemented by, for example, a memory circuit that quantizes the amount of jitter, uses this as an address, and stores the interference t corresponding to that value as the memory content. .

FIG. 4 is a block diagram for explaining in detail a first configuration example of the data determination circuit 35 and jitter measurement circuit 37 included in the portion surrounded by the broken line in FIG. The received data signal is judged by the judgment circuit 52 according to the clock signal l obtained from the clock synchronization circuit 431, and the transmitted digital signal sequence (5) is obtained as an output. A portion of the clock signal is delayed by a delay circuit 45, and an input data signal is determined by a determination circuit 46 according to the obtained clock signal. Therefore, the determination circuits 42 and 46 sample the same data signal at different timings j1+il, as shown in FIG.

It is necessary that the data signal has as few errors as possible, so
It is desirable to sample at the optimal timing t.

When interference occurs in the radio frequency band, the jitter of the received data signal, that is, the fluctuation of the data change point of the data signal increases. Therefore, the timing t! is shorter than the optimal timing t1! If you sample with , the error will increase. As the amount of interference increases, the samples at timing It 4 also begin to have errors, but the change in increase is small compared to the increase in obscurity at timings t and l. In this embodiment, the amount of jitter is measured indirectly based on the difference in error increase. The output signal of the determination circuit 46 is, for example, the sixth
The result is as shown in Figure (b). Here, (6) the broken line indicates that an error has occurred. The signal 〆 indicates a signal obtained by delaying the output of the determination circuit 42 by the delay circuit 471. The signals in the delay circuits 45 and 47 have different sample values as shown in FIG. 6(C). This means that the amount of jitter has been indirectly measured.

FIG. 8 shows the data judgment circuit 35 and the jitter measurement circuit 3.
7 is a block diagram for explaining in detail a second configuration example of No. 7; FIG. The received data signal is judged by the judgment circuit 82 according to the clock signal obtained by the first clock synchronization circuit 83, and the output 0 is the transmitted digital signal sequence. Here, the clock synchronization circuit is
For example, assume a well-known configuration as shown in FIG. A data signal input to an input terminal 91 is successively input to a differentiating circuit 92, a detection circuit 93, and a resonator 94 whose center frequency is equal to the clock (repetition frequency).The output signal of the resonator 94 is input to a limiter circuit 95. A lock signal as shown in FIG. 10(a) can be obtained by inputting to It is desirable that the band of the resonator used in the circuit 83 is as narrow as possible.Interference occurs in the radio frequency band.
Jitter appears in the clock signal, and the amount of jitter increases as the interference increases. However, as described above, the amount of jitter varies depending on the band of the resonator.

The configuration of the second tarlock synchronization circuit 84 is also the same as that of the first one shown in FIG. However, the band of the resonator used is wider than that of the resonator used in the first clock synchronization circuit. By rubbing ζ in this way, when interference occurs in the radio frequency band, it is input to the filter 86, thereby obtaining a DC output proportional to the amount of jitter ζ. As a method for detecting the amount of jitter, various other conventionally known methods can be used.

As explained above, the present invention has the advantage of being able to detect the amount of interference by simply adding a simple circuit, compared to the method in which audio signals and data signals are transmitted simultaneously. When there is a lot of noise, the error in detecting the amount of interference increases, so in this case, it is practically useful to add a function to stop the interference detection operation. Also, on lines where fading occurs,
The relationship between the amount of jitter and the amount of interference may change depending on the fading pitch. At this time, the amount of interference can be accurately determined by adding a fading pitch detection function separately and changing the relationship between the amount of jitter and the amount of interference according to the detected value (9). .

[Brief explanation of drawings]

FIG. 1 is a block diagram of a transmitter that transmits signals for reception by the receiver of the present invention, FIG. 2 is a spectrum diagram of data signals and audio signals, and FIG. 3 is an embodiment of the receiver of the present invention. FIG. 4 is a waveform diagram for a partial block showing the first embodiment of the present invention in detail, FIG. 7 is a diagram conceptually showing the relationship between the amount of jitter and the amount of interference, and FIG. 9 is a partial block diagram showing details of the second embodiment of the present invention, and FIG. 9 is a signal waveform diagram for explaining this seizure. In these figures, 11 is an audio input terminal, 12 is a digital signal input terminal, 13 is a synthesis circuit, 14 is a transmitting circuit, 21 is a spectrum of a digital signal, 22 is a (10) spectrum of an audio signal, 31 is a receiving circuit, 32 is a high-pass filter, 33 is an audio signal output terminal, 34 is a low-pass filter,
35 is a signal judgment circuit, 36 is a digital signal output terminal,
37 is a jitter measurement circuit, 38 is a data conversion circuit, 39 is an interference amount output terminal, 41.81.91 is a data signal input terminal, 42.46.82 is a determination circuit, 43.83.84 is a clock synchronization circuit, 45 .47 is a delay circuit, 48.85
is an exclusive OR circuit, 49.86 is a low-pass filter,
92 is a differential circuit, 93 is a detection circuit, 94 is a resonator, 95
is a limiter. (11) Hand srgJ ↑ ↑ tl ↑2 Algae Diagram amount

Claims (1)

[Claims] means for receiving a composite signal of an audio signal and a digital signal; a jitter detecting means for detecting jitter in the digital signal; and a converting means for receiving the output of the jitter detecting means as an input and outputting a value determined by a predetermined functional relationship. and,
A receiver comprising: means for detecting the output of the converting means as an amount of interference.