JPH063944B2 - Receiver - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver that can be used for data communication.

Configuration of Conventional Example and Problems Thereof In recent years, mobile communication services such as pagers and car phones have become popular. In the above mobile communication, a transmission / reception device is used which is accompanied by data transmission of identification information such as a dial number of its own station or a partner station.

A conventional transmitting / receiving apparatus will be described below with reference to the drawings. FIG. 1 is a block diagram of a conventional transceiver.
In FIG. 1, I indicates a transmitter and II indicates a receiver. The transmitting device I has a tone generating circuit 2 which generates a frequency corresponding to information from the input circuit 1 which is a ten-key pad or the like. The tone generating circuit 2 is composed of, for example, oscillator groups 2a, 2b, 2c, 2d, ... Which generate different frequencies.
The switch 2e is switched according to the information from the input circuit 1,
It is configured to output a signal having a frequency corresponding to information. Further, the transmitting device I has an FM modulating circuit 3, a transmitting circuit 4, and a transmitting antenna 5. On the other hand, the receiver II has a receiving antenna 6, a high frequency amplifier circuit 7, a local oscillator circuit 8, a frequency conversion circuit 9, an intermediate frequency amplifier circuit 10, an FM demodulation circuit 11, and a frequency analysis circuit 12. The frequency analysis circuit 12 is composed of filters 12a, 12b, .... Further, the receiving device II has an information decoding circuit 13 and an output circuit 14 composed of a buzzer, a display or the like.

The operation of the transmitter / receiver configured as described above will be described below. When the input circuit 1 including a numeric keypad is operated to input information, a signal having a frequency corresponding to the input information is output from the tone generation circuit 2 and a high frequency signal is output from the tone generation circuit 2 by the FM modulation circuit 3. The signal is frequency-modulated, the transmission circuit 4 amplifies it, and the transmission antenna 5
More electromagnetic waves are transmitted. The function of the tone generating circuit 2 will be described in more detail with reference to FIG. Fig. 2
(a) is a spectrum diagram of frequencies that can be generated by the tone generating circuit 2. FIG. 2B is an output diagram showing the frequency sequence output from the tone generating circuit 2. Second
The figure (a) has shown that there are a total of n oscillators 2a, 2b, .... Each oscillator 2a, 2b, the oscillation frequency of the ...... are _{f 1, f 2,} a ...... _{f n.} The signals of these oscillating frequencies are switched by the switch 2e according to the information from the input circuit 1 and output at the time intervals shown in FIG. 2 (b). That is, the frequency switches every time T. Now, if the number n of oscillation frequencies is 10, then the numbers 0 to 9 can be associated with f ₁ to f ₁₀ , respectively, and if 4 frequencies are sent as shown in FIG. You can send digits. Next, the receiving device will be described. In the receiver II of FIG. 1, the electromagnetic wave input to the receiving antenna 6 is selectively amplified by the high frequency amplifier circuit 7, converted to an intermediate frequency by the frequency conversion circuit 9, and then the intermediate frequency amplification circuit 10
In the FM demodulation circuit 11, the frequency-converted signal is demodulated, and the signal of the frequency sequence shown in FIG. 2B is output to the output. The frequency analysis circuit 12 is composed of n filters 12a, 12b, ... For selectively separating n frequencies of frequencies f ₁ , f ₂ , ... F _n . Only the signal of f ₁ is taken out from the filter 12a and only the signal of f ₂ is taken out from the filter 12b. The information decoding circuit 13 determines the order and the frequency of the signals from the frequency analysis circuit 12, and drives the output circuit 14 such as a buzzer or a display.

However, in the above configuration, since the frequency modulation circuit is used, if the C / N of the receiver input deteriorates to some extent, the S / N of the demodulation circuit output starts to rapidly deteriorate, a so-called threshold point. Existed and was not practical at input levels below this.
Further, it is necessary to widen the reception bandwidth considering the temperature fluctuation of the local oscillation frequency. Therefore, it had the following problems. Since the reception bandwidth becomes wider than necessary, the S / N of the demodulation output deteriorates. Therefore, the limit level at which information can be decoded deteriorates, and the communication distance is also limited.

An object of the present invention is to provide a receiving device for performing data communication,
It is possible to prevent the deterioration of the reception performance due to the temperature fluctuation of the local oscillation frequency, and it is possible to narrow the reception bandwidth to the required bandwidth of the reception signal, which can improve the S / N ratio.
Another object of the present invention is to provide a receiver capable of significantly reducing malfunction due to noise.

A receiver according to the present invention is a receiver for receiving a signal including reference frequency information preset near the center of a frequency band used for information transmission, and a local oscillation circuit for determining a reception frequency, Frequency analysis means for performing frequency analysis of the received signal, and a signal from the frequency analysis means as an input,
Information decoding means for controlling the local oscillation circuit based on the difference between the frequency of the signal received at the start of signal reception and the reference frequency and for decoding the information transmitted from the frequency sequence obtained as a result of the frequency analysis, and the reference frequency signal When a signal arrives, a comparison means is provided to see that the output of the frequency analysis means after the local oscillation frequency of the local oscillation means is decoded by the information decoding means matches the reference frequency. The received signal of is detected by the frequency analysis means and the information decoding means, based on the detection result,
After controlling the local oscillating circuit so that the received signal comes near the center of the band of the frequency analysis means, it is confirmed by the comparison means that the signal corresponding to the reference frequency matches the reference frequency. Thus, the subsequent signal is received. According to such a configuration, even if the local oscillation frequency of the receiving device fluctuates due to a change in ambient temperature or the like, the signal corresponding to the reference frequency is detected by the frequency analysis circuit and the information decoding circuit, and based on the detection result, By controlling the local oscillator circuit, the reference frequency comes near the center of the reception band,
After that, since it is configured to start receiving the subsequent signal by confirming that it matches the reference frequency by the comparison circuit, there is no need to widen the reception bandwidth in consideration of temperature fluctuations, Can narrow the band. Therefore, the S / N can be improved, and thus the communicable distance can be expanded. Further, since the reception is started after the arrival of the reference frequency is confirmed by the comparison circuit, the malfunction due to noise can be remarkably reduced.

Description of Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of a transmitter / receiver according to an embodiment of the present invention. In FIG. 3, A is a transmitter and B is a receiver. The transmission circuit A includes an input circuit 1, a tone generator 15, a high frequency oscillation circuit 16, a frequency conversion circuit 17, a transmission circuit 4, and a transmission antenna 5. On the other hand, the receiving device B includes a receiving antenna 6, a high frequency amplifier circuit 7,
It has a local oscillation circuit 8, a frequency conversion circuit 9, an intermediate frequency amplification circuit 10, a local oscillation circuit 18, a frequency conversion circuit 19, a frequency analysis circuit 20, an information decoding circuit 21, a comparison circuit 22, and an output circuit 14. The same numbers are given to those having the same functions as those of the conventional example shown in FIG. The operation of the transmission / reception device of this embodiment configured as described above will be described below. First, the transmitter will be described. Information is input by operating the input circuit 1 including a numeric keypad. The function of the tone generator 15 will be described with reference to FIG. FIG. 4 (a) is a frequency spectrum diagram that can be generated by the tone generator 15. Figure 4 (b) ~ (e)
FIG. 4 is an output diagram showing an example of a frequency sequence output from the tone generator 15. Construction of the tone generator 15, for example, FIG. 4 (a) of f _{-n / 2} from f _{n / 2} to the oscillator 15a for generating a respective frequency, 15b, 15c, 15d, and ..., switch
It consists of 15e. The point that the function of the tone generator 15 is fundamentally different from the function of the conventional tone generating circuit 2 is that
That is, the reference frequency f ₀ is set near the center of the frequency band used for information transmission, and the information is defined in relation to the reference frequency f ₀ . The table shows an example in which information is defined in relation to the frequency difference from the reference frequency.

However, in FIG. 4 (a), the intervals between adjacent frequencies are all Δf. In FIG. 4 (a), the case is n = 10 (hereinafter treated as n = 10), and the numbers 0 to 9 are given as information. An example of the output of the tone generator 15 is shown in FIG. 4 (b). First, the reference frequency f ₀ is output for a time necessary and sufficient for performing operations such as frequency analysis and frequency correction of the local oscillator on the receiving side, and frequency analysis for confirmation, and then the frequency containing information. The columns are also output for the time required for frequency analysis. In the example of FIG. 4 (b), from the table, the numeral 3 → the numeral 8 → the numeral 9 (n = 1
0 means that f _{n / 2} = f ₅ ) → information is sent in the order of number 4. The signal in Fig. 4 (b) is
The signal is converted into a high frequency signal by the frequency conversion circuit 17, amplified by the transmission circuit 4, and transmitted from the transmission antenna 5 as an electromagnetic wave. Next, the receiving device will be described. Reception antenna 6
To the intermediate frequency amplifier circuit 10 are similar to the conventional case. The output of the intermediate frequency amplifier circuit 10 is converted to a lower frequency by the frequency conversion circuit 19. The frequency conversion circuit 19 converts a signal into a frequency band that can be easily processed by the frequency analysis circuit 20, and sets a conversion frequency as necessary. When the local oscillation frequency deviates due to temperature fluctuation or the like, the output of the frequency conversion circuit 19 becomes an output having a spectrum obtained by moving the spectrum of FIG. 4 (a) in parallel on the frequency axis. Therefore, there is no change in the frequency difference of each spectrum. The frequency analysis circuit 20 is composed of filters 20a, 20b, ... For separating the signal from the frequency conversion circuit 19 into each spectrum. The signal of FIG. 4 (b) is input to the frequency analysis circuit 20 in a frequency-converted form, and when a signal corresponding to the reference frequency f ₀ arrives first, the filter group (20a, 2a
The output starts from one of the filters 0b, 20c, ...). In the case of an original signal, since a signal required for frequency analysis is transmitted, it is output as signal detection from the filter after the time constant required for detection and input to the information decoding circuit 21.

Here, in the case of noise instead of the original signal, an erroneous output may be output as signal detection after the elapse of a predetermined time constant. In the information decoding circuit 21, the above-mentioned signal inputted first is set as the reference frequency f ₀ , and the local oscillation circuit 8 is controlled so that the signal corresponding to the reference frequency comes near the center of the band of the intermediate frequency amplification circuit 10. . After that, the comparison circuit 22 checks whether or not the signal corresponding to the reference frequency is output from the filter near the center of the filter group arranged in the band of the intermediate frequency amplification circuit 10.

Since the reference frequency f ₀ is sent for a sufficient time necessary for frequency analysis, correction of the oscillation frequency of the local oscillator, and frequency analysis for confirmation, the arrival of the reference frequency should be confirmed by inspection of the comparison circuit 22. Can be done. Further, even if the noise is erroneously detected as the arrival of the signal corresponding to the reference frequency at the start of the signal arrival, the noise is output only for the time required for the frequency analysis after the local oscillation frequency correction of the intermediate frequency amplifier circuit. Therefore, it is possible to remarkably reduce the discrimination error to the reference frequency due to noise. After the arrival of the reference frequency f ₀ is recognized by the comparison circuit 22,
The subsequent signal is received, the information decoding circuit 21 determines the frequency difference from the reference frequency f _0, and drives the output circuit 14. FIG. 5 is a block diagram showing an example of the configuration of the frequency analysis circuit 20, and FIGS. 6A and 6B are functional explanatory diagrams of the frequency analysis circuit 20. Now, as shown in Fig. 6 (b),
Consider a case where the reference frequency f ₀ and the frequency f ₋₁ of the difference of −Δf are sequentially input. At this time, the reference frequency f ₀ is set to the filter 2
Assuming that it is within the band of 0e, the band of the filter is designed so that when the frequency f _-1 is input next, f _-1 will be within the band of the filter 20b. Assuming that the bandwidth, center frequency, etc. have changed slightly, as shown in f ′ ₋₁ of FIGS. 6 (a) and 6 (b), the filter 20
It is also conceivable that the shift is within the band of a. However, as shown in FIG. 5, a filter group composed of a plurality of filters, such as a filter group 2 centered on the filter 20e and a filter group 1 centered on the filter 20b, is assigned for one frequency discrimination. In other words, when the frequency difference is approximately -Δf, the filter group 1 is selected, and it is possible to prevent an error in signal discrimination. Further, since the bandwidth of each filter can be narrowed, S / N can be improved and the decoding level of information can be lowered. In this example, each group is made up of three filters to form one group, but if the bandwidth of each filter is narrowed and the number of filters in one group is increased,
In addition, S / N can be improved, information can be decoded at a lower level, and the communication range can be expanded. Local oscillation circuit 8
In the control of 1, the local oscillation circuit may be configured to use a variable capacitance diode, and a DC voltage according to the frequency difference between the frequency of the incoming signal and the reference frequency may be applied to the variable capacitance diode. According to this embodiment, as described above, and transmits the difference between the reference frequency f ₀ as the information, and the reference frequency f ₀ is controlling the local oscillation circuit 8 to center the intermediate frequency amplifier circuit 10 Therefore, there is no possibility that the information cannot be received due to the influence of the fluctuation of the local oscillation frequency, and it is not necessary to widen the reception bandwidth against the temperature fluctuation and the like. As a result, the bandwidth on the receiver side can be made very narrow, the S / N can be greatly improved, and the communicable distance can be expanded. further,
Since the reference frequency is monitored by the comparison circuit 22, it is possible to remarkably reduce the error of discrimination to the reference frequency due to noise.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 7 shows a block diagram of a transmitting / receiving apparatus in another embodiment of the present invention. In FIG. 7, A is a transmitter and B is a receiver. The same numbers are given to blocks having the same functions as those in the embodiment of FIG. The transmitter A has an input circuit 1 and a tone generator 35. The tone generator 35 includes a D / A converter 23, a high frequency oscillation circuit 25, and a variable capacitance diode 24. The transmitter A has a transmission circuit 4 and a transmission antenna 5. On the other hand, the receiving device B includes a receiving antenna 6, a high frequency amplifier circuit 7, a local oscillation circuit 8, a frequency conversion circuit 9, an intermediate frequency amplification circuit 10, a local oscillation circuit 18, a frequency conversion circuit 19,
A / D converter 26, analysis unit 2 having a frequency analysis function
8. An information decoding unit 29 having an information decoding function and a comparison unit 30 having a comparison function are provided.

Here, the frequency analysis unit 28, the information decoding unit 29, and the comparison unit 30 are composed of a microcomputer 27.
Further, the receiving device B has an output circuit 14. Next, the operation will be described. The digital information from the input circuit 1 is input to the D / A converter 23 forming the tone generator 35 and converted into an analog quantity. The capacitance value of the variable capacitance diode 24 is controlled by the analog amount, and the high frequency oscillation frequency of the high frequency oscillation circuit 25 is controlled. When a ten-key switch or the like is operated, the input circuit 1 first outputs a digital signal of the reference frequency f ₀ , and then a digital signal corresponding to the input information. The digital signal is converted into an analog quantity by the D / A converter 23, and the high frequency oscillation frequency of the high frequency oscillation circuit 25 is changed according to the information. Since the analog quantity output from the D / A converter 23 changes stepwise in accordance with the information, the spectrum and output of the high frequency oscillation frequency of the high frequency oscillation circuit 25 are as shown in FIGS. 4 (a) and 4 (b). become. The signal shown in FIG. 4 (b) is amplified by the transmission circuit 4 and transmitted from the transmission antenna 5 as an electromagnetic wave. Next, the operation of the receiver B will be described.
The output of the frequency conversion circuit 19 is converted into a digital signal corresponding to the input analog signal by the A / D converter 26, and frequency-analyzed by a frequency analysis unit 28 included in the microcomputer 27 by a method such as a Fourier transform method. The analysis result is sent to the information decoding unit 29. When the information decoding unit 29 first obtains a signal corresponding to the reference frequency f _0, it outputs a signal for controlling the oscillation frequency of the local oscillation circuit 8 and controls the frequency analysis unit 28 to the center of the analyzable frequency band. Then, the comparison unit 30 checks whether or not the signal corresponding to the reference frequency actually arrives at the position of the reference frequency f ₀ .
If the reference frequency f ₀ is recognized, the subsequent signal is received and the information decoding circuit 21 takes out the information. If the comparison unit 30 does not confirm the match with the reference frequency f ₀ , it is recognized as a malfunction due to noise, the local oscillation circuit 8 is returned again to reset the operation of the receiving device, and the arrival of the reference frequency f ₀ is waited for. . After the arrival of the reference frequency, as shown in FIG.
_The frequency of ₋₂ → f ₄ → f _n / 2 → f ₋₁ is analyzed, the information decoding unit 29 determines the difference from the reference frequency f _0, and the output circuit 1
Drive 4 By configuring the oscillation frequency of the local oscillation circuit 8 in this way, it is possible to obtain a receiving device that is resistant to frequency fluctuations due to temperature changes and the comparison unit 30 inspects the arrival of the reference frequency. Therefore, malfunction due to noise can be significantly reduced. In the above embodiment, the output of the tone generator 35 has been described with reference to the form shown in FIG. 4 (b), but the signal forms shown in FIGS. 4 (c) to (e) may be used. . FIG. 4 (c) shows a mode in which the reference frequency f ₀ is inserted between the frequencies of the information and transmitted, and FIG. 4 (d) shows the reference frequency f _{0 by} −nΔf.
This is a mode in which after transmitting the frequency f _−n deviated from, the signal of f _n deviated by the distance nΔf where the sign is inverted is transmitted. Fourth
In the figure (e), two types of reference frequencies, f ₁ and f _-1 , are used. The signal forms after the reference frequencies f ₁ and f ₋₁ are the same as those in FIG. 4 (c). Furthermore, the signal form is not limited to (b) to (e) of FIG. 4, and the point is that the reference frequency is first transmitted and then the signal containing information is transmitted. For example, signals of several kinds of frequencies may be transmitted in parallel in time, or the reference frequency may be sent again at the end for the purpose of ending communication. The controlled local oscillation circuit may be either the circuit 8 or the circuit 18. The frequency analysis unit 28 may be a Fourier transform by a program of the microcomputer 27, or may be an externally connected analog or digital filter group.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, the reference frequency is first transmitted, and then the signal containing the information is transmitted, and the first reference frequency is detected by the frequency analysis circuit in the receiving device, and the local oscillation is performed. Since the circuit is controlled so that the reference frequency comes near the center of the band of the intermediate frequency amplifier circuit,
It is possible to eliminate the influence of temperature fluctuations of the local oscillation frequency, to minimize the bandwidth of the intermediate frequency amplifier circuit, to improve the S / N, to prevent malfunction due to noise, and to reduce the electric field strength. The excellent effect of being able to decipher information even in weak places can be obtained. As a result, the communicable distance can be dramatically increased. Further, since the reference frequency is monitored by the comparison circuit, it is possible to remarkably reduce the error of discrimination to the reference frequency due to noise.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional transmitter / receiver, FIG. 2 is a functional explanatory diagram of a tone generation circuit of the same, FIG. 3 is a block diagram of a transmitter / receiver in one embodiment of the present invention, and FIG. FIG. 5 is a functional explanatory diagram of a tone generation circuit of a transceiver in one embodiment of the present invention, FIG. 5 is a configuration diagram of a frequency analysis circuit of the transceiver in one embodiment of the present invention, and FIG. 6 is a transceiver in one embodiment of the present invention. Functional explanation diagram of the frequency analysis circuit of
FIG. 7 is a block diagram of a transmitter / receiver according to another embodiment of the present invention. 1 ... Input circuit, 2 ... Tone generation circuit, 3 ... FM modulation circuit, 4 ... Transmission circuit, 5 ... Transmission antenna, 6 ...
Receiving antenna, 7 ... High frequency amplification circuit, 8 ... Local oscillation circuit, 9 ... Frequency conversion circuit, 10 ... Intermediate frequency amplification circuit, 11 ... FM demodulation circuit, 12 ... Frequency analysis circuit,
13 ... Information decoding circuit, 14 ... Output circuit, 15 ... Tone generator, 16 ... High frequency oscillation circuit, 17 ... Frequency conversion circuit, 18 ... Local oscillation circuit, 19 ... Frequency conversion circuit, 20 ... ... frequency analysis circuit, 21 ... information decoding circuit, 22 ... comparison circuit, 23 ... D / A converter, 24 ...
… Variable capacitance diode, 25 …… High frequency oscillation circuit, 26
... A / D conversion circuit, 27 ... Microcomputer,
28 ... Frequency analysis unit, 29 ... Information decoding unit, 30 ...
Comparator, 35 ... Tone generator.

Claims (1)

[Claims] 1. A receiving device for receiving a signal including reference frequency information preset near the center of a frequency band used for information transmission, the local oscillating circuit for determining the receiving frequency, and the frequency analysis of the receiving signal. Frequency analysis means for performing, and a signal from the frequency analysis means as an input, and controlling the local oscillation circuit based on the difference between the frequency of the signal received at the start of signal reception and the reference frequency and the frequency obtained as a result of the frequency analysis. Information decoding means for decoding the information transmitted from the column, and the arrival of the reference frequency signal, the result of decoding the output of the frequency analysis means after the local oscillation frequency correction of the local oscillation means by the information decoding means is the reference frequency. Comparing means for seeing that the received signal upon arrival of any signal is detected by the frequency analyzing means and the information decoding means. Based on this detection result, the local oscillator circuit is controlled so that the received signal comes near the center of the band of the frequency analysis means, and then the signal corresponding to the reference frequency is matched with the reference frequency by the comparison means. A receiving device characterized in that it is configured to receive a subsequent signal by confirming that the signal is being processed.