JPS60247352A - Receiver - Google Patents

Abstract

PURPOSE:To improve S/N and also to prevent a malfunction due to noise for a receiver by transmitting first a reference frequency then the signal containing information, and detecting the first reference frequency by a frequency analyzing circuit at the receiver to control a local oscillation circuit so that the reference frequency is set at a point near the center of the band of an intermediate frequency amplifier circuit. CONSTITUTION:The output signal of a tone generating part 15 is converted into a frequency and supplied to a frequency analyzing circuit 20. A signal corresponding to a reference frequency f0 is first outputted from one of filters of filter groups 20a, 20b... and supplied to an information decoding circuit 21. The circuit 21 dfines the signal supplied first as the frequency f0 and controls a local oscillation circuit 8. Thus the signal corresponding to the frequency f0 is set at a point near the center of the band of an intermediate frequency amplifier circuit 10. Then a comparator 22 checks whether or not the signal corresponding to the f0 is generated at the point near the center of band of the circuit 10. Thus it is possible to prevent a discriminating error due to noise, etc. to the reference frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a receiving device that can be used for data communication.

Conventional configurations and their problems In recent years, mobile communication services such as pagers and car telephones have become popular. In the above-mentioned mobile communications, a transmitting/receiving device is used that transmits data for identification information such as a dial number of the own station or a partner station.

A conventional transmitting/receiving device will be described below with reference to the drawings. FIG. 1 is a block diagram of a conventional transmitting/receiving device.

In FIG. 1, 1 indicates a transmitting device, and ■ indicates a receiving device. The transmitting device 1 has a tone generating circuit 2 that generates a frequency corresponding to information from an input circuit 1 consisting of a numeric keypad or the like. This tone generating circuit 2 is made up of, for example, a group of oscillators 2a, 2b, 20.2d, which generate different frequencies, and switches a switch 2e based on information from the input circuit 1 to output a signal with a frequency corresponding to the information. It is configured to do so. Further, the transmitting device (2) has an FM modulation circuit 3, a transmitting circuit 4, and a transmitting antenna 5. On the other hand, the receiving device■
are a receiving antenna 6, a high frequency amplification circuit 7, and a local oscillation circuit 8.
, frequency conversion circuit 9, intermediate frequency amplification circuit 10, ll'M
It has a demodulation circuit 11 and a frequency analysis circuit 12. This frequency analysis circuit 12 is composed of filters 12a and 12b. The receiving device (■) also includes an information decoding circuit 13,
It has an output circuit 14 composed of a buzzer, a display, etc.

The operation of the transmitting/receiving device configured as above will be described below. When the input circuit 1 consisting of a numeric keypad or the like is operated and information is input, a signal with a frequency corresponding to the input information is output from the tone generation circuit 2, and an FM modulation circuit 3 outputs a high frequency signal from the tone generation circuit 2. The signal is frequency modulated, amplified by the transmitting circuit 4, and sent to the transmitting antenna 5.
It is sent out as electromagnetic waves. The function of the tone generating circuit 2 will be explained 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. In FIG. Figure 2(b) shows
3 is an output diagram showing a frequency sequence output from the tone generation circuit 2. FIG. FIG. 2<a) shows the oscillators 2a and 2b.

This shows that there are a total of n pieces. Each oscillator 2a, 2
The oscillation frequencies of b, . . fl, f2. ...fn. These oscillation frequency signals are switched by a switch 2e based on information from the input circuit 1 and outputted at the time intervals shown in FIG. 2(b). That is, the frequency is switched every time T. Now, if the number n of oscillation frequencies is 10, then the numbers 0 or 9-1: so i so t1. '1 from f
It is possible to correspond to up to 0, and by sending four frequencies as shown in FIG. 2(b), it is possible to send a four-digit number. Next, the receiving device will be explained. In FIG. 1 (■), the electromagnetic waves input to the receiving antenna 6 are selectively amplified by the high frequency amplification circuit 7, converted to an intermediate frequency by the frequency conversion circuit p, further selectively amplified by the intermediate frequency amplification circuit 10, and then selectively amplified by the FM demodulation circuit 11. The frequency-converted signal is demodulated, and its output is shown in Figure 2 (b).
)t, pc are output. The frequency analysis circuit 12 calculates the frequency f1. f2. . . . n filters 12 &, 1 for selectively separating n frequencies of fn
2b.

It consists of... From the filter 128, fl
Only the signal f2 is extracted from the filter 12b. The information decoding circuit 13 determines in what order and with what frequency the signals from the frequency analysis circuit 12 come, and drives an output circuit 14 such as a buzzer or a display.

However, since the above configuration uses a frequency modulation circuit, there is a so-called threshold point where when the C/N of the receiver input deteriorates to a certain extent, the S/N of the demodulation circuit output begins to deteriorate rapidly. existed, and it was not practical at input levels below this level.

Furthermore, it is necessary to widen the reception bandwidth in consideration of temperature fluctuations in the local oscillation frequency. Therefore, it had the following problems. This is because the reception bandwidth becomes wider than necessary, and the S/N of the demodulated output deteriorates.

Therefore, the level at which information could be deciphered deteriorated, and there was also a limit to the distance over which communication could be made.

OBJECT OF THE INVENTION An object of the present invention is to provide a receiving device that performs data communication,
It is possible to prevent deterioration of reception performance due to temperature fluctuations in the local oscillation frequency, and it is also possible to narrow the reception bandwidth to the required bandwidth of the reception signal 1, thereby improving S/Ni,
Another object of the present invention is to provide a reception system that can prevent malfunctions caused by noise.

Configuration of the Invention A receiving device according to the present invention includes: a frequency analysis circuit that frequency-analyzes a signal containing preset reference frequency information; and an information decoding circuit that receives the signal from the frequency analysis circuit as input.
It is equipped with a local oscillator 101 that determines the reception frequency and a comparison circuit that checks whether No. 1b, which corresponds to the reference frequency, matches the reference frequency. With this configuration, even if the local oscillation frequency of the receiving device fluctuates due to changes in ambient temperature, etc., a signal corresponding to the reference frequency is detected by the frequency analysis circuit and the information decoding circuit, and based on the detection result, the signal corresponding to the reference frequency is detected. By controlling the local oscillator circuit, the reference frequency is placed near the center of the receiving band, and then
It is configured so that reception of the subsequent signal is started when the comparison circuit matches the reference frequency.
There is no need to widen the reception bandwidth in consideration of temperature fluctuations, and the band can be narrowed. Therefore, the S/N ratio can be improved, and the communicable distance can therefore be expanded. Also,
Since reception is started after the arrival of the reference frequency is confirmed by the comparison circuit, malfunctions due to noise can be prevented.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 shows a block diagram of a transmitting/receiving device in an embodiment of the present invention. In Figure 3, Al1-
1: transmitting device, B is receiving device.

The transmitting circuit A includes an input circuit 1 , a tone generator 15 , a high frequency oscillation circuit 16 , a frequency conversion circuit 17 , a transmitting circuit 4 , and a transmitting antenna 6 . On the other hand, receiving device B includes a receiving antenna 6, a high frequency amplification circuit 7, a local oscillation circuit 8, a frequency conversion circuit 9, an intermediate frequency amplification circuit 10. It has 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. Components having the same functions as those of the conventional example shown in FIG. 1 are given the same numbers. The operation of the transmitter/receiver of this embodiment configured as described above will be described below.

First, the transmitting device will be explained. An input circuit 1 consisting of a numeric keypad or the like is operated to input information. The function of the tone generator 16 will be explained based on FIG. FIG. 4(a) is a frequency spectrum diagram that can be generated by the tone generator 15. FIGS. 4(b) to 4(e) ld are output diagrams showing examples of frequency sequences output from the tone generator 15. The configuration of the tone generator 15 is, for example, shown in FIG.
Oscillators 15a, 1, 5b, 15c generate frequencies from fn/2 to fn/2 of l.

It consists of 15d, . . . and a switch 15e. The function of the tone generator 16 that is fundamentally different from that of the conventional tone generation circuit 2 is the reference frequency f.

and information about the reference frequency f. The relationship with □ is also defined in □. The table shows an example of 1° in which information is defined in terms of the frequency difference relationship with the reference frequency.

However, in FIG. 4(a), the intervals between adjacent frequencies are all set to Δf. In FIG. 4(a), the case is n.=10 (hereinafter treated as n-10), and numbers 0 to 9 are given as information. 1 of the output of tone generator 15
An example is shown in FIG. 4(b). First, the reference frequency f0 is output, and then a frequency sequence containing information is output. In the example of Figure 4(b), from the table, number 3 - number 8 -
This means that information is sent in the order of class letter 9 - number 4. The signal shown in FIG. 4(b) is converted into a high frequency signal by the frequency conversion circuit 17, amplified by the transmitting circuit 4, and transmitted from the transmitting antenna 5 as an electromagnetic wave. Next, the receiving device will be explained. The operation from the receiving antenna 6 to the intermediate frequency amplification circuit 10 is the same as in the conventional case. A frequency conversion circuit 19 converts the output of the intermediate frequency amplification circuit 1o to a lower frequency. This frequency conversion circuit 191-1. ,
The frequency analysis circuit 20 converts the signal into a frequency band that is easy to process, and the conversion frequency is set as necessary. If the local oscillation frequency deviates due to temperature fluctuations or the like, the output of the frequency conversion circuit 19 will have a spectrum obtained by shifting the spectrum shown in FIG. 4(a) in parallel on the frequency axis. Therefore, there is no change in the frequency difference between each spectrum. Now, the frequency analysis circuit 20 is the frequency conversion circuit 19
It is composed of filters 20a, 20b, - for separating signals from the spectrum into respective spectra. The signal shown in FIG. 4(b) is input into the frequency analysis circuit 20 in a frequency-converted form, and is immediately set to the reference frequency f. A signal corresponding to the filter group (20a.

20b, 20C, -''') and input to the information decoding circuit 21.

The information is input to the information decoding circuit 21. In the information decoding circuit 21, the above-mentioned signal inputted first is set as a reference frequency fo,
The local oscillation circuit 8 is controlled so that a signal corresponding to the reference frequency comes near the center of the band of the intermediate frequency amplification circuit 10.

Thereafter, a signal corresponding to the reference frequency is transmitted to the intermediate frequency amplifier circuit 10.
Comparison circuit 2 determines whether or not it appears near the center of the band.
Inspect in step 2. This can prevent errors in determining the reference frequency due to noise or the like. The comparison circuit 22 determines the reference frequency f. After the arrival of the reference frequency f is recognized, the subsequent signal is received and the information decoding circuit 21 [Thus, the reference frequency f.

The output circuit 14 is driven by determining the frequency difference between the two. 6th
The figure is a block diagram showing an example of the configuration of the frequency analysis circuit 20, and FIGS. 6(a) and 6(b) are functional explanatory diagrams of the frequency analysis circuit 20.

Now, in Fig. 6 (as in b'l, the reference frequency ■. and -
Consider a case where frequencies f, which are the difference between Δf, are sequentially input.

At this time, the reference frequency f. If the frequency is within the band of filter 20e, then when the next frequency f is input, is the filter band designed so that f-1 falls within the band of filter 2ob? If the bandwidth, center, frequency, etc. of the filter change slightly, the filter 20 will change as shown at f'-1 in Fig. 6(a) and (b).
It is also possible that it deviates to the even range of a. As shown in FIG.
: If a filter group made up of multiple filters is assigned to one frequency discrimination as in the first suggestion, if the frequency difference is approximately 1 Δf, filter 1 is selected. Misjudgment can be prevented. -'! 7
Since the bandwidth of each filter can be narrowed, the S/N ratio can be improved and the level of information decoding can be further increased. In this example, each group consists of three filters, but if you narrow the bandwidth of each filter and increase the number of filters in one group, the S/N can be further improved. , it becomes possible to decode information at a lower level, and the communication distance can be expanded. The local oscillation circuit 8 can be controlled by configuring the local oscillation circuit using a variable capacitance diode and applying a DC voltage to the variable capacitance diode according to the frequency difference between the frequency of the incoming signal and the reference frequency. According to this embodiment, the reference frequency amount is preferably greater than or equal to 0.

The difference between the reference frequency f and the reference frequency f is transmitted as information.

Since the local oscillation circuit 8 is controlled so that the signal is located at the center of the intermediate frequency amplification circuit 1o, there is no possibility that information cannot be received due to fluctuations in the local oscillation frequency. No need for wide bandwidth. Due to this, the bandwidth on the receiver side can be made extremely narrow, making it possible to significantly improve the S/N ratio and expand the communicable distance. Furthermore, the comparison circuit 22
Since the reference frequency is monitored by the noise, the reference frequency may be incorrectly determined! 7'fr: A protective body is created.

Next, other embodiments of the present invention will be described with reference to the drawings. FIG. 7 shows [B0. A diagram is shown below. In FIG. 7, A is a transmitting device and B is a receiving device. Blocks with the same functions as those in the embodiment of FIG. 3 are given the same numbers. The transmitter A has an input circuit 1 and a tone generator 16. The tone generator 15 includes a D/A converter 23, a high frequency oscillation circuit 25, and a variable capacitance diode 24. The transmitting device A has a transmitting circuit 4 and a transmitting antenna 5. On the other hand, the receiving device B has a receiving antenna 6, a high frequency amplification circuit 7, a local oscillation circuit 8, a frequency conversion circuit 9, an intermediate frequency amplification circuit 101 and a local oscillation circuit. 18, frequency conversion circuit 19,
It has an A/D converter 26, a frequency analysis circuit 20, an information decoding circuit 21, and a comparison circuit 22. Here, frequency analysis circuit 2
0, the information decoding circuit 21 and the comparison circuit 22 are composed of a microcomputer 27. The above-mentioned receiving device B has an output circuit 14. Next, the operation will be explained. The digital information from the input circuit 1 is sent to the tone generator 1.
The signal is inputted to the D/Afi converter 23 constituting 5 and converted into an analog quantity. The capacitance value of the variable capacitance diode 24 is controlled by the analog quantity, and the high frequency oscillation frequency of the high frequency oscillation circuit 25 is controlled. When the numeric keypad, switch, etc. is operated, the reference frequency amount is input without switching from input circuit 1.

A digital signal is output, and then a digital signal corresponding to the input information is output. The digital signal is D/A
The converter 23 converts it into an analog quantity, and the high frequency oscillation circuit 2
The high frequency oscillation frequency of 5 is changed in accordance with the information. D
/ Since the analog quantity that is the output of the 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 shown in FIG.
) and (b). The operation of the zero-order receiving device B, which amplifies the signal shown in FIG. 4(b) in the transmitting circuit 4 and transmits it as an electromagnetic wave from the transmitting antenna 5, will be described.

The output of the frequency conversion circuit 19 is converted into a digital signal according to the input analog signal by the Al1) converter 26, frequency analyzed by a method such as a Fourier transform method by the frequency analysis circuit 20, and the analysis result is sent to the information decoding circuit. Sent to 21. If the information decoding circuit 21 obtains a signal corresponding to the reference frequency f0, it outputs a signal that controls the oscillation frequency of the local oscillation circuit 8, and controls the frequency to the center of the frequency band that can be analyzed by the frequency analysis circuit 20. Next, check the signal equivalent to the reference frequency or the actual reference frequency ■. The comparator circuit 22 checks whether it has arrived at the position. Here, the reference frequency f0
If it is recognized that this is the case, the subsequent signal is received and the information decoding circuit 21 extracts the information. If the reference frequency f0
If no output is obtained, then it means that high-energy noise has just been input, and the local oscillation circuit 8 is turned back on again to wait for the arrival of the reference frequency f0. After the reference frequency arrives, as shown in FIG. 4(b), the frequencies '-2-'4-'n/2-'-1 that are sent sequentially thereafter are frequency-analyzed, and the information decoding circuit 21 determines the reference frequency. The difference from the frequency of 1° is determined, and the output circuit 14 is driven. By configuring the oscillation frequency of the local oscillation circuit 8 to be controlled in this manner, it is possible to provide a receiving device that is resistant to frequency fluctuations due to temperature changes, etc., and the arrival of the reference frequency can be detected by the comparison circuit 22.
Since the test is carried out with In the above embodiment, the output of the tone generator 15 is explained in the form shown in FIG. 4(b), but for example, the signal form shown in FIG. No.

FIG. 4(C) shows the reference frequency amount between the information frequencies. This is a form in which the data is transmitted by inserting the
-nΔf the reference frequency f. After transmitting a frequency fi shifted from , a signal f shifted by a distance nΔf with an inverted sign is sent. In FIG. 4(e), two types of reference frequencies, fl and f, are used. Reference frequency f
1. The signal form after f is shown in Fig. 4(c).
is the same as Furthermore, the signal form is shown in (b) in Figure 4.
The present invention is not limited to (e), but any form may be used as long as the reference frequency is first transmitted and then a signal containing information is transmitted.

For example, signals of several types of frequencies may be transmitted to the planting array over time, or the reference frequency may be sent again at the end of the communication. The local oscillation circuit to be controlled may be either the circuit 8 or the circuit 18. It should be noted that the frequency analysis circuit 2° may be an analog filter or may be one that utilizes a modified digital conversion method.

Effects of the Invention As is clear from the above explanation, the present invention first transmits a reference frequency, then transmits a signal containing information, detects the first reference frequency by a frequency analysis circuit in the receiving device, and detects the local oscillator frequency. Since the circuit is controlled so that the reference frequency is near the center of the band of the intermediate frequency amplification circuit,
It is possible to eliminate the effects of fluctuations in the local oscillation frequency, reduce the bandwidth of the intermediate frequency amplifier circuit to the necessary minimum, improve the S/N ratio, prevent malfunctions due to noise, and reduce the electric field strength. This has the excellent effect of making it possible to decipher information even in places where the light is weak. As a result, the communication distance can be dramatically extended. Furthermore, since the comparison circuit monitors the reference frequency, it is possible to prevent errors in determining the reference frequency due to noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional transmitting/receiving device, FIG. 2 is a functional explanatory diagram of a tone generation circuit of the same device, FIG. 3 is a block diagram of a transmitting/receiving device according to an embodiment of the present invention, and FIG. 4 is a block diagram of the present invention. A functional explanatory diagram of a tone generation circuit of a transmitting/receiving device in an embodiment of the present invention, FIG. 5 is a configuration diagram of a frequency analysis circuit of a transmitting/receiving device in an embodiment of the present invention, and FIG. A functional explanation diagram of the frequency analysis circuit of
FIG. 7 is a block diagram of a transmitting/receiving device in another embodiment of the present invention. 1...Input circuit, 2. Tone generation circuit, 3...FM
Modulation circuit, 4... Transmission circuit, 6 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, 16 ... 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. Name of agent: Patent attorney Toshio Nakao Haga 1 person No. 4
Figure 5 Figure 6

Claims (1)

[Claims] A receiving device that receives a signal including preset reference frequency information, comprising a frequency analysis circuit that analyzes the frequency of the received signal, an information decoding circuit that receives the signal from the frequency analysis circuit as input, and determines the reception frequency. It has a local oscillation circuit and a comparison circuit for checking whether the signal corresponding to the reference frequency matches the reference frequency, 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, After controlling the local oscillation circuit so that the reference frequency information comes near the center of the reception band, the comparison circuit determines that the signal corresponding to the reference frequency matches the reference frequency, so that the subsequent signal is received. A receiving device characterized in that it is configured to do the following.