JPH04200030A - Individual selective call receiver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a selective call receiving device that makes individual calls and transmits individual data.

BACKGROUND OF THE INVENTION FIG. 2 is a block diagram showing the configuration of a direct conversion type receiver used in a conventional individual selective call receiving apparatus.

In FIG. 2, 101 is an antenna, 102 is a high frequency amplifier that is connected to this antenna 101 and amplifies the received signal from the antenna 101, 103 is a local oscillation frequency, and 104 is a 90-frequency amplifier in which the output signals of the local oscillator 103 are manually input to each other. 'Phase shifter that outputs outputs FO with different phases, 105, 106
are the output FO of the phase shifter 104 and the high frequency amplifier 10, respectively.
This is a frequency converter that manually converts the output of 2 and outputs an audio frequency of ΔF with second-order distortion.

Moreover, 107 and 108 are respective frequency converters 107.
Audio frequency amplifier for amplifying the output of 108, 109.1
10 are low-pass filters that pass the low frequency components of the outputs of the audio frequency amplifiers 107 and 108; 11;
1 and 112 are low-pass filters 109 and 110, respectively.
a limiter that inputs the output of and suppresses the output level, 11
3 is a phase comparator that compares the phases of the outputs of both limiters 111 and 112; 114 is a data filter that inputs the output of the phase comparator 113 and removes noise other than frequency modulation; 1
A waveform shaper 15 inputs the output of the data filter 114 and shapes the waveform.

Next, the operation of the above conventional example will be explained. aerial line 10
1 is a carrier wave (
FO±ΔF) is received and output to the high frequency amplifier 102. The local oscillator 103 oscillates an output frequency (FO) and outputs it to the phase shifter 104, and outputs (FO) whose phases differ by 90 degrees from each other are sent to the frequency converter 1.
It is output to 05 and 106.

The frequency converter 105 converts the output of the high frequency amplifier 102 (F○
±ΔF) and one output (FO) of the phase shifter 104 to obtain the audio frequency (I wave) of ΔF of the second-order distortion,
It is output to the audio frequency amplifier 107.

The frequency converter 106 converts the output of the high frequency amplifier (F○±ΔF
) and the 90' different output (FO) of the phase shifter 104 to obtain an audio frequency (Q wave) of ΔF with a phase difference from the I wave of the second-order distortion, and output it to the audio frequency amplifier 108. are doing.

The I-wave low-pass filter 109 and the Q-wave low-pass filter 110 are both input to the limiters 111 and 112 with less suppression of interference waves of adjacent frequencies or higher to stabilize performance for large inputs. ing. The phase comparator 113 can demodulate the FSK modulation signal by comparing the phases of the output waveforms of the two limiters 111 and 112, 1 wave and Q wave. A data filter 114 removes noise higher than the modulation frequency, and a waveform shaper 115 converts it into a digital signal.

In this way, even in the conventional direct conversion type receiver described above, the individual selective calling number and display information can be replaced with digital signals from the carrier wave. At that time, the frequency converter 10
5 to waveform shaper 115 can be integrated into an IC.

Further, FIG. 3 is a block diagram showing the configuration of another single superheteron system receiving section used in the conventional individual selective call receiving apparatus.

In FIG. 3, the antenna 101 and the high frequency amplifier 102 are the same as those in FIG. 119 is a frequency converter 11 that mixes the output of the local oscillator 117 with the output of the local oscillator 117 to convert the carrier wave to an intermediate frequency.
120 is an intermediate frequency amplifier that amplifies the output of the mechanical filter 119.

121 is a limiter that inputs the output of the intermediate frequency amplifier 120 to stabilize against large inputs; 122 is a limiter 1;
A demodulator 114 and 115 input the output of 21 and convert FSX modulation to AM modulation, and 114 and 115 are the data filter and waveform shaper, respectively, described in FIG.

Next, the operation of the conventional example shown in FIG. 3 will be explained. In FIG. 3, the antenna 101, high frequency amplifier 102, data filter 114, and waveform shaper 115 are all (same as in FIG. 2). Image frequency (F-21F
) Surface acoustic wave filter 1 to ensure the sensitivity ratio of
16 is a component that is not suitable for miniaturization and thinning. The local oscillator 117 oscillates at a frequency of (FO-IF). The frequency converter 118 converts the carrier wave (FO±ΔF) to an intermediate frequency (IP±ΔF). Mechanical filter 119 having the effect of attenuating adjacent interference waves
are usually made of ceramic, and are particularly unsuitable for miniaturization and one-type construction. The limiter 121 that receives the output signal of the intermediate frequency amplifier 120 is designed to stabilize performance against large inputs. Demodulator 22 converts FSX modulation to AM modulation.

In this way, even with the single superheterodyne receiver shown in FIG. 3, the individual selective calling number and display information can be replaced with digital signals from the carrier wave. In this case, everything from the intermediate frequency amplifier 120 to the waveform shaper 115 can be implemented as an IC.

Problems to be Solved by the Invention However, in the above conventional direct conversion system individual selective call receiving device, the frequency of the carrier wave and the oscillation frequency of the local oscillator 103 completely match, so the local oscillator 103 and phase shifter 104 are completely If they are not separated using a shield case or the like, there are problems in that they will be suppressed and have a negative impact on performance, or that they will cause mutual interference with other sets of the same frequency.

Furthermore, incorporating the phase shifter 104 into an IC increases the variation, and there are also problems in that it is difficult to realize low resistance because it requires a large chip area.

In the other conventional single superheterodyne individual selective call receiving device shown in FIG. was there.

The present invention solves these conventional problems,
Individual selective calling makes it possible to set the local oscillator frequency to a frequency that does not interfere with the carrier wave without using a mechanical filter that is difficult to miniaturize, and allows the phase shifter to be built into an IC. The purpose of this invention is to provide a receiving device.

Means for Solving the Problems In order to achieve the above object, the present invention provides a frequency converter for converting a carrier wave (FO) to an intermediate frequency (M/N) FO, and a frequency converter for converting a carrier wave (FO) to an intermediate frequency (M/N) FO. The local oscillation frequency of (M/
(N-M)) and outputs a signal of frequency (M/N)FO having a phase difference of 90 degrees to two systems, and the output of the two systems of this phase shifter ( Two systems of frequency converters corresponding to the modulation degree from the frequency of the intermediate frequency (M/N') FO and the frequency of the carrier wave FO ((N -M)/
N) Mix it with the FO frequency to output the (M/N) FO intermediate frequency and add it to two systems of frequency converters.

On the other hand, a phase shifter divides the frequency of ((N-M)/N)FO of the local oscillator into (M/(N-M)), and divides the frequency by 9
Frequency shifted to have a phase difference of 0' (M/N
) The FO signal is applied to two systems of frequency converters, and a frequency corresponding to the modulation degree is output from the intermediate frequency (M/N) FO.

According to the present invention, since the modulated signal is demodulated without using the same frequency as the carrier wave, it is possible to suppress the paging sensitivity and mutual interference without shielding the local oscillator. It has the effect of being able to.

Embodiment FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In FIG. 1, 1 is an antenna, 2 is a high-frequency amplifier that inputs and amplifies the reception signal received by the antenna 1, and 3 is the output of the carrier wave FO of the high-frequency amplifier 2 and the output from the local oscillator 8 ((N-M This is a frequency converter that mixes the local oscillation signal of the frequency of )/N)FQ and outputs the intermediate frequency of (M/N)FO.

9 is output from the local oscillator 8 ((N-M)/
N) Local oscillation signal of FO frequency (M/(N-M))
This is a phase shifter that outputs two systems of signals of frequency (M/N)FO, which are obtained by dividing the frequency to .

Each of the frequency converters 4 and 10 mixes the output of the phase shifter 9 and the output of the frequency converter 3, and outputs a frequency corresponding to the degree of modulation.

5.11 is an audio frequency amplifier that amplifies the outputs of the frequency converters 4 and 10; 6 is an I-wave low-pass filter that inputs the output of the audio frequency amplifier 5 and produces low-frequency components; 12 is an audio frequency amplifier Input the output of 11 to the Q low-pass filter that passes the low-frequency components, and input the outputs of the ■-wave low-pass filter 6 and the Q-wave low-pass filter 12 to 7.13, respectively. 14 is a phase comparator that compares the phases of the outputs of the limiters 7 and 13. 15 is a phase comparator that inputs the output of the phase comparator 14.
Data filter for removing noise above the modulation frequency, 16
performs waveform shaping of the output of this data filter 15,
This is a waveform shaper that converts into digital signals.

Next, the operation of the above embodiment will be explained. Antenna 1 carries a carrier wave (FO) modulated with an individual selective calling number and display information.
±ΔF) and outputs it to the high frequency amplifier 2. The local oscillator 8 oscillates the output frequency ((N-M)/Nl○ and outputs it to the frequency converter 3.The frequency converter 3 generates the carrier wave (FO±ΔF) of the output of the high-frequency amplifier 2.
and the output of local oscillator 8 ((N-M)/N) 2 of FO
By mixing the two outputs, the intermediate frequency of (,M/N)FO is output.

The frequency divider and phase shifter 9 inputs the frequency ((N-M)/Nu○ from the local oscillator 8 and divides the frequency by two using rising and falling detection. Frequency (M/N) FO to frequency converter 4
and is output to 10.

Frequency converter 4 is the output (M/N) FO of frequency converter 3
and one output (M/N) FO of the frequency divider and phase shifter 9 are input, and the audio frequency (■ wave) of ΔF of the second-order distortion is obtained and output to the audio frequency amplifier 5.

The frequency converter 10 outputs the output (M/N) F of the frequency converter 3.
O and 90' different outputs of frequency divider and phase shifter 9 (M/N
) F O is input, and an audio frequency (Q wave) of ΔF having a phase difference from the first wave of second-order distortion is obtained and output to the audio frequency amplifier 11.

I-wave low-pass filter 6 and Q-wave low-pass filter 1
2 both reduce the suppression of interference waves of adjacent frequencies,
It is input to limiters 7 and 13 to stabilize performance for adult power. The phase comparator 14 compares the phases of the output waveforms of the two limiters 7.13 for I wave and Q wave,
The modulated signal of SK can be demodulated. A data filter 15 removes noise higher than the modulation frequency, and a waveform shaper 16 converts the signal into a digital signal.

When the individual calling number with the demodulated signal matches the self-calling number pre-stored in the memory (not shown), a decoder (not shown) outputs a display and sound signal, and this sound signal A sounding body (not shown) is activated to make the user confirm that there is an individual call.

In this way, even in the receiver of the above embodiment, the individually selected calling number and display information can be replaced with digital signals from the carrier wave, and the level of mutual interference can be reduced to that of the heterodyne system without completely shielding the local oscillator 8. It can be suppressed. In addition, surface acoustic wave filters and mechanical
Since no filter is required, it has the advantage of being smaller and thinner.

Also, if the output frequency of the local oscillator 8 is (4FO15) and the intermediate frequency is (FO15), the frequency is divided by 1, and the phase shifter 9 divides the frequency by 4, and then shifts the phases by 90 degrees to directly convert from the intermediate frequency. Even if you use the local oscillator 8
A similar circuit can be realized with just one.

In this way, there are an infinite number of frequencies that can be realized, but in order to reduce the current consumption of the frequency divider and phase shifter 9 and to ensure the image ratio, the local oscillation frequency 8 is set to the output frequency (FO/3 ) is most advantageous. Therefore,
The local oscillation frequency may satisfy the condition of ((N-M)/N)FO.

Effects of the Invention As is clear from the above embodiments, the present invention has the following effects.

(1) Since the output frequency of the local oscillator and its harmonic components do not match the carrier wave, there is little effect on paging sensitivity to weak input and little effect on mutual interference with other sets of the same channel frequency.

(2) Since no surface acoustic wave filter or mechanical filter (ceramic filter) is required, it is suitable for miniaturization and thinning.

(3) Since the phase shifter for obtaining the I wave and Q wave is a frequency dividing circuit that can be digitally processed, it is possible to completely incorporate the phase shifter into an IC.

(4) Although there are three frequency conversion circuits, since they use a common local oscillator, this method is not disadvantageous compared to the conventional direct conversion method, and is suitable for miniaturization and thinning.

(5) Compared to the two frequency conversion circuits of a conventional direct conversion receiver, the number of frequency conversion circuits increases to three, but the frequency of up to two of them is reduced to 1/3, which is advantageous in terms of current consumption. .

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an individual selective call receiving device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a direct conversion method of a conventional individual selective calling receiving device, and FIG. 3 is a block diagram showing a conventional individual selective calling receiving device. 1 is a schematic block diagram showing a single superheterodyne system of a call receiving device; FIG. 1... Antenna, 3, 4.10... Frequency converter, 5
．． 11... Audio frequency amplifier, 6, 12... Low pass filter, 7.13... Limiter, 8... Local oscillator, 9... Frequency divider and phase shifter, 14... Phase Comparator. 15...Data filter, 16...Waveform shaper. Figure 2 Figure 3

Claims (1)

[Claims] Carrier wave modulated with individual selective calling number and display information (
FO), a local frequency oscillator of ((N-M)/N)FO, and the carrier wave FO inputted to (M/N).
) a frequency converter that outputs the intermediate frequency of the FO;
(N-M)/N) The local oscillation frequency of FO is (M/(N-)
A phase shifter that outputs two systems of frequency (M/N) FO that is frequency-divided into M)) and has a phase difference of 90° from each other; Individual selection comprising two systems of frequency converters that output frequencies corresponding to the modulation degree from the frequency and the intermediate frequency (M/N) FO, and a demodulator that compares their phases and outputs decoded digital signals. Call receiving device.