JPH04269022A - Selective call receiver - Google Patents

Abstract

PURPOSE:To easily change a reception frequency without increasing a current consumption much. CONSTITUTION:A crystal vibrator 22 is connected to a 1st local oscillation circuit 20 via a socket 21 and replaced with each other. On the other hand, since a decoding control section 30 of an antenna tuning circuit 3 sets any of control signal lines 35-37 to a high level based on the information written in a storage section 31 corresponding to the reception frequency, any of transistors(TRs) 9-11 connecting to the control signal lines set to a high level is turned on. Since only a capacitor among capacitors 5-7 connecting to the TRs 9-11 set to the ON state is connected in parallel with a trimmer capacitor 2, the reception frequency is easily changed without need of fine-adjustment by setting the capacitors 5-7 to a capacitance minimizing the transmission loss in response to the reception frequency band.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a selective call receiver, and more particularly to a selective call receiver whose reception frequency can be changed.

0002

2. Description of the Related Art When a paging signal is transmitted using a plurality of frequencies, a selective paging receiver must change the reception frequency according to the frequency of the corresponding paging signal.

[0003] In such a case, conventionally, the reception frequency is changed by replacing the crystal resonator in the local oscillation circuit and adjusting a plurality of tuning circuits including the antenna tuning circuit, or by providing a synthesizer-type local oscillation circuit. The configuration allows the receiving frequency to be changed arbitrarily.

0004

SUMMARY OF THE INVENTION The conventional selective call receiver described above has the following problems. ■When adjusting multiple tuning circuits including the antenna tuning circuit along with the crystal oscillator, an operation service company other than the manufacturing company must perform the adjustment themselves, as the adjustment requires skilled technology and a jig. is difficult. ■If the receiving frequency can be changed using the synthesizer method,
Since the current consumption in the local oscillation circuit is extremely large compared to the current consumption in the local oscillation circuit constituted by a crystal resonator, the life of the battery becomes extremely short.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a selective calling receiver that can easily change the receiving frequency without increasing current consumption.

[0006]

[Means for Solving the Problem] In order to achieve the above object, the invention according to claim 1 provides a receiving section that receives a calling signal of a predetermined frequency modulated with an individual identification code, and a receiving section that receives a calling signal of a predetermined frequency modulated with an individual identification code. A demodulation unit that demodulates the calling signal to reproduce the identification code; a storage unit that stores its own identification code; and a comparison between the identification code demodulated by the demodulation unit and the identification code stored in the storage unit. In a selective call receiver that includes a comparison section and a notification section that issues a call notification when the comparison section determines that both identification codes match, the reception section receives paging signals of a plurality of predetermined frequencies. The configuration includes reception frequency selection means for selecting and receiving one of the frequencies.

[0007] Furthermore, the invention according to claim 2 is based on claim 1.
In the selective calling receiver described in , the reception frequency selection means includes a local oscillation circuit whose source is an exchangeable crystal oscillator, and an antenna tuning circuit capable of selectively changing the tuning frequency according to the reception frequency. and a tuning frequency control circuit that selects a tuning frequency in the antenna tuning circuit depending on a crystal resonator in the local oscillation circuit.

[0008]

[Operation] In the inventions according to claims 1 and 2 configured as described above, the receiving frequency selection means in the receiving section selects one of the calling signals of a plurality of predetermined frequencies and outputs the calling signal. Therefore, no troublesome adjustment is required to change the receiving frequency.

Further, in the invention according to claim 2 configured as described above, when the crystal resonator in the local oscillation circuit is replaced, the tuning frequency control circuit selects the tuning frequency of the antenna tuning circuit in accordance with the reception frequency. urge

0010

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a block diagram of a selective call receiver according to an embodiment of the present invention.

In the figure, an antenna 1 and an RF amplifier 2
An antenna tuning circuit 3 is inserted between the trimmer capacitor 4 and the capacitor 5.
8, transistors 9 to 11, and resistors 12 to 17, and is configured to minimize transmission loss at a desired reception frequency. Note that the resistors 12 to 17 are transistors 9
~11 is a bias resistor that provides voltage for switching operation.

The output signal of the RF amplifier 2 is input to a band pass filter 18, which uses a SAW to limit the band to about ±3-5 MHz of the reception frequency.

The output signal of the bandpass filter 18 is input to one input terminal of the first mixing circuit 19, and
The local oscillation signal output from the first local oscillation circuit 20 is input to the other input terminal of the first mixing circuit 19, and the first mixing circuit mixes both signals and outputs a desired first intermediate frequency signal. are doing. Here, the first local oscillation circuit 20 includes a socket 2.
A crystal oscillator 22 for a first local oscillation circuit is connected through 1, and the crystal oscillator 22 can be replaced depending on a desired receiving frequency.

The first intermediate frequency signal output from the first mixing circuit 19 is input to a band pass filter 23, and the signal band-limited by the band pass filter 23 is passed to the second mixing circuit 2.
It is input to the first input terminal in 4. The local oscillation signal output from the second local oscillation circuit 25 is input to the other input terminal of the second mixing circuit 24, and the second mixing circuit outputs a desired second intermediate frequency signal. Note that a second local oscillation circuit crystal resonator 26 that cannot be replaced is connected to the second local oscillation circuit 25 .

The second intermediate frequency signal output from the second mixing circuit 24 is input to the IF amplifier 27.
The amplified output signal is input to a demodulator 29 via a bandpass filter 28. The demodulator 29 demodulates the modulated data signal and transfers the data signal to the decoding controller 3.
Output to 0.

A storage unit 31 that stores its own calling number is connected to the decoding control unit 30, and the decoding control unit 30 determines whether the data signal input from the demodulation unit matches the calling number stored in the storage unit 31. Then, a notification control signal is output to the call notification section 32, and when the call notification section 32 receives the call control signal, it drives the speaker 33 or the light emitting diode 34 to make a notification. Note that the storage unit 31 stores the own calling number, information on whether the notification is to be made through the speaker 33 or the light emitting diode 34, and information on the reception frequency.

Control signal lines 35 to 37 are connected from the decoding control section 30 to the bases of transistors 9 to 11 in the antenna tuning circuit 3, respectively.
0 makes the output level of any one of the control signal lines high according to the reception frequency information stored in the storage section 31.

Next, the operation of this embodiment having the above configuration will be explained. In this embodiment, the signal passband resulting from band-limiting by the bandpass filter 18 is divided into three frequency bands, and the desired receiving frequency determined by the first local oscillation circuit crystal oscillator 22 is divided into three frequency bands. A method is used in which the information written in the storage unit 31 is changed depending on which band it belongs to.

That is, the storage section 31
Based on the information written in, the decoding control unit 30 sets any of the control signal lines 35 to 37 to a high level. Then, one of the transistors 9 to 11 connected to the control signal line that has become high level is turned on.

Of the capacitors 5 to 7, only those connected to the transistors 9 to 11 that are in the on state are connected in parallel to the trimmer capacitor 4, so the capacitors 5 to 7 are connected in accordance with the reception frequency band. By setting the capacitance value to a value that minimizes transmission loss, it becomes possible to easily change the receiving frequency without requiring fine adjustment.

[0021]

Effects of the Invention As explained above, the present invention enables the receiving frequency to be selectively changed, and thus provides a selective calling receiver that can easily change the receiving frequency without increasing current consumption. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a selective call receiver according to an embodiment of the present invention.

[Explanation of symbols]

3...Antenna tuning circuit 20...First local oscillation circuit 21...Crystal oscillator 22...Socket 30...Decoding control unit 31...Storage section 35-37...Control signal line

Claims (2)

[Claims] Claim 1: A receiving section that receives a paging signal of a predetermined frequency modulated with an individual identification code; a demodulation section that demodulates the paging signal received by the receiving section to reproduce the identification code; and its own identification code. a storage unit that stores the identification code; a comparison unit that compares the identification code demodulated by the demodulation unit with the identification code stored in the storage unit; and a comparison unit that compares the identification code that is stored in the storage unit; In the selective calling receiver, the receiving section is provided with reception frequency selection means for selecting and receiving one of a plurality of predetermined frequency calling signals. Features a selective call receiver. 2. The selective calling receiver according to claim 1, wherein the reception frequency selection means includes a local oscillation circuit whose source is an exchangeable crystal oscillator, and selects a tuning frequency according to the reception frequency. 1. A selective call receiver comprising: an antenna tuning circuit that can be changed in frequency; and a tuning frequency control circuit that changes the tuning frequency of the antenna tuning circuit in accordance with a crystal oscillator in the local oscillation circuit.