JPH0530143A - Radio transmission/reception equipment for fsk modulation system - Google Patents

Abstract

PURPOSE:To eliminate the need for a reception side-only local by sharing the signal of the local oscillator generating the signal with a transmission frequency as a local oscillation signal for frequency-converting into an intermediate frequency signal on a reception-side. CONSTITUTION:A transmission-side converts 1a binary transmission data signal into the data signal of quaternary-two columns, delays 2 the phase of the data signal of one column by a half bit, and offset PSK-modulates 3 the signal of the local oscillation circuit 4 generating the signal with the transmission frequency by the data signal of two columns. The reception side uses the signal of the circuit sharing a reception wave passing through a transmission/reception common unit 6 as the local oscillation signal, frequency-converts it in an IF band by a mixer 7 through BPF 8, demodulate 9 it into the signal of a base band and reproduces the binary data signal in an identification circuit 10. Thus, the reception side-only local oscillator becomes unnecessary by sharing the signal of the circuit 4 on the reception-side, and BPF of a narrow band becomes unencessary on the transmission-side since a system is a direct modulation one.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FSK modulation type radio transmitting / receiving apparatus.

[0002]

2. Description of the Related Art A conventional FSK modulation type transmitting / receiving apparatus is
As shown in FIG. 2, as a transmission unit, a variable baseband amplifier 12 for setting the modulation degree and a capacitance changing element such as a varactor diode are connected to a high-frequency oscillation circuit, and the varactor diode is connected to the baseband amplifier 12. Input signal F
FSK with transmission signal generator 13 that generates SK modulated signal
It constitutes the modulation circuit 13A. Further, a bandpass filter (BPF) 1 for removing unnecessary sidebands is provided in this output circuit.
4, the duplexer 6 is connected. On the other hand, as a receiver,
A mixer 7 and a receiving local oscillation circuit 1 for splitting a received wave from an antenna by a duplexer 6 and converting it into an intermediate frequency signal.
1, an intermediate frequency signal filter (BPF), an FM demodulation circuit 9 for FSK signal demodulation, and an identification circuit 10 for data identification of a plurality of demodulated data signals. Here, the transmission section was provided with a high-frequency oscillator as the transmission signal generator 13, and the reception section was provided with the reception local oscillation circuit 11.

[0003]

This conventional FSK modulation type radio transmission / reception device directly modulates a high frequency oscillation signal with a transmission data signal to obtain a transmission wave. On the other hand, the received wave requires a local oscillator dedicated to the receiving side to convert the frequency to the IF band, and requires two high frequency oscillators, which is expensive. In a heterodyne system, which is another configuration (not shown), a local oscillator is shared for transmission and reception, and a signal generated by generating an FSK modulated signal in the IF band is mixed with a local oscillation signal for frequency conversion. Has a drawback in that a narrow bandpass filter is required to sufficiently suppress unnecessary waves on the transmission side, resulting in a large loss of transmission output and a large configuration, which is expensive.

[0004]

A radio transmission / reception apparatus of the FSK modulation system of the present invention comprises a circuit for converting a binary transmission data signal into a 4-value 2-column data signal and a 4-value 2-column data signal. A circuit for delaying the phase of the data signal in one column by half a bit, a local oscillation circuit for generating a signal at the transmission frequency, and a 4PSK modulation circuit for offset PSK modulating the signal of the local oscillation circuit with the data signals in the two columns. , This 4
And a low-pass filter connected to the output of the PSK modulation circuit, which is shared as a local oscillation signal for frequency-converting the signal of the local oscillation circuit into an intermediate frequency signal on the receiving side.

[0005]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

On the transmission side shown in FIG. 1, a 2-4 value conversion circuit 1 for converting a transmission data signal from a binary 1-column signal to a 4-value 2-column signal and a phase of one column of the data signals of the two columns. A delay circuit 2 for delaying the signal by half a bit, a local oscillator circuit 4 for generating a signal equal to the transmission frequency, and a two-phase data signal whose phase is shifted by half a bit from the local oscillator signal are input to input a 4-phase PSK signal. A so-called offset PSK modulation circuit 3A is configured with the 4PSK modulation circuit 3 that directly generates In addition, a low-pass filter (LP
F) 5, the transmission / reception duplexer 5, and the antenna 6 are used for transmission.
Since the offset 4PSK signal having the cosine pulse waveform is essentially equal to FSK with a modulation index of 0.5, the transmitted wave is equivalent to the case of FSK modulation.

Next, on the receiving side, the signal of the local oscillation circuit 4 which shares the received wave that has passed through the antenna 6 and the duplexer 5 is used as the local oscillation signal, and the mixer 7 frequency-converts it to the IF band. To do. In the IF band, the BPF 8 for the intermediate frequency signal is passed through to avoid interference, the FM demodulation circuit demodulates it to a baseband signal, and the identification circuit 11 reproduces a binary data signal.

[0008]

As described above, according to the present invention, an equivalent FSK signal is generated by the offset PSK modulation method using the high frequency signal of the local oscillator, and the signal of this local oscillator is transmitted to the IF band of the received wave. Since it can be commonly used for frequency conversion, there is an effect that a local oscillator dedicated to the receiving side becomes unnecessary. On the other hand, compared to the conventional example of the heterodyne system, the direct modulation system eliminates the need for a narrow band BPF on the transmission side,
It is possible to provide a wireless transmission / reception device of the FSK modulation system at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional FSK modulation wireless transceiver.

[Explanation of symbols]

 1 2-4 value conversion circuit 2 half bit delay circuit 3 4PSK modulation circuit 3A offset PSK modulation circuit 4 local oscillation circuit 5 LPF 6 duplexer 7 mixer 8, 14 BPF 9 FM demodulation circuit 10 discrimination circuit 11 reception local oscillation circuit 12 Baseband amplifier 13 Transmission signal generator 13A FSK modulation circuit

Claims (1)

Claim: What is claimed is: 1. A circuit for converting a binary transmission data signal into a 4-value 2-column data signal, and a phase of a 1-column data signal of the 4-value 2-column data signal. It is connected to a circuit for bit-delaying, a local oscillation circuit for generating a signal at a transmission frequency, a 4PSK modulation circuit for offset PSK modulating the signal of the local oscillation circuit with the data signals of the two columns, and an output of the 4PSK modulation circuit. With a low pass filter
An FSK modulation type wireless transmission / reception device, characterized in that the signal of the local oscillation circuit is shared as a local oscillation signal for frequency conversion to an intermediate frequency signal on the receiving side.