JP2517108B2 - Digital transceiver - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital transmission / reception device used for digital communication, mobile communication and the like.

2. Description of the Related Art FIG. 2 shows the configuration of a conventional digital transmitter / receiver.

The upper part of FIG. 2 shows a transmitter, in which the data from the input terminal 1 is phase-modulated by the phase modulator 2, and the phase-modulated signal is band-limited by the band-pass filter (BPF) 3 and band-limited. The signal is multiplied by the carrier wave from the carrier wave oscillator 4, frequency-shifted (FM modulated) (multiplier 5), and output through the terminal 9.

The lower part of FIG. 2 shows the receiving device, which is connected to the terminal from the transmitting device.
When the received signal input via 10 is input to the reference signal generator 12, the reference signal generator 12 generates a reference signal according to the detection method, and the detector 13 multiplies this reference signal and the received signal. It is detected by this. When this detected signal is input to the low-pass filter (LPF) 14, the baseband signal is extracted, and when the clock regenerator 16 regenerates the clock of this baseband signal, the discriminator 17 uses this clock to generate the baseband signal. The signal is identified and the received data is output via terminal 18.

Therefore, in the receiving apparatus of the above-mentioned conventional example, it is possible to reproduce the clock by the output signal of the detector 13 and identify the received data.

However, in the above-mentioned conventional digital transmitter / receiver, the receiver reproduces the clock by the output signal of the wave detector 13 to identify the received data, so that a mark or a space (signal "0") is added to the transmitted signal. However, there is a problem in that the discriminator 17 cannot discriminate the data at the optimum timing.

In view of the above conventional problems, it is an object of the present invention to provide a digital transmitter / receiver capable of identifying data at an optimum timing even when a mark or a space is continuous in a transmission signal.

Means for Solving the Problems In order to achieve the above object, the present invention divides a data clock in a digital transmission device, and AM-modulates a constant envelope modulated signal by the divided clock. The digital receiver receives a frequency-divided clock by extracting the divided clock with a clock generator that generates a clock having the same frequency as the data clock from the digital transmitter, and the received signal from the digital transmitter. An envelope detector for resetting the clock generator is provided, and the received signal from the digital transmitter is demodulated into a baseband signal, and this baseband signal is identified by the clock from the clock generator.

Effect of the Invention With the above configuration, the present invention can obtain a clock that synchronizes with data in a receiving device even when a transmission signal, a mark, and a space are continuous, and thus can identify data at an optimum timing.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a digital transmitting / receiving apparatus according to the present invention, and the same components as those shown in FIG. 2 are designated by the same reference numerals.

In the upper part of FIG. 1, 2 is a phase modulator for phase-modulating the data from the input terminal 1, 3 is a band pass filter (BPF) for band limiting the signal phase-modulated by the phase modulator 2, and 4 is a Carrier wave oscillator for generating carrier wave, 5
Is a multiplier for multiplying the signal band-limited by the bandpass filter 3 and the carrier wave from the carrier wave oscillator 4 to perform frequency shift (FM modulation).

Further, 7 is a divider for dividing the data clock from the terminal 6, 8 is a low-pass filter (LPF) for band-limiting the signal divided by the divider 7, and 19 is a low-pass filter 8. A clock signal whose band is limited by
It is a multiplier that multiplies the signal from and AM-modulates and outputs via a terminal 9.

Here, the frequency divider 7 and the low pass filter 8 are configured such that the band limited by the low pass filter 8 is sufficiently lower than the band limited by the band pass filter 3.

In the lower part of FIG. 1, reference numeral 11 denotes the terminal 10 from the transmitter.
A limiter that limits the amplitude so that the received signal input via the signal has a constant envelope, 12 is a reference signal generator that generates a reference signal according to the detection method by the signal from the limiter 11,
13 is a detector that detects the signal by multiplying the signal from the limiter 11 and the reference signal from the reference signal generator 12,
Reference numeral 14 is a low-pass filter (LPF) that extracts a baseband signal from the signal from the wave detector 13, and 17 is a discriminator that discriminates data by the baseband signal from the low-pass filter 14.

Further, 15 is an envelope detector that detects the received signal input through the terminal 10 by envelope detection and extracts the divided clock from the transmitter, 16a is a clock of the discriminator 17 by free-running oscillation. Is a clock generator that generates
16a is reset by the clock extracted by the envelope detector 15.

The clock from the clock generator 16a is supplied to the reference signal generator 12 when necessary.

 Next, the operation of the above embodiment will be described.

In FIG. 1, the data input from the input terminal 1 from the transmitter is the phase modulator 2, the bandpass filter 3,
The constant-envelope-modulated data by the carrier wave oscillator 4 and the FM-modulating multiplier 5 and the data clock input from the terminal 6 are multiplied by the frequency divider 7 and the low-pass filter by the band-limited clock, respectively. Multiplied by unit 19
AM modulated and transmitted. Therefore, the transmission signal consists of constant envelope modulated data and envelope modulated clock. In this case, the band of the clock limited by the low pass filter 8 is sufficiently lower than the band of the data limited by the band pass filter 3, and the data and the clock are synchronized.

On the other hand, in the receiver, the received signal is limited by the limiter 11
The amplitude of the constant envelope component is detected by the detector 13, and the detected signal is detected by the low pass filter (LP
F) When input to 14, the baseband signal is extracted,
The discriminator 17 discriminates the baseband signal from the low-pass filter 14 by the clock from the clock generator 16a, and outputs the received data via the terminal 18.

Here, since the envelope detector 15 extracts the AM-modulated clock, the clock can be extracted even when the mark or space is continuous in the transmission data. Therefore, the clock generator 16a uses the envelope. Since it is reset by the clock extracted by the detector 15, the data can be identified at the optimum timing.

As described above, according to the present invention, in the digital transmitter, the data clock is frequency-divided, the constant-envelope modulated signal is AM-modulated by the frequency-divided clock, and the digital clock is transmitted. In the receiving device, a clock generator that generates a clock having the same frequency as the data clock from the digital transmitting device and a frequency-divided clock are extracted by the received signal from the digital transmitting device. Since an envelope detector for resetting is provided, the received signal from the digital transmitter is demodulated to a baseband signal, and this baseband signal is identified by the clock from the clock generator, so that there are no marks or spaces in the transmitted signal. Even when continuous,
A clock that synchronizes with the data can be obtained at the receiving device, and therefore the data can be identified at the optimum timing.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital transmitting / receiving apparatus according to the present invention, and FIG. 2 is a block diagram showing a conventional digital transmitting / receiving apparatus. 2 ... Phase modulator, 3 ... Bandpass filter (BP
F), 4 ... Carrier oscillator, 5,19 ... Multiplier, 7 ... Divider, 8,14 ... Low-pass filter (LPF), 11 ... Limiter, 12 ... Reference signal generator, 13 ...... Detector, 15 …… Envelope detector, 16a …… Clock generator, 17 …… Identifier.

Claims (1)

(57) [Claims] 1. A first modulator for performing constant envelope modulation of data, a divider for dividing a data clock, and an AM for a signal modulated by the first modulator by the divided clock. A digital transmitting device having a second modulator for modulating, a clock generator for generating a clock having the same frequency as a data clock from the digital transmitting device, and a clock divided from a received signal from the digital transmitting device. And an envelope detector that resets the clock generator with this clock, a limiter that extracts constant envelope information from the received signal from the digital transmitter, and a baseband signal demodulated from the output of the limiter. A digital receiver having means for identifying the baseband signal by the clock from the clock generator. Tal transceiver.