JPS62152231A - Sub-channel transmitting system - Google Patents

Abstract

PURPOSE:To transmit the sub-channel transmitting data without increasing excessively the occupancy band width by using the output of a carrier reproducing device as a pilot signal when main channel transmitting data are demodulated by main demodulator. CONSTITUTION:Main channel transmitting data (a) is converted to a modulating wave by a main modulator 1, and sub-channel transmitting data (b) is two-phase- modulated and AM-modulated by a sub-modulator 2 and synthesized by an adder 3. A carrier reproducing device 5 extracts the carrier component from the modulating wave of sub-channel transmitting data received from a transmission line 4. A sub-demodulator 6 uses the output of the carrier reproducing device 5, executes the synchronizing detection and obtains sub-channel data (d). A main demodulator 7 uses the carrier extracted by the carrier reproducing device 5 as a pilot signal, executes a demodulating and timing control and obtains main channel receiving data (c).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sub-channel transmission method for a data modem, and particularly to a sub-channel transmission method when the data modem uses a modulation/demodulation method using a pilot signal.

[Conventional technology]

Conventionally, data modems using voice lines with transmission speeds of 9.5 kbps or less have occupied frequency bandwidths that are narrower than the line bandwidth, so they use unused frequency bands in the line band. Low-speed FSK transmission was performed and used as a secondary channel.

[Problem that the invention seeks to solve]

However, if the transmission speed of the main channel is further improved, it is necessary to further widen the occupied bandwidth, and on top of that, in order to use pilot signals to improve the stability of the control system inside the receiver, the line There are no unused frequency bands in the band, and it is impossible to perform subchannel transmission in the above-described manner.

[Means for solving problems]

In order to solve such problems, the present invention provides a transmitter having a main modulator for transmitting main channel transmission data and a submodulator for transmitting subchannel transmission data, and a transmitter for transmitting main channel transmission data. The receiver includes a main demodulator that receives and demodulates the sub-channel transmission data, a sub-demodulator that receives and demodulates the sub-channel transmission data, and a carrier regenerator that extracts the carrier wave of the sub-channel transmission data. .

[Effect]

In the present invention, the output of the carrier wave regenerator is used as a pilot signal when the main demodulator demodulates the main channel transmission data.

〔Example〕

An embodiment of the sub-channel transmission system according to the present invention is shown in the figure. In this sub-channel transmission method, when the main channel transmission data modulation/demodulation method uses an out-of-band pilot signal, this out-of-band pilot signal is subjected to two-phase phase modulation or amplitude modulation, and this signal is used as the sub-channel signal. That is.

In the figure, 1 is a main modulator, 2 is a sub-modulator, 3 is an adder, 4 is a transmission path, 5 is a carrier wave regenerator, 6 is a sub-demodulator, and 7 is a main demodulator. The sub-modulator 2 constitutes a transmitter, and the carrier wave regenerator 5, sub-demodulator 6, and main demodulator 7 constitute a receiver.

The main channel transmission data a is converted into a modulated wave by the main modulator 1, and the sub-channel transmission data b is converted into a modulated wave by the sub-modulator 2.
The modulated waves are converted into a phase modulated wave or an amplitude modulated wave, and these modulated waves are added by an adder 3 and sent to a transmission line 4.

The carrier wave regenerator 5 extracts the carrier wave component from the modulated wave of the subchannel transmission data received from the transmission path 4 . A square-law circuit or a Costas loop circuit is used for this purpose.

The sub-demodulator 6 performs synchronous detection using the carrier wave extracted by the carrier wave regenerator 5 to obtain sub-channel reception data d. The main demodulator 7 handles the carrier wave extracted by the carrier wave regenerator 5 as a pilot signal, performs demodulation and timing control, and obtains main channel reception data C.

〔Effect of the invention〕

As explained above, the present invention provides a transmitter having a main modulator and a sub-modulator, and a receiver having a main demodulator, a sub-demodulator, and a carrier wave regenerator, thereby converting main channel transmission data. The effect is that a signal obtained by applying two-phase phase modulation or amplitude modulation to the biloft signal necessary for transmission can be used as a sub-channel signal, and it is possible to transmit sub-channel transmission data without significantly increasing the occupied bandwidth. There is.

[Brief explanation of drawings]

The figure is a system diagram showing an embodiment of the sub-channel transmission system according to the present invention. ■...Main modulator, 2...Sub modulator, 3...
Adder, 4...Transmission line, 5...Carrier regenerator,
6...Sub demodulator, 7...Main demodulator.

Claims (1)

[Claims] It has a main modulator for transmitting main channel transmission data and a sub-modulator of a two-phase phase modulation method or an amplitude modulation method for transmitting sub-channel transmission data in a frequency band that does not overlap with the main channel transmission data spectrum. It has a transmitter, a main demodulator that receives and demodulates the main channel transmission data, a sub-demodulator that receives and demodulates the sub-channel transmission data, and a carrier regenerator that extracts a carrier wave of the sub-channel transmission data. 1. A sub-channel transmission system, comprising: a receiver, wherein the output of the carrier regenerator is used as a pilot signal when the main demodulator demodulates the main channel transmission data.