JPS6042965A - Data signal modulating circuit - Google Patents

Abstract

PURPOSE:To transmit surely a carrier only when a data exists by deciding the presence of data from a transmission data signal so as to extract an on/off control signal of the carrier even when the carrier on/off control signal is not inputted. CONSTITUTION:When a transmission data signal 3-7 is inputted to an input terminal 3-5 of a modulator and the mode is changed from the idle state to the active state, a data sense circuit 3-3 comprising a retrigger type monostable multivibrator or a counter or the like detects the head of a frame to turn on a data sense signal 3-9. A carrier signal output gate 3-4 is controlled by the data sense signal 3-9 and outputs a transmission carrier signal 3-10 only when the data sense signal 3-9 is turned on. Further, the data sense circuit 3-3 detects the end of frame at a prescribed time T4 after the transmission data signal 3-7 changes from the active state to the idle state so as to turn off the data sense signal 3-9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention is directed to a data signal modulation circuit that turns on and off a transmitting carrier signal as required. The present invention relates to a data year modulation circuit when modulated signal transmission is used in a part of the transmission path in which a code signal is transmitted.

[Background of the invention]

The configuration of a conventional modulator is shown in Figure 1. In a conventional modulator, a transmission data signal 1-6 and an indispensable transmission carrier signal 1-6, which is transmitted to a modulation/demodulation system to guarantee the transmission data signal, are transmitted.
Control 8. Carrier control signals 1-7 are input
The transmission data signal 1-6 is sent to the transmission data modulation circuit 1-
1 is the first word.

The 0 carrier signal output gate 1-2 inputted to the carrier signal output gate 1-2 was turned on and off by the carrier control signal 1-7, and a transmission carrier belief 1-1 was obtained.

However, this modulator requires transmission data signals 1-6, carrier control signals 1-7, and carrier control signals 1-6.
- In configurations without 7 inputs.

It has been impossible to realize a modulator that turns on and off the transmitted carrier signal depending on the presence or absence of the transmitted data signals 1-6.

[Purpose of the invention]

An object of the present invention is to provide a data signal that transmits and turns on the carrier signal only during the data period of the transmitted data signal in a modulation circuit that does not have a signal input to control the on/off of the carrier, and that also allows the receiving system to reliably reproduce the data. The object of the present invention is to provide a modulation circuit.

[Summary of the invention]

One aspect of the present invention is to achieve such objects.

In a modulator that turns on and off a carrier signal as required, even when there is no carrier on/off control signal input, the carrier on/off control signal is extracted by determining the presence or absence of data from the transmitted data signal.7. The feature is that the carrier is transmitted only when there is data.

In addition, by starting to output the carrier signal at the same time as the transmission data starts, delaying the transmission data, and applying modulation to the carrier signal, relatively speaking, carrier selection starts before data transmission. It is characterized by configuring a unique modulator.

[Embodiments of the Invention] An embodiment in which the present invention is applied to the transmission data signal shown in FIG. 2 will be described in detail with reference to the drawings.

As shown in FIG. 2(a), the transmission data signal used in this embodiment has no level change for data @1#, and has both positive and negative polarities for data "0#".

This is a data signal in which the level changes for the first half bits alternately.

Further, as shown in FIG. 2(b), there is an idle period in which the signal level does not change and an active period in which the signal level changes.

The active period is separated by a flag (8 bits: "01111110") shown in FIG. 2(C).

Start flag 2-1. The data 2-2 sandwiched between the end flag 2-3 and the end flag 2-3 is a frame.

(Figure 2 (d)) Data 2-2 sandwiched between flags is 5 consecutive bits.
There is a zero insertion that adds data '0'K next to 't'-'l' data, and continuous data '1' is inserted in the frame.
7 has a maximum of 6 hits for the flag.

FIG. 3 shows a block diagram and a time chart of a modulation circuit when one transmission data signal having the above signal waveform is applied to the present invention.

When the transmission data signal -3-7 is input to the input terminal 3-5- of the modulator and changes from the idle state to the active state, the data sensing circuit 3-3 consisting of a retrigger type monostable multi-by-break or a counter is activated. The beginning of the frame is detected.

Turn on the data sense signal 3-9. The carrier signal output gate 3-4 is controlled by the data sense signal 3-9, and outputs the transmission carrier signal 3-10% only during the period when the data sense signal 3-9 is on.

The data sense circuit 3-3 also receives the transmission data signal 3-3.
After a predetermined time T4 after the signal 7 changes from the active state to the idle state, the end of the frame is detected and the data sense signal 3-9 is turned off.

By turning on the data sense signal 3-9.

The carrier signal output gate 3-4 is closed and carrier transmission is stopped.

Furthermore, the transmission data signal is input to a zero delay circuit 3-1 composed of a delay line or a counter, etc.
A delayed data signal 3-8 delayed by T3 from -7 is output. The modulation circuit 3-2 modulates the delayed data signal 3-8 and outputs a transmission carrier signal 3-10 through the carrier signal output gate 3-4.

By outputting the carrier signal modulated by the delayed data signal 3-8, data transformation is started later than the rise of the carrier signal.Thereby, reliable data reproduction can be performed on the receiving line.

Here, the operation of the data sense circuit 3-3 will be explained with reference to FIG.

In the data sense circuit, the data sense signal is turned on from the time point 4-1 when the transmission data signal changes from the idle state to the active state. After turning on the data sense signal, the time t1 from the first data "0" to the next data "0" is monitored.

If this t□ is shorter than the preset time ``■''4, the data sense 1'' signal is kept on 2, and the interval t2 of the next data ``0'' is monitored.

Also, if tl is longer than T4, 1 hour starts from the start of monitoring.
After 4 hours, turn off the data sense signal.

The on state continues until data "0" of the next transmission data signal. Time monitoring tls t2・・・・・・・・・tn
By doing so, a data sense signal is obtained.

Here, during the active period, as shown in FIG. 2, the maximum value of the interval between data "0" and the next data "0" is:
This is the 7-bit time of the flag. Therefore, if T4>7 bit time, the data sense signal will not turn off during the active period of the transmission data signal.

As a result of the above, the data sense signal and the transmitted data signal are
It turns on from the time 4-1 when it becomes active from idle, turns off 14 hours after the last "0" data 4-2 of the active period, and then turns off at the beginning of the next active period 4-1.
At 3, the signal turns on again.

〔Effect of the invention〕

As explained above, according to the present invention, even though there is no 1% separate carrier control signal input, idle/
It determines whether it is active and turns on the carrier signal only during the period when it is determined to be active.

Furthermore, by starting data modulation with a delay from the rise of the carrier signal, it is possible to transmit and output a carrier signal that can reliably generate data in the receiving system.

Furthermore, in this embodiment, the transmission data signal has been described as a signal shown in FIG. This method can be applied to encoded signals (Manchester coating, OM, I, etc.) by setting the frame end detection time T4. .

[Brief explanation of drawings]

Figure 1 (al is a block diagram of a conventional modulator, Figure 1 (b)
is a time chart showing the operation of a conventional modulator, FIG.
), (b), (C), and (d) are diagrams showing the signal form, signal state, flag pattern, and frame structure of transmission data, respectively, which are explained in detail of the present invention, and FIG. 3 (
a) is a block diagram of a modulator according to the invention, FIG. 3(b)
4 is a time chart showing the operation of the modulator according to the present invention, and FIG. 4 is a time chart showing the operation of the data sense circuit. No 4 given←i / ゛jilz (f) /-5 habit'' ((1) <12 (C) 2-/ 2-2 2-.3

Claims (1)

[Claims] In a data signal modulation circuit that does not have a carrier control signal input to control the on/off of the transmitted carrier signal, the data source circuit determines the presence or absence of data based on the input transmitted data signal, and only transmits the transmitted carrier signal when data is present. What is claimed is: 1. A data signal modulation circuit characterized in that data signal modulation is started with a delay from the rising edge of a transmission carrier signal by selecting the data signal and further delaying the data signal in a delay circuit.