JPS6012827B2 - Signal detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting only a data signal when it is superimposed on another signal. Particularly in button telephones, etc., the present invention relates to a method for detecting only a data signal when this signal is superimposed on another signal. The present invention relates to a detection method that is effective when used to detect a data signal superimposed on a changing power supply line.

Conventionally, in a button telephone device, a connection corresponding to a control signal is constructed between a key telephone main device and a button telephone slave device using a multi-core cable to transmit the control signal.

Recently, a control system using a microcomputer has been introduced to key telephone devices, and control signals are being converted into data signals and transmitted through a pair of lines. Moreover, sharing the line as a transmission line with a power supply line is often used as an effective means of reducing the number of cable cores. A follow-up example of such a configuration is shown in FIG. Here, 21 is a communication line, 22 is a power supply and data line, 23 is a button telephone main unit, 24 is a button telephone handset, and 25 is a plurality of button telephone handsets. In such a configuration, the data signal is transmitted superimposed on the power supply line of the device, so it is difficult to detect the superimposed data signal due to fluctuations in the power line voltage due to the operation of the telephone handset, which is a load. Become. In order to avoid this, the telephones 24 and 25 are loaded to the power line 22 using a constant current load method to prevent voltage fluctuations on the power line 32 due to the operation of the telephones 24 and 25, and the data signal is detected using a simple zero-bell detection method. I went by means. In the main device 23 of FIG. 1, the transmitting means includes a power source 26, a choke coil 27 for improving the AC impedance of the line 22 with respect to the power source 26, a transistor 29 and a resistor 30 connected in parallel to the line 22. The signal terminal 281 is provided at the base of the transistor 29.

Further, detection means for detecting signals transmitted from the button telephone handsets 24 and 25 include a coupling capacitor 31, detection level setting resistors 32 and 33, and a detection transistor 34.
, an emitter follower output resistor 35, an output terminal 36, and a power supply terminal 37.

In such a configuration, three emitter resistors of the transistor 29 are selected to form a constant current type transmitting circuit, and at this time, the transistor 29 is a transistor that has sufficient collector loss to prevent saturation between the collector and emitter. need to use.

As mentioned above, this conventional method always consumes the maximum amount of power as long as the button telephone device as a system is in the power-on state, and the power supply circuit of the main device becomes large, which is not economical and has a heat dissipation structure. In addition, there were also drawbacks such as the need to always configure the power supply based on the maximum amount of power consumed even in key telephone handsets.

In order to solve these drawbacks, the present invention uses a constant-voltage load system for the power supply of the button telephone cordless handset to operate with the minimum power consumption necessary for operation, and also transmits data signals by superimposing them on such power lines. The present invention provides a data signal detection method that is not affected by power line voltage fluctuations due to load fluctuations. The present invention will be explained in detail below with reference to the drawings.

FIG. 2 is an embodiment of the present invention, and shows an example of a key telephone handset.

1 and 2 are the first differentiation circuit DIF and the second differentiation circuit DI.
Capacitor and resistor that make up F2, 3 is a diode, 4
is a transistor, 5 is a load resistance, 6 is an integrating circuit, 7 is a Schmitt circuit, 8 is a first pulse generating circuit, 9 is a matching circuit, 1 is a second pulse generating circuit, 11 is a power source, 1
2 is a transmitting circuit, and 13 is a power supply circuit.

The configuration of the transmitting circuit 12 is 32, 33, 34, 35 in FIG.
, 36, 37. Further, FIG. 3 shows operating waveforms of each part in FIG. 2, which is an embodiment of the present invention.

Here, the data signal superimposed on the power supply line 11 is transmitted in the state shown in FIG. 3 due to load fluctuations of the power supply. The data signal itself is characterized by the rise of the data signal as a pulse, compared to fluctuations in the power supply voltage due to power supply load fluctuations.
Fall characteristics are fast enough. Therefore, by passing this signal (i.e., part of the enlarged image is shown ■') through the differentiating circuit shown in 1 and 2 in Figure 2, the differential output based on the front green and trailing edges of the data signal is obtained as shown in Figure 3 ■, @ It is obtained as follows.Differential output■
becomes @ through the transistor 4, and drives the first pulse generating circuit 8 through the integrating circuit 6 for noise removal. In this embodiment, the pulse generating circuit 8 is constituted by a monostable circuit, and its output pulse (2) is configured such that 7f>7d with respect to the pulse width 7d of the data signal. Furthermore, one differential output ■ is inverted by the transistor 4 and becomes @, and is output by the noise removal integrating circuit 6 to ■
Then, it passes through the Schmitt circuit 7, becomes ■, is added to the matching circuit 9, matches the output ■ of the first pulse generating circuit 8, and becomes the output @, and in response, the second pulse 3 is obtained as a data signal output from the pulse generating circuit (here, a monostable multipipulator) 10. Here, the integrating circuit 6 has the effect of preventing pulse noise superimposed on the power supply line 11 from passing through the differentiating circuits DIF, DIP2, and the first pulse generating circuit 8
The matching circuit 9 is provided so as not to be driven during the output period (7f).

In addition, in the Schmitt circuit 7 (used for waveform shaping), it is difficult to maintain a constant threshold level due to variations in element type and characteristics in a configuration using general logic elements. By dividing the amount of feedback and making it possible to change the threshold level,
It is configured such that it can always be set to a constant threshold level, and together with the integration circuit 6 mentioned above, contributes to improving the noise margin of the present invention. At this time, it goes without saying that the time constant of the integrating circuit 6 is set smaller than the time constant of the differentiating circuits DIF, . . . DIF2. In this way, the integrating circuit 6 and the Schmitt circuit 7 are used to improve the noise margin, and essentially have a differential pulse modification function as part of the function of the differentiating circuits DIF and DIF2. Therefore, it can be deleted for signal processing of a line with a large noise margin. In addition, instead of the transmitting circuit 12 shown in FIG. 2, the transmitting circuit may use a signal transmitting method (see Tokukan Akihan - Chichimura No.) for which a patent application was filed by the present inventor on the same date as the present application. can.

As described above, according to the present invention, by focusing on the pulse width of the signal to be detected and providing the first and second pulse generation circuits, it is possible to reliably detect the target signal.

Further, according to the method of the present invention, it is possible to use a constant voltage load as a power source, which has the advantage of reducing power consumption of the device.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional configuration example, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Fig. 3 is a waveform diagram of each part to explain the operation of the embodiment of Fig. 2. be. Figure 1 Figure 2 Figure 3 Mela

Claims (1)

[Claims] 1. A first differentiation circuit that outputs a leading edge differential pulse in response to the leading edge of each pulse of a received pulse signal having a predetermined pulse width; a first pulse generating circuit that outputs a single pulse having a pulse width wider than the pulse width of the received pulse signal, and outputs a trailing edge differential pulse in response to a trailing edge of each pulse of the received pulse signal; a second differentiating circuit; a matching circuit for matching the trailing edge differentiated pulse with a single pulse from the first pulse generating circuit; and a matching circuit for matching the single pulse from the first pulse generating circuit; A signal detection method including a second pulse generation circuit that outputs each pulse of the pulse signal as a received output. 2. At least one of the first differentiating circuit and the second differentiating circuit includes an integrating circuit having a time constant smaller than a time constant of the differentiating circuit, and a Schmitt circuit driven by the output of the integrating circuit. 2. The signal detection method according to claim 1, wherein the signal detection method is configured to increase noise margin.