JPS643097B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for verifying the level of a continuous frequency signal (for example, a ripple control signal) such as an audio frequency superimposed on an AC power wave of a power distribution line or dedicated line. It is about improvement.

In the present invention, a continuous frequency signal refers to a signal with a continuous waveform at a constant level, and is attenuated by momentarily shorting the lines of the carrier line through a capacitor and inductance. The phase pulse signal of the vibration waveform is not included.

A conventional continuous frequency signal level verification method will be explained with reference to FIG. The continuous frequency signal is separated from the alternating current power wave by a filter, and _the filter output ₁ shown in FIG. Rise time T ₂ and fall time
The reception level decreases at T ₃ . Furthermore, in the case of power distribution line transmission, even if the transmission level is constant, the reception level on the receiving side varies due to changes in the load connected to the power distribution line. Therefore, conventionally, when installing the receiver, the filter output 1 is measured,
The reception threshold level was set taking into consideration filter characteristics and load fluctuations. However, even if the set reception threshold level is _L2 , the level changes relatively due to load fluctuations, so it becomes _L3 when the load is light, and becomes _L1 or _L0 when the load is heavy. Therefore, when the load is normal, the number of signal pulses 2 is as shown in Figure 1C, whereas when the load is light, the number of signal pulses 2 is large as shown in Figure 1D, and it is originally a continuous frequency signal. Since signal pulse 2 occurs where there is no signal,
Poor reception occurs. When the load is heavy, the number of signal pulses 2 decreases as shown in FIG. 1B, or no signal pulses 2 are generated at all, so poor reception still occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a continuous frequency signal level verification method that solves the above-mentioned problems and can always set an optimal reception threshold level in response to fluctuations in reception level.

In order to achieve this object, the present invention sets the reception threshold level to a level lower than the peak level of the first signal train of the continuous frequency signal, so that every time reception starts, The present invention is characterized in that the reception threshold level is reset according to the state at that time.

Hereinafter, the present invention will be explained in detail with reference to FIGS. 2 to 4.

The transmitter first transmits a start signal (guard signal) consisting of a signal train of continuous frequency signals to a start channel having a predetermined time width, and transmits a start signal (guard signal) consisting of a signal train of continuous frequency signals to a plurality of signal channels following the start channel. Send code pulse signal. A code is constructed by a combination of the presence/absence of code pulse signals in a plurality of signal channels. Such a transmission method is already known.

When the receiver receives the start signal 4 consisting of the signal train of the continuous frequency signal 3 on the start channel CH ₁ as shown in FIG. 2A, the receiver receives the start signal 4.
Based on the peak level L _P of , the reception threshold level Ls is set and held at a level of a predetermined ratio lower than the peak level L P . As a result, the level of the code pulse signal 5 in the subsequent signal channels CH ₂ . . . is verified using the reception threshold level Ls. The signal pulse 6 generated by the level verification as shown in FIG. 2B is integrated to generate the code pulse 7 shown in FIG. 2C. In this way, since the reception threshold level Ls is set every time reception starts according to the peak level L _P of the start signal 4,
The reception threshold level Ls can always be set to an optimal value, and the continuous frequency signal 3 can be accurately received without being affected by load fluctuations.

An example of a receiver level verification circuit is shown in FIG. 3, and a time chart of its operation is shown in FIG.

In FIG. 3, 8 is an input terminal connected to a power distribution line, 9 is a filter, 10 is a comparator, 11 is an integrator, 12 is an output terminal, 13 is a buffer, 14
is a peak hold circuit consisting of a diode 15, switches SW ₁ and SW ₂ , and a capacitor 16;
is a buffer, and 18 is a voltage divider consisting of voltage dividing resistors 19 and 20. As shown in FIG. 4, the switch SW ₁ is turned on only for the start channel CH ₁ , and the switch SW ₂ is turned off for the start channel CH ₁ and the signal channel CH ₂ .

The filter 9 receives a start signal 4 and a code pulse signal 5 from the AC power wave input from the input terminal 8.
Separate. In the start channel CH ₁ , the switch SW ₁ is on and the switch SW ₂ is off, so the start signal 4 passes through the buffer 13 and charges the capacitor 16. Therefore, capacitor 16
The voltage is held at the peak level L _P of the start signal 4 at the end of the start channel CH ₁ , the impedance is exchanged by the buffer 17, and the voltage is divided into a predetermined ratio by the voltage divider 18.
It is output to the comparator 10 as the reception threshold level Ls. Comparator 10 pulses code pulse signal 5 into signal pulses 6 by comparing it with a reception threshold level Ls. Integrator 11 integrates signal pulse 6 to form code pulse 7 and outputs it from output terminal 12 .

In FIG. 3, the level of the output of the filter 9 is immediately tested, but the level may be tested after noise is separated from the filter output.

As explained above, according to the present invention, the reception threshold level is set to a lower level based on the peak level of the first signal train of the continuous frequency signal, so that every time reception starts, Since the reception threshold level is reset according to the state at that time, it is possible to always set the optimum reception threshold level in response to fluctuations in the reception level.

[Brief explanation of drawings]

Figure 1 is a waveform diagram illustrating a conventional continuous frequency signal level verification method, Figure 2 is a waveform diagram illustrating an embodiment of the present invention, and Figure 3 is a level verification method implementing an embodiment of the present invention. A block diagram showing an example of a circuit,
FIG. 4 is a time chart showing the operation of the circuit shown in FIG. 3... Continuous frequency signal, 4... Start signal, 5
...Code pulse signal, 6...Signal pulse, 9...
...Filter, 10...Comparator, 11...Integrator,
14...Peak hold circuit, 18...Voltage divider,
L _P ...Peak level, Ls...Reception threshold level, CH ₁ ...Start channel, CH ₂ ~
CH ₅ ...Signal channel.

Claims (1)

[Claims] 1 In a continuous frequency signal level verification method in which a continuous frequency signal separated from an AC power wave is compared with a reception threshold level and a waveform with a level higher than the reception threshold level is verified as a signal pulse, A continuous frequency signal level verification method characterized in that a reception threshold level is set to a level lower than the peak level of the first signal train.