JPS6260858B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for separating and detecting a phase pulse signal injected onto an AC voltage wave of an AC distribution line or dedicated line from noise.

In the conventional phase pulse signal detection method, in order to separate the phase pulse signal and noise, the noise is initially measured, a reception threshold level higher than the average noise level is set, and anything exceeding the reception threshold is detected. It is detected as a phase pulse signal. However, noise at a level higher than the reception threshold level set in this way may sometimes occur. If the noise is random noise that is not synchronized to the phase, the phase pulse signal can be separated from the noise by an integral test that detects the number of times within a given time, but always in the same phase of each cycle of the alternating voltage wave. In the case of existing standing noise, it could not be distinguished from the phase pulse signal. As shown in FIG. 1, when a phase pulse signal 1 and standing noises 2 and 3 are present, conventional methods cannot prevent erroneous reception due to the standing noise 3 exceeding the reception threshold level 4. Ta. 5 is a signal dead zone.

In order to eliminate this drawback, each channel on the alternating voltage wave into which the phase pulse signal is to be injected is subdivided into several phase units, and prior to the communication of the phase pulse signal, the alternating voltage wave is injected with the same phase pulse signal. Separates the noise in the frequency band, calculates and stores the average noise level over a predetermined number of cycles in each phase unit, then starts communication of phase pulse signals, and calculates the average received level over a predetermined number of cycles in each phase unit. The applicant has already proposed a method of subtracting the average noise level from this average reception level and using the difference as the phase pulse signal level.

When this detection method is used in a terminal that is called by a repeater and sends back information, if a predetermined number of cycles have not elapsed after the repeater started transmitting the phase pulse signal, the terminal will emit the phase pulse signal. Since the signal is not detected, there is a problem that it takes time to detect the signal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a phase pulse signal detection method capable of solving the above-mentioned problems and detecting a phase pulse signal quickly within a predetermined number of cycles.

To achieve this objective, the present invention subdivides each channel on the alternating voltage wave into which a phase pulse signal is to be injected into a plurality of phase units, and for each cycle of the alternating voltage wave, the level of each phase unit is Remember, 1
Every time a cycle is stored, the average received level is calculated by averaging the levels from a predetermined number of cycles before to the current cycle for each phase, and the level from twice the predetermined number of cycles to the predetermined number of cycles before is calculated. The average noise level is calculated by averaging in each phase unit, the average noise level is subtracted from the average reception level for each phase unit, and if the difference is larger than a predetermined value, it is detected as a phase pulse signal. , the average reception level and the average noise level are always calculated and the difference between them is calculated.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

In the present invention, each channel into which a phase pulse signal is to be injected is subdivided into a plurality of phase units. The mode is shown in FIG. Channels CH1 to CH21 into which the phase pulse signal is to be injected are set in the phase pulse signal carrying range 7 on the AC voltage wave 6 where there is relatively little noise. channel
CH1 is the pilot channel, channel CH
2 to CH9 are channels for terminal selection, channels CH10 and CH11 are channels for digit selection,
Channels CH12 to CH21 are respectively assigned to return channels. Each channel CH
1 to CH21 further include phase units U1 to CH21 having a phase angle width sufficient to reproduce the phase pulse signal waveform.
Subdivided into U10. In Figure 2, channel 1 is
Although it is subdivided into 10 phase units, it is actually 20~
It is desirable to subdivide into about 100 phase units (2 to 10 μs).

The terminal device is equipped with a detection circuit shown in FIG. 4, for example, and constantly monitors the AC voltage wave 6 since it is not known when the phase pulse signal will be transmitted from the repeater. That is, when the phase pulse signal is not being transmitted, from the AC voltage wave 6 input via the connection terminal 8 connected to a carrier line such as an AC distribution line,
A filter 9 separates noise in the same frequency band as the phase pulse signal, and detects the noise level in each phase unit U1 to U10 of channels CH1 to CH21. The A/D converter 10 has channels CH1 to CH
The noise level is A/D converted in synchronization with a signal from the control circuit 11 instructing 21 phase units, and the memory 12 stores them. FIG. 2 shows an example where standing noise 13 exists in channel CH9. Since this standing noise 13 exceeds the reception threshold level 14, it causes erroneous reception.
The memory 12 constantly stores data D _2S from twice the predetermined number of cycles S to data D ₁ from the current cycle.

Every time the phase pulse signal carrying range 7 in one cycle ends, the arithmetic circuit 15 averages the levels from a predetermined number of cycles S before to the current cycle for each phase, and uses this as the average received level. Further, the levels from twice the predetermined number of cycles S to before the predetermined number of cycles S are averaged for each phase, and this is taken as the average noise level. Even if the memorized level contains random noise components, the random noise components will converge to zero by averaging, so
The average level is only the standing noise component. Then, the arithmetic circuit 15 subtracts the average noise level from the average received level and outputs the difference as a phase pulse signal level. The verification circuit 16 determines that if the difference between the highest levels of the phase units U1 to U10 exceeds the reception threshold level 14 for each channel,
Output pulses are output from output terminal 17. When the phase pulse signal is not being transmitted, the average reception level and the average noise level are equal, so the difference between them is zero, and the output of the verification circuit 16 is at a low level.

The repeater starts emitting phase pulse signals, e.g., phase pulse signal 1 as shown in FIG.
8 into the pilot channel CH1 and others, the terminal receives them along with the noise 13 and stores, calculates and verifies them as described above. If the data at the start of transmission of the phase pulse signal 18 is Di (Fig. 3), the difference between the average received level and the average noise level is small while the accumulation of data Di~ _D1 related to the phase pulse signal 18 is small. , the difference increases as the accumulation of data Di~D ₁ increases, and unless the condition of the carrier line such as the AC power distribution line is very bad, the difference will disappear at the reception threshold before a predetermined number of cycles S have passed after the start of transmission. level 14 is exceeded and a phase pulse signal 18 is detected.

This situation is shown in FIG. The repeater begins transmitting the phase pulse signal 18 at time _t3 and continues transmitting until time _t5 , a predetermined number of cycles S later. The terminal device detects the phase pulse signal 18 at time _t4 , before a predetermined number of cycles S has elapsed after the start of transmission, but at that time, the average noise level is the average level of the predetermined number of cycles S from time _t1 to time _t2 . The average reception level is the average of the levels of a predetermined number of cycles S from time t ₂ to time t ₃ . Since the predetermined number of cycles S is set assuming the worst condition of the carrier line, in many cases the phase pulse signal 18
can be detected quickly. This allows the terminal to quickly send information back to the repeater.
Information gathering time can be shortened.

Note that the storage of the level in phase units, the averaging, and the subtraction are not limited to digital processing, and may be performed by analog processing.

As explained above, according to the present invention, each channel on an AC voltage wave into which a phase pulse signal is to be injected is subdivided into a plurality of phase units, and the level of each phase unit is adjusted for each cycle of the AC voltage wave. Remember, 1
Every time a cycle is stored, the average reception level is calculated by averaging the levels from a predetermined number of cycles before to the current cycle for each phase, and the level from twice the predetermined number of cycles to the predetermined number of cycles before is calculated. The average noise level is calculated by averaging in each phase unit, the average noise level is subtracted from the average reception level for each phase unit, and if the difference is larger than a predetermined value, it is detected as a phase pulse signal. Since the average reception level and the average noise level are always calculated and the difference between them is calculated, the phase pulse signal can be detected quickly within a predetermined number of cycles.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram showing a general phase pulse signal and standing noise, FIGS. 2 and 3 are diagrams showing phase units and reception levels for subdividing channels in the present invention, and FIG. 4 is a waveform diagram showing a general phase pulse signal and standing noise. FIG. 5 is a block diagram showing an example of the detection circuit to be implemented, and a time chart showing its operation. 6...AC voltage wave, 9...filter, 11...
Control circuit, 12...Memory, 13...Noise, 1
4...Reception threshold level, 15...Arithmetic circuit, 16...Verification circuit, 18...Phase pulse signal, CH1 to CH21...Channel, U1 to U1
0...phase unit, S...predetermined number of cycles.

Claims (1)

[Claims] 1. Subdivide each channel on the AC voltage wave into which a phase pulse signal is to be injected into a plurality of phase units, store the level of each phase unit for each cycle of the AC voltage wave, and store the level of each phase unit each time one cycle of storage is completed. Then, the average received level is calculated by averaging the levels from a predetermined number of cycles before to the current cycle in each phase unit, and the levels from twice the predetermined number of cycles before to a predetermined number of cycles before are averaged for each phase unit. A phase pulse signal detection method that calculates an average noise level by subtracting the average noise level from the average reception level for each phase unit, and detects a signal whose difference is larger than a predetermined value as a phase pulse signal.