JPH01303948A - Fsk demodulator - Google Patents

Abstract

PURPOSE:To attain correct reception even if a change in the signal quantity and noise quantity is large by providing plural level detection circuits. CONSTITUTION:The 1st and 2nd level detection circuits 16a, 16b are connected to a smoothing circuit 15 to constitute a carrier detector 17A. The level detection circuits 16a, 16b output a detection signal in a different signal level depending on the output from a smoothing circuit 15 and the signal processing circuit is operated normally by any of the 1st and 2nd carrier detection levels. Thus, even if the signal and noise vary largely, normal reception is attained. Since only the level detection circuit and the signal processing circuit are increased in the circuit configuration, the device is constituted easily and inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an FSX demodulator 1, particularly an FSK11L'A device of a power line carrier transmission device using a power line as a transmission path.

[Prior Art] FIG. 4 is a block diagram showing the entire conventional power line carrier transmission device. In the figure, (1) is a power line, (2a)
, (2b) are transmission devices and have the same configuration. <3) is the joint that connects to the power line (1), (4) is the joint (3)
(5) is a receiving section connected to the coupling section (3); (6) is a communication control section connected to the transmitting section (4) and receiving section (5); Transmission device (2a)
is configured.

5 is a block diagram showing the configuration of the receiver (6) in FIG. 4. In FIG. 0, (11) is a block diagram showing the configuration of the receiver (6) in FIG.
(12) is a limiter that inputs the signal (A) from the bandpass filter (11) and outputs the P-wave signal (B), and limits its amplitude.
B> is the amplitude limited signal (C
) and demodulates the FS, (14) is the FS
A slicer (15) that inputs the FS demodulated signal (D) from the demodulator (13) and passes only signals between predetermined levels.
(16) inputs the signal (F) from the smoothing circuit (15) and detects the level. The level detection circuit (17) is °, the smoothing circuit (15,
) and a level detection circuit (16), and (18) is a signal processing circuit that processes the output signal (E) of the slicer (14) and the output signal (G) of the level detection circuit (16). It is.

FIG. 6 is a diagram showing operating waveforms of each part in FIG. 5.

FIG. 7 is a level diagram showing the operation of FIG. 5.

The conventional FSX demodulator is configured as described above, and in FIG. 4, the transmission device (2) connected to the power line (1) exchanges signals using the power line (1) as a transmission path.

For example, the transmission signal from the transmission device (2a) is transmitted from the power line (1
), and the signal is received by the transmission device (2b).The internal operation of the transmission device (2) is to start the transmission section (4) based on a command from the communication control section (6) and generate a signal. death,
A signal is superimposed on the power line (1) through the coupling part (3).

The signal superimposed on the power line (1) is input from the coupling section (3) to the receiving section (5), where the signal is processed and the received data is transferred to the 1 communication control section (6).

This receiving section (6) has a configuration as shown in FIG. 5 in the case of an FSK receiving section. A signal as shown in FIG. 6(A) (
A) is connected to the bandpass filter (1) through the coupling part (3) in FIG.
1) is input. The signal (
B) becomes only the signal band component as shown in FIG. 6(B), and becomes a rectangular wave as shown in FIG. 6(C) by the limiter (12). The rectangular wave signal (C) is converted into a demodulated waveform as shown in FIG. 6 (D) by the FS demodulator (13), and converted into a digital demodulated signal as shown in FIG. 6 (E) by the slicer (14). In this way, since FSX demodulation is frequency demodulation, the presence or absence of a signal is determined by the carrier detector (17).The smoothing circuit (15) converts the AC waveform (B) into a DC level signal (F). However, when the level detection circuit (16) receives a signal exceeding the set level, it outputs a signal level detection output as shown in Fig. 6 (G).This output signal (E) and output signal (G) is processed by the signal processing circuit (18) to perform FSX signal reception processing.

[Problems to be Solved by the Invention] In the conventional FSX receiving section as described above, the S/N ratio, which is the ratio of signal to noise, is good as shown in FIG. normal reception operation is possible when the noise level is higher than the carrier detection level and the noise level is lower than the carrier detection level.1 In transmission using normal communication lines, there is no problem with this configuration because the signal and noise can be determined quantitatively. In transmission using power lines, problems arise because signal attenuation is large and noise is large.

For example, as shown in FIG. 7(b), even if the S/N ratio is good, the noise is higher than the carrier detection level.

Unable to operate normally. FIG. 7(C) shows a case in which normal operation cannot be performed because the signal is smaller than the carrier detection level, and there is a problem in that even if the S/N ratio is good, the signal cannot be received normally.

This invention was made in order to solve this problem.If the S/N ratio is good, the range of normal reception can be expanded even if the signal and noise levels change.
The purpose is to obtain an SK demodulator.

[Means for Solving the Problems] A 13K demodulation device according to the present invention is a power line carrier transmission device using a power line, and includes a bandpass filter to which a signal is input, a limiter connected to the bandpass filter, and a limiter connected to the bandpass filter. A carrier detector comprising an FS demodulator connected to the FS demodulator, a slicer connected to the FS demodulator, a smoothing circuit connected to the bandpass filter, and a plurality of level detection circuits connected to the smoothing circuit. and a plurality of signal processing circuits each receiving the output of the slicer and the plurality of outputs of the carrier detector.

[Operation] In the present invention, since a plurality of level detection circuits are provided, reception can be performed normally even if the signal amount and noise amount change greatly.

[Embodiment] FIG. 1 is a block diagram showing the configuration of an FSK demodulator according to an embodiment of the present invention. In the figure, (11) to (
15) is similar to the conventional device described above. (16a)
and (16b) is the first circuit connected to the smoothing circuit (15).
and 6 smoothing circuits (15) which are the second level detection circuits.
, first and second level detection circuits (16a), (16
b) constitutes a carrier detector 17A). (1
8a) and (18b) are the same signal processing circuits as in FIG.

FIG. 2 is a level diagram showing the operation of the present invention.

FIG. 3 is a block diagram showing the configuration of an FSK demodulator according to another embodiment of the present invention. It is similar to that in Figure 1. In addition, a smoothing circuit (15), a first level detection circuit (16a), a second level detection circuit (16b)... an n-th level detection circuit (
16n) constitutes a carrier detector (17B).

In the FSX demodulator configured as described above, for example, the carrier detection level of the first level detection circuit (16a) is set to the first carrier detection level, and the carrier detection level of the second level detection circuit (16b) is set to the second carrier detection level. The carrier detection level is set to be the first carrier detection level>the second carrier detection level. Each level detection circuit (16
a) and <16 b) output detection signals at different signal levels depending on the output from the smoothing circuit (15). As shown in FIG. 2, this operation is normal at both the first carrier detection level and the second carrier detection level in FIG. 2(a). In FIG. 2(b), normal operation occurs only at the first carrier detection level, and in FIG. 2(c).

It operates normally only at the second carrier detection level.

Since there are two carrier detection levels in this way, normal reception is possible even if there are large changes in signal and noise. In addition, the configuration circuitry can be easily and inexpensively constructed since only the level detection circuit and the signal processing circuit are increased.

In the above embodiment, two level detection circuits and two signal processing circuits are provided, but as many as n may be provided as shown in FIG. As explained above, the electric power a using the power line
A carrier transmission device includes a bandpass filter to which a signal is input, a limiter connected to the bandpass filter, an FS demodulator connected to the limiter, a slicer connected to the FS demodulator, and the bandpass filter. a carrier detector composed of a smoothing circuit connected thereto and a plurality of level detection circuits connected to the smoothing circuit; and a plurality of signals inputting the output of the slicer and each inputting the plurality of outputs of the carrier detector. By multiplexing level detection circuits, it is possible to respond to large changes in signal and noise.

It also has the advantage of being easy to configure and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the configuration of an FSK recovery device according to an embodiment of the present invention, FIG. 2 is a level diagram showing the operation of the invention, and FIG. 3 is an FSK reconstruction apparatus according to another embodiment of the invention.
FIG. 4 is a block diagram of the configuration of the SK demodulator, and FIG. 4 is an overall block diagram of the power line transmission device. FIG. 5 is a block diagram of a conventional FSX demodulator. 6 is an operational waveform diagram of each part of FIG. 5, and FIG. 7 is a level diagram showing the operation of FIG. 5. In the figure, (11)... bandpass filter, (12)...
...Limiter, (13) ---FSfi adjuster, (14L
... Slicer, (15) ... Smoothing circuit, (16a>. (16b) ...<16n) ... Level detection circuit. (17A>, (17B>---・Carrier detector, (1
8a>. (18b)...<18n)...Signal processing circuit. Note that the same reference numerals in each figure indicate the same or equivalent parts. Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A power line carrier transmission device using a power line includes a bandpass filter to which a signal is input, a limiter connected to this bandpass filter, an FS demodulator connected to this limiter, and a slicer connected to this FS demodulator. , a carrier detector composed of a smoothing circuit connected to the bandpass filter and a plurality of level detection circuits connected to the smoothing circuit; and a carrier detector that receives the output of the slicer and receives the plurality of outputs of the carrier detector, respectively. An FSK demodulator comprising: a plurality of input signal processing circuits.