JPS60237748A - Msk signal detecting circuit - Google Patents

Abstract

PURPOSE:To obtain a stable MSK signal by multiplying a signal passed through a BPF, passing its output through a BPF of frequency which is twice as high as a mark and a space and detecting the obtained signal, and outputting it through a comparing circuit. CONSTITUTION:A received MSK signal containing noises over a wide range is impressed to an input terminal 11 and passed through the BPF12, and sent to a frequency multiplying circuit 13, and a signal of frequency twice as high as mark and space frequencies is led to parallel BPFs 14 and 15. Then, only a component of frequency twice as high as the mark signal frequency and a component of frequency twice as high as the space signal frequency are extracted by the BPFs 14 and 15 respectively and then mixed and detected 16, and the mixed signal is outputted from a terminal 17 through the comparing circuit 17.

Description

[Detailed Description of the Invention] [Technical Field] The present invention includes a band-pass filter, a frequency multiplier circuit, a detection circuit, and a comparison circuit in order to detect the presence or absence of an MSK signal. The present invention relates to the MSK signal detection circuit used.

[Prior art]

Conventional signal detection circuits separate and detect the paired mark and space frequencies from the received MSN signal, which contains noise over a wide band. Q: A filter with a high value and high quality was required, and an expensive LO filter was used, but as an alternative to that, an operational amplifier (
Hereinafter, it will be abbreviated as op-AMP. ), capacitance, and a filter suitable for IC implementation in which the resistor was replaced with an analog switch was developed and is called tL, 5CF (X-capacitor filter).

As a conventional example, Fig. 2 shows an example of a signal detection circuit composed of a reception band-pass filter (hereinafter abbreviated as RX-BP?), a signal detection band, and a comparison circuit.
is the receiving MBK) power terminal of the conventional example, and the MSF signal containing noise over a wide band is inputted to 22 RX-BPFs, with many out-of-band noises, and 26 CD-BPFs. In general α, 23 CD-BPF mark frequency bands and pace frequency band? Comparison of Q values covered by each α High, 8
A filter frequency characteristic with a good /IN ratio is desired, and a bandpass type Nilter of about 4th + 4th order or higher is usually required. Normally, f′i0
P-AM, P is required for the order J, and it is necessary to pay attention to the shape of the capacitor, and it does not affect the chip and has a large effect6.
On the other hand, the present invention is intended to solve all of these problems, and its purpose is to reduce the filter order even if the filter has a low Q value and a low number of filters. An object of the present invention is to provide an MSK signal detection circuit that has a stable detection function even with respect to 7.0 variations.

〔overview〕

The signal detection circuit of the present invention includes a frequency multiplier circuit, a multiplication frequency j-number bandpass filter (1), a multiplication frequency bandpass filter (2
), a detection circuit, and a comparison circuit.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

In FIG. 1, when a signal to the reception M13 containing broadband noise is input to the reception MSK signal input terminal 11,
After passing through the RX-BPF' of 12, the paired mark frequency component and space frequency component are taken out, and after being made into frequency components twice the mark and space frequencies in the frequency multiplier circuit of 13, The multiplication frequency pass filter (2) outputs only the double component of the mark signal frequency, and the multiplier frequency pass filter (2) outputs only the double component of the space signal 1 frequency, and after mixing, the detection The signal is detected through a circuit, passes through all 17 comparison circuits, and is output from 18 MSK signal detection output terminals.

Further, an embodiment of the 130 frequency multiplier circuit will be explained based on FIG.

In Figure 6, 31.52 is A OP - AMP
35,541fi detection diode, 35~3
9 are each constituted by a resistor that determines the circuit gain.

〔effect〕

As described above, according to the present invention, in order to detect adjacent mark frequency components and space frequency components as an MBK signal detection circuit, it is necessary to use n, approximately ±1QQEzC, for each of the normal mark frequency and space frequency. It is common to detect components with a bandwidth within 100Hz (Hertz), and it is necessary to fully consider the configuration of the detection filter as well as variations.

Since the first difference in the frequency of water-cooled BBf Iga-no-ba space is doubled, the detection bandwidth is also ±200) 12
It has a simpler filter configuration, and is stable even with slight variations in filter characteristics.
This has the effect of enabling MSK signal detection.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an entire embodiment of the signal detection circuit of the present invention. FIG. 2 is an example of a conventional signal detection circuit. FIG. 3 shows an embodiment of the frequency multiplier circuit used in the invention. 11.21... Reception MBK signal input terminals 12, 22
・RX-BPF 15・・・・・・・・・・・・Frequency multiplier circuit 1
4・・・・・・・・・・・・・・・Multiple frequency passing filter (1) 15・・・・・・・・・・・・Multipling frequency passing filter (2) 16・・・・・・・・・
...Detection circuit 17.24...Comparison circuit 23...CD-BPF31
．． 32... operational amplifier 33,! 14...Detection diode 35-39...Resistance or more Applicant Suwa Seikosha Co., Ltd. Agent Patent Attorney Mogami Figure 2

Claims (1)

[Claims] A signal detection circuit that receives an MSK signal consisting of a mark frequency convergence and a space frequency signature and detects the presence or absence of an MSN signal includes a first band-pass filter that passes all of the mark and space frequencies; A frequency multiplier circuit is connected to the output of the band-pass filter, and second and third band-pass filters are connected to the output of the frequency multiplier circuit to pass a frequency at twice the frequency and wave number of each mark and space. The outputs of the second and third bandpass filters are both input to a detection circuit, the output of the detection circuit is input to a comparison circuit, and the output of the comparison circuit is used as an output of the signal detection circuit. Characteristic MSK signal detection circuit.