JPS6277735A - Data reception circuit - Google Patents

Abstract

PURPOSE:To attain accurate operation control by making a data demodulation output effective only when a base band signal detection output exists and no noise detection output exists to prevent mis-detection of a data signal by a pseudo signal at reception. CONSTITUTION:A detection circuit 11 detects a base band signal via a BPF 10 during the execution of reception processing operation, gives an H output to an AND circuit 12 and when the output of a comparator 5 is at H, the circuit 11 gives an H output of an AND circuit 16. On the other hand, an output of a high frequency demodulation section 2 is inputted to a noise detection circuit 14 via a BPF 13 and an H output at the noise detection is sent to the AND circuit 16 via an inverter 15 and the H output is given to a control section 7. The circuit 16 demodulates a data signal when no noise exists. Thus, the normal data signal is demodulated by the function of the circuits 12, 16 when the base band signal exists and no noise exists and the control section 7 controls accurately various operations.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention provides
In particular, the data reception circuit used in the [to make] improvements.

(Technical deficiencies of the invention) A conventional data receiving circuit has a configuration as shown in FIG. 3, which includes an antenna 1. a high frequency demodulator 2. a buffer amplifier 3.
Low pass filter (LPF) 4°] inverter 5. Reference voltage? li6. A control section 7 is provided. In such a conventional data receiving circuit, a modulated wave transmitted from a data transmitting circuit (not shown) at Ij receives FM modulation using a predetermined baseband signal (data signal), is received by an antenna 1, and is then transmitted to a high frequency demodulation section. 2 and is demodulated into M.

The baseband signal obtained by this FM demodulation process is amplified to a predetermined level by a buffer amplifier 3, then passed through a low-pass filter 4, and then passed through a comparator 5.
is input to the comparison signal input terminal of Here, the low-pass filter 4 passes only the data signal and removes the noise component, thereby allowing the S/F of the baseband signal to pass through.
It has the ability to improve the N (signal-to-noise) ratio.

On the other hand, a predetermined voltage corresponding to the threshold level (Na1ll value) is input from the reference power supply 6 to the reference signal input terminal of the comparator 5, and the data signal input to the comparison signal input terminal is A10 conversion is performed using the threshold level as a reference, and output from the comparator 5 as a logic level data signal,
It is input to the control section 7.

The control unit 7 executes various operation controls based on the data signal.

During execution of the reception processing operation, the low-pass filter 4 generates an output with a waveform as shown in FIG. 4(a) depending on the reception situation. In other words, in the same figure (a>), the mode (■) is the demodulated output when only the digital signal is received without modulation by the baseband signal, and similarly, the modes (2) and (2) are the demodulated output when the baseband signal is normally received. These are demodulated outputs during reception and when the received electric field strength is reduced due to fading, etc.In response to the output of the low-pass filter 4 in such a mode, the comparator 5 outputs a signal as shown in FIG. Generates a waveform output in accordance with the waveform.

In other words, when the output as shown in Embodiment 1 is inputted from the low-pass filter 4, the above-mentioned comparator 5 generates a normal data signal as shown in Embodiment V; When an output as shown in aspect (2) is inputted, the comparator 5 generates a pseudo signal as shown in aspect (2). This occurs because the gain of the comparator 5 is high even though only the carrier is being received. Similarly, when an output as shown in aspect (2) is inputted from the low-pass filter 4, the comparator 5 generates a pseudo signal as shown in aspect (2). This occurs because when the received field strength decreases due to fading or the like, noise components in the receiving section increase and are demodulated.

[Problems with background technology]

In this way, in the conventional data receiving circuit described above, when receiving a modulated wave unattended or when receiving a signal with a decrease in the received field strength due to noise, etc., the problem occurs due to the high gain of the comparator or the noise in the receiving section. There is a problem that a pseudo signal may be mistakenly detected as a regular data signal by the l control section, and in such a case, normal operation control cannot be executed.

In particular, with multi-channel access type radio equipment, because data signals are sent and received to configure a specific channel line, it is possible that not only fading, but also noise may occur when switching channels, and the transmitter/receiver may start up. Since data signals are transmitted and received in consideration of the characteristics, noise conditions and unmanned conditions frequently occur.This problem was conspicuous.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and is intended to prevent erroneous detection of data signals caused by spurious signals generated during unmanned reception of modulated waves or reception with a reduction in received field strength due to fading, etc. , it is an object of the present invention to provide a data receiving circuit that can ensure accurate operation control.

[Summary of the invention]

Therefore, the present invention includes a data demodulation circuit that demodulates a modulated wave, converts the baseband signal obtained by the demodulation to a logic level and outputs it, a baseband signal detection circuit that detects the baseband signal, and an audio The output of the data demodulation circuit is enabled only when the noise detection circuit detects a frequency other than the band and the baseband signal detection circuit has a baseband signal detection output, and the noise detection circuit does not have a noise detection output. provide logical means to
The above object is achieved by obtaining a demodulated data signal only when there is a baseband signal and no noise.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the circuit configuration of a data receiving circuit according to the present invention, and is similar to the conventional data receiving circuit shown in FIG. The buffer amplifier 3, the [1-pass filter 4 and In between, a baseband signal detection circuit 1 is connected through a bandpass filter (BPF) 10.
1 is connected, and the output of the baseband signal detection circuit 11 is connected to the AND circuit 1 along with the output of the comparator 5.
2. Further, a noise detection circuit 14 is connected between the high frequency demodulation section 2 and the buffer amplifier 3 through a band pass filter (BPF) 13, and the output of the noise detection circuit 14 is connected to the inverter 15.
The signal is inputted to the AND circuit 16 together with the output of the AND circuit 12 through the AND circuit 16 . The control operation of this data receiving circuit will be described in detail below with reference to the time chart 11 in FIG.

First, F by a predetermined baseband signal (data signal)
A modulated wave subjected to M modulation and transmitted from a data transmitting circuit (not shown) is received by the antenna 1 of the data receiving circuit described above, and then guided to the frequency demodulating section 2 where it is FM demodulated. The baseband signal obtained by this FM demodulation process is further amplified to a predetermined level by a buffer amplifier 3, and then passes through a low-pass filter 4.]
Input to the comparison signal input terminal of the comparator. Here, the low-pass filter 4 functions to improve the S/N (signal-to-noise) ratio of the baseband signal by passing only the data signal and removing noise components. On the other hand, the reference signal input terminal of the comparator 5 is connected to a reference power supply 6, which is connected to a reset hold level (
The data signal input to the comparison signal input terminal is A/D converted using the threshold level as a reference, and the data signal is converted into a logic level data signal. It is output from the comparator 5 and input to the AND circuit 12.

During execution of the reception processing operation, the low-pass filter 4 generates an output with a waveform as shown in FIG. 2(a), and in response to the output, the comparator 5 generates a waveform as shown in FIG. A waveform output like this is generated. In other words, in contrast to mode (2) of the output waveform of the low-pass filter 4 when the baseband signal is normally received, a normal demodulated data signal as shown in mode V is obtained at the comparator 5, but only the carrier is received. [Regarding mode I or ■ of the output waveform of the low-pass filter 4 when reception is performed with a reduction in received field strength due to fading or the like]] An output containing a mixture of pseudo signals as shown is obtained.

Now, during execution of the reception processing operation, the buffer amplifier 3
The output is input to the low-pass filter 4 and, at the same time, is input to the baseband signal detection circuit 11 through the band-pass filter 10. Here, the bandpass filter 10 passes only the baseband signal among the outputs of the buffer amplifier 3, and the baseband signal detection circuit 11
The baseband signal, which is a 0-pass output, is detected. As shown in FIG. 2(C), the baseband signal detection circuit 11 generates an output at the "1-1" level when the baseband signal is detected, and sends the output to the AND circuit 12. input.

At this time, the AND circuit 12 includes the comparator 5
An output as shown in FIG. 2(b) is input from the comparator 5, and the output is at the "H11 level" only when the output of the comparator 5 and the output of the baseband signal detection circuit 11 are both at the "H'" level. is generated and its output is input to the AND circuit 16.

In other words, the AND circuit 12 has the function of demodulating the data signal only when there is a baseband signal, and since the demodulation operation is not performed when only the carrier is received, its output is It exhibits a waveform as shown in FIG. 4(d).

On the other hand, during execution of the reception processing operation, the output of the high frequency demodulator 2 is input to the buffer amplifier 3, and at the same time,
The signal passes through the bandpass filter 13 and is also input to the noise detection circuit 14 . Here, the noise detection circuit 14 detects noise from the output of the baseband signal outputted from the high frequency demodulation section 2 that has passed through the bandpass filter 13, and when the noise is detected, the noise is at a "tobi" level. When no detection is detected, an output of "'L" level is generated. The outputs of the noise detection circuit 14 are each inverted by an inverter 15, and as shown in FIG. 3(e), when there is no noise, the output is at the '11' level and is input to the AND circuit 16. When the AND circuit 16 receives a signal from the AND circuit 12 (d
), and the output of the AND circuit 12 and the output of the inverter 15 are both ``H''.
'' level, generates an output of 1-V level and inputs the output to the control section 7. In other words, the output level is 1-V.

The AND circuit 16 has a function of demodulating the data signal only when there is no noise, and when the noise is detected as the received electric field strength decreases due to fading etc., the demodulation operation is performed. Therefore, the output exhibits a waveform as shown in FIG.

In other words, in a cohesive manner, only when there is a baseband signal and no noise, a normal data signal as shown in FIG. The control unit 7 to which the data signal is input can accurately control various operations based on the data signal.

Incidentally, the upper side shows an embodiment of a radio device using a multi-channel access method, and the baseband signal detection circuit 11 is provided for the purpose of detecting beats occurring on the same channel. The output directly led from the baseband signal detection circuit 11 to the control circuit 7 is used as interference information for each channel. Similarly, the noise detection circuit 14 is also an indispensable configuration for this type of radio equipment.
The output directly led from the control circuit 4 to the control circuit 7 is used as channel blockage information. As described above, the radio equipment using the multi-channel access method has the baseband signal detection function and the fill
Since it is equipped with a detection function, it is easy to configure the circuit, and since the line is configured by transmitting and receiving data signals, it is not only possible to cause fading, but also to be affected by noise when the channel is cut, and the transmitter/receiver. The present invention is particularly useful when considering the frequent occurrence of noise conditions and unmanned conditions, since data signals are transmitted and received taking into account the characteristics of the system.

〔Effect of the invention〕

As explained above, according to the data receiving circuit of the present invention,
A baseband signal detection circuit and a noise detection circuit are provided, and only when the baseband signal is detected and noise (frequency other than the voice band) is detected, the data signal [1
1 output, it is possible to avoid erroneous detection of spurious signals as legitimate data signals, which occur during unmanned reception of modulated waves or reception with a strong reduction in the received electric field due to fading, etc. It has the excellent advantage of being able to ensure accuracy in motion control based on this method.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a data receiving circuit according to the present invention, and FIG. 2 is a timing chart showing output waveforms of each part in the data receiving circuit shown in FIG.
FIG. 3 is a block diagram showing the circuit configuration of a conventional data receiving circuit, and FIG. 4 is a timing chart showing output waveforms of each part in the data receiving circuit shown in FIG. DESCRIPTION OF SYMBOLS 1... Antenna, 2... High frequency demodulation part, 3... Buffer amplifier, 4... Low pass filter, 5... Comparator, 6... Reference power supply, 7... Control part, 10
．． 13...Band pass filter, 11...Baseband signal detection circuit, 12.16...AND circuit, 14
...Noise detection circuit, 15...Inverter.

Claims (1)

[Scope of Claims] A data demodulation circuit that demodulates a modulated wave, converts the baseband signal obtained by the demodulation to a logic level, and outputs the same; a baseband signal detection circuit that detects the baseband signal; a noise detection circuit that detects a frequency other than the voice band; and an output of the data demodulation circuit only when the baseband signal detection circuit has a baseband signal detection output and the noise detection circuit does not have a noise detection output. 1. A data receiving circuit comprising: validating logic means.