JPH0474021A - Method and apparatus for detecting carrier - Google Patents

Abstract

PURPOSE:To realize a stable detection method in which automatic adjustment is attained by storing a maximum value and a minimum value of the conversion of a DC output resulting from rectifying and smoothing a detection output in the operating state of a control input of a digital signal and outputting an output representing non-carrier when a maximum value of an input digital signal is larger than the stored maximum in the inoperating state of the control input. CONSTITUTION:A reception detection output being a DC signal through a BPF 13, a rectifier circuit 15 and a smoothing circuit 16 is converted by an A/D converter circuit 17 and a maximum value and a minimum value of the circuit 17 are stored in a nonvolatile memory 20 via a control circuit 18 when a control input terminal 19 is set to the operating state. The circuit 18 reads a digital signal from the A/D converter circuit 17 when the terminal 19 is set to an off state and compares it with a maximum value read from the nonvolatile memory 20 and outputs an output representing no-carrier from an output terminal 21 when the signal is over the maximum value. Thus, the stable carrier detection method is realized, in which fluctuation due to adjustment is less and automatic adjustment is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a carrier wave detection method and apparatus for preventing interference in radio equipment and for indicating out of communication range.

Conventionally, in this type of carrier wave detection method and device, the detection output of a radio receiving circuit is passed through a bandpass filter, the DC output is input to a comparator, and a comparison level is divided by a variable resistor to give a voltage. , the presence or absence of a carrier wave can be detected based on the output of the comparator.

FIG. 3 shows the configuration of a conventional carrier wave detection device. In FIG. 3, a received radio wave captured by an antenna 1 is detected by a receiving circuit 2, band-limited by a bandpass filter 3, amplified by an amplifier circuit 4, rectified by a rectifier circuit 5,
The signal is smoothed by the flat # circuit 6 and input to the comparator 8. The comparator 8 compares the input DC voltage with the reference voltage divided by the variable resistor 7, and outputs the presence or absence of a carrier wave to the output terminal 9.

In this way, even with the conventional carrier wave detection device, the presence or absence of a carrier wave can be detected by adjusting the reference voltage with the variable resistor 7 with respect to the detection output of the receiving circuit 2.

Problems to be Solved by the Invention However, in the conventional carrier wave detection method and device, it is necessary to adjust the reference voltage using a variable resistor, and the output of the smoothing circuit generally contains ripples, so it is difficult to compare. There was a problem in that the output of the device was unstable and required skill to adjust it.

The present invention solves such conventional problems, and aims to provide a stable carrier wave detection method and apparatus thereof that can be automatically adjusted with little adjustment fluctuation.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention converts the output of the smoothing circuit into an A/D converter so that the digital signal including the ripple component can be stored, and input the digital signal at the time of operation of the control input. The digital signal is used as a reference level, and the presence or absence of a carrier wave is determined by comparing the magnitude of this reference level with the magnitude of a digital signal newly input when the control human power is not operating.

Effects According to the present invention, carrier wave detection can be performed by switching the control input between operating and non-operating states with the above-described configuration, so that carrier wave detection can be automatically adjusted.

Furthermore, the present invention allows the carrier wave detection section to be built into one microprocessor, thereby simplifying the configuration of the device.

Embodiment FIG. 1 shows the structure of an embodiment of the present invention. In FIG. 1, 11 is an antenna, 12 is a receiving circuit, 13 is a bandpass filter, 14 is an amplifier circuit, 15 is a rectifier circuit, 16
is a smoothing circuit. 17 is an A/D (analog/digital) conversion circuit, which includes a rectifier circuit 15 and a smoothing circuit 16.
The rectified and smoothed DC voltage is converted into a digital signal and input to the control circuit 18. A control circuit 18 controls the carrier wave detection section. A control input terminal 19 inputs the operating state to the control circuit 18. 2o is non-volatile memory,
The digital signal from the A/D conversion circuit 17 is transferred to the control circuit 18.
It is stored and output under the control of Reference numeral 21 denotes an output terminal, which outputs the carrier wave detection determination result of the control circuit 18.

Next, the operation of the above embodiment will be explained. In the embodiment, when the control input terminal 19 is in the operating state (hereinafter referred to as on), the control circuit 18 reads the digital signal sampled for a certain period of time by the A/D conversion circuit 17, extracts the maximum value and the minimum value, It is stored at a specific address in the nonvolatile memory 20. At this time, when the control input terminal 19 changes to an inactive state (hereinafter referred to as OFF) during the reading time of the digital signal, the maximum and minimum values of the digital signal up to the time of change are extracted, and the non-volatile memory 20 is Store at a specific address. Further, when the control input terminal 19 is off, the control circuit 18 reads the digital signal sampled for a certain period of time from the A/D conversion circuit 17, compares it with the maximum value read from the nonvolatile memory 20, and detects a signal that is greater than or equal to the maximum value. If there is, output without a carrier wave from the output terminal 21,
If there is no signal greater than the maximum value, output with a carrier wave is performed from the output terminal 21.

2, according to the embodiment, carrier wave detection adjustment is not done by turning a variable resistor like in the past (but by simply inputting an adjustment value and turning on the control input of the control input terminal 19). Since the non-volatile memory IJ 20 only requires a part of the memory normally used to store the operating mode of the radio and the unique number, the carrier wave detector can be configured using a microprocessor with a built-in A/D conversion circuit, so a carrier wave detection device with a simple configuration can be realized.

Next, another process of the control circuit 18 in the device will be explained with reference to the flowchart shown in FIG. In this flowchart, the handling of the digital signal from the A/D conversion circuit 17 after reading the state of the control input terminal 19 is determined.

First, in step 31 it is determined whether the control input terminal 19 is on, and if it is on, step 32
It is determined whether the on state has elapsed for a certain period of time, and if the certain period has not elapsed, a new digital signal from the A/'D conversion circuit 17 is read (step 33), and its maximum value is already stored in the nonvolatile memory 2o. If it is larger than the maximum value of the stored digital signal (step 34)
, the stored maximum value is updated in step 35.
), and if the minimum value of the new input signal is smaller than the stored minimum value of the digital signal (step 36), the stored minimum value is updated (step 37).
The counter is incremented (step 38) and the process returns to step 31.

Next, if it is determined in step 31 that the control input terminal 19 is off, or if it is determined in step 32 that the on state has elapsed for a certain period of time, it is determined in step 39 whether or not to write to the nonvolatile memory 20. In the case of writing, write the maximum and minimum values of the digital signal from the A/D conversion circuit 17 to the nonvolatile memory 20 (step 40), then set the nonvolatile memory 20 to read mode (step 41), and set the mode. (step 42), and performs other control processing.

Further, if writing to the nonvolatile memory 20 is not performed in step 39, in step 43, the A/D conversion circuit 17
A new digital signal is read in from the controller, and its maximum value is compared with the maximum value already stored in the non-volatile memory 20 (step 44). If the newly input maximum value is larger, no carrier wave is output. Step 45)
If it is smaller, compare the minimum value of the new digital signal with the minimum value of the already stored digital signal.Step 4
6) If the minimum value of the newly input digital signal is smaller than the stored minimum value, output a signal with a carrier wave (step 47), and if it is larger, add the counter (step 48). Then, in step 49, it is determined whether a certain period of time has elapsed in this state, and if it has elapsed, in step 50, an output is set to the output terminal 21, and the mode is set to a mode set state, and the process moves to other control processing. - If the fixed time has not elapsed, return to step 43.

According to this flowchart, the maximum and minimum values of the digital signal read from the nonvolatile memory 20 and the maximum and minimum values of a new digital signal sampled for a certain period of time from the A/D conversion circuit 17 are read and compared. As a result, if there is a signal below the minimum value, even if there was a signal exceeding the maximum value before that, the signal is read from the A/D conversion circuit 17 so that an output with a carrier wave is output from the output terminal 21. By weighting the signal values, it is possible to realize a carrier wave detection method that is more suitable for the purpose.

Effects of the Invention As is clear from the above-mentioned embodiments, the adjustment of carrier wave detection is not a mechanical work of turning a variable resistor as in the past (inputting an adjustment value and operating a control input). This has the effect that automatic adjustment can be easily set.

Further, according to the present invention, as the nonvolatile memory, it is sufficient to use a part of the memory that is normally used for storing the operation mode of the radio device and the unique number, and the carrier wave detection section is replaced with a built-in A/D conversion circuit. By using a microprocessor to configure the carrier wave detection device, there is an advantage that a carrier wave detection device with a simple configuration can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a carrier wave detection device according to an embodiment of the present invention, FIG. 2 is a flowchart showing another processing procedure in a control circuit in the same device, and FIG.
The figure is a block diagram showing a schematic configuration of a conventional carrier wave detection device. 11... Antenna, 12... Receiving circuit, 13...
Bandpass filter 14... Amplification circuit, 15... Rectifier circuit, 16... Smoothing circuit, 17... A/D conversion circuit, 18... Control circuit, 19... Control input terminal, 20
...Nonvolatile memory, 21...Output terminal.

Claims (3)

[Claims] (1) After passing the detection output of the radio receiving circuit through a bandpass filter, the amplified, rectified and smoothed DC output is converted into a digital signal, and the maximum and minimum values of the digital signal are calculated when the control input is in the operating state. A carrier wave detection method that performs output without a carrier wave when a maximum value of a digital signal newly inputted when the control input is in an inactive state is larger than the maximum value of the stored digital signal. (2) Even if the absence of a carrier wave is detected by comparing the maximum values, if the minimum value of the newly input digital signal is smaller than the minimum value of the stored digital signal, output with a carrier wave is performed. 1) Carrier wave detection method described. (3) An A/D conversion circuit that converts the detected output of the radio reception circuit through a bandpass filter, amplified, rectified and smoothed DC output into a digital signal, and the maximum output of the digital signal from the A/D conversion circuit. It is equipped with a non-volatile memory that stores values and minimum values, a control input terminal that selectively inputs an operating state and an inactive state, an output terminal that outputs a carrier wave presence/absence determination result, and a control circuit to which these are connected. , when the control input terminal is in an operating state, the control circuit
The maximum and minimum values of the digital signal from the A/D conversion circuit are detected and stored in the nonvolatile memory, and when the control input terminal is in an inactive state, at least the A/D
A carrier wave detection device comprising means for comparing the maximum value of a digital signal newly input from the converter with the maximum value of the digital signal stored in the nonvolatile memory to determine the presence or absence of a carrier wave, and outputting the result to the output terminal. .