JP3266121B2 - Method and apparatus for detecting single frequency signal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a single-frequency signal (tone signal) for starting in a multi-carrier modulation system or the like. The present invention relates to a method and an apparatus for detecting a single-frequency signal, which masks a generated short pulse, operates a small number of circuits during standby, and detects a tone signal with a relatively small circuit configuration.

[0002]

2. Description of the Related Art Conventionally, a method and an apparatus for detecting a single-frequency signal of this kind have been used for detecting a tone signal of a start request in a multicarrier modulation system (for example, Japanese Patent Application Laid-Open No. 6-62092). "Paging tone signal detection circuit" and JP-A-8-313566 "Frequency detector"). These tone signals are signals of a plurality of frequency waves, and depending on the frequency of the incoming tone signal,
The starting procedure and operating conditions of the device are set.

FIG. 7 is a block diagram showing a configuration of a transceiver in a conventional multicarrier modulation system.
In this transceiver 700, transmission data 701 is mapped to frequency domain data by mapper 702. This mapping signal is converted into a signal in the time domain by the inverse fast Fourier transform in the IFFT section 703. The signal in the time domain is converted into an analog signal by the D / A converter 704 and transmitted from the hybrid transformer 705 to the transmission line 706.

Similarly, a signal in the time domain from the opposite device is:
Digitally converted by the A / D converter 707, and
The unit 708 performs FFT processing and converts the signal into a frequency domain signal. The signal in the frequency domain is restored by the demapper 709, and the restored received data 711 is transmitted. Also,
When the signal level corresponding to the frequency of the tone signal demodulated in the frequency domain from FFT section 708 exceeds a set threshold, level comparing section 710 outputs detection signal S114 indicating the arrival of the tone signal.

The transceiver 700 in such a multi-carrier modulation system operates the A / D converter 707 and the FFT unit 708 even in the standby state during standby, so that the power consumption during standby increases. For example,
When the transceiver is mounted on a portable communication device, the power supply is a battery, and the operation time is shortened by the large power consumption.

FIG. 8 is a block diagram showing a configuration of a conventional tone detection circuit. The tone detection circuit 800 has a multi-stage configuration for transmitting a detection signal S114 having frequencies f1... Fn. The band-pass filter (BPF) 801 extracts the frequency of the tone signal of the input received signal S101 by limiting the band. The received signal S101 is used as the power measurement unit 80
2, where the power of the received signal S101 is calculated and measured in units of time, and is input to the comparator 803. Comparator 8
03 outputs the detection signal S114 of the corresponding frequency f0 when the power in the time unit calculated by the power measurement unit 802 exceeds the threshold value. Note that the other detectors of the multi-stage configuration also perform other frequencies f1.
Is output as the detection signal S114.

The tone detection circuit detects the frequency f
If the actual number of detections of 0... Fn is large, a detection unit for the number of detections is required, and the circuit scale becomes large. Also, BPF
801 is an analog circuit (for example, CR circuit or LC circuit)
In this case, the characteristics vary widely, making it difficult to detect a high-precision tone signal. Furthermore, in order to obtain high accuracy, a multistage BPF 801 (analog circuit) is required, and in this case also, the circuit scale becomes large.

[0008]

As described above, in the above-mentioned conventional example, it is difficult to obtain a good tone signal detection characteristic with respect to a received signal on which noise is superimposed, and it is not possible to reduce power consumption during standby. There is a disadvantage that the circuit scale is increased.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, in which good tone signal detection characteristics can be obtained even for a received signal on which noise is superimposed, and power consumption during standby is reduced. It is another object of the present invention to provide a method and apparatus for detecting a single-frequency signal, which can reduce the circuit scale.

[0010]

In order to achieve the above object, the present invention provides a method for detecting the frequency of a received signal having a different frequency.
In the detection method of the single frequency signal to detect each
And compares the received signal with the threshold to detect the level.
And when the received signal exceeds a threshold
Measuring the pulse width of the comparison result; and
Counting the number of pulses for a certain period of time
Toe that detects the single frequency signal of the received signal from the number of pulses
Signal arrival determination step.
A method for counting the number of pulses.
The pulse set based on the pulse width measurement result.
The pulse width is shorter than the pulse width.
I'm skiing.

Further , in the tone signal arrival determination step,
The same single frequency signal at least twice in a row
The detected single frequency signal,
And determine if the signal is the same single frequency signal
It is carried out.

[0012] The present invention relates to the frequency of received signals of different frequencies.
Single frequency signal detector to detect each number
Level is detected by comparing the received signal with a threshold.
Level detection means, and the received signal exceeds a threshold
Sometimes the width of the pulse output from the level detection means is
A pulse width measuring means for measuring, and the received signal has a threshold
Output from the level detecting means when
Counting means for counting the number of
The number of pulses counted by the counting means
Frequency identification that outputs a detection signal indicating a single frequency signal
Means for detecting a single-frequency signal, comprising:
The counting means is set by the pulse width measuring means.
Do not count pulses with a pulse width shorter than the pulse width
The masking process is performed.

[0013] Further , as the level detecting means, the reception signal
No. Two performing level detection as compared to positive and negative threshold
There is a configuration using a comparator.

As the frequency identification means, the count
The number of pulses counted by the means and the pulses counted
Detection from time, indicating a single frequency signal in the received signal
A decoder for outputting signals and a flip-flop circuit are provided.
There is a configuration that can be obtained.

[0015] In the pulse width measuring means,
It is configured to measure the average value of the loose width.

In the comparing means, a positive or negative threshold
The minimum and noise levels of the received signal, respectively.
It is configured to be set in the middle.

Further , the same single unit
When the frequency signal is detected at least twice consecutively,
The single frequency signal detected by
Multiple incoming calls to determine whether the signal is a single frequency signal
It is configured to further include a counter.

The method and apparatus for detecting a single frequency signal according to the present invention measures the width of a pulse as a result of comparison between an incoming received signal and a threshold value.
The number of pulses in a fixed time is counted, and a single frequency signal (tone signal) in the received signal is detected from the counted number of pulses. In this case, the path to count
Of Luz performs masking against short pulse than the pulse width is set from the measurement results of the measured pulse width, so that not counted.

As a result, since short pulses generated by noise are not masked and counted, a tone signal can be reliably detected even for a received signal on which noise is superimposed, and good detection characteristics can be obtained. In the standby state, only the comparator operates, and the FFT unit and the like described in the conventional example do not operate, so that the power consumption in the standby state is reduced. further,
Since the tone signal can be detected with a relatively small-scale circuit configuration such as a comparator, a counter, and a timer, even if the number of tone signals to be detected increases, it can be dealt with by changing only the decoder for frequency detection. The circuit scale can be reduced.

The method and apparatus for detecting a single frequency signal according to the present invention further comprises the step of further detecting the detected single frequency signal when the same single frequency signal is continuously detected in the tone signal arrival determination. The incoming call is counted to determine whether the signals are the same single frequency signal. As a result, the tone signal can be detected more accurately.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method and an apparatus for detecting a single frequency signal according to the present invention will be described in detail with reference to the drawings. In the following text and figures, the same components as those in FIGS. 7 and 8 are denoted by the same reference numerals.

FIG. 1 is a block diagram showing a configuration of a first embodiment of a method and apparatus for detecting a single frequency signal according to the present invention. The tone detection device 100 outputs a logical value “1” (high level) obtained by comparing the input received signal S101 with a positive threshold value S105.
, The input reception signal S101 and the negative threshold value S10
6, the comparator 104 that outputs a logical value “1” (high level) by comparing the reference clock signal S102 with the comparator 1
There is provided a pulse width measuring unit 107 which receives an output logic value of No. 03, an output of the timer 111 , and a count value from the up / down counter 110 and outputs an operation permission signal S115 and a pulse width setting signal S116.

The tone detecting device includes a counter 108 which receives a reference clock signal S102, an output logic value of the comparator 103, an operation permission signal S115, and a pulse width setting signal S116, and outputs a count value.
08 and 109, and an up / down counter 110 that inputs the count value and the operation permission signal S115 and outputs the count value to the pulse width measurement unit 107, a reference clock signal S102, and an operation permission signal S115. The timer 111 that notifies the pulse width measurement unit 107 and the frequency identification unit 113 of the start and the expiration of the set time , the count value from the counter 109 and the operation permission signal S115 are input, and the count value is sent to the frequency identification unit 113. Output of counter 112 and timer 111 (timer value)
And a count value of the counter 112, and a frequency identification unit 113 for transmitting a detection signal S114 indicating a detected tone signal (frequency f0, f1, f2... Fn).

The comparators 103 and 104 can be realized by analog circuit comparators. Also, the counter 10
8, 109, 112, up / down counter 110, and timer 111 can be realized by relatively simple digital circuits.

FIG. 2 is a block diagram showing the internal configuration of the pulse width measuring section 107. This pulse width measurement unit 107
Reference clock signal S102 the count value of the output and the up-down counter 110 outputs a logical value and the timer 111 of the comparator 103 and is inputted with, a timer 401 to start the counter 402 and 403, a reference clock signal S102 comparator The output logic value of 103, the output of the timer 111 , and the count value of the up / down counter 110 are input,
And a counter 402 for outputting the operation permission signal S115.

The pulse width measuring section 107 receives the reference clock signal S102, the output logic value of the comparator 103, the output of the timer 111 , and the count value of the up / down counter 110, and outputs a count value. 403, a shifter 404 for shifting (phase shifting) the count value of the counter 403, an output of the timer 111 , a count value of the up / down counter 110, a shift output of the shifter 404, and an operation permission signal S115 from the counter 402.
And a D-type flip-flop (D / F / F) circuit 405 for sending a logic value by flip-flop processing as a pulse width setting signal S116.

FIG. 3 is a block diagram showing the internal configuration of the frequency identification unit 113. The frequency identification unit 113 decodes and outputs the count value of the counter 112, and a decoder 501 implemented by a sequential circuit or a memory,
When the output of 1 changes from the logical value “0” to the logical value “1”, the output logical value “0, 1” of the decoder 501 is held,
And a D-type flip-flop circuit 502 that outputs a detection signal S114 having frequencies f0... Fn.

Next, the operation of the first embodiment will be described. The tone detection device (circuit) shown in FIG. 1 includes (1) level detection, (2) pulse width measurement,
It operates in the order of (3) pulse number measurement and (4) tone signal arrival determination.

FIG. 4 shows the received signal S101, the comparator 103,
FIG. 4 is a diagram for explaining processing of a counter 104 and counters 108 and 109; (1) The comparator 103 outputs a logical value “1” when the received signal S101 exceeds the positive threshold value S105, and outputs a logical value “0” when the received signal S101 does not exceed the positive threshold value S105. . Comparator 104 outputs a logical value “1” when received signal S101 exceeds negative threshold value S106, and outputs a logical value “0” when received signal S101 does not exceed negative threshold value S106.

(2) In the pulse width measurement, when the output of the comparator 103 becomes a logical value "1", the pulse width measuring unit 107 operates to calculate the average value of the pulse width of the output from the comparator 103. After the measurement of the pulse width is completed, the counters 108, 109, 112, the up-down counter 11
0 and an operation permission signal S115 to the timer 111,
At the same time, a pulse width setting signal (count value) 116 is output to the counters 108 and 109.

(3) In the measurement of the number of pulses, when the received signal S101 shown in FIG. 4A is a sine wave, the comparators 103 and 104, as shown in FIG. The value "1" is output. Here, the theory of the comparator 103
The number of pulses of the logical value “1” is fixed by the timer 111
By counting the time, the incoming signal (received signal S
The frequency of 101) can be specified. Noise may be superimposed on such an incoming signal (received signal S101). In this case, as shown in FIG. 4C, when the incoming signal (received signal S101) is near the positive threshold value S105 and the negative threshold value S106, the output pulses of the comparators 103 and 104 (logical value “1”) )) Before and after. For this reason, an error occurs in the count values of the counters 108 and 109, and the number of pulses of the received signal S101 is counted many times, so that the frequency measurement in detecting the tone signal may be erroneous.

The counters 108 and 109 correspond to the comparator 10
When the outputs of the signals 3 and 104 have the logical value "1", the count is incremented at the rise of the reference clock signal S102. Then, it is reset when the output of the comparator 103 has the logical value “0”. When the counters 108 and 109 count up to the count value of the pulse width setting signal S116, they output a logical value "1" and stop the operation. Note that the example of FIG. 4D illustrates a case where the pulse width setting signal S116 has the count value “4”. Accordingly, as shown in the sections a and b in FIG. 4, the output logic value "1" of the counters 108 and 109 makes it possible to mask short pulses generated before and after the normal pulse so as not to count them.

The up / down counter 110 counts up when the initial count value is “0” and the output of the counter 108 changes from the logical value “0” to the logical value “1”, and the output of the counter 109 is increased. When the logical value changes from “0” to “1”, the countdown is performed. When the count value becomes "+2" or "-2", a logical value "1" is output, and the count value is set to "0".

FIG. 5 is a diagram for explaining the waveform of the received signal S101, the outputs of the counters 108 and 109, and the count value of the counter 112. When the received signal S101 is a sine wave as shown in FIG.
109 mutually outputs a logical value "1" as shown in FIGS. 5 (b) and 5 (c). Therefore, the output of the up / down counter 110 does not become the logical value “1”. Counter 11
2 increments each time the counter 109 outputs a pulse. When one of the counters 108 and 109 continuously outputs the logical value “1” , the up / down count is performed.
The output of the data 110 becomes the logical value “1”, and the pulse width measuring unit 107 is reset. In this case, the processing is started again from the level detection of the above (1).

[0035] (4) In the tone signal incoming determination, frequency identification unit 113, the timer 11 1 as shown in FIG. 5 (e)
At the end of the set time , referring to the count value N of the counter 112 (FIG. 5 (d)), if this count value corresponds to the frequency of the detected tone signal , the detection signal S11
4 is output.

Next, the main part of this operation will be described in detail with reference to FIGS. (1) In the level detection, the positive threshold value S105 and the negative threshold value S106
It is set between the minimum level of 101 and the noise level.

(2) In the pulse width measurement, when the output of the comparator 103 becomes a logical value “1”, the pulse width measurement unit 107 starts operating, and the timer 401 sets the counters 402 and 40
Release the reset of 3. The counter 402 is a comparator 1
When the output of 03 changes from the logical value “0” to the logical value “1”, the count is incremented. When the count value reaches a predetermined value (hereinafter, this count value is referred to as M1), the counter 402 outputs a logical value “1” and stops counting up.

The counter 403 generates the reference clock signal S1
When the output of the comparator 103 has the logical value “1” at the time of the rise of 02, the count is performed. Here, the counter 403 when the count value of the counter 402 is M1
Is M2. In this case, the average pulse width W1 of the output logical value "1" of the comparator 103 is obtained by the following equation (1).

[0039]

W1 = M2 / M1 (1)

Assuming that M1 is a value of a power of 2, Equation 1 can be realized by shifting. For example, the value of the pulse width setting signal S116 is set to 1 / the value calculated by (Equation 1).
2 (pulses less than 1/2 of the average value are generated pulses due to noise). If M1 is 128, the shifter 404 becomes
It becomes an 8-bit shifter. If the set time of the timer 401 expires before the count value of the counter 402 reaches M1, the output of the comparator 103 becomes a logical value “1” due to noise.
The timer 401 resets the counters 402 and 403, and the output of the comparator 103 again becomes the logical value “1”.
Stop the operation until.

Each part of the pulse width measuring section 107 shown in FIG. 2 (configuration from the timer 401 to the D-type flip-flop circuit 405) expires when the set time of the timer 111 expires and the output of the up / down counter 110 becomes a logical value "1". Is reset. When the count value of the counter 102 reaches M1, the pulse width measurement unit 107 sets the operation permission signal S115 to a logical value “1”, and sets the pulse width setting signal S
The count value is set to 116 and output, and the next (3) pulse number measurement is performed.

(3) In the pulse number measurement, the above-mentioned (3)
In the operation of (1), after the pulse width measurement unit 107 is reset, (1) the detection operation is performed again from the level detection processing, and when the set time of the timer 111 expires,
The presence or absence of a tone signal is determined by the following (4) tone signal arrival determination.

[0043] (4) in the tone signal incoming determination frequency identification unit 113, when during setting time of the timer 111 has expired, with reference to the count value N of the counter 112, corresponding to tone signal this count is detected If the frequency corresponds to the frequency to be detected, the detection signal S114 is output. Here, the set time of the timer 111 is 1 msec, and the detection frequency of the tone signal is f0 = 180 kHz, f1 = 200 kHz.
An example of detecting a tone signal with z, f2 = 220 kHz will be described.

When the operation permission signal S115 changes from the logical value "0" to the logical value "1", the timer 111 starts its operation, and outputs the logical value "1" after the set time expires after 1 msec. . The count 112 counts the number of times that the output of the counter 109 has changed from the logical value “0” to the logical value “1” during 1 msec.

In this case, the frequency is 180 kHz, 200 k
The count value of the counter 112 and the detection signal in the detection of the tone signals of Hz and 220 kHz are as follows.

[0046]

[Table 1]

FIG. 6 is a block diagram showing the configuration of the frequency identification unit according to the second embodiment. This frequency identification unit 11
3A is an example in which the tone signal to be detected has three frequencies, a decoder 801 for decoding the output of the counter 112,
A set time of the timer 111 is input, a delay unit 802 for delaying the input, a decode output of the decoder 801, a set time of the timer 111 and a delay measurement time of the delay unit 802 are input, and a logical value by flip-flop processing is output. D-type flip-flop circuit 803 and the frequencies f0, f1, and f2 of the tone signals obtained by counting the outputs (logical values) of the D-type flip-flop circuit 803 (detection signal S11
Counters 804, 805, 806 for determining 4)
Are provided.

Next, the operation of the frequency identification section 113A will be described. In the first embodiment described above, when the set time of the timer 111 has expired, the presence or absence of a tone signal is determined. In the second embodiment, in order to prevent erroneous detection, when tone signals of the same frequency are detected several times consecutively, it is determined that the tone signal has arrived correctly. The decoder 801 and the D-type flip-flop circuit 803 have the same configuration as in the first embodiment. However, the D-type flip-flop circuit 803 resets the output when the output of the delay unit 802 has a logical value “1”. Timer 1
The set time 11 is delayed by the delay unit 802 and input to the D-type flip-flop circuit 803. For this reason, the D-type flip-flop circuit 803 converts the decoding result of the decoder 801 into one-pulse counters 804, 805, and 80.
6 is output.

Each of the counters 804, 805, and 806 outputs the output of the D-type flip-flop circuit 803 at a frequency f.
Counts up when the logical value “0” corresponding to 0, f1, f2 (detection signal S114) changes to logical value “1”, and when the output corresponding to another frequency becomes logical value “1”. (In the case of the counter 804, when the frequency f1 or the frequency f2 becomes the logical value “1”), the count value is set to the logical value “0”. Counters 804, 805, 806
If the counter value reaches a preset value,
Assuming that the corresponding tone signal has arrived, the detection signal S1
14 (frequency f0, f1, f2) is set to a logical value "1".

[0050]

As is apparent from the above description, according to the method and apparatus for detecting a single frequency signal of the present invention, the pulse width of the comparison result between the received signal and the threshold value is fixed. The number of pulses is counted by time, and a single frequency signal (tone signal) in the received signal is detected from the counted number of pulses. In this case, masking is performed on a pulse shorter than the pulse width set from the measurement result of the measured pulse width.

As a result, the short pulse generated by noise is masked, the counting is not performed, and the tone signal can be detected with certainty even in the received signal on which the noise is superimposed. can get.

In the standby mode, only the comparator operates, so that the power consumption in the standby mode is reduced. Furthermore, since tone signals can be detected with a relatively small-scale circuit configuration, even if the number of tone signals to be detected increases, it can be dealt with by changing only the decoder for frequency detection, thereby reducing the circuit scale. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a single frequency signal detection method and apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a pulse width measurement unit in FIG.

FIG. 3 is a block diagram illustrating an internal configuration of a frequency identification unit in FIG. 1;

FIG. 4 is a diagram for explaining processing waveforms of a comparator and a counter in FIG. 1;

FIG. 5 is a diagram for explaining a received signal waveform, an output of a counter, and a count value in the first embodiment.

FIG. 6 is a block diagram illustrating a configuration of a frequency identification unit according to the second embodiment.

FIG. 7 is a block diagram illustrating a configuration of a transceiver in a conventional multicarrier modulation system.

FIG. 8 is a block diagram showing a configuration of a conventional tone detection circuit.

[Explanation of symbols]

103, 104 Comparator 107 Pulse width measurement unit 108, 109, 112, 401 to 403, 804 to 8
06 Counter 110 Up / down counter 111, 401 Timer 113, 113A Frequency discriminator 404 Shifter 405, 502, 803 D-type flip-flop circuit 501, 801 Decoder 802 Delay unit S101 Received signal S102 Reference clock signal S105 Positive threshold value S106 Negative Threshold value S114 detection signal S115 operation permission signal S116 pulse width setting signal

Claims (8)

(57) [Claims] (1)The frequency of the received signal at a different frequency
In the detection method of the single frequency signal to detect each
hand, Level detection is performed by comparing the received signal with the threshold.
And The comparison result when the received signal exceeds the threshold
Measuring the width of the ,Counting the number of pulses of the comparison result for a predetermined time
When, A single frequency signal of the received signal is calculated from the counted number of pulses.
A tone signal arrival determination stage to be detected; A method for detecting a single-frequency signal having In the step of counting the number of pulses, A pulse set based on the pulse width measurement result
Mask that does not count pulses with a pulse width shorter than the width
Of detecting a single frequency signal characterized by performing
Law. 2. In the tone signal arrival determination step, when the same single frequency signal is detected at least twice consecutively, the detected single frequency signal is further counted, and the same single frequency signal is counted. 2. The method for detecting a single frequency signal according to claim 1, wherein an incoming call determination as to whether the signal is a frequency signal is performed. (3)The frequency of the received signal at a different frequency
In a single frequency signal detection device for detecting each, Level for performing level detection by comparing the received signal with a threshold
Detecting means; Detecting the level when the received signal exceeds a threshold;
Pulse width measurement to measure the width of the pulse output from the means
Means, Detecting the level when the received signal exceeds a threshold;
Count the number of pulses output from the means for a certain period of time
Counting means; The received signal is calculated from the number of pulses counted by this counting means.
Output a detection signal indicating a single frequency signal at
Number identification means; A single frequency signal detection device comprising: The counting means, Shorter than the pulse width set by the pulse width measuring means
Performs masking processing that does not count pulses of pulse width.
A single-frequency signal detecting device. 4. The single-frequency signal detection device according to claim 3, wherein two comparators for performing level detection by comparing a received signal with positive and negative threshold values are used as said level detection means. 5. The number of pulses and pulses counted by said counting means as said frequency identification means.
4. The single-frequency signal detecting device according to claim 3, further comprising a decoder and a flip-flop circuit for outputting a detection signal indicating a single-frequency signal in the received signal from the counted time . 6. The pulse width measurement means, according to claim 3, wherein the measuring the average value of the pulse width
A single frequency signal detection device as described. 7. The single-frequency signal detecting apparatus according to claim 4 , wherein the comparing means sets the positive and negative threshold values to an intermediate value between the minimum level and the noise level of the received signal. 8. When the same single-frequency signal is detected at least twice consecutively by the frequency discriminating means, the detected single-frequency signal is further counted to be the same single-frequency signal. 6. The apparatus according to claim 5 , further comprising a plurality of counters for determining whether an incoming call has occurred.
A single frequency signal detection device as described.