JPH09200071A - Cw tone filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CW tone filter by which a tone scale of a CW tone signal or a side tone signal from a receiver is optionally changed. SOLUTION: An input signal is given to a band-pass filter 1, where a prescribed band limit is received and converted into two signals whose phase difference is 90 deg. t a Hilbert filter 2 and and a delay circuit 3 and given respectively to 1st and 2nd multipliers 4, 5. On the other hand, a signal with a phase difference of 90 deg. from an output signal of a low frequency oscillator 7 is fed to the 1st multiplier 4 and an output signal of the low frequency oscillator 7 is given to the 2nd multiplier 5 respectively, in which multiplication processing is conducted. The result of multiplication is added/subtracted by an adder/ subtractor 6, then a signal resulting from a frequency of the input signal changed by an oscillated frequency of the low frequency oscillator 7 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter device, and more particularly, to a so-called CW tone signal obtained by demodulating a radiotelegraph signal by a receiver to improve its intelligibility and intelligibility. The present invention relates to a CW tone filter device.

[0002]

2. Description of the Related Art Wireless telegraphic communication, which is a method of wireless communication, enables communication by encoding with a combination of a time when a radio wave is emitted and a time when the radio wave is stopped. In this wireless telegraphic communication, in order to allow the user to recognize a telegraph signal (hereinafter referred to as "CW signal") received by a receiver, in general, the reception frequency of the receiver is slightly different from the transmission frequency. By shifting and generating a beat signal between the transmission frequency and a so-called carrier frequency that is deviated from the transmission frequency, it is possible to recognize as a sound that can be discerned by the human auditory sense. Is being done.

The frequency of the beat signal (CW tone signal) output from the receiver is usually a constant frequency due to the frequency characteristics of the filter used in the intermediate frequency circuit of the receiver. By the way, as a technique for improving the intelligibility and intelligibility of such a CW signal, conventionally, for example, a technique in which a CW tone signal output from a receiver is passed through a narrow band pass filter is known. there were.

Further, in order to improve the intelligibility corresponding to the difference in personal hearing, the tuning frequency is made variable by making the center frequency of the intermediate frequency filter variable, for example, in the receiver. , There was one that allowed the growl signal to be changed.

[0005]

However, when the frequency of the beat signal can be changed by changing the tuning frequency in the receiver as described above, the reception side transmits to the communication partner. At this time, since the transmission frequency of the transmitter is usually matched with the reception frequency, the center frequency of the transmission wave from the reception side deviates from that of the communication partner. For this reason, as it is, the communication is performed in a state where the transmission frequencies are shifted from each other. Therefore, in order to avoid such an inconvenience, it is necessary to adjust the transmission frequency for each communication, and the efficiency in the communication procedure is deteriorated. There is a problem of inviting.

In order to confirm the CW signal to be transmitted, a circuit for generating an audible signal (so-called side tone) corresponding to the operation of the electronic key is incorporated in the transmitter, and when the signal sound is transmitted, Some of the receivers are configured to be output as a so-called audio output, but as described above, the low-frequency output of the receiver is passed through a narrow band filter, and the intelligibility of the CW signal, If the intelligibility is improved, the side tone signal sound may be inaudible due to the narrow band filter. what if,
Even when the side tone signal sound is heard, the pitch is usually fixed in each radio, so that there is a problem that the pitch cannot be adjusted so that the user can easily hear it.

The present invention has been made in view of the above situation, and provides a CW tone filter device capable of improving the intelligibility and intelligibility of a CW tone signal regardless of the frequency of a receiver or a transmitter. It is a thing. Another object of the present invention is to provide a CW tone filter device capable of adjusting the pitch of a CW signal or side tone signal from a receiver regardless of the frequency of the receiver or transmitter.

[0008]

In a CW tone filter device according to the present invention, a band limiting means for limiting the band of an input signal and an output signal of the band limiting means are connected to each other.
A phase difference signal generating means for separately generating two signals having a phase difference of 0 degree, a low frequency signal oscillating means for oscillating a low frequency signal in a predetermined range, and an output signal of the low frequency oscillating means of 90 degrees. Quadrature modulation for performing quadrature modulation between the phase shifter for obtaining a signal having a phase difference, the two signals of the phase difference signal generator, and the respective output signals from the low frequency signal oscillator and the phase shifter. And means.

In particular, the phase difference signal generating means performs a Hilbert transform on the output signal of the band limiting means and outputs a signal having a 90 degree phase difference from the output signal, and the output of the band limiting means. It is preferable to include a delay circuit for delaying and outputting the same signal as the signal delay that occurs in the Hilbert filter. Further, the quadrature modulation means performs a multiplication of one of the two signals generated by the phase difference signal generation means and having a phase difference of 90 degrees with the output signal of the low frequency oscillation means. A multiplier and a second multiplier for multiplying the output signal of the phase shift means by the other signal of the two signals generated by the phase difference signal generation means and having a phase difference of 90 degrees from each other; An adder / subtractor that adds and subtracts the operation result of the first multiplier and the operation result of the second multiplier,
The thing which comprises is preferable.

In such a configuration, the input signals are appropriately band-limited by the band-limiting means to remove noise, and then the phase difference signal generating means 9
There are two signals having a phase difference of 0 degree, and one of the signals is in the first multiplier that constitutes the quadrature modulation means,
It is multiplied with the output signal of the low frequency signal oscillator. Further, of the two signals generated by the phase difference signal generating means, the other signal advances the phase of the output signal of the low frequency oscillating means by 90 degrees in the second multiplier constituting the quadrature modulating means ( Or a delayed signal, and the multiplication result of the second multiplier and the multiplication result of the first multiplier are added / subtracted by an adder / subtractor that constitutes quadrature modulation means. As a result, a signal in which the center frequency of the input signal that has passed through the band limiting means is changed according to the output frequency of the low-frequency oscillating means is obtained from the adder / subtractor, and the pitch of the input signal can be changed as desired. A changeable CW tone filter device is to be provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The members, arrangements, and the like described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.

The CW tone filter device according to the embodiment of the present invention comprises a bandpass filter (denoted as "BPF" in FIG. 1) 1 and a Hilbert filter (denoted as "HT" in FIG. 1) 2 And a delay circuit (denoted as “Delay” in FIG. 1) 3 and two multipliers 4 and 5
, An adder / subtractor 6 and a low frequency oscillator (in FIG. 1, “O
SC) 7) and a 90-degree phase shifter (shown as "Phase Shifter" in FIG. 1) 8.

The bandpass filter 1 is for removing an extra signal contained in the input signal by appropriately limiting the band of the input signal. That is, the input signal to this device is a CW tone signal or a side tone signal output from a receiver (not shown). Particularly, in the case of a CW tone signal, the beat noise of the interference signal at the time of reception must be included. Therefore, it is for removing such interference signal sound and noise sound. Therefore,
The bandwidth of the bandpass filter 1 is determined by how much the interference signal or noise sound is removed. The center frequency of bandpass filter 1 in the embodiment of the present invention is set to 800 Hz.

The Hilbert filter 2 is for performing the Hilbert transform on the input signal input through the bandpass filter 1 and outputting a signal having a phase lead of 90 degrees with respect to the input signal. Here, the use of the Hilbert filter 2 for phase adjustment means that the same phase adjustment is performed on all frequency components included in the input signal without changing the amplitude characteristic of the input signal by passing the Hilbert filter 2. This is because it can be applied and the input signal is not distorted. The delay circuit 3 is provided so that the signal from the bandpass filter 1 that is not subjected to the phase processing by the Hilbert filter 2 has the same time delay as the signal that has passed through the Hilbert filter 2, and for example, a delay line or the like. It is composed of

The first multiplier 4 includes a Hilbert filter 2
From the signal from the 90 ° phase shifter 8
The second multiplier 5 multiplies the signal from the delay circuit 3 and the signal from the low frequency oscillator 7 respectively. The adder / subtractor 6 calculates the second calculation result of the first multiplier 4 and the second calculation result.
The addition or subtraction is performed with the calculation result of the multiplier 5.

The low frequency oscillator 7 has, for example, an upper limit of 400 Hz.
By adjusting the variable resistor 7a, a low frequency signal of a sine wave up to a certain degree can be output while changing the oscillation frequency. The output frequency of the low frequency oscillator 7 may be changed continuously or stepwise.

The output signal of the low frequency oscillator 7 is input to the second multiplier 5 and also to the 90 ° phase shifter 8. The 90-degree phase shifter 8 outputs the phase of the output signal from the low-frequency oscillator 7 by advancing (or delaying) its phase by 90 degrees. For example, assuming that the 90-degree phase shifter 8 advances the phase of the input signal by 90 degrees, if the output signal of the low-frequency oscillator 7 is a so-called sin wave, the 90-degree phase shifter 8
From, a so-called cos wave is obtained, and this cos wave is input to the first multiplier 4.

Next, the operation of the CW tone filter device having the above configuration will be described with reference to FIGS. First, as an input signal, a CW tone signal output as a so-called audio output of a receiver (not shown) or a side tone signal generated for confirmation of the CW signal during transmission and output as an audio output of the receiver is used. Suppose it is entered.

CW tone signal (or side tone signal) at the time of input to the CW tone filter device
The pitch does not have to be optimal for the user's feeling, and may be an appropriate pitch. The input signal under such a condition is band-limited by the bandpass filter 1 to remove interference signals and noise, and then input to the Hilbert filter 2 and the delay circuit 3, respectively.

The signal passed through the Hilbert filter 2,
The signal passed through the delay circuit 3 becomes a signal having a phase difference of 90 degrees from each other, the signal passed through the Hilbert filter 2 is sent to the first multiplier 4, and the signal passed through the delay circuit 3 is sent to the second multiplier 4. It will be input to each of the multipliers 5.

On the other hand, the first multiplier 4 is supplied with a signal having a 90 ° phase difference from the output signal of the low frequency oscillator 7,
While the signal from the Hilbert filter 2 is multiplied, the output signal of the low-frequency oscillator 7 is input to the second multiplier 5, and the signal from the delay circuit 3 is multiplied. . Then, these first and second multipliers 4,
The output signal of 5 is added or subtracted by the adder / subtractor 6 to obtain a signal in which the pitch of the signal passed through the bandpass filter 1 is changed.

That is, when the output signal of the adder / subtractor 6 is represented by a frequency spectrum, the signal that has passed through the bandpass filter 1 as shown in FIG. 2 is, for example, the portion shown by the solid line in FIG. Then, the signal that has passed through the bandpass filter 1 can be obtained as a signal whose frequency is changed in accordance with the output frequency of the low-frequency oscillator 7 in the variable range ΔF of the output frequency of the low-frequency oscillator 7. There is.

The variable range of the oscillation frequency of the low frequency oscillator 7 corresponds to the range in which the pitch of the input signal can be changed, but the upper limit value is not necessarily the same as in the above-described embodiment of the invention. Does not have to be 400 Hz, and should be appropriately set in accordance with a desired pitch change range.

In the embodiment of the invention described above, the first
In the multiplication and addition / subtraction processing performed in the portion configured by the multiplier 4, the second multiplier 5 and the adder / subtractor 6, two carrier waves having the same frequency and different phases by 90 degrees (in the embodiment of the invention described above, Corresponds to the output signal of the low-frequency signal oscillator 7 and the output signal of the 90-degree phase shifter 8 and different signals (in the above-described embodiment of the invention, the output signal of the Hilbert filter 2 and the delay signal). It can be regarded as a quadrature modulation which is amplitude-modulated by the output signal of the circuit 3) and then combined (corresponding to addition / subtraction by the adder / subtractor 6).

[0025]

As described above, according to the present invention,
By adopting a configuration in which the frequency of the CW tone signal obtained by the receiver can be changed, the pitch of the CW tone signal or so-called side tone signal can be set to a desired state regardless of the tuning state of the radio device. Therefore, the intelligibility and intelligibility of the CW tone signal can be improved regardless of the tuning state of the wireless device.

Further, unlike the conventional apparatus that simply passes the CW tone signal through a narrow band bandpass filter to improve the intelligibility and intelligibility of the CW tone signal, the conventional CW tone signal is used.
When a signal is transmitted, even if a so-called side tone signal generated for confirmation of the CW signal is input to this device, the side tone signal cannot be heard due to the narrow band bandpass filter. In general, even a side tone signal having a constant pitch can have a desired pitch, and the side tone signal can be heard in an optimum state.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration example of a CW tone filter device according to an embodiment of the invention.

FIG. 2 is a characteristic diagram showing a frequency spectrum of an output signal of a CW tone filter device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Band pass filter 2 ... Hilbert filter 3 ... Delay circuit 4 ... 1st multiplier 5 ... 2nd multiplier 6 ... Adder / subtractor 7 ... Low frequency oscillator 7a ... Variable resistor 8 ... 90 degree phase shifter

Claims (3)

[Claims] 1. A band limiting means for band limiting an input signal, and a phase difference signal generating means for separately generating an output signal of the band limiting means into two signals having a phase difference of 90 degrees. A low-frequency signal oscillating means for oscillating a low-frequency signal in a predetermined range; a phase-shifting means for obtaining a signal having a phase difference of 90 degrees with the output signal of the low-frequency oscillating means; and a phase difference signal generating means. A CW tone filter device comprising: a quadrature modulation means for performing quadrature modulation between a signal and each output signal from the low frequency signal oscillation means and the phase shift means. 2. The phase difference signal generating means performs a Hilbert transform on the output signal of the band limiting means, and outputs a signal having a phase difference of 90 degrees with the output signal, and an output of the band limiting means. 2. The CW tone filter device according to claim 1, further comprising: a delay circuit that delays and outputs the same signal as the signal delay that occurs in the Hilbert filter. 3. The quadrature modulation means multiplies one of the two signals generated by the phase difference signal generation means and having a phase difference of 90 degrees with the output signal of the low frequency oscillation means. A first multiplier, and a second multiplication for multiplying the output signal of the phase shift means by the other signal of the two signals generated by the phase difference signal generation means and having a phase difference of 90 degrees with each other. 3. A CW according to claim 1 or 2, further comprising: an adder / subtractor for adding / subtracting an operation result of the first multiplier and an operation result of the second multiplier. Tone filter device.