JP6988217B2 - Receiver, receiving method, and receiving program - Google Patents

Description

The present invention relates to a receiver, a receiving method, and a receiving program for receiving a transmission signal including character information by RTTY (Radio Teletype).

A wireless communication device equipped with the RTTY function transmits character information represented by frequency shift keying (binary FSK modulation) between a first signal having a mark frequency and a second signal having a space frequency. The including transmission signal is transmitted (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-143957 Japanese Unexamined Patent Publication No. 2011-193360

When the wireless communication device (receiver) receives the transmission signal including the character information by RTTY, the interference signal may be superimposed on the frequency band including the mark frequency and the space frequency. Normally, the receiver that receives the transmission signal uses a notch filter to suppress the interference signal contained in the transmission signal (see Patent Document 2).

The auto notch function that automatically operates the notch filter is a function that searches for and suppresses the interference signal of the periodic signal. Since the first signal having the mark frequency and the second signal having the space frequency are periodic signals, when the interference signal of the periodic signal is superimposed on the frequency band including the mark frequency and the space frequency, the first and second signals are used. It is difficult to distinguish between a signal and an interfering signal. Therefore, it is not possible to activate the auto notch function to automatically suppress the interference signal.

Therefore, in the conventional receiver, the interference signal must be suppressed by the manual notch function in which the notch filter is manually operated. A receiver, a receiving method, and a receiving program capable of using an auto notch function to automatically suppress an interfering signal of a periodic signal superimposed on a frequency band including a mark frequency and a space frequency are desired.

The present invention is a periodic signal superimposed on a frequency band excluding a predetermined frequency band including each of a first frequency and a second frequency of a signal that becomes a detection signal when a binary FSK modulation signal is detected. It is an object of the present invention to provide a receiver, a receiving method, and a receiving program capable of automatically suppressing an interfering signal by an auto notch function.

The present invention comprises a storage unit that stores a plurality of parameters relating to a plurality of mark frequencies and a plurality of shift frequencies of the RTTY signal, and a first frequency determined based on a predetermined mark frequency parameter among the plurality of parameters. and a control unit for determining a second frequency determined based on the parameters of the predetermined shift frequency of the plurality of parameters and the mark frequency, and a notch filter for suppressing by searching interfere harm signals, The control unit sets the first auto notch operation prohibited frequency range in the notch filter so as to include the first frequency, and sets the second auto notch operation prohibited frequency range so as to include the second frequency. set, the notch filter provides a reception apparatus for suppressing by searching interfering signal frequency band except for the first automatic notch operation prohibition frequency range and the second automatic notch operation prohibition frequency range as the target do.

The present invention reads a predetermined parameter among a plurality of parameters relating to a plurality of mark frequencies and a plurality of shift frequencies of the RTTY signal stored in the storage unit, and a predetermined mark frequency parameter among the plurality of parameters. A first frequency determined based on the above and a second frequency determined based on the mark frequency and a predetermined shift frequency parameter among the plurality of parameters are determined, and the notch filter includes the first frequency. The first auto-notch operation prohibition frequency range is set so as to include the second auto-notch operation prohibition frequency range, and the notch filter sets the first auto-notch operation prohibition. provides a received how to suppress searches the interfering signal frequency band except the frequency range and the second automatic notch operation prohibition frequency range as a target.

The present invention comprises a step of reading out to a computer a predetermined parameter among a plurality of parameters relating to a plurality of mark frequencies and a plurality of shift frequencies of an RTTY signal stored in a storage unit, and a predetermined step among the plurality of parameters. The step of determining the first frequency determined based on the parameter of the mark frequency and the second frequency determined based on the parameter of the mark frequency and the predetermined shift frequency among the plurality of parameters, and the notch filter. By the step of setting the first auto notch operation prohibited frequency range so as to include the first frequency and setting the second auto notch operation prohibited frequency range so as to include the second frequency, and the notch filter. , the first automatic notch operation prohibition frequency range and the received program Ru to execute the automatic notch execution step of suppressing by searching interfering signal frequency band except the second automatic notch operation prohibition frequency range as the target offer.

According to the receiver, the receiving method, and the receiving program of the present invention, a predetermined frequency including each of the first frequency and the second frequency of the signal that becomes the detection signal when the signal of binary FSK modulation is detected. The interference signal of the periodic signal superimposed on the frequency band excluding the band can be automatically suppressed by the auto notch function.

It is a block diagram which shows the receiver of one Embodiment. It is a block diagram which shows the functional internal structure of the digital signal processor in the receiver of one Embodiment. It is a figure which shows the mark frequency of RTTY. It is a figure which shows the space frequency of RTTY. It is a figure which shows an example of the transmission signal which contains the character information transmitted by RTTY. FIG. 3A is a diagram showing a state in which an interference signal is superimposed on FIG. 3A. FIG. 3B is a diagram showing a state in which an interference signal is superimposed on FIG. 3B. It is a figure which shows the 1st and 2nd auto notch operation prohibition frequency range set in the frequency band extracted by the reception filter. It is a figure which shows the state which suppresses the interference signal superimposed in the frequency band extracted by a receive filter by a notch filter. It is a flowchart which shows the control process of the digital signal processor by the control part in the receiver of one Embodiment. It is a flowchart which shows the processing of the digital signal processor in the receiver of one Embodiment.

Hereinafter, the receiver, the receiving method, and the receiving program of one embodiment will be described with reference to the accompanying drawings. The receiver of the present embodiment shown in FIG. 1 is a wireless communication device that receives radio waves as an example. The receiver is not limited to the wireless communication device, and may be a personal computer or the like that receives a transmission signal via the Internet.

In FIG. 1, the antenna 1 receives radio waves transmitted from another wireless communication device or a relay station. The receiving circuit 2 receives a transmission signal including character information to be described later transmitted by radio waves and generates an IF (intermediate frequency) signal. The receiving circuit 2 A / D-converts the IF signal and supplies it to the digital signal processor 3 (hereinafter, DSP3).

A memory 4, a speaker 5, and a control unit 6 are connected to the DSP 3. The memory 4 is, for example, a flash memory, and stores a computer program (reception program) that operates the DSP 3 as described later. The control unit 6 can be configured by a central processing unit (CPU) of a microcomputer. The control unit 6 may be composed of a plurality of CPUs such as a main CPU and a sub CPU.

An operation unit 7, a non-volatile memory 8, and a display 9 are connected to the control unit 6. The non-volatile memory 8 is an example of a storage unit, and various parameters are stored in the non-volatile memory 8. In FIG. 1, the control unit 6 and the DSP 3, the control unit 6 and the non-volatile memory 8, the control unit 6 and the display 9, and the DSP 3 and the memory 4 are connected by a bus.

FIG. 2 shows the functional internal configuration of DSP3. The DSP 3 operates as shown in FIG. 2 by executing the receiving program stored in the memory 4. As shown in FIG. 2, the DSP 3 has a detection unit 31, a reception filter 32, and a notch filter 33. Further, the DSP 3 includes a mark frequency bandpass filter 34 (hereinafter, mark frequency BPF 34), a space frequency bandpass filter 35 (hereinafter, space frequency BPF 35), a character decoder 36, and an auto gain control unit 37 (hereinafter, AGC37). ).

With reference to FIGS. 3A, 3B, and 4, how to transmit character information by RTTY will be described. In RTTY, in order for the transmitter and the receiver to communicate with each other, the mark frequency, the shift amount (shift frequency) from the mark frequency to the space frequency, and the baud rate, which is the communication speed, are set to be the same in advance.

As the mark frequency, for example, a frequency such as 1275 Hz called low tone and 2125 Hz called high tone is often used, and as a shift frequency, frequencies such as 170 Hz, 200 Hz, 425 Hz, and 850 Hz are used. The binary values corresponding to the mark frequency and the space frequency may be reversed between the mark frequency and the space frequency as long as the relationship between the transmitter side and the receiver side can be maintained. From the above, the RTTY signal is a binary FSK modulation signal that modulates two frequency shifts of the mark frequency and the space frequency.

Here, the case where the mark frequency is 1275 Hz and the shift frequency is 850 Hz is taken as an example. In the initial state, the wireless communication device (transmitter) transmits an audio signal at a mark frequency of 1275 Hz as shown in FIG. 3A. The transmitter transmits character information by a pattern combining a first signal having the mark frequency shown in FIG. 3A and a second signal having a space frequency of 2125 Hz when the shift frequency shown in FIG. 3B is 850 Hz.

As shown in FIG. 4, the transmitter shifts from the initial state of transmitting the first signal of the mark frequency to the second signal of the space frequency for a predetermined time (22 ms). The second signal of 22 ms is a start pulse which means the start of one character of the character information.

The transmitter transmits a first signal or a second signal every 22 ms following the start pulse. Bits B0 to B4 represent characters represented by 5 bits. The pattern of bits B0 to B4 is just an example. The transmitter shifts to the first signal for a predetermined time (31 ms) following the bit B4. The first signal of 31 ms is a stop pulse which means the end of one character.

In this way, the transmitter can transmit the transmission signal by binary FSK modulation in which the first signal and the second signal are used as binary values and modulated by frequency shift. For example, FIG. 3A shows a state of shifting to the first frequency due to the result of frequency modulation with the first signal, and FIG. 3B shows a state of shifting to the second frequency due to the result of frequency modulation with the second signal. It is in a transferred state.

The receiver receives and decodes the transmitted signal transmitted as shown in FIG. The receiver can display the decoded information on the display 9.

In FIG. 2, the detection unit 31 detects the input IF signal, generates a detection signal (demodulation signal), and supplies the detection signal to the reception filter 32. As shown in FIGS. 3A and 3B, the reception filter 32 uses a bandpass filter having a frequency band 32fb (reception band) including a mark frequency and a space frequency as a pass band to obtain first and second signals from the detection signal. Extract the frequency band to be included. The bandwidth of the frequency band extracted by the reception filter 32 and the position of the frequency at which the detection signal of the frequency band is extracted are set by the control unit 6.

The detection signal of the frequency band extracted by the reception filter 32 is input to the notch filter 33. 3A and 3B show a state in which the interference signal is not superimposed on the frequency band including the mark frequency and the space frequency. However, as shown in FIGS. 5A and 5B, the interference signal may be superimposed on the frequency band including the mark frequency and the space frequency. 5A and 5B show a case where an interfering signal of a periodic signal is superimposed on the frequency between the mark frequency and the space frequency.

If the jamming signal is a periodic signal, it is difficult to distinguish between the first and second signals and the jamming signal, and even if the notch filter 33 is simply operated to activate the auto notch function, the jamming signal can be suppressed. Can not.

Therefore, the control unit 6 reads the RTTY parameter currently set from the non-volatile memory 8. The parameters to be extracted are, for example, set mark frequency information and set shift frequency information. Further, the control unit 6 determines the first frequency from the mark frequency and the second frequency (space frequency) from the mark frequency and the shift frequency based on the set RTTY parameters, with respect to the notch filter 33 of the DSP 3. Then, the first auto notch operation prohibited frequency range is set so as to include the first frequency, and the second auto notch operation prohibited frequency range is set so as to include the second frequency.

As an example, the first auto notch operation prohibited frequency range may be the mark frequency of 1275 Hz to ± 50 Hz, and the second auto notch operation prohibited frequency range may be the space frequency of 2125 Hz to ± 50 Hz. FIG. 6 shows the relationship between the mark frequency (first frequency), the space frequency (second frequency), and the reception band in the state where the first and second auto notch operation prohibited frequency ranges are set. ..

When the notch filter 33 is operated to activate the auto notch function, the notch filter 33 targets the frequency bands extracted by the reception filter 32, excluding the first and second auto notch operation prohibited frequency ranges. Search for the disturbing signal of the periodic signal. Therefore, as shown in FIG. 7, the notch filter 33 can suppress the disturbing signal by the band blocking filter having the narrow band indicated by the frequency band 33fb as the blocking zone. The notch filter 33 does not erroneously recognize the first or second signal as an interfering signal and suppress it.

The detection signal whose interference signal is suppressed by the notch filter 33 is input to the mark frequency BPF34, the space frequency BPF35, and the AGC37. The control unit 6 sets the mark frequency for the mark frequency BPF 34 and sets the shift frequency with respect to the mark frequency for the space frequency BPF 35.

The mark frequency BPF 34 sets a predetermined pass band centered on the mark frequency, and supplies a first signal extracted from the frequency band of the pass band to the character decoder 36. In the space frequency BPF35, a frequency obtained by shifting the mark frequency by the shift frequency is set as the space frequency, a predetermined pass band centered on the space frequency is set, and a second signal extracted from the frequency band of the pass band is used as a character. It is supplied to the decoder 36.

The character decoder 36 decodes each character between the start pulse and the stop pulse to generate character data. The character data is supplied to the control unit 6, and the control unit 6 displays characters based on the character data on the display 9.

The AGC 37 automatically controls the gain of the input detection signal within a predetermined range. The detection signal output from the AGC 37 is converted into an analog signal by a D / A converter (not shown) and supplied to the speaker 5. The speaker 5 generates a predetermined sound.

The detection signal output from the AGC 37 is supplied to the speaker 5 to generate sound in order to visually confirm that the transmission signal is being received. Since characters are displayed on the display 9 and it can be visually confirmed that the transmission signal is being received, it is not necessary to generate sound from the speaker 5.

The control process of the DSP 3 by the control unit 6 will be described with reference to the flowchart shown in FIG. In FIG. 8, when the process is started, the control unit 6 reads out and sets a predetermined parameter among the plurality of RTTY parameters stored in the non-volatile memory 8 for the DSP 3 in step S1. The RTTY parameter includes a mark frequency and a shift frequency indicating how much the shifted frequency with respect to the mark frequency becomes the space frequency.

In step S2, the control unit 6 determines the bandwidth for extracting the detection signal and the position (reception band) of the bandwidth, and sets it for the reception filter 32. For example, the control unit 6 may set the reception band so as to include the first frequency (mark frequency) and the second frequency (space frequency) based on the RTTY parameter. In step S3, the control unit 6 sets the first auto-notch operation prohibited frequency range including the first frequency and the second auto-notch operation prohibited frequency range including the second frequency with respect to the notch filter 33. Set and end the process.

Next, the processing of the DSP 3 will be described with reference to the flowchart shown in FIG. In FIG. 9, when the DSP3 starts the process, in step S11, the first frequency corresponding to the mark frequency and the second frequency corresponding to the space frequency are determined based on the parameters of RTTY.

In step S12, the DSP 3 sets the reception band based on the first frequency and the second frequency. The reception band may be the minimum frequency and the maximum frequency at which the notch filter 33 described below operates. For example, in FIG. 6, the reception band may be set with a frequency lower than the first frequency, which is the mark frequency, as the minimum frequency and a frequency higher than the space frequency as the maximum frequency. Assuming that the predetermined frequency is 275 Hz in FIG. 6, the minimum frequency is 1000 Hz, the maximum frequency is 2400 Hz, and the reception band (frequency band 32 fb) is 1400 Hz.

The DSP 3 acquires the first and second auto-notch operation prohibited frequency ranges in step S13, and calculates the auto-notch operation frequency range of the notch filter 33 in step S14. The auto notch operation frequency range is a frequency range excluding the first and second auto notch operation prohibited frequency ranges in the frequency band 32fb.

In step S15, the DSP 3 (notch filter 33) searches for an interfering signal in the auto notch operating frequency range and detects the presence or absence of the interfering signal. At this time, if there is an interfering signal, the notch filter 33 detects the frequency at which the interfering signal is located. The notch filter 33 determines in step S16 whether or not there is an interfering signal of the periodic signal.

If the jamming signal is not detected in step S15, or if the jamming signal is detected but not a periodic signal, it is determined in step S16 that there is no jamming signal of the periodic signal (NO), and DSP3 is in steps S15 and S16. Repeat the process of. When it is determined in step S16 that there is an interference signal of the periodic signal (YES), the notch filter 33 sets the auto notch function to ON in step S17.

When the auto notch function is set to on, the disturbing signal of the periodic signal is suppressed by the notch filter 33 as described with reference to FIG. 7.

In step S18, the DSP 3 determines whether or not a predetermined instruction to turn off the auto notch function has been given by the control unit 6. The predetermined instruction to turn off the auto notch function includes an instruction to turn off the auto notch function itself, an instruction to turn off the RTTY function, and an instruction to turn off the power of the receiver.

If a predetermined instruction to turn off the auto notch function is not given in step S18 (NO), DSP3 returns the process to step S16 and repeats the processes of steps S15 to S18. As a result, the notch filter 33 can suppress the jamming signal corresponding to the jamming signal of each frequency even if the frequency of the jamming signal of the periodic signal changes.

If a predetermined instruction to turn off the auto notch function is given in step S18 (YES), DSP3 ends the process.

As described above, the receiver, the receiving method, and the receiving program of the present embodiment have the first and second auto notches including the first frequency and the second frequency, respectively, based on the parameters of the binary FSK modulation. The operation prohibited frequency range is set, and the interference signal of the periodic signal is searched for and suppressed in the frequency band excluding the first and second auto notch operation prohibited frequency ranges. Therefore, according to the receiver, the receiving method, and the receiving program of the present embodiment, the interference signal of the periodic signal superimposed on the frequency band including the mark frequency and the space frequency can be automatically suppressed by the auto notch function.

The receiver, receiving method, and receiving program of the present embodiment further, each of the character information is based on the detection signal extracted by the mark frequency bandpass filter and the detection signal extracted by the space frequency bandpass filter. Decode characters to generate character data. According to the receiver, the receiving method, and the receiving program of the present embodiment, the character information can be displayed on the display.

The present invention is not limited to the present embodiment described above, and various modifications can be made without departing from the gist of the present invention.

3 Digital signal processor (DSP)
6 Control unit 8 Non-volatile memory (storage unit)
31 Detection unit 32 Receive filter 33 Notch filter 34 Mark frequency bandpass filter 35 Space frequency bandpass filter 36 Character decoder 37 Auto gain control unit

Claims (6)

A storage unit that stores a plurality of parameters related to a plurality of mark frequencies and a plurality of shift frequencies of the RTTY signal, and a storage unit.
Advance a first frequency determined based on the parameter of the predetermined mark frequency, a second frequency determined based on the parameters of the predetermined shift frequency of the mark frequency and the plurality of parameters of said plurality of parameters The control unit that determines and
A notch filter for suppressing by searching interfere harm signals,
Equipped with
The control unit
The notch filter is set with a first auto-notch operation prohibited frequency range so as to include the first frequency, and a second auto-notch operation prohibited frequency range is set so as to include the second frequency.
The notch filter is
The interference signal is searched for and suppressed in the frequency band excluding the first auto-notch operation prohibited frequency range and the second auto-notch operation prohibited frequency range.
Receiving machine. A reception filter having a reception band including the first frequency and the second frequency is further provided.
The notch filter searches for and suppresses an interference signal in the reception band.
The receiver according to請Motomeko 1. Read out a predetermined parameter among a plurality of parameters relating to a plurality of mark frequencies and a plurality of shift frequencies of the RTTY signal stored in the storage unit.
A first frequency determined based on a predetermined mark frequency parameter among the plurality of parameters, and a second frequency determined based on the mark frequency and a predetermined shift frequency parameter among the plurality of parameters. Confirmed,
In the notch filter, the first auto notch operation prohibited frequency range is set so as to include the first frequency, and the second auto notch operation prohibited frequency range is set so as to include the second frequency.
The notch filter searches for and suppresses an interfering signal in a frequency band excluding the first auto-notch operation prohibited frequency range and the second auto-notch operation prohibited frequency range.
Receive method. A receiving filter, set the reception band including a pre-Symbol first frequency and said second frequency,
The notch filter searches for and suppresses an interfering signal in the reception band.
The receiving method according to請Motomeko 3. On the computer
A step of reading out a predetermined parameter among a plurality of parameters relating to a plurality of mark frequencies and a plurality of shift frequencies of the RTTY signal stored in the storage unit.
A first frequency determined based on a predetermined mark frequency parameter among the plurality of parameters, and a second frequency determined based on the mark frequency and a predetermined shift frequency parameter among the plurality of parameters. Steps to confirm and
A step of setting a first auto-notch operation prohibited frequency range so as to include the first frequency in the notch filter, and setting a second auto-notch operation prohibited frequency range so as to include the second frequency, and a step of setting the notch filter.
An auto-notch execution step of searching for and suppressing an interfering signal in a frequency band excluding the first auto-notch operation prohibited frequency range and the second auto-notch operation prohibited frequency range by the notch filter.
Receive program Ru allowed to run. To the computer,
Further execute the step of setting a reception band including the first frequency and the second frequency,
As the auto notch execution step, the notch filter is used to execute a process of searching for and suppressing an interference signal in the reception band.
Reception program according to請Motomeko 5.

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