JP4583097B2 - Radio apparatus and noise attenuation method - Google Patents

Description

  The present invention relates to a radio device and a noise attenuation method.

  FIG. 4 is a block diagram of a radio 40 that is an example of a conventional radio. In FIG. 4, 41 is a receiving antenna, 42 is a mixing circuit, 43 is a roofing filter, 44 is a noise blanker, and 45 is an IF filter.

  The wireless device 40 is provided with a tuning circuit (not shown). The tuning circuit tunes a signal input from the receiving antenna 41 to a predetermined frequency. Further, the input signal is converted into an intermediate frequency (IF) signal by the mixing circuit 42. The mixing circuit 42 performs mixing based on the signal output from the local transmitter.

  The IF signal output from the mixing circuit 42 is input to the roofing filter 43. The roofing filter 43 limits the frequency band of a signal to be passed. The frequency band set in the roofing filter 43 is the maximum frequency band of signals that are normally received.

  A downstream stage of the roofing filter 43 is provided with an A / D converter (not shown) for converting an analog signal into a digital signal. The input signal converted into the digital IF signal by the A / D converter is input to the noise blanker 44. In the noise blanker 44, processing for detecting noise with respect to an input signal and processing for removing noise are performed.

  The signal processed and output by the noise blanker 44 is input to the IF filter 45. Among signals input to the IF filter 45, a signal having a predetermined frequency corresponding to the frequency band of the filter 45 passes through the filter 45.

  In the radio device 40 described above, the digital signal processing part is composed of a DSP (digital signal processor). The roofing filter 43 is provided to limit the signal band so that the DSP can perform signal processing.

  That is, if the frequency band of data input to the DSP is too wide, signal processing by the DSP cannot be performed, so the roofing filter 43 limits the signal frequency band.

  By the way, in a conventional wireless device, when an intermediate frequency (IF) input signal frequency-converted by a mixing circuit is input to a noise blanker as it is, the frequency band is too wide and the noise blanker malfunctions due to interference of signals outside the band. I sometimes woke up. Even if the roofing filter 43 is provided as in the case of the wireless device 40, the frequency band is wide, so that interference of signals outside the band cannot be prevented.

  Therefore, an object of the present invention is to prevent malfunction of a noise blanker due to an out-of-band signal in a wireless device.

To solve the above problems, the present invention includes a noise Blanc mosquitoes for removing noise contained in the given signal,
Provided before with respect to the noise blanker, it sets the frequency band corresponding to the operation mode, a band pass filter which passes the signal of the frequency band of the input signal corresponding to the received signal supplied to the noise blanker,
And a demodulation circuit that is provided downstream of the noise blanker and demodulates the received signal based on an output signal of the noise blanker .

  According to the wireless device of the present invention, the band pass filter is provided in the preceding stage with respect to the noise blanker, and the frequency band corresponding to the operation mode is set in the band pass filter. Then, among the input signals input to the band pass filter, signals within the frequency band pass through the band pass filter. And the signal which passed the band pass filter is input into a noise blanker.

  Thereby, since the signal of the frequency band according to the operation mode is input to the noise blanker, it is possible to prevent the noise blanker from malfunctioning due to interference of signals outside the band.

The applied signal with an A / D converter for the digital data,
The band-pass filter and noise blanker while being constituted by a D SP (digital signal processor), the signal which is a digital signal by the A / D converter is input as the input signal to the bandpass filter,
Roofing filter is provided in front with respect to the A / D converter, it is possible to signal passed through the roofing filter is so applied to said A / D converter.

  The roofing filter passes a signal in a frequency band that can be processed by the DSP among the input signals. This enables signal processing in a bandpass filter and a noise blanker configured by the DSP.

  And the signal which passed the roofing filter is further restrict | limited by the frequency band of a band pass filter, and the signal which passed the band pass filter is input into a noise blanker. Thereby, the signal of the frequency band according to the operation mode can be input to the noise blanker, and the malfunction of the noise blanker can be prevented.

  Further, when setting the frequency band corresponding to the operation mode to the band-pass filter, it is possible to input data in this frequency band to the band-pass filter. Thereby, the process for setting a frequency band to a band pass filter is easy.

Further, the present invention is a noise attenuation method in a wireless device that performs a process of attenuating noise by a noise blanker,
A band limiting step of allowing a signal corresponding to a reception signal of the radio to pass by being limited by a frequency of a frequency band corresponding to the operation mode of the radio;
And a noise attenuation step of performing processing for attenuating noise by the noise blanker for signals that were passed to restrict by the band limiting step,
A noise attenuation method for demodulating the received signal based on a signal obtained in the noise attenuation step .

  According to the present invention, since the signal limited by the frequency in the frequency band corresponding to the operation mode of the radio is input to the noise blanker, the interference of signals in frequencies other than the frequency band corresponding to the operation mode is prevented, and the noise blanker malfunctions. Can be prevented.

  According to the present invention, since the signal limited in the frequency band according to the operation mode of the radio is input to the noise blanker, it is possible to prevent signals other than the frequency band corresponding to the operation mode from interfering with the noise blanker. . Thereby, the malfunction of the noise blanker can be prevented.

  A wireless device 20 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The noise attenuation method according to an embodiment of the present invention is implemented by the radio device 20. According to the radio device 20 described below, pulse noise can be processed.

  As shown in FIG. 1, the radio 20 includes a receiving antenna 1, a receiving circuit 2, a roofing filter 3, an A / D converter 4, a bandpass filter (BPF) 5, a noise blanker 6, and a demodulation. A circuit 7, a D / A converter 9, and an external memory 8 are provided.

  In the wireless device 20, the band pass filter 5, the noise blanker 6, and the demodulation circuit 7 are configured by a DSP (digital signal processor), and the digital signal is processed by the DSP.

  The receiving antenna 1 receives a radio signal. The receiving circuit 2 tunes the signal input from the receiving antenna 1 to a target predetermined frequency, and further performs frequency conversion to obtain an IF (intermediate frequency) signal.

  An IF signal as an input signal output from the receiving circuit 2 is input to the roofing filter 3. The roofing filter 3 performs a process of limiting the frequency band on the input signal.

  That is, the roofing filter 3 passes a signal in a frequency band that can be processed by the DSP among the input signals. As a result, the bandpass filter 5, the noise blanker 6 and the demodulation circuit 7 constituted by the DSP can process the input digital signal.

  The signal output from the roofing filter 3 is input to the A / D converter 4 and converted into digital data. The IF signal converted into digital data by the A / D converter 4 is input to a bandpass filter (BPF) 5 as an input signal.

  The bandpass filter 5 performs band limitation on the input IF signal. That is, only a signal component in a certain frequency band is passed through the input signal. The frequency band set in the band pass filter 5 can be variably set by external setting.

  The band pass filter 5 is set with a frequency band corresponding to the operation mode (AM, FM, reception frequency, different reception channel, etc.) of the radio device 20. An operation parameter (filter coefficient) corresponding to the selected operation mode is set in the bandpass filter 5 by the DSP.

  Thereby, the frequency band of the signal which the band pass filter 5 passes changes according to the operation mode of the radio. The IF signal that has passed through the bandpass filter 5 is input to the noise blanker 6.

  The noise blanker 6 attenuates the noise component and outputs the input signal (digital IF signal). The noise blanker 6 includes a noise detection unit and a blank processing unit which are not shown.

  The noise detection unit detects whether or not the input signal input to the noise blanker 6 includes noise of a predetermined value or more. A threshold for detecting noise is set in the noise detection unit, and noise is detected based on a comparison between this threshold and an input signal.

  When noise is detected by the noise detection unit, the blank processing unit performs blank (attenuation) processing on the input signal. The blank processing unit performs blank processing based on the attenuation gain for the input signal. The blanked signal is output from the noise blanker 6 to the demodulation circuit 7.

  On the other hand, when no noise is detected by the noise detection unit, the blank processing unit does not perform blank processing. The signal input to the noise blanker 6 is output to the demodulation circuit 7 as it is.

  The demodulation circuit 7 demodulates the signal input from the noise blanker 6. That is, the signal input from the noise blanker 6 is demodulated into an audio frequency signal by the demodulation circuit 7. The demodulated signal (AF signal) is converted into an analog AF signal by the D / A converter 9 and supplied to, for example, the speaker 11 or a signal processing circuit (not shown).

  The external memory 8 stores frequency band data to be set in the bandpass filter 5 and data necessary for signal processing of the noise blanker 6. The external memory 8 also stores other data necessary for controlling the operation of the radio device 20.

  As the data of the frequency band to be set in the band pass filter 5, the data input by the external setting is stored in the external memory 8. This data is set in the bandpass filter 5 by the DSP.

  The wireless device 20 is provided with a control microcomputer (not shown), and the control microcomputer includes a ROM and a RAM. A program for controlling the operation of the wireless device 20 by the control microcomputer is stored in the ROM.

  The control microcomputer inputs / outputs data to / from the external memory 8 as necessary. Based on the operation of the control microcomputer, each block shown in FIG. 1 is controlled to execute processing based on the DSP.

  The wireless device 20 includes an operation unit (not shown). This operation unit is operated by a user of the radio device 20, and condition information for operating the radio device 20 can be input by the operation unit.

  For example, the operation unit can select the operation mode of the wireless device 20 according to the user's key operation. Further, it is possible to input data of a frequency band set in the band pass filter 5 by operating the operation unit.

  Next, an example of the operation of the wireless device 20 described above will be described with reference to FIG. FIG. 2 is a flowchart showing the operations of the bandpass filter 5 and the noise blanker 6.

  When the operation mode, the reception frequency, and the like are set in the radio device 20, the reception circuit 2 receives the target signal in synchronization with the reception frequency in the set operation mode, performs frequency conversion, and outputs an analog IF signal. . On the other hand, the DSP supplies data in the frequency band corresponding to the selected operation mode to the band pass filter 5.

  The analog IF signal output from the receiving circuit 2 is input to the roofing filter 3. Among signals input to the filter 3, a signal having a frequency in the frequency band set in the filter 3 passes through the roofing filter 3.

  The analog IF signal output from the roofing filter 3 is input to the A / D converter 4. The A / D converter 4 performs sampling at a predetermined cycle and converts the analog IF signal into a digital IF signal.

  The A / D converter 4 sequentially supplies the converted digital data (data pieces) to the DSP. The DSP sequentially takes the digital data supplied from the A / D converter 4 into a first-in first-out (FIFO) buffer or the like. Then, the processing shown in FIG. 2 is sequentially executed for each captured digital data.

  An IF signal is input from the A / D converter 4 to the bandpass filter 5 (step S1), and the IF signal is processed by the bandpass filter 5 for band limitation (step S2). The signal that has passed through the bandpass filter 5 is input to the noise blanker 6 (step S3).

  The noise blanker 6 detects noise for the input signal. And the noise blanker 6 will perform a blank process, if noise is detected, and will output the signal which carried out the blank process. On the other hand, when no noise is detected, the noise blanker 6 does not perform blank processing and outputs the input signal as it is.

  When the noise blanker 6 outputs a signal to the demodulation circuit 7, the noise blanker processing is terminated (step S4).

  According to the radio device 20 described above, the band pass filter 5 is provided, and a frequency band corresponding to the operation mode is set in the band pass filter 5. Thereby, the frequency band of the signal input to the noise blanker 6 can be limited according to the operation mode of the wireless device.

  Thereby, it is possible to prevent a signal in a band other than the frequency band corresponding to the operation mode from being input to the noise blanker 6, and to prevent malfunction of the noise blanker 6 due to interference of signals outside the band.

  According to the radio device 20, the frequency band corresponding to the operation mode can be set in the bandpass filter 5 by inputting digital data in the frequency band to be set. Thereby, the process for setting a frequency band to the band pass filter 5 can be facilitated.

  In the above description, the band-pass filter 5, the noise blanker 6, and the demodulation circuit 7 have been described using examples of processing digital signals. In carrying out the present invention, the band-pass filter, the noise blanker, and the demodulation circuit can be configured by analog circuits.

  FIG. 3 is a block diagram of a part of the radio device 30 configured by an analog circuit. As illustrated, the wireless device 30 includes a band pass filter 35, a noise blanker 36, and a demodulation circuit 37. Each of these parts is constituted by an analog circuit. The noise attenuation method according to an embodiment of the present invention can be implemented by the radio device 30. Moreover, according to the radio device 30, pulse noise can be processed.

  In addition, since the radio device 30 does not process a digital signal, the roofing filter 3 and the A / D converter 4 provided in the radio device 20 are not provided. A circuit for processing an analog signal of the radio device 20 is also provided in the radio device 30 in the same manner.

  The analog IF signal output from the reception circuit of the radio device 30 is input to the band pass filter 35. The bandpass filter 35 performs band limitation on the input signal.

  The band pass filter 35 can adjust the circuit constant so that the frequency band can be variably set. The circuit constants of the bandpass filter 35 are adjusted so that the frequency band corresponds to the operation mode of the radio device 30. The frequency band (that is, circuit constant) of the band pass filter 35 can be variably set by external setting.

  The signal that has passed through the bandpass filter 35 is input to the noise blanker 36. The noise blanker 36 detects whether or not the input signal includes noise. When detecting the noise, the noise blanker 36 performs blanking (attenuation) processing based on the attenuation gain on the input signal. On the other hand, the noise blanker 36 does not perform blank processing on the input signal when no noise is detected.

  In the noise blanker 36, a noise detection circuit for detecting noise in the input signal is provided. This noise detection circuit can be constituted by a comparator. The comparator compares the voltage value of the input signal with the voltage value of the reference signal input as a threshold for noise detection, and detects noise.

  The noise blanker 36 outputs a blanked signal or a signal that has not been blanked to the demodulation circuit 37. The demodulation circuit 37 demodulates the signal input from the noise blanker 36 into an audio frequency (AF) signal.

  According to the radio device 30 described above, the band pass filter 35 is provided, and a frequency band corresponding to the operation mode is set in the band pass filter 35. Thereby, the frequency band of the signal input to the noise blanker 36 can be limited according to the operation mode of the wireless device.

  Thereby, it is possible to prevent a signal in a band other than the frequency band corresponding to the operation mode from being input to the noise blanker 36, and to prevent malfunction of the noise blanker 36 due to interference of signals outside the band.

It is a block diagram of the radio | wireless machine which is one Embodiment of this invention. It is a flowchart of an example of operation | movement of a radio | wireless machine. FIG. 3 is a block diagram of a radio device in which a band pass filter, a noise blanker, and a demodulation circuit are configured by analog circuits. It is a block diagram of the conventional radio | wireless machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reception antenna 2 Reception circuit 3 Roofing filter 4 A / D converter 5 Band pass filter 6 Noise blanker 7 Demodulation circuit 8 External memory 9 D / A converter 11 Speaker 20 Radio | wireless machine 30 Radio | wireless machine 35 Band pass filter 36 Noise blanker 37 Demodulation circuit 40 Radio 41 Receiving antenna 42 Mixing circuit 43 Roofing filter 44 Noise blanker 45 IF filter

Claims (3)

And noise Blanc mosquitoes for removing noise contained in the given signal,
Provided before with respect to the noise blanker, it sets the frequency band corresponding to the operation mode, a band pass filter which passes the signal of the frequency band of the input signal corresponding to the received signal supplied to the noise blanker,
A demodulation circuit that is provided in a subsequent stage with respect to the noise blanker and demodulates the received signal based on an output signal of the noise blanker;
A radio equipped with. The applied signal with an A / D converter for the digital data,
The band-pass filter and noise blanker while being constituted by a DSP (digital signal processor), the signal which is a digital signal by the A / D converter is input as the input signal to the bandpass filter,
The roofing filter is provided before with respect to the A / D converter, signal passed through the roofing filter is provided to the A / D converter, a radio apparatus according to claim 1. A method of attenuating noise in a wireless device that performs processing to attenuate noise by a noise blanker,
A band limiting step of allowing a signal corresponding to a reception signal of the radio to pass by being limited by a frequency of a frequency band corresponding to the operation mode of the radio;
And a noise attenuation step of performing processing for attenuating noise by the noise blanker for signals that were passed to restrict by the band limiting step,
A noise attenuation method for demodulating the received signal based on the signal obtained in the noise attenuation step .

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