JPH10229349A - Radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain smooth and quick tuning, in response to a reception signal strength changing momentarily. SOLUTION: A reception circuit 3 applies reception processing to an input signal, based on an output frequency from a frequency synthesizer 4. An MPU 2 generates frequency information subject to adaptive control, based on a coefficient from an adaptive filter 11 having a function of adaptive operation as to a frequency of a signal with a maximum amplitude in the received signals at a tracing speed, in response to the reception signal strength. That is, the tracing speed is increased when the reception signal is strong and the tracing speed is decreased, when the reception signal is weak, and the frequency synthesizer 4 is controlled so that a difference between the generated frequency and the preset frequency is zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio, and more particularly, to a radio capable of quick tuning with a simple configuration.

[0002]

2. Description of the Related Art For example, in a radio receiver having a function of easily matching the frequency of a partner station with the frequency of the own station when receiving CW or unmodulated waves, the frequency of the own station is matched with the frequency of the partner station received. Therefore, the tuning function is necessary, and the user simultaneously listens to the frequency-dependent outgoing tone of the received signal from the partner station and the corresponding side tone sound generated by the own station, and adjusts the receiving frequency so that there is no difference between the two sounds. It was manually variable. Such a receiver requires considerable skill in judging the difference between two sounds, and it is difficult to make sure that they match.

Therefore, a configuration as shown in FIG. 6, which detects a peak of a received signal and sweeps the received frequency so that the peak is maximized, is used as a radio device for automatically matching its own frequency to the received signal frequency. Proposed. In FIG. 6, a reception signal to which a frequency signal from a frequency synthesizer 4 is input and received and subjected to predetermined reception processing is output as a sound from a speaker 5 and received by a level determination circuit 6. The signal level (intensity) is detected and supplied to the MPU (microcomputer) 2. MPU
2 adjusts the output frequency of the frequency synthesizer 4 based on the level detected by the level determination circuit 6. That is, the MPU 2 adds and subtracts the output frequency of the frequency synthesizer 4 by a predetermined frequency step α,
The data of the frequency synthesizer 4 is changed while performing frequency addition until the maximum peak is detected. The frequency step α at this time can be set arbitrarily.

[0004] As shown in FIG. 7, a reception signal from a reception circuit 3 of a receiver is decomposed into respective frequency components using an FFT circuit 7 that performs frequency processing such as an FFT analyzer, and the MPU 2 There is also a receiver that controls a receiving circuit such as the frequency synthesizer 4 such that a receiving frequency indicating a maximum peak from a received signal decomposed into each frequency component is centered.

[0005]

However, as described above, a radio device that changes the frequency manually requires not only the skill of the user but also the difficulty of high-precision adjustment.

[0006] Further, in the configuration in which the reception frequency is swept as shown in FIG. 6 to match the target frequency, it takes time to sweep the reception frequency. In particular, the frequency step α
If is set finely, accurate peak detection can be performed, but not only the time required for the detection becomes long, but also a sweep reception circuit is required. In addition, if the configuration is such that there is only one receiving circuit and there is no dedicated receiving circuit for sweeping, it becomes impossible to receive while the receiving frequency is being swept.

Further, in a radio using an FFT circuit as shown in FIG. 7, the FFT circuit 7 is required to have a sufficient memory capacity and DSP speed for performing FFT processing calculations. Since the amount of memory and the speed of the DSP are proportional to the cost, it is expensive to perform processing that satisfies the performance.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radio device capable of quick tuning with a relatively simple configuration.

[0009]

In order to solve the above-mentioned problems, a radio device according to the present invention comprises: a receiving circuit for receiving an input signal based on an output frequency from a frequency synthesizer and outputting the received signal as a received signal; A signal strength determination circuit for determining a signal strength of a received signal, an adaptive filter having a function of adaptively operating a frequency having a maximum amplitude in the received signal whose coefficient is varied, and a following speed according to the received signal strength Generate the adaptively controlled frequency information based on the coefficients of the adaptive filter, so that the difference between the generated frequency and a preset frequency at a tracking speed according to the received signal strength becomes zero. A control circuit for controlling the frequency synthesizer.

Here, when the received signal strength is strong, the following speed is increased, and when it is weak, the following speed is decreased. This following speed is performed by varying the size of the adaptive filter coefficient variable step.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of a wireless device according to the present invention.

The present embodiment has a receiving circuit 3 that receives an output frequency signal from a frequency synthesizer 4, performs predetermined receiving processing on an input signal, and outputs the received signal as a received signal. Is output from the speaker 5 and subjected to IIR filtering by the adaptive filter 11 constituting the DSP 1. The coefficient information of the adaptive filter 11 is stored in the MPU 2 having the frequency determination processing circuit 21.
Is output to The frequency determination processing circuit 21 determines the frequency based on the filter coefficient from the adaptive filter 11, and controls the output frequency of the frequency synthesizer 4 so that the determined frequency matches a predetermined frequency. With such a configuration, an auto notch filter is configured.

This auto notch filter has a receiving circuit 3
The automatic notch filter operates so that the notch frequency matches the frequency of the signal having the maximum amplitude in the received signal from the filter, and therefore the filter coefficient is varied.

In FIG. 1, a DSP 1 receives a coefficient of an auto notch filter controlled so that a notch frequency of the auto notch filter matches a frequency of a signal having a maximum amplitude in a received signal, and performs a notch based on the coefficient. Calculate the frequency. The DSP 1 also obtains a difference F between the calculated notch frequency and a preset frequency to obtain an MPU 2
To send to. The MPU 2 varies the frequency of the frequency synthesizer 4 based on the frequency difference so that the signal frequency of the maximum amplitude in the received signal matches a preset frequency. For example, assume that the receiving circuit outputs a beat sound of 800 Hz when receiving a signal of 14.100 MHz. At this time, if the receiving frequency is shifted by 1500 Hz (14.095 MHz), the receiving circuit 3 outputs a 1300 Hz beat sound. At this time, in the auto notch filter, the coefficient of the notch frequency of 1300 Hz is taken into the DSP1. The DSP 1 obtains a difference from a preset frequency of 800 Hz, and determines that the reception frequency is +500 Hz. The MPU 2 controls the frequency synthesizer 4 so as to make this difference zero, and adds the output frequency of the frequency synthesizer 4 to 500 Hz. These operations are repeatedly performed, and when the difference becomes zero, the reception frequency becomes 14.
The frequency becomes 100 MHz, which can be matched with the target reception signal frequency.

By the way, in the adaptive operation of the auto notch filter, the error is small when the received signal strength is strong, and the error is large when the received signal strength is weak. Therefore, when the coefficient updating operation of the auto notch filter is always performed in a constant step, quick tuning may not be obtained. For example, when the received signal strength is weak, a large error occurs in the adaptive operation, and smooth operation becomes difficult.
Further, when the received signal strength is strong, the adaptive operation can be performed at a higher speed, but the speed is limited to a speed determined by a certain step, and the performance cannot be fully utilized.

Therefore, in the present embodiment, the MPU 2 receives the received signal strength from the receiving circuit 3 and sends out the received signal strength S to the DSP 1. The DSP 1 varies the steps of the coefficient updating operation of the auto notch filter based on the received signal strength S given from the MPU 2. That is,
When the received signal strength is strong, the step of updating the coefficient of the auto notch filter is set large to increase the adaptive following speed of the auto notch filter, and when the received signal strength is weak, the step of updating the coefficient of the auto notch filter is set small. To reduce the adaptive following speed of the auto notch filter. This process enables the adaptive operation of the auto notch filter at the optimal speed for the received signal strength that changes every moment, as compared to the case where the coefficient updating operation of the auto notch filter is always performed in a fixed step, and quick tuning. Becomes possible.

FIGS. 2 and 3 show DS in the above embodiment.
The flowchart of the operation processing procedure of P1 and MPU2 is shown. Referring to FIG. 2, the received signal strength is read from the MPU 2 (step S1), and it is determined whether the read received signal strength is stronger than a predetermined reference value (step S2). Here, if it is determined to be weak, the coefficient update step is set small (step S3), and if it is determined to be strong, the coefficient update step is set large (step S4), and then the adaptive filter processing is executed. (Step S5). Subsequently, filter coefficients supplied from the adaptive filter 11 of the DSP 1 are read, and a frequency corresponding to the read coefficients is calculated (step S6). Next, a difference frequency between the frequency indicated by the read coefficient and a preset frequency is obtained (step S7), and the obtained difference frequency is transmitted to the MPU 2 (step S8).

As shown in FIG. 3, the MPU 2 has a DSP 1
Then, difference frequency information is read from (step S11), and it is determined whether or not the difference is 0 (step S12). here,
If the difference is 0 (True), the process ends. If the difference is not 0 (False), coefficient data of the frequency synthesizer 4 is generated based on the difference so that the difference becomes 0 (step S13). Subsequently, the data generated in step S13 is set in the frequency synthesizer 4, and the process returns to step S11. Such behavior, that is,
The control of the frequency synthesizer 4 is repeated until the difference between the frequency indicated by the coefficient of the auto notch filter and the preset frequency disappears.

FIG. 4 shows a configuration diagram of an auto notch filter constituted by an adaptive filter. In the figure,
The notch filter 100 has a transfer function H (z), and the MPU 2 reads the coefficients of the notch filter and performs processing. Filters 200 and 300 having transfer functions G1 (z) and G2 (z) are filters for creating an adaptive signal for updating coefficients. That is, the output signals α1 and α2 from the filters 200 and 300 are added by the adder 400, and the added signal is output to the update unit 500 as the adaptive signal α (n). The update unit 500 updates the coefficients of the filters 100 to 300 based on the output signal of the notch filter 100 and the adaptive signal.

This auto notch filter is an IIR adaptive notch filter using the stochastic gradient method, and its transfer function is H (Z) = (1 + WZ ^-1 + Z ^-2 ) / (1 + rWZ ^-1 + r
² Z ⁻² ) where W = ⁻² cos (ωn). Here, ωn is the notch angular frequency. r is an arbitrary real number satisfying 0 ≦ r <1, and is a coefficient that determines the sharpness of the notch characteristics of the notch filter. In this case, a predetermined value is set in advance.

The coefficient w of the auto notch filter 100
To obtain the frequency, the notch angular frequency ωn is obtained as ωn = cos ⁻¹ (−W / 2), and the notch frequency fn is obtained as fn = 2πωn.

In the above-described embodiment, the adaptive filter is constituted by an auto notch filter constituted by an adaptive filter. However, the present invention can be similarly implemented by an auto peak filter constituted by an adaptive filter.

In order to detect the frequency of the received signal, D
It is also possible to implement the method using FM detection by SP. In the FM detection by the DSP, unlike the analog FM detection, the reception signal frequency can be accurately detected. FIG. 5 shows the configuration diagram.

In FIG. 5, components denoted by the same reference numerals as those in FIG. 1 are components having the same functions. The signal received by the receiving circuit 3 is the FM detection circuit 1
2, the signal detected by the FM detection is fed to the integration circuit 13
And the frequency information is obtained. The frequency information obtained in this way is sent to the frequency detection circuit 21 of the MPU 2 to make it coincide with the frequency of the partner station as described above.

[0025]

As described above, in the radio of the present invention, it takes less time to match the reception frequency than in the conventional radio which sweeps the reception frequency. Further, even with one receiver, it is possible to output a received sound at the time of frequency tuning. Also, compared to the method using an FFT analyzer, the amount of memory used is small, and the DSP and MP
The speed of U is also slow. Furthermore, the circuit is small,
Since the current consumption is small, it can be easily mounted on a wireless receiver. In particular, according to the present invention, since the following speed of the notch filter is changed according to the received signal strength,
Even when the received signal strength changes every moment, the coefficient is updated at the optimum step for the change, and smooth and quick tuning is possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a wireless device according to the present invention.

FIG. 2 is a flowchart showing an operation processing procedure of a DSP 1 in the embodiment shown in FIG.

FIG. 3 is a flowchart showing an operation processing procedure of the MPU 2 in the embodiment shown in FIG.

FIG. 4 is a configuration diagram of an auto notch filter configured by an adaptive filter.

FIG. 5 is a configuration diagram of another embodiment of a wireless device according to the present invention.

FIG. 6 is a diagram illustrating a configuration example of a conventional wireless device.

FIG. 7 is a diagram illustrating another configuration example of a conventional wireless device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 DSP 2 MPU 3 reception circuit 4 frequency synthesizer 5 speaker 11 adaptive filter 12 FM detection circuit 13 integration circuit 21 frequency judgment processing circuit 100 notch filter 200, 300 filter 400 adder 500 update section

Claims (3)

[Claims] A receiving circuit for receiving an input signal based on an output frequency from a frequency synthesizer and outputting the received signal as a received signal; a signal strength determining circuit for determining a signal strength of the received signal; An adaptive filter having a function of performing an adaptive operation on a frequency having a maximum amplitude in the received signal, and generating the adaptively controlled frequency information based on a coefficient of the adaptive filter at a following speed according to the received signal strength. And a control circuit for controlling the frequency synthesizer such that a difference between the generated frequency and a preset frequency becomes zero. 2. The wireless device according to claim 1, wherein the following speed is increased when the received signal intensity is high, and the following speed is decreased when the received signal intensity is low. 3. The wireless device according to claim 1, wherein the following speed changes the adaptive filter coefficient variable step.