JP5257187B2 - Wireless receiver - Google Patents

Description

  The present invention relates to a wireless receiver, and more particularly to a wireless receiver having a function of automatically controlling a reception bandwidth when adjusting a reception frequency.

For example, an amateur radio receiver can switch over many frequency bands such as long wave band (LF), short wave band (HF), ultra high frequency band (VHF), ultra high frequency band (UHF), etc., and can receive over a wide frequency range. is there. In such a radio receiver, a relatively large circular frequency adjusting dial is provided to switch the receiving frequency, and by rotating the dial, the radio that is in a call for a communication partner while increasing or decreasing the receiving frequency is obtained. There are many operations for searching for signals.
In recent years, rotary encoders have been used as frequency adjustment dials in place of conventional multi-contact mechanical rotary switches. The rotary encoder is equipped with a sensor that generates different pulse signals depending on the rotation direction of the left and right. By supplying the pulse signal to the digital circuit including the CPU, the rotation amount is detected by software, and it corresponds to the rotation amount. Thus, the reception frequency is changed.

By the way, it is not limited to amateur radio, but when searching for an incoming signal while operating the frequency adjustment dial to change the received frequency, the presence / absence of the incoming signal is judged while subtracting the rotation speed of the dial. Often to do. That is, when there is no incoming signal at a nearby frequency, the operator rotates the dial at a relatively high speed to change the received frequency at a high speed. Rotate to match the incoming signal with the pass band of the receiver band limit filter (typically an intermediate frequency filter).
In such an operation, when the dial is rotated at a high speed, it is preferable that the band-limiting filter (hereinafter, an example of an intermediate frequency filter) of the wireless receiver has a wide pass bandwidth. As is well known, after capturing an incoming signal, it is preferable that the received signal is narrow enough to match the frequency band allowed on the transmission side in terms of noise reduction.
Therefore, conventionally, in order to cope with such a situation, a radio receiver having a function of switching a band-limiting filter of a radio receiver, that is, a passband width of an intermediate frequency filter as necessary has been proposed. Conventionally, as a means for switching the pass band of the intermediate frequency filter of a radio receiver, a wide band filter, a narrow band filter, and a switch for switching them are provided, and when changing the frequency quickly, the filter is switched to the wide band filter. When the frequency can be captured, it is common to switch to a narrow band filter.

  As a method for automatically switching the passband width of the intermediate frequency filter, for example, Patent Document 1 discloses a method shown in FIG. The intermediate frequency passband automatic switching device shown in FIG. 6 divides a signal received via an antenna 101 and a high frequency amplifier 102 into two by a distributor (hybrid) 103, one of which is a first mixer 104a, a changeover switch 114a, The output is led to the first intermediate frequency amplifier 107a via the intermediate frequency filters 106a to 106d having different passband frequencies connected in parallel and the second changeover switch 114b, and the output thereof is passed through the first detector 108a to the low frequency amplifier. 109 to be supplied. In addition, the other of the two-branched received high-frequency signals passes through the second mixer 104b, the fifth intermediate frequency filter 106 ′, the second intermediate frequency amplifier 107b, and the second detector 108b, and the detection signal is reduced. It is configured to supply to the frequency amplifier 109. Further, a part of the output of the second detector 108b is also supplied to the low-pass filter 110 that passes the frequency of the audio band of 300 Hz or less and the high-pass filter 111 that passes the audio signal of 2700 Hz or more. The comparator 112a, 112b compares the signal level with a threshold value, supplies the signal level to the filter switching control circuit 113, and selects one of the four intermediate frequency filters 106a to 106d according to the output of the filter switching control circuit. The changeover switches 114a and 114b are controlled. The reception frequency adjusting dial 115 is provided with contact sensor means for detecting that the operator touches the dial. When the sensor output is supplied to the CPU 116, the operation signal is sent from the operation determination circuit 117 to the filter. The switching control circuit 113 is configured to be supplied.

  Since the operation of this circuit is described in detail in Patent Document 1, further explanation will be omitted, but low frequency and / or high frequency noise is included in the audio signal demodulated by the route of the second detector 108b. The presence is detected through the low-pass filter 110 and the high-pass filter 111, and the intermediate frequency filters 106a to 106d having different four passband frequencies are mixed based on the detection result. A filter having a pass band from which the noise signal is rejected is selected. The filter selection control is canceled when the operator touches the reception frequency adjustment dial, and the filter with the widest band is selected.

JP-A-1-286529

However, there is a possibility that efficient operation cannot be performed by manually switching the passband width of the filter as in the conventional case described above. That is, the operation of turning the filter changeover switch on and off as needed while rotating the frequency adjustment dial while concentrating on nerves and listening to the reception sound from the speaker hinders the smooth dialing operation.
In the filter switching method described in Patent Document 1, the filter switching state is controlled depending on whether or not the user is touching the frequency adjustment dial. There was a problem in usability even when trying to solve the problems related to the adjustment dial operation. That is, in the method described in Patent Document 1, it is possible to automatically select a filter from which noise at that time is eliminated in a state where a target frequency is captured, but when the operator touches the dial, the filter Therefore, it has been difficult to select a desired filter while operating the reception frequency adjustment dial or to set the pass bandwidth.
The present invention eliminates the problems associated with the operation of the conventional reception frequency adjusting dial as described above, and can quickly capture a desired incoming signal, and is equipped with an easy-to-use filter switching circuit. The purpose is to provide a machine.

In the present invention, in a radio receiver according to claim 1 in order to achieve the object, a receiving frequency adjustment means for changing the reception frequency, a variable can filter means the frequency of the lower and upper passband, before Symbol comprising a filter control means for controlling the filter means, and a frequency change direction detection means for frequency adjustment to detect the increase or decrease direction of the frequency due to the operation of the prior Symbol reception frequency adjusting means, said filter control means, said frequency change direction detection If more frequency is detected to be the direction of increasing the unit, when controlled in so that widened the upper limit of the passband, or it has been detected is the direction of decreasing frequency, Control is performed to widen the lower limit of the passband .
According to a second aspect of the present invention, in the wireless receiver according to the first aspect, the filter means includes a DSP, and the passband frequency is controlled by digital processing.

  As described above, the present invention includes reception frequency adjusting means for changing the reception frequency, filter means capable of controlling the passband frequency and / or the passband width, and filter control means for controlling the filter means. The frequency adjustment amount per unit time by the operation of the reception frequency adjusting means, that is, the frequency change speed is detected, and the passband frequency and / or the passband width are controlled based on the detected frequency change amount. With this configuration, if the operator arbitrarily rotates the reception frequency adjustment dial, a filter having a suitable frequency band is automatically selected, and a quick reception operation is possible.

1 is a block diagram illustrating an example of a wireless receiver according to the present invention. The figure which shows an example of the memory data which shows the example of filter zone | band control in an example of this invention. It is a figure which shows the example of the pass band of the filter in this invention, (a) is a band diagram of a narrow-band filter, (b) is a band diagram of a filter which has a wide band on the low frequency side, (c) is on the high frequency side The band diagram of a filter having a wide band. The block diagram which shows the modification Example of this invention. The block diagram which shows the other example of this invention. The block diagram of the radio | wireless communication apparatus provided with the conventional filter change means.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
FIG. 1 is a block diagram showing an embodiment of a radio receiver according to the present invention. The radio receiver shown in this example is a radio receiver including a high-frequency amplifier 1 that inputs a signal from an antenna (ANT), a frequency converter 2 that converts a high-frequency signal into an intermediate frequency, and a local oscillator 3. The example which applies this invention is shown. The output of the frequency conversion unit 2 is supplied to three frequency band filters (hereinafter referred to as IF filters) 4 to 6 having different pass bandwidths through switching diodes D1 to D6 arranged at input / output ends. . A signal that has passed through the IF filter selected from these three is converted into an audio signal by the detection unit 7, and then supplied to the speaker 9 through the audio amplification unit 8. Further, in this example, a microcomputer (microcomputer) CPU 10 is provided for adjusting the reception frequency and generating a signal for controlling the switching diodes D1 to D6, and controls the local oscillator 3 as a reception frequency adjustment means. A reception frequency input unit 11 and a filter selection unit 12 are provided.
The CPU 10 stores a necessary program and information in a memory circuit, and as shown in the figure, at least a reception frequency setting process, a frequency change speed determination process, a band frequency and / or a band of an IF filter which is a band limiting filter IF filter setting processing for performing frequency width setting processing can be performed.

Hereinafter, specific operations and processes will be described assuming an amateur radio receiver. In this example, the receiving frequency input means includes a desired frequency band setting switch such as LF or UHF, as well as a rotary encoder that rotates the dial as described in the conventional example to increase or decrease the frequency. The filter selection means is a switch for selecting and setting an IF filter having characteristics of a specific band frequency and / or band frequency width at the operator's will. In the description of the present invention below, do not use.
First, the band that the operator desires to receive is set by a selection switch, AM modulation and FM modulation are set as required, and in the case of SSB, upper / lower band-wave modulation is set. These pieces of information are supplied to the CPU 10 and desired settings are made. When these settings are completed and a reception frequency adjustment dial (hereinafter simply referred to as a dial) is rotated, a pulse signal is supplied from the rotary encoder to the CPU 10, and the actual reception frequency changes according to the rotation direction. As is well known, the reception frequency is changed by changing the frequency control signal supplied from the CPU 10 to the local oscillator 3.

  A feature of this embodiment is that a speed at which the frequency is changed by rotating the dial is detected, and one of the IF filters 4 to 6 is selected according to the speed. That is, when the operator changes the dial rotation speed, the number of pulses per unit time generated from the rotary encoder changes according to the rotation speed, so the frequency change speed can be determined by counting the number of pulses. It is. For example, as shown in FIG. 2, when the number of pulses per unit time is between zero (0) and 10 pulses, it is often the case that some received signal is captured and monitored, or the frequency is finely adjusted. Therefore, an IF filter having a normal pass band width (in this example, a narrow band filter 6) is selected, and the switching diodes (D5 and D6) at the input and output ends of the filter are biased by a circuit not shown. A conduction state is established by passing an electric current. In addition, when the number of pulses per unit time generated from the rotary encoder is 11 pulses to 50 pulses, the filter is wider by one step (5), and at higher speeds of 51 pulses / s to 100 pulses / s, the filter is wider by two steps. In order to select (4), the diode switches (D1 to D4) at the input / output ends of the respective filters are turned on.

With this control, when a dial is rotated at high speed over a wide frequency range, a filter with a wide pass bandwidth is selected, so there is a slight increase in noise, but there is an incoming signal at a certain frequency away Can be detected quickly, and a target signal can be quickly captured. Moreover, when the dial rotation is slowed down when approaching the target signal, it automatically returns to the normal passband width, so that noise is reduced and intelligibility is increased.
In this example, three IF filters having different pass bandwidths are provided. However, more filters can be provided and switching can be performed with fine divisions.

FIG. 3 is a filter band diagram for explaining a modification of the present invention. The three IF filters shown in FIG. 1 show cases in which the pass bandwidth is increased or decreased equally on both sides of the center frequency. For example, as shown in FIG. Depending on whether it is rotating in the direction of increasing the frequency or in the direction of decreasing the frequency, control is performed so that the band is widened to the high frequency side or the low frequency side as seen from the center frequency F0 of the filter. You can also. That is, when the filter shown in FIG. 3 (a) is a normal narrowband filter, but the dial rotation direction is a decreasing direction, the passband is widened in the direction of lower frequency as shown in FIG. 3 (b). Thus, conversely, when the dial is rotating in the direction of increasing the frequency, as shown in FIG. 3C, control is performed so as to widen the band to the higher frequency side as seen from the center frequency F0 of the filter. 3B and 3C, although the center frequency values are different, the pass bandwidth is the same, so the frequency of the filter having the same frequency bandwidth is changed corresponding to the increase / decrease direction of the reception frequency. It can also be called a thing.
According to this example, since the reception band is expanded only on the frequency side in the direction in which the reception frequency is changed, the presence of the intended incoming signal can be sensed by the minimum necessary band expansion. Therefore, an increase in noise accompanying the expansion of the passband can be minimized. In this example as well, as described with reference to FIGS. 1 and 2, it is possible to switch between filters having a plurality of pass bandwidths in accordance with the dial rotation speed.

  FIG. 4 is a block diagram showing another embodiment of the present invention. The wireless communication device shown in this example is characterized in that a plurality of IF filters are realized by a DSP (Digital Signal Processor) 13. In general, a DSP is a one-chip microprocessor built exclusively for the processing of time-series data such as audio, video, and measured values, as is well known. Has been realized. Since the DSP can perform specific processing while reducing the burden on the CPU that performs processing of the entire apparatus, it is also frequently used in digital processing of communication devices, and the filtering processing necessary in the present invention is digitally performed. Also suitable for The other blocks are substantially the same as those in the example of FIG. In addition, as shown in FIG. 4, the DSP 13 can implement a band limiting filter having a frequency variable function by an existing technology, and thus detailed description is omitted. Corresponding to the dial rotation direction and the rotation speed, increase / decrease and switching of the pass bandwidth can be freely controlled by a program.

FIG. 5 is a block diagram showing still another embodiment of the present invention. In the example described above, the passband filter is an IF filter. In this example, the voice band after detection demodulation is used. An example in which a band limiting filter is inserted is shown. That is, in the radio receiver shown in FIG. 5, the same reference numerals as those already described are blocks having the same function, and the feature of the radio receiver shown in this example is that the output of the detector 7 is the passband. The audio amplifier 8 and the speaker 9 are supplied to the audio amplifier 8 and the speaker 9 via the required filters through three different audio filters 15 to 17 and switches SW1 to SW6 inserted in the respective input / output terminals. Of the three audio band filters, 15 is a wide band filter, 16 is a medium band filter, and 17 is a narrow band filter.
According to this configuration, in a radio receiver that directly converts a high-frequency signal into a baseband signal, it is difficult to control the band frequency and the width of the band-limiting filter as described above, or the processing circuit When it becomes expensive, as shown in FIG. 5, as in the case described above in the voice band, by using a filtering function that changes the frequency band and bandwidth, it is audibly similar to each of the above embodiments. Effects can be obtained.

The present invention need not be limited to the above-described embodiments, and various modifications are possible. For example, in the passband control example of the filter shown in FIG. 3, it is also useful for reducing the noise of the received demodulated output signal to reduce the passband width on the side opposite to the increase / decrease direction of the reception frequency. In other words, the passband is widened in the direction of adjusting the reception frequency, but in the opposite direction, the overall passband width can be narrowed within a range that does not fall below the normal (regular) passband width.
In addition, as a reception frequency adjusting means, instead of a rotary dial, a dial or knob that rotates within a predetermined angle range on the left and right may be provided, and the reception frequency changing speed may change according to the rotation angle. Good. Alternatively, a lever that can be slid up and down or left and right may be provided, and the reception frequency changing speed may be changed according to the amount of sliding from the center position. The illustrated local oscillator 3 is not limited to this, but is generally one that controls the frequency by changing the division ratio of the variable frequency divider provided in the loop of the PLL frequency synthesizer. Is.

DESCRIPTION OF SYMBOLS 1 High frequency amplification part, 2 Frequency conversion part, 3 Local oscillator, 4 thru | or 6, 14 IF filter, 7 Detection part, 8 Voice amplification part, 9 Speaker, 10 CPU, 11 Reception frequency input means (dial, rotary encoder), 12 Filter selection input means, 13 DSP, 15 to 17 audio filter, ANT antenna, SW1 to SW6 selector switch, D1 to D6 switching diode

Claims (2)

A reception frequency adjustment means for changing the reception frequency, a variable can filter means the frequency of the lower and upper passband, and filter control means for controlling said filtering means, the frequency is the frequency adjustment by the operation of the reception frequency adjusting means Frequency change direction detecting means for detecting the increase / decrease direction of
With
Said filter control means, when it is the direction the frequency increases is detected by the frequency change direction detection means controls so as to increase the upper limit of the passband, and a direction to decrease the frequency A radio receiver characterized in that control is performed so as to widen the lower limit of the passband when is detected . 2. The radio receiver according to claim 1 , wherein the filter means includes a DSP, and the passband frequency is controlled by digital processing.

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