JPH11205174A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver with a simplified circuit configuration and reduced number of parts by supplying to a first mixer a signal which is outputted by a voltage controlled transmitter provided on the main body of a radio receiver. SOLUTION: Switches SW1 and SW2 are turned to a switching weather band side wx. A signal received by an antenna AT is supplied through the switch SW1 to a weather band additional reception part 10, passed through a band pass filter 11, amplified by an amplifier 12 and passed through a band pass filter 13. Further, this signal and a signal oscillated by a VCO 24 are mixed by a first mixer 14, and the output signal of the firs mixer 14 is passed through a band pass filter 14 and outputted to the weather band additional reception part 10. Then, this signal is supplied through the switch SW2 to a radio reception part 20 and the audio signal to weather band is outputted from the radio reception part 20. In this case, a local oscillation frequency at the weather band additional reception part 10 is supplied from the main body 20 of the radio reception part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a receiver.

[0002]

2. Description of the Related Art A weather band is provided as one of radio frequency bands in the United States.
This is a frequency band of a frequency-modulated signal, and its reception frequency is 162.400 to 162.550 MHz, and its maximum deviation is 5 kHz. A normal FM broadcast signal having a frequency band other than the weather band has a frequency shift of 75 kHz.

FIG. 2 is a circuit diagram showing a conventional receiver RE capable of receiving a weather band and a normal FM broadcast signal.

[0004] The conventional receiver RE has a distribution network N
T, a reception unit R1 exclusively for weather band, and a reception unit R2 exclusively for FM signal.

[0005] The reception unit R1 dedicated to the weather band includes a band-pass filter BPF1 _WB and a low-noise amplifier AMP1 _WB.
, Band-pass filter BPF2 _WB , first mixer MIX1 _WB for weather band, and voltage-controlled oscillator VCO
_WB , PLL _WB , 10.7 MHz first intermediate frequency filter CF1 _WB, and first intermediate frequency amplifier AMP
2 _WB and a second mixer MIX2 _WB for weather band,
10.25 MHz crystal oscillator X'tal _WB and 450
KHz second intermediate frequency filter CF2 _WB and FM
And a demodulation circuit DMD _WB .

[0006] FM signals dedicated receiver R2 is a band-pass filter BPF1 _FM, and _FM low noise amplifier AMP1, a band-pass filter BPF2 _FM, the first mixer M for FM
IX1 _FM , voltage controlled oscillator VCO _FM , PLL
_FM and 10.7 MHz first intermediate frequency filter C
F1 _FM , the first intermediate frequency amplifier AMP2 _FM , and 1
0.7 MHz second intermediate frequency filter CF2
_{It has an FM} and an FM demodulation circuit DMD _FM .

[0007]

The basic components of the weather band dedicated receiving unit R1 and the FM signal dedicated receiving unit R2 are the same, however, due to differences in reception frequency and the like, different circuit configurations are used as described above. It has become. That is, in the conventional receiver RE that can receive the weather band and the normal FM broadcast signal, the frequency band differs between the weather band and the normal FM broadcast signal, and the maximum deviation is different. A weather band dedicated receiving unit R1 for receiving a weather band and an FM signal dedicated receiving unit R2 for receiving a normal FM signal are separately provided.

Therefore, the weather band and the normal FM
A conventional receiver capable of receiving a broadcast signal has a problem that the circuit configuration is complicated and the number of parts is large.

An object of the present invention is to provide a receiver capable of receiving a weather band and a normal FM broadcast signal, which has a simple circuit configuration and a small number of parts. It is.

[0010]

According to the first aspect of the present invention,
A first method for converting a signal received by an antenna into a predetermined frequency
, A radio reception unit main body including a second mixer and a voltage controlled oscillator, and a radio reception unit main unit after processing a signal received by an antenna by the weather band addition reception unit Or a switching means for switching between inputting directly to the radio receiving unit main body without passing through the weather band additional receiving unit, and a signal output by the voltage controlled oscillator provided in the radio receiving unit main unit. And a connection means for supplying to the first mixer.

According to a second aspect of the present invention, in the first aspect, the radio receiving unit main body includes two filters having different intermediate frequency pass bands and filter switching means for switching the two filters. Is a receiver.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a receiver RE1 according to one embodiment of the present invention.

The receiver RE 1 includes an antenna AT, a weather band additional receiving unit 10, a radio receiving unit main body 20,
Connecting means 30 and switches SW1, S as switching means
W2.

The weather band additional receiving section 10 includes, for example, a band pass filter 11 of 162.5 MHz, a low noise amplifier 12, a band pass filter 13, and a first for converting a signal received by the antenna AT into a predetermined frequency. It has a mixer 14 and, for example, a bandpass filter 15 of 86.6 MHz. In theory,
The bandpass filters 13 and 15 may be omitted.

The radio receiving unit body 20 is basically the same as a conventional FM radio used in Japan, and includes a band-pass filter 21, an amplifier 22, and a second
Mixer 23, voltage-controlled oscillator 24, and PLL 25
, A wideband filter 26, a narrowband filter 27, and F
It has an M demodulation unit 28 and switches SW3 and SW4.
The switches SW3 and SW4 are examples of a filter switching unit that switches between two filters 26 and 27 having different frequency pass bands.

The connection means 30 is a connection means for supplying the signal output from the voltage controlled oscillator 24 to the first mixer 14.

The switch SW1 selects whether the signal received by the antenna AT is input to the weather band additional receiving unit 10, or is directly input to the radio receiving unit 20 without passing through the weather band additional receiving unit 10. The switch SW2 is a signal to be input to the radio receiving unit 20, the signal processed by the weather band additional receiving unit 10, or the signal added to the weather band additional receiving unit 10.
Is a switch for selecting an antenna AT reception signal that does not pass through. When the switch SW1 is switched to the WX side terminal, the switch SW2 is also switched to the WX side. When the switch SW1 is switched to the FM side terminal, the switch SW2 is also switched to the FM side. Switches SW1 and SW2 are linked.

That is, the switches SW1 and SW2 are examples of switching means. The switching means causes the signal received by the antenna AT to be processed by the weather band additional receiving unit 10 and then input to the radio receiving unit main body 20. This is an example of a signal switching unit that switches whether to make the signal input to the radio receiving unit main body 20 directly without passing through the weather band additional receiving unit 10.

Next, the operation of the above embodiment will be described.

First, it is assumed that the switches SW1 and SW2 are respectively connected to the FM side terminals. In this case, the signal received by the antenna AT is directly input to the radio receiving unit main body 20, and the audio signal of the FM broadcast is transmitted to the radio receiving unit main body 2.
Output from 0.

Here, it is assumed that the switches SW1 and SW2 are switched, and each of them is switched to the weather band side WX. In this case, the signal received by the antenna AT is supplied to the weather band additional receiving unit 10 through the switch SW1, passes through the band pass filter 11, is amplified by the low noise amplifier 12, and is
, The signal having passed through the band-pass filter 13 and the signal oscillated by the VCO 24 are mixed by the first mixer 14, and the output signal of the first mixer 14 passes through the band-pass filter 15, The signal is output to the band addition receiving unit 10. The signal is supplied to the radio receiving unit 20 via the switch SW2, and the weather band audio signal is output from the radio receiving unit 20.

Here, the reception frequency of the weather band is represented by f
_W (= 162.5 MHz), and the frequency of the output signal of the first mixer 14 (the first intermediate frequency,
If the received frequency of the _{VOC 24} is f _rW and the oscillation frequency of the _{VOC 24} is f _OSCW , then f _OSCW = f _{W −fr W}
Since the local oscillation frequency f _OSC of the radio receiving unit main body 20 is set 10.7 MHz below the reception frequency _{fr w} of the Japanese band, _{fr r} = f _OSC +10.7 (MHz).

∴ f _OSCW = f _{W −fr W} = f _W − (f _OSC
+10.7) = f _W −f _OSC −10.7 That is, f _OSCW = f _W −f _OSC −10.7.

Here, the weather band additional receiving unit 10 receives the local oscillation frequency f _OSC from the radio receiving unit main body 20 and uses the supplied local oscillation frequency f _OSC as the local oscillation frequency f _OSCW of the weather band. Therefore, f _OSCW = f _OSC . Therefore, from the above equation,
f _OSC = f _OSCW = f _W −f _OSC −10.7, so that 2 · f _OSC = f _W −10.7, and ｆf _OSC =
(F _W -10.7) / 2.

Here, if f _W = 162.5, then f _OSC =
(162.5-10.7) /2=75.9 (MHz), and therefore, _frW = 75.9 + 10.7 = 86.6 (MHz).

In the above embodiment, since the local oscillation frequency in the weather band additional receiving section 10 is supplied from the radio receiving section main body 20, the weather band additional receiving section 10 includes a PLL for performing local oscillation or There is no need to provide a crystal oscillator.

To receive the weather band, the switches SW3 and SW4 are switched to the narrow band filter 27 having a band of 5 kHz. To receive the FM broadcast signal, the switches SW3 and SW4 are switched to the band of 75 kHz. To the broadband filter 26 having By doing so, it is possible to select an appropriate band according to the maximum deviation.

That is, it is generally known that a local oscillation frequency is obtained by using a PLL and a VCO and a crystal oscillation circuit is used. However, a local oscillation frequency is obtained by using a PLL and a VCO. In case, 150MHz
Highly stable, high C / N VCO and high performance P
There is a problem that an LL circuit is required. In order to obtain a local oscillation frequency by using a crystal oscillation circuit, it is necessary to generate 150 MHz by using a high-order overtone oscillator and a multiplication circuit, and a second local oscillation frequency for channel selection. There is a problem that a VCO and a PLL are required to obtain a frequency. However, in the above embodiment, since the local oscillation frequency for the first mixer 14 is supplied from the radio receiving unit main body 20, the weather band additional receiving unit 10 includes a PLL and a crystal for performing local oscillation. There is no need to provide an oscillator, and PLL,
There is an advantage that the above problem caused by providing a crystal oscillator does not occur.

Further, in the above embodiment, since the first intermediate frequency is as high as 86.6 MHz, the image frequency to be subjected to image disturbance falls outside the band of the first intermediate frequency, and the No worries about interference.

[0030]

According to the present invention, in a receiver capable of receiving a weather band and a normal FM broadcast signal, the circuit configuration is simple and the number of parts is small.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a receiver RE1 according to one embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional receiver RE that can receive a weather band and a normal FM broadcast signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Weather band addition reception part, 14 ... 1st mixer, 20 ... Radio reception part main body, 23 ... 2nd mixer, 24 ... VCO, 25 ... PLL, 30 ... Connection means, SW1, SW2 ... Signal switching means Switch.

Claims (2)

[Claims] 1. A radio including a first mixer for converting a signal received by an antenna into a predetermined frequency, and a second mixer, a voltage-controlled oscillator, and an FM demodulator. A reception unit main body; a signal received by the antenna is processed by the weather band addition reception unit, and then input to the radio reception unit main unit;
A signal switching unit for switching whether the signal is directly input to the radio receiving unit without passing through the weather band additional receiving unit; and a connecting unit for supplying a signal output from the voltage controlled oscillator to the first mixer. A receiver comprising: 2. The receiver according to claim 1, wherein the radio receiving unit main body includes two filters having different intermediate frequency pass bands from each other, and filter switching means for switching the two filters. .