JPH03204241A - Multiplex superheterodyne radio receiver - Google Patents

Abstract

PURPOSE:To eliminate the need for the installation of a local oscillation circuit at every frequency conversion circuit by giving each component signal from plural band pass filters to plural mixer circuits as a local oscillation signal. CONSTITUTION:An output signal composed of a fundamental wave component whose frequency is fo and harmonic components whose frequencies are an integral number of multiple of the frequency fo is always sent from a local oscillation circuit 20 to a 1st local oscillation frequency filter 4b and a 2nd local oscillation frequency filter 7b. Then a 1st local oscillation frequency filter 4b extracts a 5th high frequency which is 5fo from the sent output signal and sends it to a 1st mixer circuit 4a. On the other hand, the 2nd local oscillation frequency filter 7b extracts a 3rd harmonic wave 3fo from the sent output signal and sends it to a 2nd mixer circuit 7a as a 2nd local oscillation signal. Thus, it is not required to provide a local oscillation circuit at every frequency conversion circuit.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a multiplex superheterodyne radio receiver [Prior art and its problems] A conventional multiplex superheterodyne radio receiver includes a local oscillation circuit for each frequency conversion circuit. For example, a double super-hetero gain radio receiver, which was used in the past, had a configuration as shown in FIG. That is, the high frequency amplifier circuit 2 amplifies the received signal from the antenna l, and the bandpass filter 3
Frequency fs from the received signal amplified by high frequency amplifier circuit 2
After removing high frequency components other than the carrier wave component, the received signal (frequency ts) is applied to the first frequency conversion circuit 4. The first frequency conversion circuit 4 includes a first mixing circuit 4a, a first local oscillation frequency filter 4b, and a first local oscillation circuit 4c, and the oscillation signal from the first local oscillation circuit 4c is transmitted through the first local oscillation frequency filter 4b , only the signal with frequency fl is selected and given to the first mixing circuit 4a as a local oscillation signal, and the first mixing circuit 4a combines the received signal (frequency fs) from the bandpass filter 3 with the first local oscillation frequency filter 4b. (fs f+) and (fs +f+) by mixing the local oscillation signal (frequency f+) from
A signal containing the following components is sent out.

The first intermediate frequency filter 5 has a frequency (fs f
+) as a first intermediate frequency signal and sends it to the first intermediate frequency amplification circuit 6. The first intermediate frequency amplification circuit 6 amplifies the sent first intermediate frequency signal to a predetermined level and sends it to the second frequency conversion circuit 7. The second frequency conversion circuit 7 includes a second mixing circuit 7a,
It consists of a w42 local oscillation frequency filter 7b and a second local oscillation circuit 7c, and the oscillation signal from the second local oscillation circuit 7c has a frequency of f by the second local oscillation frequency filter 7b.
Only the signal of l is selected and given to the second mixing circuit 7a as a local oscillation signal, and the second mixing circuit 7 receives the first intermediate frequency signal (frequency (f
s f+)) and a second local oscillation frequency filter 7b.
(fs −f+−fl) and (fs −f+
+f2). The second intermediate frequency filter 8 has a frequency (f+ fl fl ) from the signal wave sent from the second frequency conversion circuit 7.
This circuit extracts the signal as a second intermediate frequency signal and sends it to the second intermediate frequency amplification circuit 9. The second intermediate frequency amplification circuit 9 amplifies the sent second intermediate frequency signal to a predetermined level and sends it to the detection circuit IO. Detection circuit i
o detects the second intermediate frequency signal, obtains the transmitted signal wave, and supplies it to a signal processing section such as a decoder, and the transmission contents are notified or displayed.

As described above, in the double superheterodyne radio receiver, the first frequency conversion circuit 4 and the second frequency conversion circuit 7
A first local oscillation circuit 4c and a second local oscillation circuit 7C are provided separately.

Similarly, in the triple superhetero gain radio receiver, a local oscillation circuit is provided for each of the three stages of frequency conversion circuits, resulting in a total of three local oscillation circuits.

However, providing a local oscillation circuit for each frequency conversion circuit as described above requires a large number of parts, increases manufacturing costs, and impedes miniaturization.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and eliminates the need to provide a local oscillation circuit for each frequency conversion circuit, thereby making it possible to reduce manufacturing costs and downsize. The purpose of the present invention is to provide a multiplex superheterodyne radio receiver.

[Summary of the Invention] In order to achieve the above object, the present invention selectively extracts the fundamental frequency component signal or its multiple harmonic component signals from the oscillation signal of a single local oscillation circuit through bandpass filters. The gist of this invention is that these are respectively given to each frequency conversion circuit as a local oscillation signal.

[Example] The present invention will be specifically described below based on an example shown in the drawings. In this embodiment, the present invention is applied to a double superheterodyne radio receiver.

Figure 1 shows the circuit configuration of this embodiment, and circuits with the same symbols as the circuits in Figure 3, which shows the conventional example, have the same configuration and functions as the circuits in Figure 3. be.

As can be seen from FIG. 1, the configuration of this embodiment is generally similar to the configuration of the conventional example shown in FIG. However, unlike the conventional example, the first frequency conversion circuit 4 and the second frequency conversion circuit 7 are not provided with local oscillation circuits, respectively.
Instead, a single local oscillator circuit 20 is provided. The oscillation signal from this local oscillation circuit 20 is transmitted to the first local oscillation frequency filter 4b of the first frequency conversion circuit 4 and the second local oscillation frequency filter 4b of the first frequency conversion circuit 4.
The second local oscillation frequency filter 7b of the frequency conversion circuit 7 has a configuration similar to that of the second local oscillation frequency filter 7b.

In this embodiment, as will be described later, the local oscillation circuit 20 includes a crystal oscillator with a natural frequency fO, and is a circuit that constantly sends out a signal wave with a fundamental frequency of fO, and the i1 local oscillation frequency filter 4b has the above-mentioned fundamental frequency. A bandpass filter that passes only the signal with a frequency five times fO, that is, the fifth harmonic.
The second local oscillation frequency filter 7b has the fundamental frequency f
This is a bandpass filter that allows only a signal with a frequency three times that of O, that is, the third harmonic, to pass through.

FIG. 2 shows a specific configuration of the local beam circuit 20. As shown in FIG. That is, a crystal oscillator X,
A capacitor section C1 consisting of a capacitor C1 and a trimmer capacitor C2 is further connected in series with an inductance L1,
A multiplication amplifier circuit is constructed in which an output is taken out from the emitter of the transistor T'' via a capacitor C6.

1-Continuation Next, the operation of this embodiment configured as described above will be explained.

As mentioned above, the local oscillation circuit 20 always outputs the frequency f.
The output signal consisting of the fundamental wave component of Q and each harmonic component whose frequency is an integral multiple of this is passed through the first local oscillation frequency filter 4.
b and the second local oscillation frequency filter 7b. Then, the first local oscillation frequency filter 4b extracts the fifth harmonic having a frequency of 5fO from the sent output signal and sends it to the first mixing circuit 4a as a first local oscillation signal. On the other hand, in the second local oscillation frequency filter 7h, the third harmonic having a frequency of 3fo is extracted from the sent output signal and sent to the second mixing circuit 7a as a second local oscillation signal.
sent to.

Therefore, the received signal with the frequency fs received by the antenna 1 and sent to the first frequency conversion circuit 4 via the high frequency amplification circuit 2 and the bandpass filter 3 is sent to the first mixing circuit 4a as the first local oscillation signal with the frequency 5fo. and is sent to the first intermediate frequency filter 5. In this Ml intermediate frequency filter 5, the frequency (f, -5fo
) is extracted and sent to the first intermediate frequency amplification circuit 6. In the first intermediate frequency booster circuit 6, this first
The intermediate frequency signal is amplified and then sent to the second mixing circuit 7a. Then, in the second mixing circuit 7a, the first intermediate frequency signal whose frequency is <(fs 5fo) as described above and the second local oscillation signal whose frequency is 3fo are mixed, and the mixed wave is sent to the second intermediate frequency filter 8. It will be done. And this second
The intermediate frequency filter 8 changes the frequency from the above mixed wave to ((
fs −5fo ) −3fo ) i.e. (fs 8
fo) is extracted and sent to the second intermediate frequency amplification circuit 9. In the second intermediate frequency amplification circuit 9, this second intermediate frequency signal is amplified, provided to the detection circuit IO, detected by the detection circuit 10, and then sent to a signal processing section such as a decoder.

Note that when this embodiment is used as a POC3AG paging receiver, the frequency f of the received signal is 2.
One wave in the 80MHz band, for example 280MHz, and the second wave
The frequency of the intermediate frequency signal (fs 8fo) is 455KH
z, so the frequency f of the fundamental wave component of the oscillation signal from one local oscillation circuit 20 is equal to jp 34.9 MHz.

As described above, in this embodiment, the conventionally required two local oscillation circuits can be reduced to one, and the number of components can be reduced, which in turn enables cost reduction and miniaturization.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified and applied in various ways without departing from the scope of the present invention.

[Effects of the Invention] As detailed above, the present invention selectively extracts a fundamental frequency component signal or a plurality of its high frequency component signals from an oscillation signal of a single local oscillation circuit through bandpass filters, Since it is related to a multiplex superheterodyne radio receiver in which each of these is given as a local oscillation signal to each frequency conversion circuit, there is no need to provide a local oscillation circuit for each IRfII number conversion circuit, and as a result, the equipment It is possible to provide a multiplex superheterodyne radio receiver that enables reduction in operating cost and miniaturization.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the circuit configuration of an embodiment of the present invention, FIG. 2 is a diagram showing the detailed configuration of the local oscillation circuit in FIG. 1, and FIG.
The figure is a diagram showing a circuit configuration of a conventional example. Second mixing circuit, 7b... Second local oscillation frequency filter, 7c... Second local oscillation circuit, 8...
...Second intermediate frequency filter, 9...Second intermediate frequency amplification circuit, 10...Detection circuit, 20...
...Local oscillation circuit.

Claims (1)

[Claims] In a multiplex superheterodyne radio receiver that is equipped with a plurality of mixing circuits and performs multiple stages of frequency conversion using these circuits, a single local oscillation circuit and a fundamental frequency component of an oscillation signal from the local oscillation circuit are provided. A multiplexer comprising a plurality of bandpass filters through which the signal or its harmonic component signal passes, and each component signal from the plurality of bandpass filters is applied to the plurality of mixing circuits as a local oscillation signal. Superheterodyne radio receiver.