JPS59221035A - Radio transmitting and receiving device - Google Patents

Abstract

PURPOSE:To decrease the number of necessary crystal oscillators by using the same crystal oscillator to obtain the 1st local transmission frequency of a reception system and the wave to be modulated of a transmission system. CONSTITUTION:The 1st local oscillation frequency F1 of a superheterodyne reception system is modulated by the information to be transmitted and radiated through an antenna. While the modulation of the same degree as that applied to the frequency F1 is also applied to the 2nd local oscillation frequency F3. Then the modulation components of transmission information mixed into the frequency F1 are offset by the 2nd mixing circuit 3. As a result, a crystal oscillator can be shared. This can decrease rationally the number of crystal oscilators.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a wireless transmitter/receiver using a super-heterodyne method in a receiving system, and in particular to an ice crystal oscillator that is essential for transmitting and a first local oscillation frequency in the receiving system. The present invention relates to a wireless transmitting/receiving device configured so that it can also be used as an ice crystal oscillator necessary for the application.

There have been various wireless transmitting and receiving devices that have both a transmitting system and a receiving system, and in particular employ a super-heterodyne system for the receiving system, but the basic configuration that is common to all of them is shown in Figure 1. become that way. To briefly explain the basic configuration of this conventional example, the reception frequency Fr input from the antenna is manually input to the first mixing circuit or the first mixer 1.
The beat is removed from the first local oscillation frequency IFI, and generally its beat-town component is extracted via the first intermediate frequency filter circuit 2. In the figure, the intermediate frequency is abbreviated as IF, the high frequency is RF, and the low frequency to audio band wave is A.
It is abbreviated as F.

The first intermediate frequency F2 output from the first intermediate frequency filter 71 path 2 is manually inputted to the second mixing circuit or the second mixer 3,
The second local oscillation frequency F3 and the second local oscillation frequency F3 are
The intermediate frequency filter circuit 4 is manually powered. The second intermediate frequency filter circuit 4 also generally has a frequency F2. The difference between F3 and the resulting second intermediate frequency to final fixed frequency @F4 is inputted to the detection circuit 7 in order to demodulate the signal information. After this detection output passes through a suitable low frequency amplification circuit 9, it is used as an electric terminal for reproducing information.
The sound is radiated from the acoustic converting means, generally a speaker IO, as an Of auditory information signal.

In such a conventional super-heterodyne receiving system, in order to achieve stable reception especially in a region where the continuous frequency is quite high, the first local oscillation frequency fiF1 is Circuit 8, second local oscillation frequency F
In the second local oscillation circuit 6 for producing the reference frequency, highly stable dedicated crystal oscillators XI and X2 must be provided, respectively, for the reference frequency. Note that since the first local oscillation frequency is generally a fairly high value, a multiplier circuit 5 is inserted between the first local oscillation circuit 8 and the first mixing circuit 1 as necessary. In any case, it is first understood that such a super-heterotine receiving system requires an expensive crystal oscillator.

Next, if we consider the transmission system, information signals such as voice input from the microphone 15 are generally 1. I is sent as a modulation signal to the modulation circuit 13 via a suitable low frequency amplification circuit 16.
j- and modulates the carrier wave frequency generated by the oscillation circuit 14. Most generally, this modulated wave is not at the continuous frequency itself, but at an appropriate multiplier circuit I2! After being multiplied by 5 to make the carrier frequency Ft, the power output is amplified in the high frequency amplifier circuit 11 and radiated from the antenna. However, in such a transmission system, if the transmission frequency Ft is to be similarly stabilized, a crystal oscillator Xt with high frequency stability is required in the oscillation circuit 14 for forming a modulated wave.

From the above, it can be seen that at least three crystal oscillators are required in a wireless transmitter/receiver with such a conventional configuration.
As is well known, this type of crystal oscillator is extremely expensive, which is a serious obstacle to reducing costs.

The present invention has been made in view of the above circumstances, and is aimed at rationally reducing the number of crystal oscillations, which should basically be five. On the other hand, we would like to provide a circuit device with fewer crystal oscillators, although functionally it can perform exactly the same function as using three conventional crystal oscillators. This is what I did.

As a result of following the above 1-1 principle, in the present invention, as will be clear from the explanation based on the embodiment described above, the first local oscillation frequency formation and the modulated wave formation of the transmission system are provided. This makes it possible to use a single crystal oscillator.

FIG. 2 shows a relatively basic embodiment of the invention; t1
It's happening. The components corresponding to each configuration f in the conventional configuration shown in FIG. 1 have the same reference numerals as in FIG. The low frequency information signal for transmission, which is converted into an electrical signal through the transmitter and amplified through the appropriate low frequency amplification circuit 16, modulates the first local oscillation frequency Fl in the receiving system. That is, the first local oscillation circuit 8
The first modulation circuit 17 is connected in the line from
is inserted, and the transmission information signal from the low frequency amplifier circuit 16 is transmitted.
1;I is applied to the first modulation circuit 17. In the end, the frequency Fl, which is the first local oscillation frequency for the receiving system, is used as the transmission carrier frequency Ft in the present invention, and is radiated from the antenna via the high frequency amplification circuit 11. In this way, first of all, the oscillation circuit 1411 for forming the modulated wave for transmission shown in FIG. -One Xt becomes unnecessary.

However, if this is done, the modulation component due to the information transmitted from the microphone 15 will naturally be added to the first mixing circuit l. Therefore, if no countermeasures are taken to prevent this, this signal will ride on the first intermediate frequency F2 and will be stopped as a received signal in the receiving system.

Therefore, in the present invention, a second modulation circuit 18 having the same modulation degree as the first modulation circuit 17 is also inserted in the line from the second local oscillation circuit 6 to the second mixing circuit 3 in the receiving system. ing. By doing this, in the second mixing circuit 3, F2. Modulated wave components in the transmission system intervening in F3 are canceled out. It is extremely easy to achieve the same degree of modulation by using a potentiometer in the cylinder. Further, as described above, in the second mixing circuit 3, generally the image frequency signal F2. It is convenient to take the difference component of F3, but when taking the sum component, a cancellation effect cannot be expected unless one modulation component is reversed in phase. However, such reverse phase processing can be performed extremely easily and inexpensively using existing techniques.

As described in 1- below, according to the present invention, it is possible to omit a transmission-only oscillation circuit, and therefore the number of extremely expensive crystal oscillations f can be reduced.
can be reduced by one. Instead, another modulation circuit 18 and a second multiplier circuit 18 are required in the second local oscillation system, but these structures themselves are quite simple, and the cost required for them is also the same as that of a crystal oscillator. This is extremely small compared to the price of the item.

Considering the idea or gist of the present invention based on this embodiment, the first local oscillation frequency for the super-heterotine reception system is modulated with information to be transmitted, and while this is radiated from the antenna, the super-heterotine reception system The second local oscillation frequency for the second local oscillation frequency is also modulated with the same modulation degree as that applied to the first local oscillation frequency, to prevent the transmission information modulation component from leaking into the reproduction system. 2.As long as the configuration satisfies these gist configurations, is the other circuit configuration optional? 1; and the present invention is of course applicable to a case where, for example, each local oscillation frequency is formed by a phase-locked loop (PLL) circuit. It should be noted that, as a matter of course, in the second illustrated circuit configuration, the transmission frequency Ft, the reception frequency Fr, the first local oscillation frequency F1 . 1st
The correlation of intermediate frequency F2 is as follows.

Ft=Fl=Fr+F2HH+ (1)
As described in detail above, according to the present invention, the receiving system has a super
In a wireless transmitter/receiver that uses a heterotine system,
The number of crystal oscillators can be reduced, which can greatly contribute to lower product prices.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of a conventional wireless transmitter/receiver that employs a super-heterotine system in its receiving system, and FIG. 2 is a schematic configuration diagram of an embodiment of the present invention. In the figure, l is the 17th III combiner circuit, 3 is the FT52 mixing circuit, 6 is the second local oscillation circuit, 7 is the detection circuit, 8 is the first local oscillation circuit, 13 is the modulation circuit, 14 is the oscillation circuit, and 17 is the ft52 mixer circuit. 1 modulation circuit, 18 a second modulation circuit, XI, X2 . Xt
is crystal oscillation f-1.

Claims (1)

[Claims] The reception frequency and the fiS1 local oscillation frequency are added to a first mixing circuit to create a first intermediate frequency, and the first intermediate frequency and the second local oscillation frequency are added to a second mixing circuit to create a first intermediate frequency. In a wireless transmitting/receiving device that employs a super-heterodyne system for the reception system that creates two intermediate frequencies, the first local oscillation frequency for the super-heterodyne reception system described in item 11 is modulated with the information to be transmitted, and this is transmitted from the antenna to the width frequency. On the other hand, the second local oscillation frequency of the receiving system described above is also modulated by the same modulation factor as that applied to the first local oscillation frequency by the information J, and thereby the I-
A wireless transmitting/receiving device characterized in that a modulation component caused by the transmitted PJ report mixed in the first local oscillation frequency is canceled out.