JPS60196020A - wireless communication device - Google Patents

Abstract

PURPOSE:To omit an oscillator, a modulator, a frequency converter, an excitation amplifier, a filter, etc. and to attain the miniaturization and economical properties of a radio communication device, by changing the circuit constitution of a transmitter for a duplex communication system having different transmission reception frequencies. CONSTITUTION:The conventional transmission oscillator, frequency converter, BPF, excitation amplifier, BEF, etc. are omitted. The modulation signal of a modulation controller 17 is distributed to both a modulator 18 of the 2nd local oscillator 6 and a frequency synthesizer 25 by a branching circuit 27 to give the modulation of the same amplitude to the modulator 18 and the synthesizer 25. The synthesizer 15 which oscillates the transmission frequency also oscillates a carrier frequency by an indication of a controller 26. This oscillation output is branched into two parts by a branching circuit 28. One of these two branched outputs is supplied to a power amplifier 24 via a switch circuit, and the other output is supplied to a frequency converter 3 of a receiver in the form of a frequency of the 1st local oscillator. An amplifier 24 amplifies the excited power given from the synthesizer 25 and delivers it to an antenna 1. The other output (b) of the circuit 27 is applied to the modulator 18 of the 2nd local oscillator 6 to be modulated to the 2nd local oscillation frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a wireless communication device of a simultaneous transmission and reception type in which the transmission frequency and the reception frequency are different9, and the frequencies are set to a constant value depending on the channel used.

Conventional configuration and its problems Figure 1 shows a wireless telephone that accesses a telephone exchange through a base radio station and can make simultaneous calls with telephone subscribers of wired telephone networks and wireless telephone systems by dialing. This is an example.

The configuration of this conventional example will be explained below with reference to FIG. 1.

In Figure 1, 1 is an antenna, 2 is an antenna duplexer (
DUP), 3 is a second frequency converter C, and is used with an additional device receiving amplifier if necessary.

4 is a bandpass filter (BPF), 6 is a second frequency converter (
C), 6 is the second local oscillator O17 is a bandpass filter (BP
F), and in narrowband communication such as mobile radio, this BP
A selection filter is used that gives F a steep selection characteristic and attenuates adjacent channel frequencies by several tens of dB to 100 dB. 8 is an IF amplifier, which has a relatively wide band and high gain, and has a built-in limiter that limits the output to a constant amplitude. Further, IC circuits that output the level of an input signal as received information, and have a built-in noise squelch circuit or frequency converter are generally used. 9 is IF
frequency signal detector (DET), which is the IF
Some are built into the IC of the amplifier 8. IF amplifier 8
a is the output part for analog signals such as voice calls, and b is the output part for digital signals such as control data.In the case of a multi-channel switching car phone, it outputs an individual ring signal, a channel switching signal, turns on the transmitter and handset, Various signals, such as an OFF signal, which differ depending on each system, are output as digital signals to a controller (CONT) 26, which will be described later. 10 is an analog signal amplifier, 11 is a handset ON/OFF switch, and 12 is a handset, which is shown built into the handset. This handset is displayed with the assumption that it will operate as a ringer speaker that generates the ringing tone when it is called by the base station, but it is of course possible to install a separate speaker in addition to this handset to amplify the ringing tone, or to use the handset as a ringer speaker. Another method is to use a speaker for free calls.

13 is a number dialing unit that sends the called party number to the base station;
A comprehensive representation of various control switches (herein referred to as function buttons), such as ON and OFF switches for sending pre-stored numbers and making hands-free calls, in which calls are made without lifting the handset. shall be. Reference numeral 14 is a transmitter built into the handset, but it can be placed elsewhere by using the function button mentioned above.
This is an inclusive representation of all microphones for use in the field-free mode. 15 is a so-called hook switch (H5) that turns on and off by lifting the handset from the stand, and is represented by a mechanical switch, but this is a switch that operates electromagnetically or optically. This comprehensively shows the ON and OFF signals to the controller 26, which will be described later.
It is sent as F information. A switch 16 turns on and off the analog signal from the transmitter 14, and is controlled by the controller 26 together with the receiver switch 11. The above-mentioned units 11 to 16 are generally referred to as mobile telephones, and are often housed in one unit.

17 is an analog signal processor that processes the audio signal of the transmitter 14 according to the characteristics of the audio, and is an audio signal compressor and an excessive audio signal processor for suppressing audio peaks and increasing the average output. This expression includes an instantaneous deviation limiter (IDC), etc., which prevents overmodulation caused by. The compressor is operated as a paired expander with the expander of the analog amplifier 10.

18 is the modulator Mo, and 19 is the oscillator 0.These do not exist independently, but are often combined together, and the order in which they are displayed is also (MO-0) or (0-
This is a comprehensive representation of modulators of various modulation types, denoted as Mo).

A frequency converter (C) 20 mixes the frequency 18 of a frequency synthesizer (SYNTH) 25, which will be described later, and the frequency 11 of the oscillator 19, and converts the mixture into a transmission frequency fT. Depending on the magnitude relationship between the reception frequency fR and the transmission frequency fT, the (+) or (-) case is selected (fT-fS). 21 is a range filter (BPF).

(・Frequency when the number of IJ channels is a few to several thousand channels −・The frequency band used by the synthesizer 260 is the channel spacing f
c, and the number of channels is NO, then h=Nc' fc. Now, in the case of fc-25KHz and Nc: 1000, the used band 9 is a wide band of 25 MHz. Frequency f of frequency synthesizer 25, oscillator 19
The bandpass filter 21 that reduces the streakiness caused by the combination of frequencies to about -70 dB with respect to one transmission frequency is required to have a wide band and sharp selectivity, and is large in size. In addition, small-sized devices have a large insertion loss. 22 is a preamplifier;
It provides a high frequency output necessary for exciting the power amplifier 24.

23 is a transmission noise suppression filter (BPF) for the reception band;
Reference numeral 24 denotes a power amplifier at the final stage, which requires an output of 5 or 10 W in the case of a car phone, and an output of about 1 W in the case of a mobile phone. This power amplifier 24 is ICi-based and can obtain 5 or 1oW with excitation of several tens of mW, and automatically reduces the transmission output in multiple stages according to the reception input level9.The base station side Functions such as lowering the transmission output by control number 18 from
Some have been. 25 is a frequency synthesizer, 6υ
, the frequency is locked to a stable and highly accurate oscillator, and the frequency of hundreds to thousands of channels can be controlled by a controller 26 if necessary.
This frequency is used as the first local oscillation and transmission frequency of the receiver.

Reference numeral 26 is a controller for the radio, which receives various control signals from the base station, sends response signals to the base station, and controls the operation of the radio, such as transmission based on the reception level and instructions from the base station. It is provided with various control functions such as output control and communication connection of the in-vehicle telephone.

As explained above, when the bandpass filter 21 with a wide band and high selectivity is used to synthesize the transmission frequency fT from the frequency synthesizer 25 and the oscillator 19, if the bandpass filter 21 is large, the radio equipment can be made smaller. There are obstacles and drawbacks above.

Furthermore, if the filter 21 is made smaller, the insertion loss increases, so there is a drawback that an excitation amplifier 22 is required. Furthermore, since the input to the excitation amplifier 22 is lowered, a bandpass filter is required to reduce transmitter noise at the receiving frequency 4 due to C/N deterioration.

Purpose of the Invention The present invention eliminates the drawbacks of the conventional example described above, and by changing the circuit configuration of the transmitter, a transmitting oscillator, a modulator, a frequency converter, a bandpass filter, an excitation amplifier, a bandlimiting filter, etc. The purpose of this invention is to simplify, downsize, and make the radio equipment economical by eliminating the

Structure of the Invention In order to achieve the above object, the present invention uses the transmission frequency as the local oscillation frequency of the receiver, and sets the first intermediate frequency f to the difference frequency CfX = fT between the transmission frequency fT and the reception frequency fRQ.
-fR). In addition, the transmission frequency is directly modulated to a frequency synthesizer, which is then power amplified and used as a transmission output. On the other hand, modulation equivalent to the transmission frequency fT is applied to the second local oscillator to cancel the modulation component of the local transmitter that occurs at the first intermediate frequency. This makes it possible to eliminate the transmitting oscillator, frequency converter, bandpass filter, excitation amplifier, and bandlimiting filter, thus simplifying the radio equipment.
This has the effect of making it possible to downsize and become more economical.

DESCRIPTION OF THE EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, parts 1 to 26 using the same numbers as in FIG. 1 have the same functions as in FIG. In FIG. 2, a transmitting oscillator 19, a frequency converter 20,
The bandpass filter 21, the excitation amplifier 22, the bandlimiting filter 23, etc. are removed as they are unnecessary. On the other hand, the modulation signal is sent to the branch circuit 27 in order to give equal amplitude modulation to both the modulator 18 of the second local oscillator 6 and the frequency synthesizer 26.
It is distributed to both.

Hereinafter, the configuration and operation of the present invention will be explained using FIG. 2.

25 is a frequency synthesizer that oscillates a transmission frequency fT, and the channel spacing is f. , number of channels N.

The carrier frequency is oscillated according to instructions from the controller 26, and the output is several tens of mW. This output is branched into two by a branch circuit 28, one of which is supplied to the power amplifier 24 via a switch circuit. The other one is supplied to the frequency converter 3 of the receiver as the first local frequency. A power amplifier 24 amplifies or attenuates the excitation power from the synthesizer 26 and outputs it from the antenna duplexer 2 to the antenna 1, from which radio waves are radiated. Further, the power amplifier 24 has a built-in directional coupler and a level comparator provided on the output side, and compares the reference voltage Ecp of the controller 26 with the forward power Ef of the directional coupler to output a transmission output. A function is provided to adjust the level to a reference level.

The audio signal from the transmitter 14 is applied to a modulation signal controller (IDC) 17 via a signal switch 16, and is subjected to at least one of level compression, audio peak limiting, and unnecessary wave removal. The frequency synthesizer 2 is removed from one output a of the branch circuit 27.
5, and gives FM modulation or PM modulation of (f±Δf) to the output of the frequency synthesizer 25. The other output of the branch circuit 27 is applied to the modulation circuit 18 of the second local oscillator 6. The second local oscillator 6 is, for example, a crystal oscillator, and may be of a type in which a variable capacitance diode is used as the load capacitance, and the frequency is changed by applying a modulation signal to the variable capacitance diode. This is the second
A modulation of (fL±Δf) is applied to the local frequency fL. The modulation signal is either (fL±ΔF) or (f
L + J) depends on the size of the transmitting and receiving frequency, (fT>
fR) or (fT<fR).

Next, the condition (fT>fR) will be explained.

Reception frequency f□, frequency fs of frequency synthesizer 26
, the transmission frequency fT, and the first intermediate frequency f1 are as follows.

(When both transmitting and receiving waves are unmodulated) fI-4-fR = fT-fi f8 = fT (When fT is not modulated and fR is modulated) fs-(fR Δf)-(ft+: △f)CfT modulation,
fR without modulation) Cf, ±Δf)-fR-cfI±Δf) (fT modulation,
For fR modulation) Cf8±△f, )-CfR±△f2)-Cf, ±△f1
+:Δf2).

When connecting from a base station exchange to a general wired telephone network, the modulation level is reduced by the telephone line loss.

Standard telephone line loss is -12.5 if there are 4 lines up to the toll office.
dB, when the distance to the center station is 4 m, it is -16 dB, and this loss is compressed to about the remainder by the compander of the base station exchange, and Δf becomes a smaller value by -6, 25 dB and -s dB ◇ Output of frequency converter 3 If both the receiving frequency fR and the transmitting frequency fT or fs are modulated and the line loss is -12.6 dB, the average value of the composite Δf is 122.
It becomes 4 times. Also, in the case of line loss -16 dB, the composite △f
The average value is 1063 times. Therefore, ΔF = 6
The composite △f in the case of KHz is 7.35 KH at the peak value
z ~5.8 KHz, average value 6.12 KHz
~5.32 KHz. Here, the bandpass filter 4 attenuates the carrier wave component of the adjacent channel by about 20 dB, and the degree of attenuation at the ±12 KHz detuning point is only 1.
．． Since it is about 5 dB, the sideband components are not extremely attenuated by the bandpass filter 4 and the composite Δf
There is no problem with that. In addition, in the case of a telephone line, if both parties talk freely at the same time, it is impossible to understand what the other party is saying.
In the telephone line load theorem, the actual time spent talking is considered to be the overall A, and if both parties make the same amount of calls, it is considered strong, and true simultaneous calls are an extremely short period of time when the number of calls is the same. Recognize. Therefore, it is only necessary to know what kind of phenomenon is caused by the modulated signal of the transmitter of the own station.

When (f8±△f, ) is added to the transmission frequency (fT-fs), the output of the frequency converter 3 is Cf8±△f+),7'R-(h±ΔF1). Second frequency converter 6 is added to the second local oscillator frequency (
fL±ΔF2) is converted into the second IFfi.

If ΔF1−ΔF2, f, 〉fL, then (fI±△
f,)-Cf8±△f,,)-f,,f□<If fL, (fL±△f2)-Cf8±△f,)=fi Then, the second IFf is connected to the transmitting wave fT. The included modulation components are canceled and not output.

However, in reality, the component Δ(Δf, -Δf2
−Δ). The sidetone level of ordinary telephones is -12 ~
-15 dB, and it is said that Δ should be maintained at (Δf1/1o), that is, about -20 dB, and the component Δ that could not be canceled from the detector 9 is output from the detector 9 to the audio amplifier. It is expanded by a built-in expander, the relative signal level ratio is doubled, and the level is lowered to -20 dB component 1j-40 dB. When an expander is used, the degree of signal cancellation by the second frequency converter 5 may be about -10 dB.

If an expander is not included after the detector 9, it is sufficient to reduce the residual component of cancellation to about -20 dB, but it is difficult to maintain this value (although it is possible to implement it).

Although the above description has been made regarding a car telephone type radio device, the same effect can be obtained by using it in a simultaneous transmitting/receiving radio device in which the transmitting/receiving frequency is kept at a constant value. Moreover, although a relatively wideband radio device has been described for mobile communication, similar effects can be obtained with a narrowband communication radio device.

Effects of the Invention The present invention has the above-described configuration, and provides the following effects.

(1) Since the modulated transmission frequency can be used as it is as the first local oscillation frequency of the receiver, frequency converters, bandpass filters, amplifiers, etc. are unnecessary, which is advantageous for simplifying, downsizing, and economical circuits. .

(No) Since the output of the frequency synthesizer is used at a high level as the transmission frequency, the C/N is large, and therefore the improvement effect of reducing transmitter noise in the receiving frequency band is also large.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional wireless communication device for mobile communication.
FIG. 2 is a block diagram showing an embodiment of a wireless communication device for mobile communication according to the present invention. 1...Antenna, 2...Antenna cooperator, 3゜6.20...Frequency converter, 4,7,
21.23...Band filter) -6, 19...
...Local oscillator, 8゜10.22.24...
・Amplifier, 9...Signal detector, 11.16...
...ON, OFF switch, 12...Telephone receiver, 13...Number dial section, 14...
・Telephone, 16...Hook switch, 17...
... Analog signal processor, 18 ... Modulator, 26 ... Frequency synthesizer, 26 ...
...Controller.

Claims (1)

[Claims] When the transmitting and receiving frequencies are different, a receiving and simultaneous transmitting and receiving method is adopted for standby, and means for frequency converting the first local frequency of the double superheterodyne receiver to a first intermediate frequency as the transmitting frequency; means for converting the frequency from the intermediate frequency of the transmitter to the second intermediate frequency; A wireless communication device configured to receive a desired reception frequency using means for substantially canceling modulation components.