JPS6046622A - Simultaneous transmitting/receiving communication system using local oscillator of receiver also as channel oscillator of transmitter - Google Patents

Abstract

PURPOSE:To prevent side tones by making the phase level of a modulating signal component included in a demodulated output from a receiver coincide with that of a modulating signal when a modulated output from a transmitting channel oscillator is used as an output from a local oscillator of the receiver and cancelling the modulating signal component. CONSTITUTION:An output of the transmitting channel oscillator OSC which is modulated by an output signal S1 from a voice signal circuit AF is inputted to a mixer in the receiver RX and a demodulated signal including a modulating signal component phase-delayed by a fixed angle by an IF filter or the like is obtained as the output of the mixer. On the other hand, an output signal S1 of a voice signal circuit AF is converted into a signal S3 through a phase shifter PS and a level adjusting circuit VOL. Then, both the signals S2, S3 are inputted to a subtractor SUB to cancell the modulating signal component S2 in the output of the receiver RX.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simultaneous transmitting and receiving communication system in which a local oscillator is shared with a channel oscillator.

2. Description of the Related Art Hitherto, a communication device for simultaneous transmission and reception, such as a wireless telephone, has generally been configured as shown in FIG.

That is, the oscillation output of the transmission channel oscillator O8C is modulated by the output of the audio signal circuit AP, and is transmitted from the antenna ANT at the transmission frequency fc via the amplifier AMP and the antenna duplexer AD-6.
The received signals of frequency fn input to the receivers B and X via the antenna duplexer AD=i are mixed with the signal fr generated by the local oscillator LO of the receivers 1 and Frequency f of the signal received via IP-i
All of the intermediate frequencies fx lower than R are extracted and converted into audio signals through the frequency side valve device DISC. .

At this time, in order to simplify the design of the antenna duplexer AD+
It is often configured to satisfy fT-fR1=fI. In this case, the oscillation frequency of the local oscillator LO has the same fT as that of the channel oscillator O8C, so if a single oscillator can be used for both, it is effective in reducing the cost of the communication device.

However, if both the optical oscillators O8C and LO=i are simply made common, the transmitted signals modulated by the modulation signal of the audio signal circuit AP will be directly demodulated by the receiver E, and this will be heard as a sidetone. The problem was that he was very unwell.

The present invention was made in order to solve the above-mentioned problems in communication devices using a simultaneous transmitting and receiving method. The modulated signal component contained in the demodulated output of the receiver is canceled by matching the phase and level of the modulated signal with the modulated signal, or if the receiver is a double or more superheterodyne system, the second or By providing a subsequent local oscillator with a modulation function using the modulated signal subjected to the required phase shift, all of the modulated signal components contained in the first mixer output are canceled at the intermediate frequency conversion stage in the receiver, or the channel The local oscillator of the receiver is shared with the channel oscillator of all transmitters, and the modulated signal component contained in the modulated output of the oscillator is canceled by the modulated signal whose phase is inverted before being input to the first mixer of the receiver. The purpose is to provide a simultaneous transmission and reception communication system.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

FIG. 2 is a block diagram showing an embodiment of the above-mentioned second method among the communication methods according to the present invention.

In this figure, the output of the transmitting channel oscillator O8C modulated by the output signal Sl of the audio signal circuit AP is input to the mixer of the receiving 4ffE/X (not shown), and the output has a constant phase due to IF filter etc. A demodulated signal including the modulated signal component S2 delayed by an angle is obtained.

On the other hand, the output signal S] of the audio signal circuit AF is converted into a signal S3 via a phase shifter PS and a level adjustment circuit VOL6. Afterwards, these two signals S2 and S3 are inputted to the subtractor SUB = SUB and the receiver B
- This cancels the modulated signal component 82f in the X output.

FIG. 3 is a diagram showing the waveforms of the modulated signal components Sl, 82, and S3. If the output signal Sl of the audio signal circuit AP is a sine wave, S2 is a waveform of the modulated signal components Sl, 82, and S3. Since the phase of the modulation signal Sxi is delayed by an angle ψ, the phase shifter PS causes the modulation signal Sxi to be delayed by ψ, and the level adjustment circuit VOL adjusts the level/k and the subtraction circuit SUB cancels S2 and S3. .

Alternatively, the phase of the modulated signal Sliψ+π is shifted and the signal S3
This and the modulated signal component S in the receiver R/X output
2 may be canceled by the adder ADD.

Similarly, the phase shifter PS and the level adjustment circuit VOL [both or one of them may be inserted between the receiver R/X and the front subtractor or adder 5UBorADD.

The communication system according to the present invention exhibits exactly the same function even if it is modified as described below.

FIG. 4 is a block diagram showing an embodiment of the second communication method according to the present invention.

That is, when the receiver R.X is of the double super-heterodyne type, the channel oscillator O8C is used as the first local oscillator LOt of the first mixer M I X 1 constituting the receiver R.x=1, Its modulated output signal f
τ and the received input signal fTL to the first mixer M I
] After mixing, first intermediate frequency filter 1. The entire signal fx is extracted as the F1 output and inputted to the if-two mixer MIX2.

On the other hand, the level adjustment circuit VOL and phase adjust the modulation signal so that its level and phase are respectively the same modulation degree as the modulation signal component in the output fx of the first intermediate frequency filter IF1 and the opposite phase of the modulation phase of the output fX. It is adjusted by shifter P8, and its output modulates the output of second local oscillator LO2.

Thereafter, the second local oscillator output modulated as described above may be input to the frequency discriminator DISC via the amplifier IF2 including the second intermediate frequency filter.

When the above configuration is adopted, the second local oscillator LO2
It would be convenient to use an inexpensive voltage controlled crystal oscillator VCXO.

Furthermore, if the channel oscillator O8C is of the phase modulation type, it goes without saying that the second local oscillator LO2 is also of the phase modulation type.

Although the double super-heterodyne method was explained as an example, the method of the present invention can also be applied to a receiver equipped with a large number of intermediate frequency stages. The modulated signal component contained in the output signal from the first intermediate frequency stage onward may be canceled using the modulated output signal of the local oscillator.

FIG. 5 is a block diagram showing still another embodiment of the dependent communication system according to the present invention. Both of the above two embodiments use a modulated signal component as an input signal to the first mixer of the receiver. In contrast, in this embodiment, all modulated signal components are removed in advance from the signal input to the first mixer.

That is, the modulated output signal, which is the output of the transmitter O8C, is input to the modulation circuit MOD.

On the other hand, the level of the modulation signal is adjusted by the level adjustment circuit VOL so that the modulation degree of the modulation circuit MOD becomes equal to the modulation degree of the modulated signal output from the channel oscillator O8C, and then the inverting amplifier R...AMP -i, and its output is input to the modulation circuit MOD.

In the modulation circuit MOD, the channel oscillator O8
Since the modulated signal component contained in the C output is canceled by the phase-inverted modulated signal, it is sufficient to input the modulated signal component to the first mixer of the carrier wave total receiver R/X which is the output thereof.

At this time, the phase difference between the modulated input signal to the channel oscillator O8C and the modulated output signal to the modulation circuit MOD is extremely small and can be virtually ignored, so a phase shifter is unnecessary, which is advantageous in terms of circuit simplification.

However, it is obvious that a phase shifter having an equivalent function may be used in place of the inverting amplifier R..AMP.

Similarly, the modulation circuit MOD may have a configuration as shown in FIG.

That is, the output of the channel oscillator O8C, which has been set to an appropriate frequency by the first frequency divider (1/N) 1, is transferred to the voltage controlled oscillator VCO, the second frequency divider (1/N) 2 and the phase comparator C.
It is input to the phase comparator c-OMP as a reference signal of the closed loop phase synchronization system constituted by OMP, the level is adjusted by level adjustment circuits VO and L, and the inverting amplifier 1 (
. . . The voltage controlled oscillator Vc cancels all the modulation signal components contained in the output of the first frequency divider (1/N) by the modulation signal whose phase is inverted by AMP.

As an output, a carrier wave from which all modulation signal components have been removed can be obtained.

Here, if the modulator of the channel oscillator osc is of a frequency modulation type and the modulated signal component F is fully equipped with a pre-emphasis circuit, the modulated signal that is the output of the channel oscillator 08C is phase modulated, so the modulation circuit MO
D must be a frequency modulator, and on the other hand, if the modulator of the channel oscillator O8C is a phase modulation type, the modulation signal circuit AP does not have a pre-emphasis circuit, so the modulation circuit MOD is also a phase modulator. Needless to say, it should be a frequency modulator with a pre-emphasis circuit added.

In the three embodiments described above, only the method of removing sidetones from the receiver output has been described, but there are cases where a person who requires low-level sidetone transmission fee is required in a group that uses all of these types of communication equipment. There is.

In order to meet such demands, it is necessary to completely change the level, phase, or modulation degree of the V-key signal component to be canceled in the above-mentioned figures 2, 4, and 5. All you have to do is adjust it to upset the balance of cancellation.

Since the present invention is configured and operates as described above, it is possible to save the expensive high-stability oscillator in a simultaneous transmitting/receiving communication device, and it is therefore extremely effective in reducing the cost. .

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of a conventional simultaneous transmitting/receiving communication device, Fig. 2 is a block diagram showing an embodiment of the communication system according to the present invention, and Fig. 3 shows the phase relationship of the modulation/demodulation signal. The chart diagram, FIGS. 4 and 5 are block diagrams showing other embodiments of the communication system according to the present invention, and FIG. 6 is a block diagram showing an entire embodiment of the modulation circuit shown in FIG. 5. O20・・・・・・Transmission channel oscillator,
R,・Phase shifter, VOL...
...Level adjustment circuit. SOB or ADD-=-----Subtractor (adder),
LO2・・・・・・・Second local oscillator, B・・A
MP・・・・・・Inverting amplifier, MOD・・・・・・
...Modulation circuit patent applicant Toyo Tsushinki Building Co., Ltd.

Claims (2)

[Claims] (1) In a communication device using a simultaneous transmitting and receiving communication system in which the output of a channel oscillator of a transmitter modulated by an audio signal or the like is used as the output of a local oscillator of a receiver, a demodulated signal containing a modulated signal component, which is the output of the receiver, and a demodulated signal containing a modulated signal component, which is the output of the receiver, are used. The modulation signal component in the output of the receiver is canceled by matching the phase with the modulation signal input to the channel oscillator or shifting it by 1800 degrees, and by subtracting or adding it after making the levels of the two completely match. A simultaneous transmitting and receiving communication system in which the receiver's local oscillator is shared with the transmitter's channel oscillator. (2) In a communication device using a simultaneous transmission communication system in which the output of the channel oscillator of the transmitter modulated by an audio signal etc. is used as the output of the first local oscillator of the receiver, the signal level is adjusted to the required value and the phase is adjusted. The output of the second or subsequent local oscillator modulated by the modulation signal shifted by a required value is input to the second or subsequent mixer of the receiver. A simultaneous transmitting and receiving communication system in which a first local oscillator of a receiver is shared with a channel oscillator of a transmitter, characterized in that modulated signal components contained in the output of a mixer are canceled. G) A channel oscillator output of a transmitter modulated by an audio signal, etc., a phase inverted signal of the modulation signal that has undergone the required level adjustment, and a modulation signal component that is input to the entire modulation circuit and included in the channel oscillator output. A feature is that the local oscillator of the receiver is removed by using the output of the modulation circuit that cancels the above as a local oscillator of the receiver.
A simultaneous transmitting and receiving communication system in which the receiver's local oscillator is shared with the channel oscillator of all transmitters.