JPH0537438A - Doppler compensation type transmitter/receiver - Google Patents

Abstract

PURPOSE:To shorten catching time. CONSTITUTION:Control voltages are respectively supplied from a loop filter 3 to a voltage controlled oscillator VCO (R) 4 and VCO (T) 7 which output frequency characteristic is inverted to the control voltages. When there is no Doppler shift in received signals, a received frequency and the control voltage is turned to a central value, a transmitted frequency from the VCO (T) 7 is transmitted at the central value, an opposite side communicating station is set on standby for reception at the central value, and the frequency can be immediately caught. When there is the Doppler shift in a receiving frequency [fr], signals are transmitted at a transmitting frequency [ft] depending on the [V1] of the control voltage, the opposite side communicating station receives the frequency signal of the central value on standby for reception receiving the Doppler shift to the transmitting frequency [ft], and the signal can be immediately caught.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Doppler-compensated transceiver for use in mobile communications or the like, which outputs a transmission carrier wave compensated for Doppler caused by movement.

[0002]

2. Description of the Related Art Conventionally, a transmission / reception device used in mobile communication or the like uses a carrier tracking system with a wide band width in order to capture a signal in a short time in consideration of a Doppler shift amount of a carrier generated by a relative speed between communication stations. Is set to. When a wide dynamic range is required, the bandwidth is set narrow and a function of sweeping the transmission carrier frequency or the reception center frequency is added.

[0003]

However, in the conventional Doppler-compensated transceiver, when the carrier tracking system is set to a wide bandwidth, the S / N ratio is poor and the receiving dynamic range is small, so that a low transmission power system is used. Or it was difficult to use as a telecommunications system. Further, when used in a low transmission power system or a long distance communication system, the bandwidth of the carrier tracking system is set narrow in order to increase the S / N ratio. In this case, the transmission carrier frequency or the reception center frequency is swept in order to capture the signal on the receiving side, but since it sweeps to cover the maximum range of the predicted Doppler shift amount, the capture time is long. Therefore, it has been difficult to establish a communication line connection between a plurality of communication stations in a short time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a Doppler compensation type transceiver which has been made in view of this problem and which can shorten the acquisition time and can be connected to a plurality of communication stations in a short time.

[0005]

To achieve this object, a Doppler-compensated transceiver according to the present invention comprises a receiver including a PLL including a loop filter and a first voltage-controlled oscillator, A second voltage controlled oscillator having an output frequency characteristic opposite to the control voltage of the first voltage controlled oscillator that outputs the transmission carrier signal by being controlled by the output voltage from the loop filter is provided.

In a communication network including a master station and a plurality of slave stations, the slave station is a receiver including a PLL including a loop filter and a first voltage controlled oscillator. And a second voltage-controlled oscillator that has an output frequency characteristic opposite to the control voltage of the first voltage-controlled oscillator that outputs the transmission carrier signal by being controlled by the output voltage from the loop filter. To do.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the Doppler compensation type transceiver of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of the embodiment.

In FIG. 1, this example includes a PLL 1 used for acquisition and tracking of a reception carrier wave of a receiver. The PLL 1 includes a phase detector 2 to which a received signal is input,
The phase detector 2 includes an output end, a loop filter 3 to which the input end is connected, and a voltage controlled oscillator (VCO (R)) 4 to which a control voltage from the loop filter 3 is supplied.

Further, in this example, the 90 ° phase shifter 6 to which the output signal of the VCO (R) 4 is supplied, and the 90 ° phase shifter from here
A phase detector 5 for supplying a phase-shifted signal and a received signal and outputting a demodulated signal is provided, and a VCO (T) 7 to which a control voltage from the loop filter 3 is supplied, and a VCO
A modulator 8 to which a transmission carrier signal from (T) 7 and a modulation signal for modulating the transmission carrier signal are supplied, and an amplifier 9 for transmitting a modulated signal as a transmission signal are provided.

Next, the operation of this configuration will be described.

FIG. 2 shows VCO (R) and VCO (T).
The characteristics of the output frequency and control voltage of
The (R) 4 and the VCO (T) 7 have opposite output frequency characteristics with respect to the control voltage, as shown in the figure.

The loop filter 3 outputs a control voltage for controlling the VCO (R) 4 so that the output frequency of the VCO (R) 4 matches the received carrier frequency.

The output signal of the VCO (R) 4 is 90 °.
The phase shifter 6 shifts the phase by 90 °, and the phase detector 5 performs coherent amplitude detection to obtain a demodulated signal.

On the other hand, the control voltage from the loop filter 3 is supplied to the VCO (R) 4 and the VCO (T) 7, respectively.

The transmission carrier signal from the VCO (T) 7 is supplied to the modulator 8, and the modulator 8 produces a VC signal by the modulation signal.
A modulated signal obtained by modulating the output signal of O (T) 7 is output. The modulated signal is amplified to the required power by the amplifier 9 and sent out as a transmission signal.

Next, the supplementary operation will be described. When the received signal has no Doppler shift, that is, when the two communication stations are relatively stationary, the received frequency becomes the center value.
Therefore, the control voltage also outputs the central value, and the VCO
The transmission frequency, which is the output frequency of (T) 7, is transmitted at the center value. That is, the communication station on the other end waits for reception at the central value and can immediately acquire it.

When the reception frequency is [fr] and has a Doppler shift, the control voltage is [V1], and at this time, the transmission frequency is [ft]. Therefore, the communication station on the other end receives the signal of the frequency of the center value which is subjected to the Doppler shift with respect to [ft] and is waiting for reception, and in this case also, the immediate acquisition can be performed.

In the above embodiment, the receiver may be a heterodyne type. Also, the VCO of the transmitter
Even in the case of the square type which multiplies the frequency of (T) 7 to generate the transmission frequency, the output frequency characteristics with respect to VCO (T) and VCO (R) and the control voltage are reversed, and the frequency change with respect to the control voltage is changed. The same effect can be obtained only by changing the sensitivity.

Further, in a communication network composed of a master station and a plurality of slave stations, by adopting the transmitting / receiving device of the present invention in the slave stations, the master station side receives signals of the same frequency from all slave stations. When receiving signals from the slave station side in a time-division manner, the time required to capture each received signal can be greatly shortened and a large capacity communication network can be constructed. .

[0021]

As is apparent from the above description, in the Doppler-compensated transceiver of the present invention, the partner communication station can always receive a signal having a frequency equal to the reception standby frequency, so that the communication station moves or stops. Regardless of the state of
Even if the Doppler shift occurs in the transmission / reception frequency, there is an effect that the communication line can be immediately connected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a Doppler compensation type transceiver of the present invention.

FIG. 2 is a characteristic diagram showing output frequencies with respect to control voltages of two VCOs in the example.

[Explanation of symbols]

1 PLL 2 phase detector 3 loop filter 4 VCO (R) 5 Phase detector 6 90 ° phaser 7 VCO (T) 8 modulator

Claims (2)

[Claims] 1. A receiver composed of a PLL comprising a loop filter and a first voltage controlled oscillator, and the first signal output from a carrier wave signal controlled by an output voltage from the loop filter. A Doppler-compensated transceiver including: a second voltage-controlled oscillator having an inverse output frequency characteristic with respect to a control voltage of the voltage-controlled oscillator. 2. A communication network comprising a master station and a plurality of slave stations, wherein the slave station comprises a PLL including a loop filter and a first voltage controlled oscillator. And a second voltage controlled oscillator whose output frequency characteristic is opposite to the control voltage of the first voltage controlled oscillator which outputs a transmission carrier signal by being controlled by the output voltage from the loop filter. Doppler compensation type transceiver characterized by.