JP2595751B2 - Wireless transceiver - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital radio relay system, and more particularly to a heterodyne relay system in which a signal is transmitted only by a transmission / reception apparatus without requiring a demodulator and a modulator.

(Prior Art) Digital wireless relay systems are broadly classified into detection and regeneration relay systems and non-regenerative relay systems (heterodyne relay). The current mainstream detection and regeneration relay system converts the frequency to the baseband band for each relay station and demodulates the interference noise and waveform distortion generated in each section (roll-off filter, waveform distortion equalizer, and error correction circuit). And the like, and the modulation operation is performed again to transmit the signal. In this regenerative relay system, the interference noise can be removed by the demodulator, so even if the regenerative repeater is demodulated and cascaded,
There is a feature that interference noise components generated in each relay section are not added. However, since a demodulator and a modulator are required for each relay station, the structure of the relay is complicated, and power consumption is increased, so that there are disadvantages in economy and network flexibility.

On the other hand, the heterodyne relay is a system in which a signal received at each relay station is converted into an intermediate frequency band, and then converted again into a radio frequency band without detection and reproduction, and the signal is transmitted.
This method has the advantage that the demodulator and the modulator are not required for each relay station, so that the structure of the relay is simplified and the network flexibility as a transmission medium is improved. However, since interference noise and waveform distortion generated in each section are added for each section, a countermeasure is required. In particular, with respect to adjacent channel interference, measures to increase the frequency interval of channels have been considered in order to avoid the influence. In this case, there are drawbacks such as a decrease in frequency use efficiency.

(Problems to be solved by the invention) An object of the present invention is to solve the above-mentioned drawbacks with the prior art, and to allow an interference wave of its own signal leaked into an adjacent channel peculiar to heterodyne relay and to provide a relay system having high frequency use efficiency. Is to provide.

(Means for Solving the Problems) The present invention synchronizes an oscillator for frequency conversion between adjacent channels in an intermediate repeater with a receiving device and a transmitting device using a reference oscillator at a low frequency stage, or a receiving device for the same channel. The main feature is that the transmitting device is synchronized by a reference oscillator at a low frequency stage. As a result, the interference wave of the own signal leaked into the adjacent channel by the reception branching filter at the relay station and the own signal recombined on the transmission side have a synchronous relationship, and are equalized by the conventional waveform equalization technology at the receiving terminal. It becomes possible.

It is different from the related art that the radio frequency oscillator is appropriately synchronized with the reference oscillator at the low frequency stage.

(Operation) According to the present invention, a heterodyne relay system that makes maximum use of a radio frequency band can be realized. Specifically, the interference wave of the own signal leaked into the adjacent channel by the reception branching filter at the relay station can be removed by the conventional waveform equalization technique at the reception terminal station, which leads to the improvement of the line quality.

(Example) Hereinafter, an example of the present invention is described based on a drawing. FIG. 4 is a block diagram showing a configuration of a heterodyne repeater, and FIG. 5 is an example of a multi-channel configuration. The input signal from the receiving antenna 1 passes through the receiving channel filters 5 and 6 and is input to the receivers 7 and 8. The signals converted to the intermediate frequency by the receivers 7 and 8 are input to the transmitters 9 and 10 and transmitted to the next relay station by the transmission antenna 4 via the channel filters 11 and 12 and the combiner 13. The synthesizer 13 may be replaced by a channel filter.

As an example, as shown in FIG. 5, when the signal of channel 1 passes through the filter 5 and the signal of channel 2 passes through the channel filter 6, the bandwidth of the channel filter is generally relatively wide. , The signal of channel 1 leaks. Similarly, the signal of channel 2 leaks into the receiver 7. When the output of the transmitter 9 and the output of the transmitter 10 are combined by the combiner 13, the interference wave of the channel 1 passing through the receiver 8 is combined with the signal of the channel 1 passing through the receiver 7. Similarly, the own signal leaked to another channel at each relay station is added to the own signal as an interference wave.

FIG. 1 shows a first embodiment of the present invention. Reference numerals 14 and 15 denote frequency conversion multipliers for channel 1 and channel 2, respectively, which are converted to intermediate frequencies by radio frequency oscillators 16 and 17, respectively. Reference numeral 20 denotes a reference oscillator of a low frequency stage, and 18, 19
The phases of the oscillators 16 and 17 are controlled via the control circuit. With this configuration, the frequency difference between channel 1 and channel 2 can be kept constant. Amplifier 2 for level adjustment
Input to the transmitter via 1, 22. Reference numerals 23 and 24 denote upconverter multipliers for channel 1 and channel 2, respectively, which are converted into radio frequencies by radio frequency oscillators 25 and 26, respectively. Reference numeral 29 denotes a low-frequency reference oscillator.
The phases of the oscillators 25 and 26 are controlled via the control circuit 28.
With this configuration, the frequency difference between channel 1 and channel 2 can be kept constant, similarly to the receiving side. as a result,
If carrier recovery is performed at an optimum phase at the receiving terminal station, the interference wave of the own signal leaked to another channel and the own signal at each relay station have a synchronous relationship. This is because the use of the same technology as the technology for equalizing reflected waves generated in the propagation path makes it easy to remove self-signal interference waves. Specifically, a transversal equalizer is effective, and equalization can be performed if the level of the interference wave is within an allowable range. For details, see "Principles of Data Communication, published by Lattice" as an example.

FIG. 2 shows a second embodiment of the present invention. Reference numeral 34 denotes a low-frequency reference oscillator that controls the phases of the radio frequency oscillator 16 for the receiver of the channel 1 signal and the radio frequency oscillator 25 for the transmitter. 35 is a low frequency reference oscillator different from 34,
The phase of the radio frequency oscillator 17 for the receiver and the radio frequency oscillator 28 for the transmitter of the channel 2 signal are controlled. According to this configuration, the frequency difference between the channel 1 and the channel 2 due to the frequency conversion between the receiving device and the transmitting device can be made constant. As in the first embodiment, if carrier recovery is performed at an optimum phase at the receiving terminal station, the interference wave of the own signal leaked to another channel and the own signal at each relay station have a synchronous relationship.

FIG. 3 is an embodiment of a control circuit of the radio frequency oscillator. The output of the low frequency oscillator 20 and the output of the radio frequency oscillator 16 converted to a low frequency by the frequency divider 36 are compared with the phase comparator 37.
, A phase (frequency) comparison is performed, and after passing through an integrator 38 designed to minimize the phase noise, the signal is input to the frequency control terminal of the oscillator 16 to stabilize the frequency.

(Effect of the Invention) As described above, it is possible to synchronize the interference wave of the own signal leaked into the adjacent channel by the reception demultiplexing filter of the relay station and the own signal recombined on the transmission side. The waves can be removed by the terminal demodulator. That is, since the channel interval can be minimized, a heterodyne relay system that makes maximum use of the radio frequency band can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an intermediate relay station showing a first embodiment of the present invention, FIG. 2 is a configuration diagram of an intermediate relay station showing a second embodiment of the present invention, and FIG. FIG. 4 is a block diagram showing a non-regenerative relay, and FIG. 5 is a block diagram showing a non-regenerative relay of multi-channel transmission. 1 ... receiving antenna, 2, 7, 8 ... receiver, 3, 9, 10 ... transmitter, 4 ... transmitting antenna, 5, 6 ... receiving channel filter, 11, 12 ... transmission channel filter, 13… Synthesizer, 14,15,23,24 …… Multiplier (mixer) for frequency conversion 16,17,24,25 …… Radio frequency oscillator, 18,19,27,28,30,31,32, 33 Control circuit 20, 29, 34, 35 Low frequency oscillator 36 Frequency divider 37 Phase comparator 38 Integrator

Claims (2)

(57) [Claims] 1. A method for receiving each channel of a signal comprising a plurality of frequency-multiplexed channels, converting the signal to an intermediate frequency by applying a first radio frequency to each channel, and converting a second radio signal to the intermediate frequency. A radio transmitter / receiver that converts a frequency into a transmission frequency by transmitting a frequency, and synchronizes the first radio frequencies in two adjacent channels by a low-frequency reference oscillator;
Means for synchronizing the second radio frequencies in the two adjacent channels with each other by a low-frequency reference oscillator. 2. A method for receiving each channel of a signal comprising a plurality of frequency-multiplexed channels, converting the signal to an intermediate frequency by applying a first radio frequency to each channel, and converting a second radio signal to the intermediate frequency. In a radio transceiver that converts a frequency to a transmission frequency and transmits the same, a first radio frequency and a second radio frequency of the same channel are synchronized with each other by a low-frequency reference oscillator. A wireless transceiver comprising means.