JPS5847339A - Radio relay system - Google Patents

Abstract

PURPOSE:To reduce both the beat disturbance and a cost for a radio system having overlapping service areas, by using the oscillating source outputs modulated by the different low band frequencies to the carrier wave for each repeater station. CONSTITUTION:A radio system has overlapping service areas through >=2 repeater stations. For such radio system, the output to be modulated given from an oscillator 1 which received the modulation of frequency with the low band frequency sent from a low band noise frequency oscillator 2 is treated as the carrier wave for each repeater station. Thus the frequencies of the carrier waves of >=2 repeaters are modulated and vary independently of each other. This prevents the occurrence of a certain beat. A medium degree of stability is sufficient for the oscillator 1 which serves as an oscillating source of the carrier wave.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a repeater used in a relay station for mobile radio, etc., and relates to reducing deterioration in speech quality due to 4+ overreach, that is, the importance of the range of radio waves.

Figure 1 shows a relay station (fixed base) of a general mobile radio system,
Transmitting/receiving station (mobile) and service area (SAI, 5A2
) relationship is illustrated. @1 In Figure 1, when a call is made from transmitting/receiving station A to B or C, the call between A and C would ideally be done via relay station R1, but the call between A and B would ideally be done via relay station R1. The relay is performed via both relay stations R1 and R2 in the service area of both R1 and R2, and the number of carrier waves of the repeater in relay R1 and the carrier frequency of the repeater in relay station R2 are During this time, beat disturbances occur due to slight frequency shifts. If the frequency deviates significantly, interference with the audible frequency will occur, and if the difference in the 0 frequency is slight (below IHz), the call will be interrupted at the trough of the beat, causing problems.

Conventionally, in order to prevent the above-mentioned problems, a highly stable oscillator is used to shift the carrier wave frequencies of the repeaters by several tens of Hz to reduce beat interference. However, as a highly stable oscillator, for example, a carrier frequency of 100 M
H! In the case of 0.01 to 0. It requires stability of 1×10 degrees, is expensive, and has problems in that the frequency must be shifted for each relay station.

The object of the present invention is to take into account the above-mentioned problems of the conventional wireless relay system, and is based on the aggravation of using a nine-carrier wave modulated at a low frequency as a carrier wave.

By using an oscillator with medium stability, we can reduce beat disturbances that occur over time and position, and thereby achieve stable wireless communication t'+ capability using relatively inexpensive equipment. be.

In Kinei-Akira, in a wireless system with overlapping service areas by two or more relay stations, each relay station has a low noise frequency.

Specifically, there is provided a wireless relay system characterized in that each relay station is modulated with a different low frequency and uses the output of telescopic oscillation as a carrier wave.

A mobile radio system as an embodiment of the invention is shown in FIG. In Figure 2, oscillator 1 has a frequency of approximately 100 MHz.
oscillates a sine wave, and its output is applied to the modulator 3.

The modulator 3 is a combination of the low noise frequency oscillator 2 and the receiving section.
Receiving the signal from the oscillator 6, the output from the oscillator 1 is
First, frequency modulation is performed at a low noise frequency, for example, 20 Hz.

The modulated wave frequency-modulated at this low-band noise frequency is treated as a carrier wave. Then, the carrier wave is further transmitted to the demodulator 6.
The signal is modulated and sent to the multiplier 4. The nine signals multiplied by the multiplier 4 are amplified by the transmitter amplifier 5 and transmitted from the antenna. To the input of the demodulator 6 described above, a relayed signal received from the receiving antenna and amplified by the receiving amplifier 7 is added.

According to a conventional repeater, the frequency stability of the oscillator as a carrier wave oscillation source is 1. For example, the carrier wave oscillation source is approximately 100 M
0.01 to 0.1 x 10 in Hz, i.e. 1
Although it is assumed that the fluctuation is within ~10 Hz, according to the repeater of the above embodiment, the frequencies of the carrier waves of two or more related repeaters are frequency modulated and change independently of each other. The frequency stability of the oscillator, which is the oscillation source of the carrier wave used, is sufficient to be about 1×10 without causing a footbeat.

In the present invention, it is also possible to similarly reduce beat interference by using oscillation source outputs modulated at different low frequencies for each relay station as carrier waves.

According to the present invention, it is possible to use an oscillator with medium stability to reduce beat disturbances that occur over time and position, thereby making it possible to use a relatively inexpensive equipment f11 to achieve a stable radio frequency. Able to perform sparse communication.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the relationship among relay stations, transmitting/receiving stations, and service areas in a general mobile radio system, and Fig. 2 is a block circuit diagram of a repeater used in a wireless relay system as an embodiment of the present invention. be. l... Oscillator, 2... Low noise frequency oscillator. 3... Variable m1ll device, 4... Multiplier. 5... Transmission section amplifier, 6... Repeater 4 unit. 7... Receiver amplifier 0 Patent applicant Fujitsu Limited Patent agent Akira Yoiki Patent attorney Kazuyuki Nishidate Patent attorney Yukio Uchida Patent attorney Akira Yamaguchi Figure 1 Figure 2

Claims (1)

[Claims] In a wireless system with overlapping service areas provided by two or more relay stations, each relay station has a low noise frequency, or each relay station has a different low frequency noise frequency.
A wireless relay system characterized in that the output of an oscillation source modulated by the R number is used as a carrier wave.