JPH0756948B2 - Space diversity receiver - Google Patents

Description

DETAILED DESCRIPTION [Outline] A space diversity receiver using an AGC amplifier at the input stage of a received signal, which monitors the reception levels of a main reception system and a sub reception system without adding a special circuit to an RF amplifier. In order to realize a space diversity type receiver that can be realized, a variable attenuator provided between each intermediate frequency amplifier of the main receiving system and the sub receiving system and its output synthesizer (16) and each intermediate frequency amplifier Equipped with a controller that controls both variable attenuators according to the AGC control voltage difference, each intermediate frequency amplifier performs AGC control on each input stage amplifier of the main reception system and the sub reception system that are independent of each other, and also monitors the reception level. Is configured to generate a signal for.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a space diversity type receiver, and more particularly to a space diversity type receiver that uses an AGC amplifier in an input stage of a received signal.

In order to improve the NF (noise figure) and to prevent the deterioration due to the decrease of the back-off at the time of up-fading, the AGC circuit is added to the amplifier at the input stage of the received signal with the multi-value of digital multiplex radio equipment It is mainly used, and space diversity is also required to improve the line quality during fading.

[Prior Art] FIG. 3 shows a conventional space diversity type receiver, in which 1 is an input stage (hereinafter abbreviated as RF) AGC amplifier, and 2 is a high frequency output of the RF amplifier 1 of a local oscillator 13. A mixer for converting an intermediate frequency (hereinafter abbreviated as IF) band signal by an oscillation output, 3 is a preamplifier of the IF output of the mixer 2, and 5 is a signal for phase detection by further amplifying the output of the amplifier 3. Is an AGC amplifier that generates a signal and is provided in both the main receiving system and the sub receiving system.

Further, 11 is a mixer which integrates the outputs of the amplifiers 5 of the main receiving system and the sub receiving system and outputs a phase difference component between the two, and 12 is a main receiving signal based on the phase difference detected by the mixer 11 and a sub receiving signal. Infinite phase shifter (EPS) so that the received signal is in phase 1
A phase shift controller that controls 4 to shift only the output of the local oscillator 13 to the sub receiving system, 16 is a combiner that combines the outputs of the amplifiers 3 of the main receiving system and the sub receiving system, and 17 is a combiner. The AGC amplifier that amplifies the output of 16 and band-limited by the bandpass filter 4 to generate the IF output, and 18 receives the detection voltage (DC voltage) of the amplifier 3 of the main receiving system and the sub receiving system. RF amplifier 1 based on higher level (good reception)
Is an AGC controller for applying AGC to.

In this way, the IF signals are generated in a form in which the correlation of the influence of radio wave propagation due to fading is reduced by synthesizing the received signals of the main receiving system and the sub receiving system while synchronizing the phases.

[Problems to be Solved by the Invention] In the conventional space diversity type receiver described above,
An indispensable synthesizer for space diversity 16
In order to prevent the deterioration of the S / N ratio of both input signals when they are combined, the common AGC control is given to each RF amplifier 1 so that the AGC is applied based on the higher received level. Since it is configured, the reception level monitor signal, which is important as a receiver, can be monitored by the input of the combiner 16 for the higher level receiving system, but for the lower level receiving system. There was a problem that it could not be monitored as it was.

In this case, a method of adding a detection circuit for receiving level monitoring in parallel with the RF amplifier 1 can be considered, but it becomes very expensive.

Therefore, an object of the present invention is to realize a space diversity type receiver capable of monitoring the reception levels of the main receiving system and the sub receiving system without adding a special circuit to the RF amplifier.

[Means for Solving the Problems] In order to achieve the above object, in the space diversity type receiver according to the present invention, as shown in principle in FIG. 1, each intermediate frequency of the main receiving system and the sub receiving system. A variable attenuator 6 provided between the amplifier 5 and its output combiner 16 and a controller 15 for controlling both variable attenuators 6 according to the AGC control voltage difference of each intermediate frequency amplifier 5 are provided. Then, each intermediate frequency amplifier 5 controls the respective input stage amplifiers 1 of the main receiving system and the sub receiving system, which are independent from each other, by AGC and generates a signal for monitoring the reception level.

[Action]

In the present invention, the main receiving system and the sub receiving system are independent of each other.
The amplification operation by the RF amplifier 1 and the IF amplifier 5 is performed.
The AGC control voltage of the IF amplifier 5 is sent to the controller 15 to control each variable attenuator 6.

At this time, the controller 15 controls the variable attenuator 6 according to the AGC control voltage difference of the IF amplifier 5. Therefore, the difference in the reception level is given to the combiner 16 as it is, and the combination as space diversity is performed.

Therefore, each AGC of the IF amplifier 5 which is the input of the controller 15
The control voltage indicates the reception level, which can be used for monitoring.

[Embodiment] FIG. 2 shows an embodiment of the space diversity type receiver according to the present invention. In this embodiment, unlike the conventional example of FIG. 3, the input signal to the combiner 16 is The output signal is obtained after the IF output of the preamplifier 3 is amplified by the IF amplifier 5, not from the preamplifier 3. However, before the combining operation in the combiner 16, the detector of the IF amplifier 5 is used.
The controller 15 which has detected the AGC control voltage difference controls each variable attenuator 6 to synthesize a signal corresponding to the reception level.
Configured to give to 16.

Then, the AGC control voltage of the detector of the IF amplifier 5 is used as a reception monitor signal, and the output of the IF amplifier 5 is also used for AGC control of the RF amplifier 1 in the input stage.

The intermediate frequency output signal of the IF amplifier 5 is sent to the mixer 2 of the main receiving system and the sub receiving system by the mixer 11, the phase shift (EPS) controller 12, and the infinite phase shifter 14 as in the conventional example. The phase of the oscillation output of the local oscillator 13 is controlled.

By having such a configuration, the main receiving system and the sub receiving system have an independent relationship with each other. Therefore, if the AGC control level of the IF amplifier 5 of each receiving system is monitored, the receiving level of each receiving system can be known. Become.

Since the amplifier 17 only changes the level when combining (+6 dB when combining / 0 dB when disconnecting on one side), the AGC range may be about 6 dB.

[Advantages of the Invention] As described above, according to the space diversity type receiver of the present invention, the main reception system and the sub reception system, each of which has an RF / AGC amplifier and an IF / AGC amplifier, have a variable gain independently of each other. Since the amplification operation is performed and the IF / AGC control voltage at this time is used as the reception level monitor, the reception level of each reception system can be monitored over the entire dynamic range of the amplifier.

[Brief description of drawings]

FIG. 1 is a block diagram showing a space diversity type receiver according to the present invention in principle, FIG. 2 is a block diagram showing an embodiment of a space diversity type receiver according to the present invention, and FIG. 3 is a conventional example. It is a block diagram showing a space diversity type receiver. In Fig. 1, 1 ... Input disconnection (RF) AGC amplifier, 5 ... Intermediate frequency (IF) A
GC amplifier, 6 ... Variable attenuator, 15 ... Controller, 16 ... Combiner. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A variable attenuator (6) provided between each intermediate frequency amplifier (5) of the main receiving system and the sub receiving system and its output synthesizer (16) and each intermediate frequency amplifier (5). A controller (15) for controlling both variable attenuators (6) according to the AGC control voltage difference, each intermediate frequency amplifier (5) being an independent input stage amplifier of the main receiving system and the sub receiving system. A space diversity type receiver characterized by performing AGC control on (1) and generating a signal for monitoring the reception level.