JPH0318134A - space diversity receiver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Summary 1] Regarding a space diversity receiver that uses an AGC amplifier in the input stage of the received signal, the reception level of the main reception system and sub reception system can be adjusted without adding a special circuit to the RF amplifier. With the aim of realizing a space diversity receiver that can monitor A controller that controls both variable attenuators according to the AGC control voltage difference of the amplifiers, and each intermediate frequency amplifier controls each input stage amplifier of the main reception system and the sub reception system, which are independent from each other, to AGCf! I
I? It is designed to perform IJ and generate a signal for monitoring the reception level. [Industrial Application Field] The present invention relates to a space diversity receiver, and particularly to a space diversity receiver that uses an AGC amplifier in the input stage of a received signal. As digital multiplex radio equipment becomes more multi-valued, receivers need to be designed to improve the NF (noise figure) and prevent deterioration due to reduction in backoff during up fading. The use of AGC circuits has become mainstream, and space diversity is also required to improve line quality during fading.

[Prior art 1] Fig. 3 shows a conventional space diversity receiver, in which 1 is an input stage (hereinafter abbreviated as RF) AGC amplifier, 2 is a local oscillator l3 which converts the high frequency output of the RF amplifier 1 into
3 is a preamplifier for the IF output of mixer 2, and 5 is a preamplifier for the IF output of mixer 2, which further amplifies the output of amplifier 3 and is used for phase detection. These are AGC amplifiers that generate signals, and these are provided in both the main receiving system and the sub-receiving system. Further, 11 is a mixer that integrates the outputs of the amplifiers 5 of the main receiving system and the sub-receiving system and outputs a phase difference between the two, and 12
is an infinite phase shifter (
EPS) 14 to shift only the phase of the output of the local oscillator l3 to the sub-receiving system; l6 is a synchronizer that combines the outputs of the amplifiers 3 of the main receiving system and the sub-receiving system; 17 is an AGC amplifier that amplifies the signal obtained by band-limiting the output of the combiner 16 with the bandpass filter 4 to generate an IF output, and 18 is the detection voltage (DC This is an AGC controller for applying AGC to the RF amplifier 1 based on the higher level (the one with better reception).

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

[Problem to be solved by the invention] In the above-mentioned conventional space diversity receiver,
Combiner 1 essential for space diversity
When the two input signals to 6 are combined, the S/N of both input signals is
A based on the higher reception level to prevent ratio deterioration.
Common AGC for each RF amplifier 1 so that GC is applied
Since it is configured to give control, the monitor signal of the reception level which is important for the receiver can be monitored manually by the signal generator 16 for the reception system of the higher level, but the monitor signal of the reception level of the lower level can be monitored manually. There was a problem that the receiving system on the other hand could not be monitored as it was. In this case, it is conceivable to add a detection circuit for monitoring the reception level in parallel with the RF amplifier l, but this would be extremely expensive. Therefore, an object of the present invention is to realize a space diversity receiver that can monitor the reception levels of the main reception system and the sub reception system without adding a special circuit to the RF amplifier.

[Means for Solving the Problems] In order to achieve the above object, the space diversity type receiver according to the present invention has a space diversity type receiver according to the present invention, as shown in principle in FIG. It includes a variable attenuator 6 provided between the frequency amplifier 5 and its output signal Hl6, and a controller l5 that controls both variable attenuators 6 according to the AGC control voltage difference of each intermediate frequency amplifier 5. . Each intermediate frequency amplifier 5 performs AGC control on each input stage amplifier l of the main reception system and the sub reception system, which are independent of each other, and generates a signal for monitoring the reception level. [Function] In the present invention, amplification operations are performed by the RF amplifier 1 and the IF amplifier 5 independently in the main receiving system and the sub-receiving system, and
AGC! of this IF amplifier 5! The I+ control voltage is sent to the controller l5 to control each variable attenuator 6. At this time, since the controller 15 controls the variable attenuator 6 according to the AC and C control voltage difference of the IF amplifier 5, the difference in reception level is directly applied to the combiner 16, and the combination as space diversity is performed. conduct. Therefore, this controller 15
Each AGC control voltage of the IP amplifier 5, which is input to the IP amplifier 5, indicates the reception level, and this can be used for monitoring. [Embodiment] FIG. 2 shows an embodiment of the space diversity receiver according to the present invention. In this embodiment, unlike the conventional example shown in FIG. 3, the input signal to the combiner 16 is is the IF output of this preamplifier 3, not from the preamplifier 3.
This is the output signal after being amplified by F amplifier 5. However, before the combining operation in the combiner 16, the AGC control voltage difference detected by the detector of the IF amplifier 5 is detected. 11i? S
15 is arranged to provide a signal to the attenuator 16 according to the reception level by controlling each variable attenuator 6. The AGC control voltage of the detector of the IF amplifier 5 is used as a reception monitoring signal, and the output of the IF amplifier 5 is also used for AGC control of the RF amplifier l in the input stage. Further, the intermediate frequency output signal of this IF amplifier 5 is sent to the mixer l1 and the phase shift (EP) as in the conventional example.
S) A controller l2 and an infinite phase shifter 14 control the phase of the oscillation output of the local oscillator 13 to the ξ mixer 2 of the main reception system and the sub reception system. By having such a structure, the main receiving system and the sub-receiving system are in an independent relationship with each other, so by monitoring the AGC control level of the IF amplifier 5 of each receiving system, the receiving level of each receiving system can be determined. become. In addition, the amplifier 17 changes the level at the time of combination (+6 dB at the time of combination)
/OdB when one side is cut), so the AGC range is 6.
About dB is enough. [Effects of the Invention] As explained above, according to the space diversity receiver according to the present invention, the RF-AGC amplifier and the IF-A
The main receiving system and the sub-receiving system, each having a GC amplifier, perform variable gain amplification operations independently of each other, and at this time the I
Since the F-AGC control voltage is used as a reception level monitor, the reception level of each reception system can be monitored over the entire dynamic range of the amplifier.
Reception level monitor

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle of a space diversity receiver according to the present invention, FIG. 2 is a block diagram showing an embodiment of a space diversity receiver according to the present invention, and FIG. 3 is a conventional example. 1 is a block diagram showing a space diversity receiver. In Fig. 1, l...input stage (RF) AGC amplifier, 5... intermediate frequency (IF) AGC amplifier, 6... variable attenuator, 15... system? 111 device, l6... synthesizer. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] a variable attenuator (6) provided between each intermediate frequency amplifier (5) of the main reception system and the sub reception system and its output combiner (16);
A controller (15) that controls both variable attenuators (6) according to the AGC control voltage difference of each intermediate frequency amplifier (5),
A space diversity type characterized in that each intermediate frequency amplifier (5) performs AGC control on each input stage amplifier (1) of the main reception system and sub reception system, which are independent of each other, and generates a signal for monitoring the reception level. Receiving machine.