JPS6223629A - Receiver - Google Patents

Abstract

PURPOSE:To vary electronically the attenuation of an attenuator by using a PINDIODE so as to constitute the attenuator, providing the attenuator to a receiver input section and controlling the bias current by an AGC voltage by the detection of reception input electric field. CONSTITUTION:A reception input electric field inputted to a receiver input terminal (a) is converted into an intermediate frequency by a frequency converter 3 via a variable resistance attenuator 1 and a pre-high frequency low noise amplifier 2. The change in the received input electric field inputted to the receiver inputterminal (a) is kept to a prescribed level within the operating rang of the AGC function of a main intermediate frequency amplifie 6 and an AGC voltage signal (c) in response to the change in the reception input electric field is extracted by an AGC detection circuit 9. A controller 10 uses the level of the AGC voltage signal (c) so as to apply a bias current (d) inputted to the PINDIODE being a component of the variable resistance attenuator 1 thereby controlling the attenuator. That is, the bias current (d) inputted to the PINDIODE of the variable resistance attenuator 1 is controlled automatically by the change in the reception input electric field to give an optional attenuation to the variable resistance attenuator 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reception input control type receiver that operates normally even when the input electric field becomes abnormally high.

[Conventional technology]

Conventionally, the configuration of this type of receiver is shown in the block diagram of FIG. In the figure, 2 is a front high frequency low noise amplifier, 3 is a frequency converter, 4 is a local oscillator, 5 is a front intermediate frequency amplifier,
6 is an intermediate frequency band filter; 7 is a main intermediate frequency amplifier having an AGC function or an amplifier having a limiter function; 8
indicates a demodulator, a indicates a receiver input terminal, and b indicates a receiver output terminal.

In order to control the input electric field of this type of receiver, the main intermediate frequency amplifier 7 in the intermediate frequency band is equipped with an AGC function or a limiter function. It relied on the AGC range of the frequency amplifier 7 or the limiter compression range.

[Problem to be Solved by the Invention J] Therefore, when a receiving input electric field higher than the appropriate standard receiving input electric field is applied to the receiver, or when a receiving input electric field exceeding the AGC range is applied, the demodulator 8 The input I-novel changes, the distortion of the pre-high frequency low noise amplifier 2, the pre-intermediate frequency amplifier 5 and the main intermediate frequency amplifier 7 increases,
This had the disadvantage of increasing receiver noise.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reception input control type receiver that eliminates such drawbacks, prevents excessive reception input electric fields from being input, and reduces reception distortion and reception noise.

[Means for solving problems]

The configuration of the receiver of the present invention includes: a variable resistance attenuator provided in the reception input stage and electronically attenuating input 1/bell according to a control signal; a reception circuit connected to the variable resistance attenuator; and a reception circuit connected to the variable resistance attenuator. level detection means for detecting a received input electric field; and when it is detected that the received input electric field has become higher than a predetermined level due to the level detection step, the amount of attenuation is increased in accordance with the input electric field to make it lower than the predetermined level. and a control means for generating the control signal for controlling the attenuation amount to be suppressed to a certain level when it is detected that the amount of attenuation has occurred, and the receiving input electric field to the receiving circuit is suppressed to a predetermined level or less.

[Example J Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, 1 is a pin diode (PIN DIO
DE) variable resistance attenuator, 2 is a pre-high frequency low noise amplifier, 3 is a frequency converter, 4 is a local oscillator, 5 is a pre-intermediate frequency amplifier, 6 is an intermediate frequency band filter, 7 is an AGC
Main intermediate frequency amplifier with limiter function, 8
9 is a demodulator, 9 is an AGC voltage detection circuit, 10 is a controller for controlling the variable resistance attenuator 1, a is a receiver input terminal, and b is a receiver output terminal.

In this configuration, the received input electric field input to the receiver input terminal a is converted to an intermediate frequency by the frequency converter 3 via the variable resistance attenuator 1 and the pre-high frequency low noise amplifier 2. This converted intermediate frequency signal is amplified by a pre-intermediate frequency amplifier 5, has out-of-band noise removed by an intermediate frequency bandpass filter 6, and is input to a main intermediate frequency amplifier 7. The signal, which has reached a certain level through the AGC function of the main intermediate frequency amplifier 7, is demodulated by the demodulator 8 and output as a baseband signal through the receiver output terminal.

Therefore, changes in the received input electric field input to the receiver input terminal a are kept at a constant level within the operating range of the AGcB function of the main intermediate frequency amplifier 6, and the AGC detection circuit 9 responds to changes in the received input electric field. The AGC voltage signal C can be extracted. The controller 10 controls the PIN that constitutes the variable resistance attenuator 1 depending on the level of the AGC voltage signal C.
It has the function of supplying and controlling the bias current d input to DIODE. That is, due to changes in the received input electric field, the input to the PIN DIODE of the variable resistance attenuator 1,
The bias current d applied is automatically controlled, and the variable resistance attenuator 1 has arbitrary attenuation characteristics.

As shown in the characteristic diagram of FIG. 2, this variable resistance attenuator 1 has a reception input electric field Pr as a reference, and when the electric field Pr becomes higher, the attenuation amount increases accordingly, and when it becomes lower than this electric field Pr, the attenuation amount increases accordingly. The electric field Pr is set so that the amount is O. Therefore, Pr
If so, the fade margin of the receiver can be increased up to the maximum variable attenuation amount without deteriorating the characteristics of the receiver.

〔Effect of the invention〕

As explained above, the present invention provides PIN DIODE
An attenuator is constructed using l- and installed at the receiver input section, and its bias current is converted to A G C' by detecting the received input electric field.
By controlling , by pressure, the amount of attenuation of the attenuator can be electronically varied. Therefore, the attenuation characteristics of the variable resistance attenuator with respect to changes in the receiving input electric field are set such that when the input electric field is higher than a predetermined input electric field Pr, the attenuation amount increases accordingly, and when the electric field is lower than the electric field Pr, the X expression becomes 0. For example, the fade margin of the receiver can be increased up to the maximum variable attenuation amount without deteriorating the receiver characteristics. Further, even when the propagation distance is very short and the received input electric field increases, the receiver can automatically operate normally with a specified standard input electric field.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a receiving input electric field automatic control receiver according to an embodiment of the present invention, Fig. 2 is a characteristic diagram of the variable attenuation amount with respect to an increase in the receiving input electric field of the variable resistance attenuator shown in Fig. 1, and Fig. 3 is a block diagram of a receiving input electric field automatic control receiver according to an embodiment of the present invention. shows a schematic diagram of an example of a conventional receiver. DESCRIPTION OF SYMBOLS 1... Variable resistance attenuator, 2... Pre-high frequency low noise amplifier, 3... Frequency converter, 4... Local oscillator, 5
... Pre-intermediate frequency amplifier, 6... Intermediate frequency bandpass filter, 7... Main intermediate frequency amplifier, 8... Demodulator, 9.
...AGC voltage detection circuit, 10...control circuit. ■ Receive X-power W-gift

Claims (1)

[Claims] A variable resistance attenuator provided in the receiving input stage and electronically attenuating the input level in accordance with a control signal, a receiving circuit connected to the variable attenuator, and a level detection means for detecting the receiving input electric field of the receiving circuit. When this level detection means detects that the received input electric field has become higher than a predetermined level, the attenuation amount is increased according to the input electric field, and when it is detected that the received input electric field has become lower than the predetermined level, the attenuation amount is kept constant. a control means for generating the control signal to suppress the received electric field to the receiving circuit to a predetermined level or less.