KR20000031135A - Apparatus for measuring received power level with temperature compensation function - Google Patents

Abstract

PURPOSE: An apparatus for measuring a received power level is provided to compensate a gain variation in an amplifier of a frequency-down converter according to a temperature, by being equipped with a temperature device which varies a resistance value in response to a temperature variation. CONSTITUTION: A first variable amplifier(210) receives an intermediate frequency signal. A second variable amplifier(220) is connected to the first variable amplifier(210). A first amplifier(230) is coupled to the second variable amplifier(220). A band pass filter(240) is connected to the first amplifier(230). A frequency mixer(250) is coupled to the band pass filter(240). A second amplifier(260) connected to the frequency mixer(250) generates a final output signal. A detector(270) detects the output signals of the second amplifier(260) and thereby controls the first and second variable amplifier(210),(220). A power level measurer(280) measures a level of the output signal of the detector(270) considering variation of a temperature.

Description

Receive power level measuring device with temperature compensation function

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station receiver of a cellular system. In particular, the present invention relates to a base station receiver having a temperature compensation function for compensating a change in gain of an amplifier according to temperature in a frequency down converter of a base station. A reception power level measuring apparatus.

The cellular wireless communication system includes a base station for transmitting and receiving radio frequency signals to and from a mobile phone in a predetermined area (cell). The base station converts a radio frequency signal received from the mobile phone into an intermediate frequency signal. A frequency down converter is used to convert

The power level of the signal received from the mobile phone is used by the base station to control the power that the mobile phone transmits. That is, the base station increases the transmit power of the mobile telephone when the received signal power level received by the base station is equal to or less than the reference value, and decreases the transmit power of the mobile telephone when the received signal power level is equal to or greater than the reference value.

In order to optimize the power control and base station cell capacity as described above, the base station receiver must accurately measure the level of the received signal power received from the mobile phone. The base station receiver amplifies the frequency down-converted intermediate frequency signal through a resistance voltage dividing circuit, detects it with a diode, and obtains a direct current (DC) voltage that can adjust the attenuation value of the attenuator using a loop filter and an integrated circuit.

If the intensity of the signal received at the base station is large, the size of the signal detected by the diode is increased, and thus the DC voltage is also increased. Therefore, the DC voltage can be measured to know the power level of the received signal received at the base station.

1 is a block diagram illustrating an example of a configuration of an apparatus for measuring a reception signal power level according to the prior art, and as illustrated, an amplifier 110 receiving an intermediate frequency signal; A variable attenuator 120 connected to the amplifier 110; An amplifier 130 connected with the variable attenuator 120; A variable attenuator 140 connected to the amplifier 130; An amplifier 150 coupled with the variable attenuator 140; A variable attenuator 160 connected to the amplifier 150 and measuring received field strength; A band pass filter (BPF) 170 connected to the variable attenuator 160; An amplifier 180 connected to the bandpass filter 170 to produce a final output; And a detector 190 for measuring the output level of the amplifier 180 to control the attenuation range of the variable attenuator 120.

In the cellular system measuring the received signal power level as described above, when the internal temperature of the base station changes due to the influence of the surrounding environment, the gain of the amplification components constituting the base station receiver changes.

This change in gain due to the temperature change, even though the transmission power transmitted from the mobile phone is constant, the reception power level measuring device measures the non-uniform signal power, and consequently affects the power control between the base station and the mobile phone. There was a problem that the call capacity of the base station is reduced.

Accordingly, an object of the present invention, which was devised to solve the problems of the prior art operating as described above, is to provide a service of a base station by using a reception power level measuring apparatus including a temperature element whose resistance value changes with a change in temperature. The present invention provides a reception power level measuring apparatus having a temperature compensation function, in which an amplifier of a base station receiver having a great influence on area and quality maintains a constant gain regardless of temperature change.

Figure 1 is an embodiment showing the configuration of a reception signal power level measuring apparatus according to the prior art.

2 is a diagram illustrating the configuration of a base station second receiver according to the present invention;

Figure 3 is an embodiment showing the configuration of a power level meter according to the present invention.

<Explanation of symbols for main parts of the drawings>

110,130,150: amplifier 120,140,160: variable attenuator

170: bandpass filter 190: detector

210,220: variable amplifier 230,260: amplifier

250: frequency mixer 270: detector

280: power level meter

A preferred embodiment of the reception power level measuring apparatus for temperature compensation of the base station receiver according to the present invention, which was devised to achieve the above object,

A first variable amplifier receiving an intermediate frequency signal;

A second variable amplifier connected with the first variable amplifier;

A first amplifier connected with a second variable amplifier;

A bandpass filter connected to the first amplifier;

A frequency mixer connected to the bandpass filter;

A second amplifier coupled to the frequency mixer to produce a final output;

A detector for detecting the output signal of the second amplifier to control the first and second variable amplifiers; And

It includes a power level meter for measuring the level of the output signal of the detector in consideration of the change in temperature.

The present invention compensates for the amplifier gain change due to temperature change inside the base station by using a temperature compensating element, especially a thermistor, in the automatic gain adjusting portion of the receiver used in the base station of the cellular system.

In a cellular system, a received radio frequency signal of a base station is input to a base station first receiver through a reception bandpass filter and a low noise amplifier, and the base station first receiver down-converts the radio frequency signal twice to a medium frequency signal of 4.95 MHz. Make it. Since the received power level of the base station is measured from the first down-converted 70 MHz first intermediate frequency signal, the base station second receiver receives the first intermediate frequency signal, down converts it, and simultaneously measures the power level.

FIG. 2 is a diagram illustrating a configuration of a base station second receiver according to an embodiment of the present invention. As shown, a first variable amplifier 210 for receiving an intermediate frequency signal; A second variable amplifier 220 connected with the first variable amplifier; A first amplifier 230 coupled with the second variable amplifier; A bandpass filter 240 connected to the first amplifier; A frequency mixer 250 coupled with the bandpass filter; A second amplifier 260 coupled to the frequency mixer to produce a final output; A detector 270 for detecting the output signal of the second amplifier to control the first and second variable amplifiers; And a power level measurer 280 that measures the level of the output signal of the detector in consideration of the change in temperature, and its operation and effect will be described in detail as follows.

The first variable amplifier 210 and the second variable amplifier 220 which amplify the first intermediate frequency signal operate by the control signal of the detector 270, and the larger the input signal, the larger the gain. If the input first intermediate frequency signal is smaller than the reference value, the first and second variable amplifiers operate as amplifiers, and if larger than the reference value, the attenuator operates.

The output signal of the second variable amplifier is amplified by the first amplifier 230 and then input to the frequency mixer 250 via a band pass filter 250 having a pass band of 1.23 MHz. The frequency mixer mixes the 70 MHz signal and the 65.05 MHz local oscillation signal input through the bandpass filter to produce a second 4.95 MHz second intermediate frequency signal. The 4.95 MHz signal is amplified by the second amplifier 260 and then output as a final output signal.

After the final output signal output from the second amplifier is rectified by the detector 270, the gain of the first and second variable amplifiers 210 and 220 is adjusted. In addition, the output signal of the detector is input to the power level meter 280 is used to measure the received power level.

The power level measurer outputs a received signal strength indicator (RSSI) as a received power level by comparing the output signal of the detector with a reference voltage.

When the temperature of the base station receiver changes due to the influence of the base station environment, the reception path gain of the base station receiver changes. Since the base station receiver always has sufficient gain by the automatic gain adjusting operation of the detector 270 which adjusts the gain of the amplifier by the final output signal, the second intermediate frequency signal of 4.95 MHz is always maintained even if the receiver path gain is changed. Have a certain level. However, the reception power level that changes with the control signal of the detector is output in the same way as the variation of the reception path gain.

In order to prevent such a change in the received power level, a thermistor is connected to the reference voltage input unit of the power level meter so that the reference voltage also changes when the temperature of the base station changes and the gain of the reception path changes.

3 is a diagram showing the configuration of a power level meter 280 according to the present invention. As shown, a comparator 10 for measuring a received power level by comparing an output signal of a detector with a reference signal, and a temperature; It consists of the thermistor 11 which changes a reference signal by the following, The operation | movement is demonstrated as follows.

When the gain of the reception path drops due to the influence of temperature, the final output signal of the second receiver is increased, and at the same time, the reference voltage of the power level meter 280 is increased by the resistance change of the thermistor. As the temperature rises, the overall gain of the receive path decreases while the resistance of the thermistor decreases and the reference voltage increases accordingly.When the temperature decreases, the overall gain of the receive path increases, whereas the resistance of the thermistor increases. The reference voltage also drops.

Therefore, by using the gain fluctuation range of the reception path due to the temperature change as the reference voltage of the comparator 10, the reception power level measuring apparatus according to the present invention outputs the reception power level measured irrespective of the temperature change.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

According to the present invention, the signal power received by the base station can be accurately measured even if the amplifier gain of the base station receiver changes due to the change of the temperature of the base station. As a result, in the base station of the cellular system, the power of the mobile telephone regardless of the change of environment. It can cope more effectively with control and network operation of base station itself.

Claims (3)

A first variable amplifier receiving a first intermediate frequency signal; A second variable amplifier connected with the first variable amplifier; A first amplifier connected with the second variable amplifier; A bandpass filter connected to the first amplifier; A frequency mixer coupled to the bandpass filter; A second amplifier connected to the frequency mixer to generate a final output signal; A detector for detecting an output signal of the second amplifier to control the first and second variable amplifiers; And And a power level measuring device for measuring a level of an output signal of the detector in consideration of a change in temperature. According to claim 1, The power level measuring device, A comparator for measuring a received power level by comparing the output signal of the detector with a reference signal; A reception power level measuring apparatus having a temperature compensation function, comprising a thermistor for changing a reference signal by a change in temperature. The method of claim 2, wherein the thermistor, A receiving power level measuring device having a temperature compensation function, which raises a reference voltage when the temperature rises and drops the reference voltage when the temperature falls.