KR19990014355A - Automatic gain control method of wireless pager - Google Patents

Abstract

The present invention relates to a method for adjusting an automatic gain of a pager,

In order to solve the problem that reception is not performed well due to interference between other radio paging signals having strong electric field intensities at positions close to other base stations, the signal received from the antenna is input to the I / F IC through an LNA (Low Noise Amplifier) And then the gain control reference value is sent to the D / A converter by a program stored in the CPU according to the electric field strength at the CPU at the outgoing side, and the D / A converter converts the gain control reference value into an analog signal again, , The gain of the amplification of the signal is automatically controlled without changing the gain control part, so that it can be received without saturation phenomenon in the modulation amplification generated in the wireless terminal.

Description

Automatic gain control method of wireless pager

The present invention relates to a method for automatic gain control of a pager.

Currently, the domestic wireless paging service providers are in short supply, the base stations are installed for each service provider, and the frequency interval of the wireless paging signal between each provider is extremely narrow.

Therefore, a coverage hole is generated which is not received at all due to interference between radio signals output from the base stations between the carriers.

For example, when a pager user of a base station uses a pager in the vicinity of a base station B, a strong signal strength of the base station of the nearby base station B is mixed and it becomes difficult to receive the pagers of the base station.

In order to solve this problem, in order to eliminate the saturation phenomenon in the modulation amplification operation of the conventional pager, a means for adjusting the gain of the amplifying operation according to the electric field intensity of the received signal is known.

1 is a diagram illustrating an example of a gain adjusting means of a conventional pager.

That is, the radio reception signal received by the antenna is detected by the RSSI (Received Signal Strength Indicator) in the I / F IC 2 via the LNA 1 and the electric field intensity of the received radio signal.

When the detected intensity of the electric field intensity is strong, the voltage value is high, which is output from the I / F IC 2 with the detected voltage signal (Analog signal).

The analog signal output from the I / F IC 2 is amplified at a predetermined ratio by the ratio calculation circuit 4 and then fed back to the LNA 1 to receive a gain signal for amplification The adjustment function allows to eliminate the saturation phenomenon of the intermodulation and to receive it.

In a conventional method for adjusting gain of a pager,

Since the analog value of the voltage variation according to the electric field intensity detected by the RSSI of the I / F IC 2 is amplified by the ratio calculation circuit 4 at a predetermined ratio and fed back to the LNA 1 side, There is a problem that the components of the ratio arithmetic circuit need to be individually changed in accordance with the gain control reference value according to the reception conditions, and therefore, the cost is large and the gain adjustment operation is cumbersome.

An object of the present invention is to convert an analog detection signal of an electric field intensity detected by an I / F IC (2) of a pager into a digital signal by a program input to a CPU of a terminal and send it to a D / A converter, The control reference value is converted into an analog signal and fed back to the LNA 1 so that the gain of the amplifying operation of the pager can be easily controlled automatically without changing any other components, thereby enhancing the function of the pager.

It is a further object of the present invention to provide a method for automatically adjusting the gain of a pager signal without requiring the replacement of a separate component, thereby providing a more economical, inexpensive and convenient automatic gain control.

Figure 1 is a schematic diagram of a gain control means of a conventional pager

Figure 2 is a schematic diagram of the gain control means of the pager of the present invention

3 is a circuit diagram of the D /

FIG. 4 is a cross-

DESCRIPTION OF THE REFERENCE NUMERALS

1: LNA, 2: I / F IC, 3: CPU,

4: ratio calculation circuit, 4a: D / A conversion circuit, R: resistance,

D: diode, Q: transistor, L: coil.

2 is a schematic diagram of automatic gain control means of the pager of the present invention.

That is, when the signal? Received from the antenna of the pager is inputted to the I / F IC 2 via the LNA (Low Noise Amplifier) 1, the electric field intensity of the radio signal .

The voltage signal 2 for the electric field intensity output from the I / F IC 2 is inputted to the CPU 3 and is calculated as a digital value by the A / D conversion circuit of the CPU 3.

The digital value of the calculated electric field intensity and the gain control reference value (which can be changed by the program) are calculated by a constant calculation formula [1] and output to the plurality of digital signals ③.

[Formula 1]

K Kmin: Y = Ymin

Kmin K Kmax: Y = Y *

K Kmin: Y = Ymax

Ymax: output maximum value, Ymax: output maximum value, Kmax: electric field intensity maximum value, Kmin: electric field intensity minimum value, : Gain ratio.

The plurality of digital signals? Outputted from the CPU 3 are converted into analog signals? By the D / A converter 4a and input to the LAN 1 side to automatically adjust the gain for the signal amplification operation.

3 is a circuit diagram of the D / A converter 4a. As shown in FIG. 3, a plurality of digital signals calculated by a gain control reference value for the electric field intensity calculated by the CPU are sent out and output to the terminals Do, D ₁ , D ₂ D ₃ ).

Is converted into an analog signal in the D / A converter 4a and is input to the LNA 1 side via the output terminal Vo.

At this time, the gain control reference value output from the output terminal of the D / A converter 4a is calculated as follows.

For example, define AGC to operate at -75 dBm for the field intensity.

Assuming that the AGC operates at the maximum at -20 dBm, it is assumed that the DC level is outputted at 0.3 V when the RSSI terminal of the I / F IC (2) is at -75 dBm.

The CPU 3 is programmed to operate from 0.3 V to 1 V (although the initial value of 0.3 V can be defined by the program).

The CPU (3) outputs a value corresponding to the 0.3V output terminal (D ₀ ~D _3).

At this time, the larger the number of output terminals of the CPU 3, the higher the decomposition concentration.

At this time, if the output of the terminal of the CPU (3) is outputted as Do = 1, D ₁ = 0, D ₂ = 0 and D ₃ = 0, the gain adjustment reference value is as follows.

Also, when D ₀ = 1, D ₁ = 1, D ₂ = 1, and D ₃ = 1

V ₀ is output from 0V to 2.8125V.

This value is input to the base side of the transistor Q ₁ of the LNA 1 of FIG. 4 to attenuate the level Levele.

This attenuation is defined to attenuate from 0dBm to 35dBm. However, the attenuation level can be adjusted by the time constant of the circuit and the program in the circuit.

In the LAN (1) circuit shown in Fig. 4, the diode D ₁ sends a signal to the ground during the operation of the AGC circuit to suppress signal transmission to the LAN terminal as much as possible.

The capacitor (C ₃ ) controls the base current and reduces the resistance when the AGC is turned on and blocks the DC component.

Transistor Q ₁ amplifies the current and transistor Q ₂ amplifies the voltage.

The resistor (R ₁ ), the capacitor (C ₄ ), and the coil (L ₁ ) serve to tune the frequency band.

Therefore, the D / A converter when the signal of the gain adjustment reference value in (4a) enter the side diode (D ₁₎ a diode (D ₁₎ becomes higher the voltage at the input terminal diode other base stations received by the antenna, so (D ₁₎ is energized A signal having a strong electric field strength of the transistor Q ₁ is grounded to automatically adjust the gain to be increased for the amplifying operation to eliminate the saturation phenomenon for the amplifying operation of the transistor Q ₁ .

The received signal of the pager is matched by a tuning circuit composed of a resistor R1, a capacitor C4 and a coil L1 to be sent to the MIX side of the I / F IC 2 and the signal received through the CPU 3 .

A method of controlling automatic gain control of a pager of the present invention is a method in which a CPU transmits a signal detected according to an electric field strength to a D / A converter by a plurality of digital signals, converts the signal into an analog signal, The gain of the amplifying operation can be automatically adjusted. Therefore, the gain can be adjusted easily and easily, and the gain can be adjusted without any additional parts, so that the pager can be used more economically and conveniently.

Claims (1)

A LAN 1 for receiving and amplifying a radio signal received from an antenna, an I / F IC 2 for amplifying the amplified signal by an intermediate frequency tuning circuit and detecting an electric field intensity, and a CPU 3 A method for adjusting a gain of a pager, comprising: The CPU 3 sends a gain control reference value to the D / A converter 4 as a plurality of digital signals according to the electric field intensity detected by the I / F IC 2, Wherein the adjustment reference value is converted into an analog signal and input to the LAN (1) to automatically adjust the gain of the amplifying operation of the signal.