KR0184488B1 - Intermodulation preventing apparatus and method thereof - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

It is a technology that prevents the occurrence of intermodulation in the area where the receiving field strength is strong when receiving from a pager.

I. The technical problem that the invention is trying to solve

In the region with strong field strength (RSSI), many frequencies are mixed in the primary amplifier due to the large number of frequency channels received by the antenna.

All. Summary of the Solution of the Invention

When the electric field strength of the received radio call information is higher than the set value, the reception sensitivity is reduced to prevent intermodulation so that the radio calling service is not interrupted due to the intermodulation in the urban area or the area close to the transmitting antenna.

la. Important uses of the invention

Applies to pagers.

Description

Intermodulation Prevention Circuit and Method of Radio Pager

The present invention relates to a circuit and a method for preventing intermodulation of a wireless pager. In particular, when a disturbance signal is generated by a signal having a plurality of channel frequency components in a region where the reception field strength is strong, the antenna reception efficiency is reduced. The present invention relates to a circuit and a method for preventing intermodulation.

A typical paging receiver notifies a subscriber by tone or vibration depending on the output mode set when there is a call. In order to check the stored message received during the call, the message corresponding to the number of times the lead key is pressed is accessed and displayed on the display unit.

However, such a pager is serviced at 138 MHz to 174 MHz or 322 MHz to 328.6 MHz, and the channel interval is in the unit of 25 KHz.

1 is a block diagram of a typical pager.

The RF signal received through the antenna 10 is applied to the antenna matching unit 12 and impedance-matched by the capacitors C1-C3 and the variable capacitor C4 to the amplifier 14. The amplifier 14 amplifies the impedance matched RF signal to a predetermined level and outputs the RF signal to the RF processor 16. The RF processor 16 receives the amplified RF information, converts the RF information into an intermediate frequency, and outputs the intermediate frequency to the IF processor 18. The IF processor 18 demodulates and converts the signal converted into the intermediate frequency and applies a received field strength (RSSI) signal to the MPU 20. Therefore, the output of the IF processor 18 becomes radio call information converted into digital data. In this case, the MPU 20 is a one chip microcontroller, and includes a ROM for storing a program for controlling the overall operation of the pager and a RAM for temporarily storing data generated during program execution. The MPU 20 receives a message output from the IF processor 18 and stores the message sequentially in an internal RAM and controls performance of a radio call function. However, such a conventional pager has two or three or more amplifiers 14 due to the large number of frequency channels received by an antenna in an area with strong field strength (RSSI) depending on the transmitter location of the Korean mobile communication service and the second mobile communication service provider. The frequency is mixed, which affects the original reception frequency, causing a problem that reception is not possible.

Accordingly, an object of the present invention is to provide an intermodulation prevention circuit and method for a wireless pager which prevents intermodulation by lowering the reception efficiency of an antenna in an area having strong electric field strength.

In order to achieve the objects of the present invention is characterized in that the antenna reception sensitivity is lowered when the electric field strength of the received radio call information is received more than the set value to prevent intermodulation.

1 is a block diagram of a typical pager

2 is a block diagram of a pager according to an embodiment of the present invention.

3 is a control flow diagram for preventing intermodulation when receiving a strong electric field according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same parts in the figures represent the same reference signs wherever possible.

2 shows a block configuration of a pager according to an embodiment of the present invention.

3 is a control flowchart for reducing antenna reception efficiency when receiving a strong electric field according to an exemplary embodiment of the present invention.

2 and 3 will be described in detail the operation of the preferred embodiment of the present invention.

The RF signal received through the antenna 10 is applied to the antenna matching unit 12 and impedance-matched by the capacitors C1-C3 and the variable capacitor C4 to the amplifier 14. The amplifier 14 amplifies the impedance matched RF signal to a predetermined level and outputs the RF signal to the RF processor 16. The RF processor 16 receives the amplified RF information, converts the RF information into an intermediate frequency, and outputs the intermediate frequency to the IF processor 18. The IF processor 18 demodulates and converts the signal converted into the intermediate frequency and applies a received field strength (RSSI) signal to the MPU 20. Therefore, the output of the IF processor 18 becomes radio call information converted into digital data. At this time, the MPU 20 receives an RSSI signal output from the IF processor 18, stores the received signal strength in the internal RAM sequentially, and outputs an antenna efficiency reduction control signal when the MPU 20 becomes higher than the set value. . The MPU 20 is a one chip microcontroller, and includes a ROM for storing a program for controlling the overall operation of the pager and a RAM for temporarily storing data generated during program execution. Referring to the flowchart of FIG. 3 for the operation of outputting the antenna efficiency reduction signal in the MPU 20, the reception field strength of the pager is typically 40 dB | Lv / m to 50B | Lv / m. In step 31, the MPU 20 checks whether the received field strength (RSSI) is greater than or equal to the first set value, for example, 60B | Lv / m. If the value exceeds 60B | Lv / m, the MPU 20 proceeds to step 32. Generates a high signal that is a signal. The generated high signal is applied to the antenna efficiency adjusting unit 22. At this time, the antenna efficiency adjusting unit 22 is configured as a transistor Q1. When the high signal, which is an antenna efficiency reduction control signal, is applied from the MPU 20, the transistor Q1 is turned on and received from the antenna 10. Passing the signal to ground reduces the RF signal applied to amplifier 14. This reduces the efficiency of the signal received through antenna 10 and lowers the level of the signal amplified by amplifier 14. Then, in step 33, if the received electric field strength is lowered and the second set value, for example, 20B | Lv / m or less, is checked, and if it is not less than 20B | Lv / m, step 32 is continued. However, when the received electric field strength is 20B | Lv / m or less, the MPU 20 generates and outputs a low signal that is an antenna efficiency decrease release signal in step 34. The generated low signal is applied to the base of the transistor Q1 and the transistor Q1 is turned off. As a result, the antenna matching unit 12 operates normally to maximize the antenna efficiency.

As described above, the present invention reduces antenna reception sensitivity when received when the electric field strength of the received radio call information is higher than a set value, thereby preventing intermodulation, so that the electric field is strong in an urban area or an area close to a transmitting antenna. Intermodulation has the advantage of preventing the interruption of the wireless paging service.

Claims (4)

In the pager, Adjusting the matching signal or increasing the amplification rate of the antenna matching unit by detecting the electric field strength of the radio call information received through the antenna and generating an antenna reception efficiency reduction control signal when the electric field intensity is received above the set value. Intermodulation prevention circuit of a wireless pager, characterized in that to reduce the reception sensitivity by adjusting to prevent intermodulation. In the pager, An antenna matching unit for outputting an impedance matching RF signal received through the antenna; An amplifier for amplifying and outputting the impedance matched RF signal to a predetermined level; An RF processor which receives the amplified RF signal and converts the converted RF signal into an intermediate frequency; An IF processor for demodulating and converting the signal converted into the intermediate frequency and outputting a received field strength (RSSI) signal; A control unit which receives a received field strength (RSSI) signal output from the output of the IF processor and outputs a reception sensitivity control signal when the received signal intensity is greater than the set value; And a reception sensitivity adjusting unit configured to input a reception sensitivity control signal output from the control unit to reduce a level of an RF signal output by impedance matching at the antenna matching unit. The method of claim 2, And the antenna efficiency adjusting unit comprises a transistor. In the pager, A method of preventing intermodulation of a radio pager, characterized in that to prevent intermodulation by decreasing reception sensitivity when an electric field strength of received radio call information is higher than a set value.