KR101014041B1 - Automatic tuning method of frequency - Google Patents

Abstract

The present invention relates to frequency tuning of radio, TV, digital multimedia broadcasting (DMB), digital audio broadcasting (DAB), and HD radio broadcasting. Therefore, the present invention relates to a method for automatic tuning of a frequency that increases the accuracy of automatic tuning by monitoring the AGC operation and compensating for automatic tuning when the electric field is weak. The present invention monitors the operation of AGC (automatic gain control) during automatic frequency tuning to compensate for the attenuation caused by AGC (automatic gain control), and further compensates for signal desensitization caused by AGC operation in a strong electric field. It is a frequency automatic tuning method that improves the performance and accuracy of the station.

Broadcast, Frequency, Hope Broadcast, Surrounding Broadcast, Signal Quality

Description

Automatic tuning of frequencies {Auto frequency selection method}

The present invention relates to frequency tuning of radio, TV, digital multimedia broadcasting (DMB), digital audio broadcasting (DAB), and HD radio broadcasting. Therefore, the present invention relates to a method for automatic tuning of a frequency that increases the accuracy of automatic tuning by monitoring the AGC operation and compensating for automatic tuning when the electric field is weak.

In general, when receiving a vehicle audio video system, digital multimedia broadcasting (DMB), digital audio broadcasting (DAB), HD radio broadcasting, etc., the user can easily select and receive a broadcast by using an automatic tuning function of the terminal.

Hereinafter, a conventional automatic tuning method of frequency will be described.

In a car audio and video system, if you select the automatic tuning function when listening to AM (amplitude modulation) or frequency modulation (FM) radio, automatic tuning is performed so that the frequency is automatically searched to receive a broadcast by selecting a frequency with an appropriate electric field strength. Function is provided.

The conventional radio tuning function of the conventional radio evaluates the strength (RF input level), frequency accuracy, and noise level of a signal of a corresponding frequency, and receives a broadcast by tuning a corresponding channel when a preset reference condition is satisfied. However, when the automatic tuning is performed by applying these conditions only, if the electric field strength of the desired broadcast is relatively weak when the electric field strength of the desired broadcast is located in the strong electric field area, the actual electric tuning is possible, but AGC (automatic) is possible. It is not possible to tune due to attenuation of gain control, and a desensitization of signal occurs due to attenuation of AGC (automatic gain control). Is generated.

In the case of conventional automatic frequency tuning, the electric field of the desired broadcast is recognized as lower than the actual strength due to wideband AGC operation (attenuation) by surrounding broadcasting, so that the actual desired broadcasting can be tuned, but the electric field is recognized as low. There is this.

The present invention has solved the above-described problems, the present invention is a radio, TV, digital multimedia broadcasting (DMB), digital audio broadcasting (DAB) (Europe), HD radio (North American) broadcasting in the strong electric field when receiving the automatic station It is an object of the present invention to provide a method for automatic tuning of a frequency to improve the tuning accuracy by improving the quality of the corresponding broadcasting frequency, but not tuning due to the attenuation of the AGC.

The present invention monitors the operation of AGC (automatic gain control) during automatic frequency tuning to compensate for the attenuation caused by AGC (automatic gain control), and further compensates for signal desensitization caused by AGC operation in a strong electric field. It is an object of the present invention to provide a method for automatic tuning of frequencies that enhances the performance and accuracy of the station.

The method of the present invention for achieving the above object is a first step of determining the amount of attenuation of AGC for a frequency selected by the CPU in automatic tuning for TV or radio broadcast reception in a strong electric field, and the frequency at the CPU. And a third step of grasping the original signal value, and a third step of compensating for the attenuation of the AGC with respect to the frequency in the CPU.

In addition, to identify the attenuation of AGC, if the AGC is a linear AGC, monitor the current flowing through the diode of the linear AGC to determine the attenuation using the reference table in the CPU.If the AGC is a step AGC, the step value of the step AGC is monitored. To determine the attenuation using the reference table in the CPU.

Compensating the attenuation of the AGC with respect to the frequency of the present invention also includes compensating for the desensitization factor due to the attenuation of the AGC, and compensating with the attenuation of the AGC with respect to the frequency is the original signal value of the frequency − Attenuation amount of the AGC + compensation value for the attenuation amount of the AGC-characterized in that it is calculated by the desensitization factor.

The present invention provides an automatic tuning function that improves the performance and accuracy of the tuning by eliminating the error of tuning, particularly in the strong electric field during automatic tuning in radio, TV, digital multimedia broadcasting (DMB), digital audio broadcasting (DAB), and HD radio broadcasting. do.

The present invention can receive a more accurate and better reception of the radio or TV signal in the vehicle when automatic tuning.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted.

In the present invention, the frequency quality of the corresponding broadcast in the electric field during automatic frequency tuning is good, but the electric field is relatively weak compared to the surrounding broadcasting. It is an automatic tuning method of frequencies that improves the sound quality of received broadcasts.

1 is a conceptual diagram of a radio / TV signal receiver according to an embodiment of the present invention.

Referring to FIG. 1, the radio / TV signal receiver according to the present invention includes an antenna 20, a band pass filter (BPF) 22, an automatic gain control (AGC) 24, a low noise amplifier (LNA) 26, It includes a mixer (28), a digital signal processor (DSP) 30, a level detector 32, an AGC control unit 34, an AGC monitor unit 36, and a CPU 38. do.

In general, when receiving a radio or TV signal, the signal received from the antenna 20 is band filtered by a band pass filter (BPF) 22, the gain is adjusted by an automatic gain control (AGC) 24, and an automatic gain control (AGC). (24) grasped and controlled the signal of the level detector (32) in the AGC control unit (34).

As described above, in this case, excessive attenuation occurs in the strong electric field, and thus the present invention could not tune even though the quality of the corresponding frequency is excellent. According to the present invention, the attenuation of the AGC (Automatic Gain Control) 24 is reduced through the AGC monitor unit 36. By grasping the field strength of the original signal through the DSP (Digital Signal Processor) 30 and compensating in the CPU 38, it is possible to solve the problems that could not be tuned even though the quality of the frequency is excellent. Resolve Desensitization.

For example, the electric field strength of the desired broadcast frequency of 97.5MHz during automatic tuning is 30dBuV, the electric field strength of the ambient broadcasting frequency of 95.9MHz is 100dBuV, the attenuation amount by the AGC 24 is 20dBuV, the reference electric field which is capable of automatic tuning is 20dBuV, the signal quality When the desensitization factor is -3 dB, conventionally, 97.5 MHz of desired broadcast is 30 (original signal)-20 (attenuation by AGC) = 10 dBuV. Could not compensate for the attenuation caused by the automatic tuning.

However, in the case of the present invention, the desired broadcast 97.5MHz is 30 (original signal)-20 (AGC attenuation amount) + 20 (AGC operation compensation)-3 (Desensitization Factor) = 27 dBuV so that 20dBuV, which is a reference electric field capable of automatic tuning, can be obtained. Since the desired broadcast 97.5 MHz is automatically tuned to receive the broadcast.

Meanwhile, in the case of the AGC 24, a linear AGC or a step AGC may be applied, and in the present invention, in the case of a linear AGC, attenuation amount and desensitization factor of the AGC may be detected by detecting a current amount. In the case of a step AGC, the CPU 38 detects the step and compensates for the attenuation of the AGC and the desensitization factor of the AGC. Process as much as possible.

2 is a diagram illustrating a case where linear AGC is applied according to an embodiment of the present invention.

FIG. 2 is a detailed configuration of using a linear AGC in a radio / TV signal receiver. The antenna 20, the linear AGC 24, the RFIC 60, the AGC control unit 34, and the CPU 38 are shown in FIG. It is made to include.

The radio signal received through the antenna 20 is attenuated in the linear AGC 24 and provided to the RFIC 60 through the RF input terminal RF In, and the AGC control unit 34 installed in the RFIC 60 is linear. By adjusting the operation of the AGC 24, the CPU 38 identifies the amount of attenuation caused by the linear AGC 24 and compensates for the original signal strength and desensitization factor to improve the performance of automatic tuning.

The AGC control unit 34 of the RFIC 60 controls the linear AGC 24 to adjust the attenuation amount.

The linear AGC 24 connects the diodes in parallel to adjust the attenuation value by adjusting the current value flowing through the diode, so that the attenuation increases as the current value flowing through the diode Diode increases.

Referring to the drawing, the linear AGC 24 is composed of a passive element RLC and a diode, and grasps the voltage V1 and V2 between the resistor R1 to determine the amount of current flowing through the diode and attenuates the original signal according to the amount of current.

If the current amount is 0-10mA, the attenuation is 3dB of the original signal. If the current is 10-20mA, the attenuation of the original signal is 6dB. If the current is 20-30mA, the attenuation of the original signal is 8dB.

In the present invention, the CPU 38 grasps the current flowing through the diode through the AD converter, determines the attenuation amount using the reference table, and receives the strength information of the original signal through the DSP 30 (FIG. 1) and the AGC 24. By compensating for the attenuation due to the N s) and compensating for the desensitization factor, the problem that a broadcast having excellent signal quality is not selected during automatic tuning is eliminated.

As described above, in the case of using the linear AGC 24 as shown in FIG. 2, the amount of current is detected and the attenuation amount is detected, and the compensation is compensated for, thereby increasing the accuracy of the automatic tuning performance in the electric field.

3 is a configuration diagram in the case of applying a step AGC according to an embodiment of the present invention.

FIG. 3 is a detailed configuration diagram in which a step AGC 24 is used in a radio / TV signal receiver and includes an antenna 20, an RFIC 60, an AGC control unit 34, and a CPU 38. .

The radio signal received through the antenna 20 is provided to the RFIC 60 via an input terminal RF In, and processes the signal attenuation at the step AGC 24 of the RFIC 60 to the RFIC 60. The gain of the step AGC 24 is adjusted by the installed AGC control unit 34.

When the CPU 38 receives the step value of the step AGC 24 from the AGC control unit 34 of the RFIC 60, the CPU 38 determines the amount of attenuation using a reference table according to the step value, and the DSP 30 (Fig. Through 1), the strength of the original signal is received to compensate for the attenuation by the step AGC 24 and the signal quality deterioration factor (Desensitization factor) to improve the performance of automatic tuning.

In Fig. 3, as an example of attenuation of 6 dB per step, signal attenuation of 12 dB for 2 steps and 18 dB for 3 steps is processed.

According to the present invention, although the broadcast of a relatively weak frequency in the strong electric field is not tuned because it is recognized as lower than the actual electric field due to the AGC operation even though the actual quality is good, by monitoring the AGC operation as described above, the original electric field value is calculated. Fully automatic tuning is possible.

4 is a flowchart of automatic channel selection operation of the frequency of the present invention.

In step 300, frequency automatic tuning is started to receive a broadcast of TV, FM, AM, and the like.

In step 310, the CPU 38 starts a frequency search to check the selected frequency, for example, 87.5 MHz, and then changes the frequency to 87.6 MHz for the next frequency check (Tune Next operation).

If a frequency of 87.6 MHz is found in step 310, the level check operation of the present invention is performed in step 320.

The CPU 38 continuously reads and grasps the electric field from the DSP 30 to confirm the electric field strength of the selected 87.6 MHz.

At this time, the CPU 38 determines the amount of attenuation in which the electric field of 87.6 MHz is attenuated through the AGC 24, and grasps the original field strength of the 87.6 MHz from the DSP 30, thereby degrading the amount of attenuation and signal quality by the AGC 24. It compensates for the desensitization factor to solve the problem that the 87.6 MHz broadcast signal was not automatically tuned even when the proper electric field and to receive a better sound quality.

In the case of using the linear AGC 24 as shown in FIG. 2, the CPU 38 reads the current value flowing through the diode as described above, grasps the attenuation amount, and compensates it. In the case of the step AGC 24 as shown in FIG. The attenuation amount is read by reading the step value, and the desensitization factor due to the attenuation is also compensated to increase the accuracy of frequency tuning.

After processing such compensation, if it does not correspond to the automatic tuning criteria, the process returns to step 310 described above to search for the next frequency to be tuned again.

If it is determined that the level check of 87.6 MHz is appropriate in step 320, the process proceeds to step 330 to perform an offset check to determine the accuracy of the frequency. It is to check the accuracy of the frequency by checking the offset of the signal of 87.6 MHz. The judgment is made by reading from the dedicated DSP 30.

If the offset check is not performed and does not correspond to the automatic tuning reference value, the process is fed back to step 310 described above to start the operation of searching for the next frequency to be tuned.

If the offset check of 87.6 MHz is appropriate in step 330, the controller proceeds to step 340 to perform USN (Ultra Sonic Noise) check, which is a value representing the extent of the adjacent channel in FM. We judge by reading from (30).

If the USN (Ultra Sonic Noise) check is performed and it does not correspond to the automatic tuning reference value, the process returns to step 310 to search for the next frequency to be tuned again.

In step 340, when the 87.6 MHz Ultra Sonic Noise (USN) check satisfies the reference value, the process proceeds to step 350 to perform a multipath check, which is a value indicating the amount of FM multipath when the FM radio signal is tuned. The CPU 38 reads from the DSP 30 to determine and if appropriate, selects and receives the broadcast of 87.6 MHz in step 360.

On the other hand, if a multipath check is performed and does not correspond to the automatic tuning reference value, the process returns to step 310 to search for a next frequency to be tuned again. The above-described offset check, ultra sonic noise (USN) check, and multipath check (Multipath check) operations can be read from a dedicated DSP.

The present invention is to compensate for the electric field by monitoring the frequency of AGC operation in order to receive the broadcast of TV, FM, AM, etc., and to check the compensated electric field, determine the noise, frequency error, etc. Tuning frequency.

As described above, the present invention monitors the AGC operation that the frequency quality of the corresponding broadcast is good in the strong electric field during automatic frequency tuning, but the electric field is relatively weaker than the surrounding broadcasting, and the automatic electric tuning is performed by compensating the electric field. Increase the accuracy and performance of station selection. In the present invention, the strong electric field is an electric field in which the tuner's AGC operates.

So far, the configuration and operation of the embodiment of the present invention have been described. The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims but also by the equivalents of the claims.

1 is a conceptual diagram of a radio / TV signal receiver according to an embodiment of the present invention.

2 is a configuration diagram in the case of applying a linear (Linear) AGC according to an embodiment of the present invention.

Figure 3 is a block diagram when the step (STEP) AGC according to an embodiment of the present invention is applied.

4 is a flow chart of automatic tuning of the frequency of the present invention.

<Description of Major Symbols in Drawing>

20: antenna 24: linear AGC, step AGC

30: DSP 34: AGC Control

38: CPU 60: RFIC

Claims (7)

In making automatic tuning for receiving a TV or radio broadcast in a strong electric field, A first step of identifying an attenuation amount of the AGC for the selected frequency in the CPU; A second step of grasping the original signal value for the frequency in the CPU; And And a third step of compensating for the attenuation of said AGC with respect to said frequency in said CPU. The method of claim 1, To grasp the attenuation amount of the AGC, And if the AGC is a linear AGC, monitoring the current flowing through the diode of the linear AGC to determine attenuation using the reference table in the CPU. The method of claim 1, To grasp the attenuation amount of the AGC, And if the AGC is a step AGC, monitoring the step value of the step AGC to determine the attenuation amount using the reference table in the CPU. The method of claim 1, Compensating the attenuation of the AGC with respect to the frequency Compensating for the signal deterioration factor (Desensitization Factor) caused by the AGC attenuation. The method of claim 1, Compensating the attenuation of the AGC with respect to the frequency And the original signal value of the frequency-the attenuation amount of the AGC + a compensation value for the attenuation amount of the AGC-a desensitization factor. The method of claim 1, Automatic tuning for the TV or radio broadcast reception, A method for automatic tuning of frequencies, which can be applied to automatic tuning for receiving DMB broadcasting, DAB broadcasting in Europe, and HD radio broadcasting in North America. The method of claim 1, And the strong electric field has an electric field of 80 dBuV or more in which the AGC operates.

Images