JP2012212977A - Broadcast wave receiver, semiconductor integrated circuit, and preset registration method for broadcast wave receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an auto preset function in a broadcast wave receiver subject to movement, such as an on-vehicle terminal, from malfunctioning due to intermodulation distortion in a strong input environment as in a place directly under an antenna.SOLUTION: A broadcast wave receiver includes a frequency search instruction unit which instructs an AGC circuit to set the operation level thereof to a first operation level and a second operation level lower than the first operation level, and also instructs a detection unit to detect the frequency of an output signal at the first operation level and the frequency of an output signal at the second operation level, respectively; a determination unit which determines, based on the field strength of a signal detected at the first operation level and the field strength of a signal detected at the second operation level, whether or not the detected signal has been generated by nonlinear distortion; and a recording instruction unit which, based on the determination result of the determination unit, issues an instruction to record the frequency of the detected signal, except the one generated by nonlinear distortion, in preset memory as the frequency of a receivable receive signal.

Description

  The present invention relates to an auto-preset function of a broadcast wave receiver, and more particularly to an auto-preset function in a strong input environment such as directly under a transmission antenna, which is a receiver with movement such as an in-vehicle terminal.

  Conventionally, in-vehicle radios have a preset memory function for storing receivable frequencies in a memory in advance. As a method of automatically setting this preset memory, there is a function called auto-preset. This function searches the band for several seconds, identifies the field strength of receivable broadcasting stations, and sets the preset memory. It is to update.

  However, the conventional auto-preset may cause a malfunction such as detecting a frequency where a broadcasting station does not exist in a radio wave environment in a reception area, particularly in a strong input environment such as directly under a transmitting antenna.

  In such an in-vehicle radio preset memory function, a preset memory to be changed according to the radio wave environment in the reception area by identifying the current location of the vehicle using GPS (Global Positioning System) or VICS (Vehicle Information Communication System). There has been proposed a method of switching between the current location (see, for example, Patent Document 1).

JP 7-202641 A

However, the way to switch preset memories depending on your location is
1 Cannot be used with terminals that do not have a means of specifying the current location, such as GPS and VICS.
2 The size of the preset memory is increased in order to comprehensively hold the preset memory for each region.
3 When the radio wave environment changes significantly, such as when an antenna is newly installed or a new broadcasting station is added, it is necessary to update the preset memory.
Etc. becomes a problem.

  Therefore, an object of the present invention is to provide a radio receiver capable of preventing malfunctions such as detecting a frequency at which a broadcasting station does not exist in auto-preset, instead of switching preset memories depending on the current location.

  A broadcast wave receiver according to a first invention includes an antenna, an AGC circuit that adjusts a level of a reception signal received by the antenna, a detection unit that detects a frequency of an output signal of the AGC circuit, and the detection unit. A broadcast wave receiver having a preset memory for storing a frequency of a detected signal that is the detected output signal, wherein the operation level of the AGC circuit is lower than the first operation level and the first operation level. Instructing the AGC circuit to set the operation level to 2, and detecting the frequency of the output signal at the first operation level and the frequency of the output signal at the second operation level, respectively. A frequency search instruction unit for instructing the detection unit; an electric field strength of the detection signal at the first operation level; and an electric field strength of the detection signal at the second operation level. Based on the above, it is possible to receive a determination unit that determines whether or not the detection signal is caused by nonlinear distortion, and the frequency of the detection signal excluding that caused by nonlinear distortion based on the determination result of the determination unit And a recording instruction unit for instructing recording in the preset memory as the frequency of the received signal.

Here, the “detection unit” detects the frequency of the output signal of the AGC circuit, but pays attention to one of the functions realized by a circuit composed of a local oscillator, a mixer, an amplifier, a DSP, and the like. It is a thing.
“Nonlinear distortion” refers to signal components other than the received wave generated inside the receiver due to the influence of the received wave, and includes, for example, intermodulation distortion and AM wave intermodulation distortion.
Furthermore, “based on the electric field strength” means using the S meter value obtained by detecting the electric field strength of the output signal by the receiver, but also includes using a numerical value obtained by converting or correcting this. .

  A broadcast wave receiver according to a second aspect of the present invention is the broadcast wave receiver according to the first aspect of the present invention, wherein the determination unit includes the electric field strength of the detection signal at the first operation level, and the second It is characterized in that it is determined whether or not a difference between the electric field intensity of the detection signal at the operation level is nonlinear with respect to a difference between the first operation level and the second operation level. .

  A broadcast wave receiver according to a third aspect of the present invention is the broadcast wave receiver according to the first aspect of the present invention, wherein the determination unit does not detect the electric field strength of the detection signal at the second operation level. It is determined that the detection signal is generated by nonlinear distortion.

  A broadcast wave receiver according to a fourth aspect of the invention is the broadcast wave receiver according to the second or third aspect of the invention, wherein the nonlinear distortion is a third-order intermodulation distortion.

  A broadcast wave receiver according to a fifth aspect of the present invention is the broadcast wave receiver according to the first aspect of the present invention, wherein the AGC circuit includes a first AGC circuit that operates at the first operation level, and the second AGC circuit. A second AGC circuit that operates at an operation level of the first AGC circuit, and the detection unit includes a first detection unit connected to the first AGC circuit and a second detection unit connected to the second AGC circuit. It is characterized by.

  A semiconductor integrated circuit according to a sixth aspect of the invention includes an AGC circuit that adjusts a level of a received signal received by an antenna, a detection unit that detects a frequency of an output signal of the AGC circuit, and the output that is detected by the detection unit A semiconductor integrated circuit that controls a preset memory that stores a frequency of a detection signal that is a signal, and sets an operation level of the AGC circuit to a first operation level and a second operation level lower than the first operation level. A frequency for instructing the AGC circuit to detect and detecting the frequency of the output signal at the first operation level and the frequency of the output signal at the second operation level. A search instruction unit; and an electric field intensity of the detection signal at the first operation level and an electric field intensity of the detection signal at the second operation level. Therefore, the determination unit that determines whether the detection signal is caused by nonlinear distortion, and based on the determination result of the determination unit, the frequency of the detection signal excluding that generated by nonlinear distortion can be received. And a recording instruction unit for instructing recording in the preset memory as the frequency of the received signal.

  A broadcast wave receiver preset registration method according to a seventh aspect of the invention includes an antenna, an AGC circuit that adjusts a level of a reception signal received by the antenna, a detection unit that detects a frequency of an output signal of the AGC circuit, and A preset registration method of a broadcast wave receiver having a preset memory for storing a frequency of a detection signal that is the output signal detected by the detection unit, wherein the operation level of the AGC circuit is set to a first operation level and the The AGC circuit is instructed to set to a second operation level lower than the first operation level, the frequency of the output signal at the first operation level, and the output at the second operation level A detection step for instructing the detection unit to detect each frequency of the signal, an electric field strength of the detection signal at the first operation level, and A determination step for determining whether or not the detection signal is caused by nonlinear distortion based on the electric field strength of the detection signal at an operation level of 2, and a phenomenon caused by nonlinear distortion based on the determination result of the determination unit And a recording step for instructing to record in the preset memory the frequency of the detection signal excluding the frequency as the frequency of the received signal that can be received.

  According to the first, sixth, and seventh inventions, the received signal and the non-linear distortion are distinguished from each other by utilizing the fact that the electric field strength of the non-linear distortion changes when the AGC operation level is changed. Thus, only the frequency of the broadcasting station can be registered in the preset memory by removing nonlinear distortion without needing the above information.

  According to the second invention, when the operation level of the AGC is changed, the received signal and the nonlinear distortion are distinguished from each other by using the fact that the change rate is different between the received signal such as the broadcast wave and the nonlinear distortion such as the intermodulation distortion. Therefore, it is possible to accurately discriminate the nonlinear distortion.

  According to the third invention, it is possible to determine whether or not the signal is caused by nonlinear distortion based on the presence or absence of the detection result of the electric field strength of the detection signal without requiring a complicated calculation.

  According to the fourth invention, the third-order intermodulation distortion that appears at a frequency of f2 × 2-f1 is close to the frequencies f1 and f2 of the received signal and has a large level, and thus easily interferes with the received signal. Can be accurately determined.

  According to the fifth aspect, the operation at the first operation level and the operation at the second operation level can be processed in parallel, and the time for the auto-preset operation can be shortened.

The block diagram of the radio receiver in the 1st, 2nd embodiment of this invention Main part block diagram of the radio receiver in 1st, 2nd embodiment of this invention Explanatory diagram showing the spectrum of the reception environment Explanatory drawing which shows the antenna input electric field strength when AGC operation level = Vagc1 Explanatory drawing which shows S meter value before AGC attenuation amount correction | amendment when AGC operation level = Vagc1. Explanatory drawing which shows S meter value in case of AGC operation level = Vagc1 Explanatory drawing which shows the antenna input electric field strength when AGC operation level = Vagc2 Explanatory drawing which shows S meter value before AGC attenuation amount correction | amendment in case of AGC operation level = Vagc2. Explanatory drawing which shows S meter value in case of AGC operation level = Vagc2 Flowchart showing the operation of the radio receiver in the first and second embodiments of the present invention The block diagram of the radio receiver in the 3rd Embodiment of this invention

(First embodiment)
Hereinafter, a radio receiver according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a radio receiver according to the present invention. In this embodiment, a radio receiver, which is a broadcast wave receiver that receives radio broadcasts, will be described as an example. However, a broadcast wave receiver that can receive both radio broadcasts and TV broadcast audio, or TV broadcasts will be described. The present invention can also be applied to a television receiver that can receive audio and television broadcast images.

In FIG. 1 is an antenna for receiving a received signal; 2. Antenna input circuit for impedance matching with the antenna; Is a high frequency amplifier circuit; 4. Mixer for conversion to intermediate frequency, Is a local oscillator for tuning to the desired frequency, 6. Is an intermediate frequency amplifier circuit, 7-1. Is an A / D converter that samples the signal converted to the intermediate frequency and converts it into a digital data string, 7-2. Is 7-2-1. DSP (Digital Signal Processor) that operates according to the program code written in the ROM of 7-3. 7-2. 7. D / A converter for converting the digital audio data demodulated in step 1 into analog audio; Is a speaker that outputs analog audio. The demodulation processing unit 7 is configured by the A / D converter 7-1, the DSP 7-2, and the D / A converter 7-3. 9. Is an AGC (Auto Gain Control) circuit that attenuates the input level to the high-frequency amplifier circuit so that it does not exceed a certain level and outputs it as an output signal to the high-frequency amplifier circuit 3. 10-1. A microcomputer that operates in accordance with the program code written in the ROM 10-2. Is a RAM in which the microcomputer stores the calculation results; Is a preset memory for writing a frequency determined to be receivable by the microcomputer; Is a key input unit that receives key input from the user.
The high-frequency amplifier circuit 3, the mixer 4, the local transmitter 5, the intermediate frequency amplifier circuit 6, the A / D converter 7-1, and the DSP 7-2 constitute the detection unit of the present invention.

  FIG. 2 is a block diagram of the radio receiver microcomputer 10 according to the first embodiment of the present invention as seen from the functions of the present invention.

  10-3 is a frequency search instruction | indication part, and outputs a frequency change command and an AGC level change command to DSP7-2. Receiving the frequency change command, the DSP 7-2 controls the local oscillator 5 to search the frequency within the reception band and obtain the S meter value. The DSP that has received the AGC level change command changes the operation level of the AGC circuit 9 to the first operation level or the second operation level.

  A determination unit 10-4 receives an S meter value (described later) reflecting the electric field strength of the detection signal output from the AGC circuit 9 based on the first operation level and the second operation level. It is determined whether it is caused by nonlinear distortion, that is, based on the electric field strength. Details of the operation of the determination unit will be described later.

  10-5 is a recording instruction | indication part, Based on the determination result of the determination part 10-4, the frequency of the received signal which can receive the frequency of the detection signal except the detection signal determined to generate | occur | produce by nonlinear distortion As a recording instruction to the preset memory 11.

The operation of the radio receiver configured as described above and the preset registration method of the radio receiver will be described below with reference to the configuration of the radio receiver of FIGS. 1 and 2 and the flowchart of FIG. .

First, an auto preset request is input from the user to the key input unit 12.
On the other hand, the frequency search instruction unit 10-3 of the microcomputer 10 issues an AGC level change command to the DSP 7-2, and sets the operation level of the AGC circuit 9 to the first operation level (Vagc1). (S101). Note that this operation is not necessary when the default is set to the first operation level.

  Then, the frequency search instruction unit 10-3 issues a frequency change command to the DSP 7-2. Then, the DSP 7-2 changes the control voltage of the VCO (Voltage Controlled Oscillator) of the local oscillator 5 to search for a frequency within the band, and tunes to a certain frequency. That is, first, the output of the local transmitter 5 is set to the lower limit frequency of the band (S102), the S meter value [dBuV] indicating the electric field strength of the reception frequency is obtained (S103), and the tuning frequency is increased by one step. This is repeated until the upper limit frequency of the band is reached (S104). The S meter value [dBuV] is a value obtained by detecting the electric field strength of the reception frequency inside the receiver. The input level sampled by the A / D converter 7-1 is converted into an AGC circuit by the DSP 7-2. 9 is corrected to an antenna input conversion level by correcting the attenuation amount.

Here, in the case of the conventional preset operation, the S meter value is read by the microcomputer 10, and the value of the S meter is equal to or greater than the threshold value Vth [dBuV] set by the program stored in the ROM 10-1. If it is, the frequency is determined to have a sufficient received electric field level and recorded in the preset memory 11.
As an example, assume a reception environment as shown in the spectrum of FIG. At this time, when it is determined that a broadcast station having an electric field strength equal to or higher than Vth [dBuV] can be received and registered in the preset memory 11, the frequencies f1, f2, and f3 are registered in the preset memory by the auto-preset operation. .
However, as shown in FIG. 4, when the AGC is operated so that the input level of the high-frequency amplifier circuit 3 becomes constant with respect to the input of Vagc1 [dBuV] or more, the attenuation is performed so that the level of f2 becomes Vagc1. Therefore, the S meter value calculated by the DSP 7-2 before correcting the attenuation in the AGC circuit 9 is as shown in FIG. That is, distortion occurs in the high-frequency amplifier circuit 3, the mixer 4, and the intermediate-frequency amplifier circuit 6, and an intermodulation component is generated at a frequency of f2 × 2-f1. Therefore, when the attenuation amount of the AGC circuit 9 is corrected, not only f1, f2, and f3 as shown in FIG. 6, but also f2 × 2-f1 becomes a level equal to or higher than Vth [dBuV] and is recorded in the preset memory 11.

  Therefore, subsequently, the frequency search instruction unit 10-3 of the microcomputer 10 issues an AGC level change command to the DSP 7-2, and the second operation level of the AGC circuit 9 is lower than the first operation level. The operation level (Vagc2) is set (S106).

Then, the frequency search instruction unit 10-3 issues a frequency change command to the DSP 7-2. Then, the DSP 7-2 changes the control voltage of the VCO (Voltage Controlled Oscillator) of the local oscillator 5 and tunes to a certain frequency in order to search for the frequency in the band as in the case of the operation at the first operation level. Let That is, first, the output of the local transmitter 5 is set to the lower limit frequency of the band (S107), and the S meter value [dBuV] indicating the electric field strength of the reception frequency is acquired (S108). Then, it is compared with the S meter value obtained at the first operation level in S103, and the determination unit 10-4 determines whether or not the change amount of the S meter value has a third-order gradient (S109). If it does not have a third-order gradient, the recording instruction unit 10-5 records the frequency of the S meter value obtained in S108 in the preset memory 11 assuming that the detection signal is a received signal (S110). On the other hand, if it has a third-order gradient, it is determined that the detection signal is intermodulation distortion, and recording is not performed in the preset memory 11, but the tuning frequency is increased by one step (S111). This is repeated until the upper limit frequency of the band is reached (S112).
Here, the case of searching up from the lower limit of the band to the upper limit has been described, but the same applies to the case of searching down from the upper limit of the band to the lower limit.

  In this embodiment, every time the S meter value is obtained at the second operation level, the S meter value obtained at the first operation level is compared one by one (S109). After completing the search at all frequencies, the corresponding S meters may be compared and determined at the end.

Next, the operation of the determination unit 10-4 will be described in detail.
If the operation level of the AGC circuit 9 is a second operation level (Vagc2) lower than the first operation level, the intermodulation component of the frequency of f2 × 2-f1 is third-order distortion as shown in FIG. The input level changes with a gradient of the third order (3 times on the dB scale). Therefore, the level rapidly decreases with respect to the change amount of Vagc1-Vagc2, which is the difference between the first operation level and the second operation level. For example, as shown in FIG. , F2 × 2-f1 intermodulation distortion component does not occur, and the S2 meter with corrected AGC attenuation does not generate f2 × 2-f1 intermodulation distortion component as shown in FIG. Alternatively, even if an intermodulation distortion component of f2 × 2-f1 is generated, only an intermodulation distortion component considerably smaller than that at the first operation level is generated. Therefore, the following determination method can be adopted.

Example 1
When the f2 × 2-f1 intermodulation distortion component is generated at the second operation level, it is sufficient to determine whether or not the amount of change in the S meter value has a third-order gradient, as in S109. Having a third-order gradient means that, for example, when the operation level of the AGC circuit 9 is reduced by 10 dB, the S meter value is reduced by 30 dB. That is, in decibels,
S1 [f_tune] −S2 [f_tune] = 3 × (Vagc1−Vagc2)
Can be determined as an intermodulation distortion component.

(Example 2)
When the intermodulation distortion component of f2 × 2-f1 does not occur at the second operation level, it is not exactly 3 times. However, if it is non-linear with respect to the difference between the first operation level and the second operation level, it can be determined that it is an intermodulation distortion component.
S1 [f_tune] −S2 [f_tune]> p × (Vagc1-Vagc2)
Here, if p satisfies a constant larger than 1, it may be determined that it is an intermodulation distortion component. p may be appropriately determined depending on the receiving circuit and the receiving environment, or may be changed according to the receiving environment.

(Example 3)
When the intermodulation distortion component of f2 × 2-f1 does not occur at the second operation level, it may be determined that it is the intermodulation distortion component. Since the intermodulation component of the frequency of f2 × 2-f1 is a third-order distortion, the level is abruptly reduced. Therefore, such a determination almost always shows a correct result.

As described above, the determination methods as in the first to third embodiments can be applied to nonlinear distortion in general. Non-linear distortion refers to signal components other than the received wave generated inside the receiver due to the influence of the received wave, and includes, for example, intermodulation distortion and AM wave intermodulation distortion.
Among these, the intermodulation distortion occurs at various frequencies, but the intermodulation distortion that appears at a frequency of f2 × 2-f1 is close to the frequencies f1 and f2 of the received signal, and is a third-order distortion and level. Therefore, it is likely to cause interference with the received signal. Of course, the present invention can be applied to higher-order (fifth-order, seventh-order, etc.) distortions generated at other frequencies.
Further, since the AM wave intermodulation distortion is a secondary distortion, it is a non-linear distortion, and the present invention can be applied to the AM wave intermodulation distortion.

  Further, although the difference (Vagc1-Vagc2) between the first operation level and the second operation level depends on the characteristics of the radio receiver, it is preferably about 10 dB when detecting third-order intermodulation distortion.

Although FIG. 1 shows the case of a superheterodyne radio receiver, a direct conversion system (A / D conversion is performed without conversion to an intermediate frequency) may be used.
An amplifier that amplifies the audio signal may be inserted between the D / A converter 7-3 and the speaker 8.
Further, in FIG. 1, the ROM 7-2-1 exists in the DSP 7-2. However, a ROM in which the program code is stored externally is prepared and downloaded to the internal RAM of the DSP from there. You may make it operate.
Similarly, in FIG. 1, the ROM 10-1 exists inside the microcomputer 10, but a ROM in which program code is stored externally is prepared and downloaded to the internal RAM of the microcomputer from there. You may make it operate.
In FIG. 1, the preset memory 11 exists outside the microcomputer 10, but may be stored in the internal RAM 10-2 of the microcomputer 10.

(Second Embodiment)
The second embodiment of the present invention is a semiconductor integrated circuit mounted on a radio receiver. The configuration is substantially the same as that of the first embodiment, and will be described with reference to FIG.

  Among the elements in FIG. 1, the high-frequency amplifier circuit 3, the mixer 4, the local oscillator 5, the intermediate frequency amplifier circuit 6, the demodulation processing unit 7, and the microcomputer 10 are mounted on a one-chip semiconductor integrated circuit 13. That is, the frequency search instruction unit 10-3, the determination unit 10-4, and the recording instruction unit 10-5, which are main components for realizing preset registration of the present invention, are all included in the one-chip semiconductor integrated circuit 13. .

  The semiconductor integrated circuit according to the second embodiment of the present invention not only controls the AGC circuit 9 outside the semiconductor integrated circuit, but also controls the detection unit included in the semiconductor integrated circuit. However, whether the control target is inside or outside the semiconductor integrated circuit has nothing to do with the essence of the present invention, and can be arbitrarily changed.

(Third embodiment)
The third embodiment of the present invention relates to a double tuner type radio receiver. Hereinafter, a radio receiver according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a block diagram of the radio receiver of the present invention. In addition, the same number is provided about the same structure as 1st Embodiment.

  The radio receiver according to the third embodiment has another tuner in addition to the radio receiver according to the first embodiment. That is, the antenna 21, the antenna input circuit 22, the high frequency amplifier circuit 23, the mixer 24, the local oscillator 25, the intermediate frequency amplifier circuit 26, the demodulation processing unit 27, and the AGC circuit 29 are further provided.

  The AGC circuit 9 operates at the first operation level, while the AGC circuit 29 is configured to operate at the second operation level.

  With this configuration, in the first embodiment, after the operation at the first operation level, the operation level is switched and the AGC circuit is operated sequentially at the second operation level. In the embodiment, the operation at the first operation level and the operation at the second operation level can be processed in parallel. In this case, it is possible to shorten the time for the auto preset operation.

  In the present embodiment, it is desirable that the characteristics of the front ends of the two tuners match. Therefore, instead of the two antennas 1 and 21 shown in FIG. 11, a single antenna is used, and a received signal is input to the antenna input circuit 2 and the antenna input circuit 22 by branching from the antenna. desirable.

  The radio receiver of the present invention is a receiver with movement such as an in-vehicle terminal, and is useful for preventing malfunction due to intermodulation distortion of a circuit during auto-preset operation under a strong input environment such as directly under an antenna. The present invention can also be applied to ordinary radio receivers and broadcast wave receivers such as television receivers where nonlinear distortion such as intermodulation distortion is a problem.

DESCRIPTION OF SYMBOLS 1 Antenna 2 Antenna input circuit 3 High frequency amplifier circuit 4 Mixer 5 Local oscillator 6 Intermediate frequency amplifier circuit 7 Demodulation processing part 7-1 A / D converter 7-2. DSP
7-2-1. ROM (DSP)
7-3. D / A converter 8 Speaker 9 AGC circuit 10 Microcomputer 10-1 ROM (microcomputer)
10-2 RAM (microcomputer)
10-3 Frequency Search Instruction Unit 10-4 Determination Unit 10-5 Recording Instruction Unit 11 Preset Memory 12 Key Input Unit

Claims (7)

An antenna, an AGC circuit that adjusts a level of a reception signal received by the antenna, a detection unit that detects a frequency of an output signal of the AGC circuit, and a frequency of a detection signal that is the output signal detected by the detection unit A broadcast wave receiver having a preset memory for storing
Instructing the AGC circuit to set the operating level of the AGC circuit to a first operating level and a second operating level lower than the first operating level, and the output signal at the first operating level And a frequency search instruction unit that instructs the detection unit to detect the frequency of the output signal and the frequency of the output signal at the second operation level, respectively.
Judging to determine whether the detection signal is generated by nonlinear distortion based on the electric field strength of the detection signal at the first operation level and the electric field strength of the detection signal at the second operation level. And
Based on the determination result of the determination unit, a recording instruction unit that instructs to record in the preset memory the frequency of the detection signal excluding that generated by nonlinear distortion as the frequency of the received signal that can be received;
A broadcast wave receiver.   The determination unit determines that a difference between the electric field intensity of the detection signal at the first operation level and the electric field intensity of the detection signal at the second operation level is the first operation level and the second operation level. The broadcast wave receiver according to claim 1, wherein it is determined whether or not the operation level difference is nonlinear.   2. The broadcast wave reception according to claim 1, wherein the determination unit determines that the detection signal is generated by nonlinear distortion when an electric field strength of the detection signal at the second operation level is not detected. Machine.   4. The broadcast wave receiver according to claim 2, wherein the nonlinear distortion is a third-order intermodulation distortion. The AGC circuit includes a first AGC circuit that operates at the first operation level and a second AGC circuit that operates at the second operation level,
2. The broadcast according to claim 1, wherein the detection unit includes a first detection unit connected to the first AGC circuit and a second detection unit connected to the second AGC circuit. Wave receiver. An AGC circuit that adjusts the level of the received signal received by the antenna, a detection unit that detects the frequency of the output signal of the AGC circuit, and a preset that stores the frequency of the detection signal that is the output signal detected by the detection unit A semiconductor integrated circuit for controlling a memory;
Instructing the AGC circuit to set the operating level of the AGC circuit to a first operating level and a second operating level lower than the first operating level, and the output signal at the first operating level And a frequency search instruction unit that instructs the detection unit to detect the frequency of the output signal and the frequency of the output signal at the second operation level, respectively.
Judging to determine whether the detection signal is generated by nonlinear distortion based on the electric field strength of the detection signal at the first operation level and the electric field strength of the detection signal at the second operation level. And
Based on the determination result of the determination unit, a recording instruction unit that instructs to record in the preset memory the frequency of the detection signal excluding that generated by nonlinear distortion as the frequency of the received signal that can be received;
A semiconductor integrated circuit. An antenna, an AGC circuit that adjusts a level of a reception signal received by the antenna, a detection unit that detects a frequency of an output signal of the AGC circuit, and a detection signal that is the output signal detected by the detection unit A preset registration method for a broadcast wave receiver having a preset memory for storing a frequency,
Instructing the AGC circuit to set the operating level of the AGC circuit to a first operating level and a second operating level lower than the first operating level, and the output signal at the first operating level A detection step for instructing the detection unit to detect the frequency of the output signal and the frequency of the output signal at the second operation level,
Judging to determine whether the detection signal is generated by nonlinear distortion based on the electric field strength of the detection signal at the first operation level and the electric field strength of the detection signal at the second operation level. Steps,
Based on the determination result of the determination unit, a recording step for instructing to record in the preset memory the frequency of the detection signal excluding that caused by nonlinear distortion as the frequency of the received signal that can be received;
A preset registration method for a broadcast wave receiver.