JPH04247723A - Detector for radio communication wave - Google Patents

Abstract

PURPOSE:To improve the rapidity and reliability of judgment by judging the existence of the radio communication wave by noise detection signal only when the possibility of the existence of the radio communication wave is judged in the detection device for radio communication wave. CONSTITUTION:When the detection smooth signal outputted from the intermediate frequency amplifier circuit in a reception part 2 is higher than the prescribed comparison level, the reception part 2 outputs the carrier detection signal to a control part 3. When the detection smooth signal in the high frequency noise in the output signal in the demodulation circuit of the reception device 2 is higher than the prescribed comparison level, the reception part 2 outputs the noise detection signal to the control part 3. And when the carrier detection signal is not outputted, it is judged that the broadcasting wave does not exist. When the carrier detection signal is outputted, it is judged that the broadcasting wave exists when the noise detection signal is not outputted, and does not exist when the signal is outputted, after the prescribed time passes. Thus, the existence of the broadcasting wave can be judged at high speed and surely.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication wave detection device for detecting radio communication waves in a superheterodyne receiver.

0002

2. Description of the Related Art Conventionally, receiving devices such as wireless communication devices have been equipped with various functions. For example, it is equipped with a function called a search function that automatically tunes the reception frequency of the wireless communication device to the frequency where wireless communication waves exist. Many of these functions require detection of wireless communication waves, but for example, in the search function, the tuning frequency is changed for each channel separation and wireless communication waves are detected each time. Since this process is repeated until the radio communication waves are detected, it is necessary to detect these radio communication waves at high speed.

[0003] Conventional methods for detecting wireless communication waves are: (1) determining that a wireless communication wave exists when the detected smoothed signal of the intermediate frequency signal output from the intermediate frequency amplifier circuit is larger than a predetermined comparison level; and (2) Demodulation. Detection of high-frequency noise in the output signal of the circuit When the smoothed signal is smaller than a predetermined comparison level, it is determined that a wireless communication wave exists. There is a method (which is notable).

0004

[Problem to be Solved by the Invention] However, in method (2), even if there is no radio communication wave at the frequency being received, if there is a radio communication wave with a strong electric field at an adjacent frequency, the adjacent interference wave causes the wireless communication wave to There is a problem that may lead to a misjudgment that . Furthermore, since the method (2) detects a high frequency in the audio frequency band, there is a problem that the detection time becomes long due to the time constants of the high frequency filter and the detection smoothing circuit.

[0005]

[Means for Solving the Problems] The present invention solves such problems, and is provided in a radio communication wave detection device for detecting radio communication waves in a superheterodyne receiving device. carrier detection means that outputs a carrier detection signal when the detected smoothed signal of the intermediate frequency signal is larger than a predetermined comparison level; noise detection means for outputting a signal; and when the carrier detection means does not output a carrier detection signal, it is determined that there is no broadcast wave, and when the carrier detection signal is detected from the carrier detection means, the noise is detected after a predetermined period of time has elapsed. The noise detection signal output from the detection means determines that a broadcast wave exists when the noise detection signal is not output, and determines that the broadcast wave does not exist when the noise detection signal is output. Features.

[0006]

[Operation] The possibility of the existence of wireless communication waves is determined based on the level of the detected smoothed signal of the intermediate frequency signal output from the intermediate frequency amplifier circuit, and only when there is a possibility, the high frequency noise of the output signal of the demodulation circuit is detected and smoothed. Since the presence of radio communication waves is determined based on the signal, the presence of radio communication waves can be determined quickly and reliably when repeatedly determining the presence of radio communication waves.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention, and the following description will be made with reference to this figure. 1 is an antenna connected to the receiving section 2. The receiving section 2 is an FM superheterodyne receiving device that demodulates radio communication waves and amplifies the demodulated signal, and reproduces it as an audio signal from a speaker or the like. Further, the receiving section 2 outputs a noise detection signal and a carrier detection signal to the control section 3. Control part 3
In order to set the receiving frequency according to the operator's operation, etc., the presence of a wireless communication wave is determined based on the noise detection signal and carrier detection signal from the receiving unit 2, and the signal is sent to the frequency synthesizer oscillator 4, which is configured with a PLL circuit, for example. It outputs a frequency setting signal and is composed of, for example, a microcomputer.

Next, details of the receiving section 2 will be explained using FIG. 2. The receiving unit 2 is a superheterodyne type receiving device, and includes a high frequency amplifier circuit (RF) 10 that tunes and amplifies the received signal of the antenna, and a frequency synthesizer oscillator 4.
a mixing circuit (MIX) 11 that mixes a local oscillation signal from the RF circuit 10 and a signal from the RF circuit 10; an intermediate frequency amplification circuit (IF) 12 that selectively amplifies an intermediate frequency signal among the signals from the MIX 11; It consists of a normal receiving circuit consisting of a demodulation circuit (DET) 13 which demodulates an intermediate frequency signal from the receiver and outputs it to a subsequent low frequency amplifier circuit to reproduce an audio signal from a speaker.

Then, a detection circuit (DET) 17 detects and smoothes the intermediate frequency signal of the IF 12 and outputs a signal indicating the level of the intermediate frequency signal, and the output signal of the DET 17 is compared with a predetermined voltage, and the output signal of the DET 17 is detected. Comparison circuit (CMP) that outputs a carrier detection signal when the voltage is higher than a predetermined voltage
18 are provided.

[0010] Also, a high-pass filter (HPF) 14 passes high frequency components in the audio frequency band of the output signal of the DET 13, that is, noise components, and a high-pass filter (HPF) 14 detects and smooths the output signal of the HPF 14 and outputs a signal indicating the level of noise in the audio signal. Detection circuit (DET) 15 and DET1
A comparison circuit (CMP) 16 is provided which compares the output signal of DET 15 with a predetermined voltage and outputs a noise detection signal when the output signal of DET 15 is equal to or higher than the predetermined voltage.

Next, the operation of the control section 3 will be explained using FIG. 3. In this embodiment, a reception frequency setting operation such as a search function in a wireless communication device will be taken as an example. When the operator performs a reception frequency setting operation, the process first moves to step S1 and performs a frequency setting operation according to the operator's operation. This is done by outputting a frequency setting signal to the frequency synthesizer section 4. This is done, for example, by outputting the frequency division ratio of the variable frequency divider circuit in the PLL circuit.

[0012] In step S2, the process waits for a predetermined time. This waits for the time required to output the carrier detection signal, and waits for a time corresponding to the time constant of the DET 17. In step S3, the presence or absence of the carrier detection signal is determined. If the carrier detection signal is not input, it is determined that there is no wireless communication wave at the reception frequency being tuned, and the process returns to step S1, where the operator's operation is again performed. Set the frequency for the corresponding function.

[0013] If the carrier detection signal is not input, the process moves to step S4 and waits for a predetermined time. This waits for the time required to output the noise detection signal, and waits for a time corresponding to the time constant of the DET 15. Note that due to the frequency relationship, the standby time in step S2 is shorter than the standby time in step S4.

In step S5, it is determined whether or not there is a noise detection signal, and if the noise detection signal is input, it is determined that there is no wireless communication wave at the receiving frequency being tuned, and the process returns to step S1, where the operator again Configure the frequency settings for the functions according to the operation. If the noise detection signal is not input, it is determined that a wireless communication wave exists at the receiving frequency being tuned, and the process moves to step S6, where the receiving frequency is fixed and a receiving operation is performed.

As described above, according to this embodiment, the presence of a wireless communication wave is first determined based on the carrier detection signal, and then it is determined based on the carrier detection signal that there is a possibility of the presence of a wireless communication wave. Since the presence of a wireless communication wave is determined based on the noise detection signal only at the time, the determination can be made quickly and reliably, and the search operation etc. can be performed quickly and reliably.

[0016]

As explained in detail above, according to the present invention, the possibility of the existence of wireless communication waves is determined based on the level of the detected smoothed signal of the intermediate frequency signal output from the intermediate frequency amplifier circuit, and the possibility of the existence of wireless communication waves is determined. Since the presence of a wireless communication wave is determined based on the detected smoothed signal of the high frequency noise of the output signal of the demodulation circuit only when there is a signal, the presence of a wireless communication wave can be determined quickly and reliably when repeatedly determining the presence of a wireless communication wave.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing details of the receiving section 2. FIG.

FIG. 3 is a flowchart showing the operation of the control section 3. FIG.

[Explanation of symbols]

2 Receiving section 3 Control section 4 Frequency synthesizer oscillator

Claims (1)

[Claims] Claim 1: In a radio communication wave detection device for detecting radio communication waves in a superheterodyne receiving device, carrier detection is performed when a detected smoothed signal of an intermediate frequency signal output from an intermediate frequency amplifier circuit is larger than a predetermined comparison level. carrier detection means for outputting a signal; noise detection means for outputting a noise detection signal when a detected smoothed signal of high frequency noise in the output signal of the demodulation circuit is greater than a predetermined comparison level; and a carrier detection signal is output from the carrier detection means. When the carrier detection signal is not detected by the carrier detection means, the noise detection signal is not outputted by the output of the noise detection signal from the noise detection means after a predetermined period of time has elapsed. 1. A wireless communication wave detection device comprising: determining means for determining that a broadcast wave is present, and determining that a broadcast wave is not present when a noise detection signal is output.