JP2996830B2 - Television ghost measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave emitted from a transmitting antenna in a television broadcast, and a direct wave (desired wave) directly arriving and a reflected wave (non-desired wave) delayed by being reflected by a building or the like. The present invention relates to a ghost measuring device for measuring the amount of ghost interference caused by reception on the same antenna on the receiving side.

[0002]

2. Description of the Related Art (Configuration) FIG. 4 shows a configuration of a conventional ghost measuring device. In FIG. 4, reference numeral 41 denotes a broadcast radio wave input terminal, and reference numeral 42 denotes a tuner for tuning to a target television broadcast radio wave. The tuner includes a high-frequency amplifier 43, an automatic gain adjustment circuit 44, and a mixer circuit 45, and amplifies a carrier wave of the broadcast radio wave. To an intermediate frequency. Reference numeral 46 denotes a synchronous detection circuit, which receives the output of the tuner 42, generates two carrier waves having the same frequency and a phase difference of 90 degrees, and performs synchronous detection on each of them. Output the components. An A / D converter 47 converts the output of the synchronous detection circuit 46 from analog to digital (hereinafter abbreviated as A / D conversion). Reference numeral 48 denotes an arithmetic processing circuit, which is a microprocessor 49, a read only memory (ROM) 50, and a random access memory (RAM) connected to a data bus and an address bus.
51 and the like, and performs arithmetic processing on the digital amount stored in the RAM 51. Reference numeral 52 denotes a printer,
8 and the processing result is printed out. 53
Reference numeral denotes a moving coil type voltmeter, which is connected to the tuner 42 and indicates an output voltage of the automatic gain adjustment circuit 44 which changes according to the electric field strength of the carrier of the input broadcast radio wave. Reference numeral 54 denotes a tuner control circuit, which is connected to the tuner 42 and has a role of tuning the tuner 42 to a target broadcast wave by a signal from the arithmetic processing circuit 48. 55 is an arithmetic processing circuit 4
8 is a system bus connecting between the A / D converter 47, the A / D converter 47, the printer 52, and the tuner control circuit 54.

(Operation) Next, the operation of the above conventional example will be described. In FIG. 4, when a tuner control circuit 54 controls a tuner 42 by a signal from an arithmetic processing circuit 48 to tune to a target broadcast radio wave with respect to a broadcast radio wave input to an input terminal 41, the tuner 42 according to the electric field intensity.
An automatic gain adjustment circuit (hereinafter abbreviated as AGC) 44 controls RF A so that the output of a high-frequency amplifier (hereinafter abbreviated as RF AMP) 43 constituting the preceding stage of the above is controlled to a constant value.
Adjust the gain of MP43. As a result, when the electric field strength of the broadcast radio wave is low, the voltage of the AGC 44 increases and the RF
The gain of AMP43 is increased, and when high, AGC4
Since the voltage of the RF AMP 43 is lowered to lower the gain of the RF AMP 43, the output voltage of the RF AMP 43 is maintained at a constant level. The output voltage of the RF AMP 43 is frequency-converted by a mixer circuit 45 at the next stage, and becomes an intermediate frequency (hereinafter abbreviated as IF; 17.75 MHz in a conventional example) and sent to the next synchronous detection circuit 46. The synchronous detection circuit 46 generates two carrier waves having the same frequency as the IF and having a phase difference of 90 degrees, and performs synchronous detection with the IF and the two carrier waves to obtain an in-phase video signal component and a quadrature video signal component.
These signals are sent to the A / D converter 47 and A / D-converted during a period of about 1 / 2H (about 30 μs) from the leading edge of the vertical synchronization pulse in the in-phase video signal component and the quadrature video signal component. The A / D converted in-phase video signal component and quadrature video signal component are sent to the system bus 55 and stored in the RAM 51 of the arithmetic processing circuit 48. Arithmetic processing circuit 48
Microprocessor 49 performs an operation according to the program stored in the ROM 50 based on the data stored in the RAM 51, obtains the amplitude, phase, and delay time of the ghost wave, outputs the results to the printer 52, and receives the results. Measure the amount of ghost disturbance at the point. The moving coil type voltmeter 53 operates with the AGC voltage of the tuner 42, and is graduated so that the electric field strength of the tuned broadcast radio wave can be recognized.

(Effect) As described above, even in the above-mentioned conventional ghost measuring device, when the target television broadcast wave is tuned due to its configuration, the electric field strength of only the broadcast wave can be known by the moving coil type voltmeter. Can be.

[0005]

However, the electric field strength of the above-mentioned conventional ghost measuring device is as follows. The accuracy of the electric field strength depends on the frequency characteristics of the tuner 42 and the level linearity. 2. Since the moving coil type voltmeter 53 is directly attached to the tuner 42, only the electric field strength of the tuned broadcast radio wave can be known. 3. Since the electric field intensities of a plurality of broadcast waves cannot be known at the same time, the ghost measuring device must be operated a required number of times. There was such a problem.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide an excellent ghost measuring device which can easily and accurately know the electric field strengths of a plurality of broadcast radio waves. It is.

[0007]

According to the present invention, in order to achieve the above object, the output voltage of an automatic gain adjustment circuit for controlling the gain of a high-frequency amplifier of a tuner is converted from analog to digital, and the obtained digital amount is converted. After being temporarily stored in the storage means, the electric field strength is output by performing arithmetic processing in an arithmetic processing circuit.

The present invention also provides a selection circuit for connecting the voltage of the automatic gain adjustment circuit to the A / D converter, and stores the converted digital data in the RAM of the arithmetic processing circuit. The comparison is made with the reference electric field intensity value stored in the ROM.

[0009]

Therefore, according to the present invention, the voltage of the automatic gain adjustment circuit is A / D converted, the digital data thereof is temporarily stored, and arithmetic processing is performed, so that the electric field strength of the broadcast radio wave can be easily and accurately known. Becomes possible. Further, by performing the arithmetic processing by comparing with the reference electric field intensity value stored in the ROM of the arithmetic processing circuit, a more accurate measurement value can be obtained. Further, the tuner is controlled by a program stored in the ROM of the arithmetic processing circuit to tune to a plurality of broadcast radio waves, and the voltage of each automatic gain adjustment circuit is A / D converted and stored, thereby obtaining a plurality of electric field strengths. It is possible to know the value easily and accurately.

[0010]

FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a broadcast radio wave input terminal, 2 denotes a tuner for tuning to a target television broadcast radio wave, and includes a high frequency amplifier (RF AMP) 3, an automatic gain adjustment circuit (AGC) 4, and a mixer circuit 5, The input broadcast wave is amplified and converted to an intermediate frequency (IF). 6
Is a synchronous detection circuit, which receives the output of the tuner 2 and generates two carrier waves having the same frequency and a phase difference of 90 degrees to perform synchronous detection, respectively. The in-phase video signal component and the quadrature video signal component Is output. 7 is A / D
The A / D converter converts the output of the synchronous detection circuit 6 and the signal selection circuit 14 described later into a digital value. Reference numeral 8 denotes a microprocessor, a read only memory (ROM) 10 and a random access memory (RAM) 1 connected to a data bus and an address bus.
1 and the like, and computes various digital quantities stored in the RAM 11. Reference numeral 12 denotes a printer, and an arithmetic processing circuit 8
And the processing result is printed out. Reference numeral 13 denotes a liquid crystal display, which is connected to the arithmetic processing circuit 8 and displays the processing result. 14 is a signal selection circuit, one input of which is connected to the output side of the AGC 4 of the tuner 2;
The other input is connected to the in-phase video signal component of the synchronous detection circuit 6, and the microprocessor 9 of the arithmetic processing circuit 8
Switches between these two signals and sets one of them to A
/ D converter 7. Reference numeral 15 denotes a tuner control circuit, which is connected to the tuner 2 and tunes the tuner 2 to a target broadcast wave by a signal from the arithmetic processing circuit 8. 1
6 is an arithmetic processing circuit 8, an A / D converter 7, a printer 12,
This is a system bus that connects between the liquid crystal display 13, the signal selection circuit 14, and the tuner control circuit 15.

(Operation) Next, the operation of the above embodiment will be described. In FIG. 1, when a tuner control circuit 15 controls a tuner 2 by a signal from an arithmetic processing circuit 8 and tunes to a target broadcast radio wave with respect to a broadcast radio wave input to an input terminal 1, the tuner 2 according to the electric field intensity thereof. The AGC 4 adjusts the gain of the RF AMP 3 so that the output of the RF AMP 3 constituting the preceding stage is controlled to a constant value. As a result, when the electric field strength of the broadcast radio wave is low, the voltage of the AGC 4 increases to increase the gain of the RF AMP3, and when it is high, the voltage of the AGC 4 decreases to decrease the gain of the RF AMP3. Is maintained at a constant level. The output voltage of the RF AMP 3 is frequency-converted by the mixer circuit 5 at the next stage, becomes IF, and is sent to the next synchronous detection circuit 6. The synchronous detection circuit 6 generates two carrier waves having the same frequency as the IF and having a phase difference of 90 degrees, and performs synchronous detection with the IF and the two carrier waves to obtain an in-phase video signal component and a quadrature video signal component.
These signals are sent to the A / D converter 7 and A / D converted during a period of about 1 / 2H (about 30 μs) from the leading edge of the vertical synchronizing pulse in the in-phase video signal component and the quadrature video signal component. The A / D converted in-phase video signal component and quadrature video signal component are sent to the system bus 16 and stored in the RAM 11 of the arithmetic processing circuit 8. The microprocessor 9 of the arithmetic processing circuit 8 performs an arithmetic operation based on the data in the RAM 11 in accordance with the program stored in the ROM 10,
The ghost wave amplitude, phase, and delay time are obtained, and the printer 1
2 and the results are output to the liquid crystal display 13, and the ghost interference wave amount at the receiving point is measured.

Next, the processing for obtaining the electric field strength from the AGC voltage will be described with reference to the flowchart shown in FIG. The microprocessor 9 of the arithmetic processing circuit 8 tunes the tuner 2 to a target channel via the tuner control circuit 15 and selects a channel (step 21).
The signal selection circuit 14 is switched to the AGC side for A / D conversion of the AGC voltage output from the GC 4 (step 2).
2) Send the AGC voltage to the A / D converter 7. The AGC voltage is A / D converted into a digital quantity (step 2).
3) is sent to the system bus 16 and the R
The information is temporarily stored in the AM 11 (step 24). The microprocessor 9 of the arithmetic processing circuit 8 reads the data stored in the RAM 11 and compares it with the reference electric field intensity value stored in the ROM 10 in advance (step 2).
5) If no correction is required, the result is displayed on the liquid crystal display 13 as it is (step 27). If correction is required, the data read from the RAM 11 is processed and corrected (step 26). A more accurate measured value is obtained and displayed on the liquid crystal display 13 (step 27). The liquid crystal display 13 is controlled by the arithmetic processing circuit 8. For example, as shown in FIG. 3, the vertical axis represents the electric field intensity value 31, the horizontal axis represents the selected channel number 32, and a bar graph format such as a bar display 33. Indicates the electric field strength of each channel. Further, the liquid crystal display 13 has a role of performing necessary display related to the operation result of the operation processing circuit 8 and simplifying handling of the ghost measuring device.

The ROM 10 of the reference electric field intensity value
Is stored in the input terminal 1 by inputting the required frequency and electric field strength of the television broadcast wave from the calibrated device,
As described above, the tuner 2 is tuned through the tuner control circuit 15, the AGC voltage at that time is A / D converted by the A / D converter 7 through the signal selection circuit 14, and sent to the system bus 16. It is stored in the ROM 10 of the arithmetic processing circuit 8. Repeat this procedure as needed. In addition, by performing this procedure for each ghost measuring device, the variation as a component of the tuner 2 with respect to the correct electric field intensity can be reduced.
Since the information is stored in the storage unit 10, it is possible to solve the field strength display error depending on the frequency characteristic and the level linearity, which is a problem in the conventional model.

(Effect) As described above, according to the above embodiment, the A / D converter 7 changes the AGC voltage of the tuner 2 to the A / D
The microprocessor 9 of the arithmetic processing circuit 8 reads the data of the RAM 11 according to the program stored in the ROM 10 and compares the read data with the reference electric field intensity value stored in the ROM 10 in advance. Then, by performing the arithmetic processing and, if necessary, performing the correction, there is an advantage that the electric field strength of the broadcast radio wave can be easily and accurately known.

According to the above embodiment, the tuner control circuit 15 is controlled in accordance with the program stored in the ROM 10 of the arithmetic processing circuit 8 to tune the tuner 2 to a plurality of broadcast radio waves in a short time. By storing the electric field intensity data in the RAM 11 and performing the above-described comparison operation correction at once, there is an advantage that a plurality of electric field intensity values can be easily and accurately known.

Further, according to the above embodiment, the electric field intensity is monitored in accordance with the program stored in the ROM 10 of the arithmetic processing circuit 8. Therefore, when the electric field intensity changes suddenly due to the propagation state of radio waves, etc. Has the advantage that inappropriate ghost measurements can be avoided.

Further, according to the above embodiment, there is an advantage that a plurality of electric field intensity values obtained as described above can be displayed on the liquid crystal display 13 at once according to a program stored in the ROM 10 of the arithmetic processing circuit 8. Have. Further, by outputting the result to the liquid crystal display 13, the result can be confirmed in a short time without outputting the result to the printer 12 each time, and there is an advantage that printer paper is saved.

[0018]

The present invention has the following effects as apparent from the above embodiment. 1. Since the AGC voltage is A / D converted and stored as a digital value, arithmetic processing can be performed, and a high-precision electric field intensity value can be obtained by performing arithmetic processing by comparing with a reference electric field intensity value stored in advance in a ROM. it can. 2. The tuner control circuit controlled by the arithmetic processing circuit can tune to a large number of television broadcast waves in a short time. 3. The above 1. And 2. And the liquid crystal display, it is possible to measure and know the electric field strength of a plurality of broadcast radio waves at a time. 4. By monitoring the electric field strength, the case where the ghost measurement is inappropriate can be avoided.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a ghost measuring device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a process of obtaining an electric field intensity from an AGC voltage according to an embodiment of the present invention.

FIG. 3 is a graph showing a display example of an electric field strength of a liquid crystal display according to an embodiment of the present invention.

FIG. 4 is a schematic block diagram of a conventional ghost measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input terminal 2 Tuner 3 High frequency amplifier circuit 4 Automatic gain circuit 5 Mixer circuit 6 Synchronous detection circuit 7 A / D converter 8 Arithmetic processing circuit 9 Microprocessor 10 ROM 11 RAM 12 Printer 13 Liquid crystal display 14 Signal selection circuit 15 Tuner control Circuit 16 System bus

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Imamura 2-2-1 Jinnan, Shibuya-ku, Tokyo Inside the Japan Broadcasting Corporation Broadcasting Center (72) Inventor Kyoko Otsuki 2-2-2 Jinnan, Shibuya-ku, Tokyo No. 1 Inside Japan Broadcasting Corporation Broadcasting Center (72) Inventor Hiroshi Miyazawa 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Japan Broadcasting Corporation Broadcasting Research Institute (58) Field surveyed (Int.Cl. ⁷ , DB name) ) H04N 17/00-17/06

Claims (2)

(57) [Claims] 1. A tuner for tuning to a television broadcast wave, a synchronous detection circuit for synchronously detecting a carrier wave having the same frequency as the broadcast wave and the broadcast wave to extract a video signal, and an analog / digital converter for converting the video signal into an analog signal. A to digital conversion
A / D converter, storage means for storing the digital quantity output from the A / D converter, an arithmetic processing circuit for processing the digital quantity according to a program, and means for outputting the result of the arithmetic processing, The digital amount obtained by analog-to-digital conversion of the output voltage of the automatic gain adjustment circuit for controlling the gain of the high-frequency amplifier in the tuner is temporarily stored in the storage means, and then the electric processing is performed by the arithmetic processing circuit. A television ghost measuring device, characterized by outputting: 2. A signal selection circuit for connecting an output voltage of an automatic gain adjustment circuit of a tuner to an A / D converter,
The digital amount obtained by the A / D converter is stored in a RAM of an arithmetic processing circuit, and the arithmetic processing circuit performs a comparison arithmetic processing with a reference electric field intensity value stored in the ROM. Television ghost measuring device.