JPH0352411A - Tuning method for receiver - Google Patents

Abstract

PURPOSE:To perform just tuning in a short time by storing tuning data just tuned by checking an AFT voltage in a memory as final value data, and using the final value data in following tuning. CONSTITUTION:A tuning voltage set with a PLL(phase locked loop) circuit 5 is supplied to the local oscillation circuit of a tuner 6, and the wave of a frequency corresponding to the voltage can be received. At this time, the wave, when its frequency being set at a central value, is detected with an AFT detection circuit 7 and is fetched in a control part 2, however, when the frequency is deviated from the central value, the tuning data is varied by one step, and the AFT voltage is fetched again, then, is checked. When the just tuning is attained by performing the fine adjustment of the tuning data step by step, the tuning data at that time is written on a RAM 14 as the final value. Thereby, quick just tuning can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for tuning a receiver such as a satellite broadcast receiver.

[Conventional technology]

In a frequency synthesizer type receiver, if the manufacturer presets the frequencies of all channels at the time of shipment, normal tuning will be performed when the user selects a specific channel.

[Problem to be solved by the invention]

However, in a satellite broadcasting system, the satellite broadcasting radio waves in the 12 (DLZ) band received by a parabolic antenna are converted to l by a down converter integrated into the parabolic antenna.
After converting to the GHz band, it is imported into a satellite broadcasting receiver, where a tuning operation is performed to select a specific channel.

In the above-mentioned down converter, frequency conversion is performed by a super heterolog system using a local oscillation frequency, but since this down converter is installed outdoors and in a place with good visibility, sunlight is Therefore, the internal temperature may change drastically and the characteristics of the electronic circuit may change.

For this reason, even if the radio waves of a specific channel are down-converted and taken into the satellite broadcasting receiver, there will be variations in the frequency of that channel. There is a risk that a situation will occur that is not easy to use, and that the image of the product is extremely unfavorable. The present invention has been made in view of these points, and its purpose is to provide a receiver tuning method that allows just tuning in an extremely short time even if the channel frequency changes. ．． [Means for Solving the Problems] To this end, the present invention provides a receiver having a frequency synthesizer type tuning section using a PLL circuit, in which tuning data that has been just tuned by checking the AFT voltage is stored in memory as final value data. Store it and use it for subsequent steps. - The final value data is used when performing the calculation.

Furthermore, by inputting channel data, the standard value tuning data and the final value data can be compared, and if the difference between them is larger than a predetermined value, the final value data can be used as the tuning data.

〔Example〕

Examples of the present invention will be described below. FIG. 1 is a diagram showing blocks for this tuning. Reference numeral 1 denotes a channel button, and 2 a control section comprising a microcomputer that inputs the operation contents of the channel button 1 and outputs tuning data. The control unit 2 is equipped with a ROM 3 in which channel selection data is written in advance, and a RAM 4 in which tuning data as final value data determined by this embodiment is written. The determined tuning data is then output to a PLL (phase lock loop) circuit 5.
The oscillation frequency of the local oscillation circuit of tuner 6 is determined by . Then, the selected radio wave is taken in, and the AFT voltage with the S-shaped characteristic obtained by performing phase discrimination, phase detection, etc. on the video intermediate wave signal is sent to the AFT detection circuit 7.
The tuning data is detected by the controller 2, and the tuning data is then fine-tuned. The tuning operation will be explained below according to the flowchart shown in FIG. First, when specific channel data is loaded into the control circuit 2 by operating the channel button 1, it is first checked whether final value data corresponding to the channel data has been written in the RAM 4. Since it is not written at first, the standard value data corresponding to the channel data is read from the ROM 3 and taken in, and set in the PLL 5 as tuning data. The standard value data written in this ROM 3 is written by the manufacturer at the time of shipment. The tuning voltage set by this PLL circuit 5 is supplied to the local oscillation circuit of the tuner 6.
Then, radio waves with a frequency corresponding to this tuning voltage will be received. At this time, if the frequency of the selected radio wave is at the center value, A
The FTii pressure shows zero, which is detected by the AFT detection circuit 7 and taken into the control section 2, but at this time it is in a just tuning state. The tuning data at this time is written into the RAM 4 as final value data.

However, if the above frequency deviates from the center value,
The AFT voltage appears as a voltage shifted in the positive or negative direction, which is detected by the AFT detection circuit 7 and taken into the control section 2. At this time, the control unit 2 changes the tuning data by one step knob, takes in the AFT voltage again, and checks just tuning. When the tuning data is fine-tuned several times one step at a time until just tuning is achieved, the tuning data at that time is written to the RAM 4 as final value data. Next, when the same channel data is sent to the control unit 2 by operating the channel button l, the final value data has been written to RAM4, so the standard value data in ROM3 and the final value data in RAM4 are compared. If the difference is within the reference value A, the standard value data is set in the PLL circuit 5 read from the ROM 3.

If the difference exceeds the reference value A, the final value data is read from the RAM 4 and set in the PI,L circuit 5 as tuning data.

In this way, if the channel frequency is shifted,
Even if the standard value data is set to PLI and the circuit, it will take a considerable amount of time (several seconds) to just tune, but once the just tuning is done, the tuning data at that time will be stored as the latest winter value data. , it will be set preferentially to the PLL circuit during the next tuning, so
This time, the tuner will be able to tune just right in an extremely short time.

The reason why the standard value data and the final value data are compared when the channel data is taken in is to give priority to the standard value data when the difference between them is small.

In addition, in the above example, RAM is used as the memory for storing the final value data.
4 was used, but non-volatile RAM is preferred. Also,
When a non-volatile RAM is used in this way, it can also be used for standard value data and final value data.

〔Effect of the invention〕

As described above, according to the present invention, even if the frequency of the input channel is shifted, −jL
Once the tuning has been performed, there is an advantage that subsequent tuning can be performed quickly.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a tuning circuit according to an embodiment of the present invention, and FIG. 2 is a flowchart explaining the tuning operation. 1...Channel button, 2...Control negative, 3...
ROM for storing standard value data, 4... RAM for storing final value data, 5... PLL circuit, 6... Tuner (satellite broadcasting receiver), 7... AFT detection circuit.

Claims (2)

[Claims] (1) In a receiver having a frequency synthesizer type tuning unit using a PLL circuit, the tuning data that is just tuned by checking the AFT voltage is stored in the memory as final value data, and the final value is used for subsequent tuning. A receiver tuning method characterized by using data. (2) A patent claim characterized in that by inputting channel data, the standard value tuning data and the final value data are compared, and if the difference is greater than a predetermined value, the final value data is set as the tuning data. The method of tuning the receiver according to the range 1 above.