JPH04100307A - Twin tuner television receiver for mobile body - Google Patents

Abstract

PURPOSE:To select a channel whose reception state is excellent by providing a controller controlling the channel selection of two sets of tuners and a changeover means of an output of an IF circuit to the television receiver so as to seek a channel of a same broadcast content automatically. CONSTITUTION:A controller 33 uses a system comprising a channel selection circuit 331a, a tuner 14a and an IF circuit 15a as a usual channel selection system when an output of the tuner 14a and the IF circuit 15a selected by the channel selection circuit 331a is sent to a post-stage circuit by an IF output switching circuit 16 and uses a system comprising a channel selection circuit 331b, a tuner 14b and an IF circuit 15b as a same broadcast content search channel selection to apply search channel selection at all times. In the case of a same broadcast content on a channel different from that for the usual channel selection based on an output of a video signal discrimination circuit 31, to which of IF circuits 15a, 15b a larger input level is given is discriminated based on the output of an input level discrimination circuit 32 and when the input level to the IF circuit 15b is discriminated to be larger, the changeover circuit 16 is selected. Thus, when a mobile body such as a vehicle moves in excess of the service area of a television broadcast wave, a channel of a same broadcast content is automatically sought and a channel whose reception state is excellent is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television receiver used in a moving body such as a vehicle.

[Conventional technology]

2. Description of the Related Art As a conventional technology related to a television receiver used in a moving body such as a vehicle, a die part tea reception system is well known.

The diversity reception system is a 7-stem system in which multiple antennas are installed and the antenna with the highest spatial and directional input level is selected for the reception channel.

[Problem to be solved by the invention]

The service area of television broadcast waves is a radius of 70 to 1100 km even in the largest Tokyo area, and a radius of about 20 to 4 km for typical local key stations.

Furthermore, satellite stations in mountainous areas have a service area with a radius of less than 10 km.

The diversity reception system is a system that identifies the reception channel and obtains the best reception conditions, so it is not effective if the mobile object moves out of the service area.

Therefore, for example, when viewing television broadcasts of the same content continuously in a vehicle moving on a highway, the
The present invention solves the above problems and provides the market with a highly practical mobile television receiver that requires searching and selecting a channel every 0 minutes and re-selecting a channel with the same content. It was made for that purpose.

[Means to solve the problem]

The mobile television receiver of the present invention includes (1) α)
2 sets of tuners, 17 circuits; b) a switching means for selecting one of the outputs of both F circuits and transmitting it to the subsequent circuit; and C) determining which of the input levels of both F circuits is higher. d) means for detecting the phase of the video signal of the outputs of both F circuits;
C) A means for determining whether the video signal modulation contents are the same or not, which is constituted by a video signal comparison means;
1. A twin tuner television receiver for a mobile object, comprising a controller that controls circuit output switching means.

(2) The means for determining which of the input levels of both F circuits is higher is determined by using the video signal S of the output of both F circuits.
/N ratio is replaced with a means for determining which one is better.

[Effect]

The mobile television receiver of the present invention is equipped with two sets of tuners and 17 circuits, one set for normal channel selection and one set for same broadcast content search channel selection.
The output of the engineering F circuit is transmitted to the subsequent circuit by the switching means.

- Broadcast content search tuner, 17 circuits constantly search and select a channel, pause at a certain channel, and modulate the video signal by matching the phase with the video signal and synchronization signal output from both F circuits. It is determined whether the contents are the same or not.

If the video signal modulation content is different, the search is performed again, the channel is temporarily stopped at the next broadcast channel, and the same operation is repeated.

If a channel with the same video signal modulation content is selected, the channel selection operation is stopped and both channels are tuned. It is determined which of the circuit input levels is higher, and if it is determined that the output of the 17th circuit of the same broadcast content search tuner has a lower input level of the circuit F circuit, search and select again. The same operation is repeated, and if it is determined that the output is large, the switching means for the output of the F circuit is switched and, at the same time, a channel selection display is made to indicate that the channel has been switched.

The tuner circuit 17 for normal tuning before switching becomes the tuner circuit 17 for tuning the same broadcast content search after switching, and the same operation is repeated.

With the operations described above, when a moving object such as a vehicle moves beyond the service area of television broadcast waves, it automatically searches for a channel with the same broadcast content and selects a channel with good reception.

[Draft side]

FIG. 7 is a circuit block diagram of an embodiment of the present invention.

(11) The television broadcast wave input from the antenna input is divided into two parts by the distributor via (12) the antenna booster for the purpose of (13) distribution loss and S/N compensation of the distributor, and (14α ) tuner, (15α) 17 circuit, and (14 hot water) tuner, (15b) 17 circuit are supplied in parallel.

Either one of the outputs of the IF circuit is selected by the IF output switching circuit (16), and the output of the chroma circuit (21) at the subsequent stage is selected by the IF output switching circuit (16).
2) Transmitted to the audio circuit.

(51) The video signal discrimination circuit detects the phase difference between the video signals output from both F circuits using the (311) synchronizing signal phase difference detection circuit, and based on the result, determines the delay amount of the (312α) (512h) delay circuit. Control and match the phase, compare it with the error amplification circuit (313), and if the output is close to zero, the F of both
It is determined that the output video signal modulation contents match, that is, they are the same broadcast contents.

(52) The input level discrimination circuit detects a high frequency noise component at the pedestal level during the vertical retrace period using a timing signal based on the synchronization signal of the output of both F circuits, samples and holds it within the vertical period, and Compare the sample-and-hold results of
It is determined that the N ratio is good.

Although the input level discrimination circuit of this embodiment is shown in the circuit block diagram using the above method, it is also possible to compare the human power levels of both 17 circuits using AGO voltage comparison as another method.

(35) The controller includes a tuning circuit (551α) (531h), a control microcomputer (532), and (555)
Consists of a display circuit.

(331α) When the output of the (14α) CHEESE and (15α) 17 circuits selected by the tuning circuit is transmitted to the subsequent circuit by the 1F output switching circuit, this thread is used for normal tuning,
(351b) Tuning circuit, (14b) Tuner, (15b
) A system of 17 circuits is used for search and selection of the same broadcast content, and search and selection are always performed.

Perform a search and pause on a broadcasting channel,
Based on the output of the video signal discrimination circuit, it is determined whether or not the broadcast contents are the same.

If the broadcast content is not the same, or if the same broadcast content is on the same channel as the normal channel selection, the search is performed again, the channel is temporarily stopped at the next broadcast channel, and the same operation is repeated.

If the same broadcast content is on a different channel than the one for regular selection,
Based on the output of the human power level discriminating circuit, it is determined which of the two F circuit outputs has a higher human power level and a better S/N ratio.

In this case, since it is mobile reception, the antenna input level changes from moment to moment for both channels independently, and accurate discrimination cannot be made by instantaneous comparison. Therefore, the embodiment circuit is a human power level discrimination circuit for each vertical return. The output is counted down within a certain period of time, and the output of the counter is used to perform a weighted judgment.

If it is determined that the output of the F circuit for searching the same broadcast content has a worse video signal S/N ratio, search and select the same broadcast again and repeat the initial operation.
At the same time as switching the F output switching circuit, the newly selected channel is superimposed on the primary color signal by the display circuit output.

The circuit F output switching circuit for normal tuning, tuning circuit, tuner, and 17 circuits before switching will be used for tuning the same broadcast content search after switching, and the same operation will be repeated.

(34) The switch circuit is a circuit that stops the function of the present invention, and is used for power saving when the function of the present invention is not required, such as when stopped or when moving within the same service area (541)
It consists of an ON/OFF switch and an electronic switch (542) that prevents malfunctions such as when the antenna input level of the receiving channel falls below the search channel selection sensitivity without the same broadcast content channel, or when moving in a tunnel. Ru. The electronic switch stops the function of the present invention when it is determined that there is no synchronization signal of the receiving channel based on the synchronization signal presence/absence determination signal used for search channel selection.

〔Effect of the invention〕

As described above, according to the present invention, in a television receiver used in a moving object such as a vehicle, while the moving object is moving across service areas of a plurality of television broadcast waves, When watching broadcasts continuously, there is no need to tune in frequently and search for channels with the same content and good reception. Instead, the system automatically searches for channels with the same broadcast content and selects the channel with good reception. It has a very sharp 5 effect.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of one embodiment of the present invention. (11) Antenna input (12) Antenna booster (15) Distributor (1aa) (1ab) Qi, --)- (15α) (15b) 11 circuits (16) Engineering F output switching circuit (21) Chroma circuit (22) Audio circuit (23) Superimpose circuit (51) Video signal discrimination circuit (311) Synchronous signal phase difference detection circuit (312α) (312b) Delay circuit (S15) Error amplification circuit (32) Human power level discrimination circuit (reactor controller a) (,531h) Tuning circuit ) Control microcomputer ) display circuit switch circuit )ONOFF switch ) electronic switch

Claims (2)

[Claims] (1) a) two sets of tuners and IF circuits, b) a switching means for selecting one of the outputs of both IF circuits and transmitting it to the subsequent circuit, and c) whichever of the input levels of both IF circuits is higher. d) means for determining whether the video signal modulation contents are the same, which is comprised of video signal phase detection means for both IF circuit outputs and video signal comparison means; and e) means for determining whether the video signal modulation contents are the same or not. 1. A twin tuner television receiver for a mobile object, comprising a controller that receives the output of the discriminator as an input and controls channel selection of two sets of tuners and IF circuit output switching means. (2) The means for determining which of the two IF circuit input levels is higher is the video signal S/N of both IF circuit outputs.
2. The twin tuner television receiver for a mobile object according to claim 1, further comprising means for determining which of the ratios is better.