JP3155589B2 - Diversity equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic antenna switching device for use in a television receiver mounted on an automobile (hereinafter, simply referred to as "television"). The present invention relates to an improvement of a so-called diversity device for selecting and switching an antenna.

[0002]

2. Description of the Related Art A receiving method in which a plurality of antennas are provided, an antenna having the best reception condition is selected, and the antennas are switched and used is a diversity receiving method for a mobile body, for example, a television mounted on an automobile or the like. It is widely known as a receiving system.

Referring to FIG. 4, a conventional diversity device will be described. The video signal 2 from the television 1 is connected to an amplifying circuit or a buffer 12 in the synchronization detecting section 11, from which it is connected to a component (composite) synchronizing signal separating circuit 13. The control circuit 1 is connected to a parallel circuit with the synchronization separation circuit 15 and passes through an oscillation circuit 16 and an oscillation circuit 17, respectively.
8 are connected to respective signals, that is, a horizontal output signal 19 and a vertical output signal 20.

[0004] In the conventional diversity receiving method, the diversity circuit operates even when the power of the television is turned off or the television is not connected. That is, as shown in FIG. 4, in a diversity device that receives a video signal 2 from the television 1 and detects a synchronization signal by the synchronization detection unit 11 to take timing of antenna switching, when the synchronization signal is no longer detected, a low-level antenna is used. In order to prevent the oscillation circuit (OSC) 1 from being set at a set period, for example, when the synchronization signal in FIG.
7 with a specific transmission cycle or control circuit 18
The antenna output level sampling and the maximum level antenna detection and switching operation (diversity operation) are performed at the cycle set in the above. Even if the video signal does not enter and the synchronization signal completely disappears, these switching operations are not performed. It was done.

[0005]

Therefore, when the power of the diversity apparatus is turned on and the television is turned off to listen to the radio, noise when the antenna is switched from the television antenna to the radio antenna is radiated to the radio antenna. Noise may be present in the audio. Therefore, when watching a television while parked in a quiet place, the above-mentioned noise at the time of antenna selection and switching becomes annoying in the television sound. That is, when comparing the antenna reception levels by the diversity apparatus, each antenna is sequentially selected, and at that time, the difference in the antenna reception levels modulates the audio carrier, which becomes audio noise (repetitive pulse of about 60 Hz), and causes a very unpleasant sound. There was a problem that.

Further, when a television having no video output is connected to a diversity device (only an antenna is connected), it is difficult to see a white line across the television screen when the antenna is switched. In order to stop the diversity operation, the power of the diversity device must be turned off, which causes a problem that the antenna is not connected to the television and the screen is not displayed.

As a countermeasure, a power switch and a manual changeover switch are provided in the diversity device. Synchronize the power of the television and the power of the diversity device. It is possible that

In the above method, the installation place of the apparatus is limited. That is, the diversity device needs to be installed under a seat, in a dashboard, or the like, but this makes it difficult to turn on and off the power supply. In order to solve this and make the operation easier, a new installation space is required.

[0009] The method requires a power supply output for a diversity device on the television side. Further, it is conceivable to turn on the power of the diversity device by detecting the current when the television is turned on, but the circuit becomes complicated and the cost increases. And so on.

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems. That is, the noise component of a video signal increases and synchronization is lost, and neither the video signal nor the noise component is lost. The operation of the diversity device is stopped in distinction from disappearance. For example, if the synchronization signal is completely lost, that is, if the TV is turned off, or if it is determined that there is no video signal by detecting the presence or absence of a video signal from the TV, one of the specific antennas should be connected to the TV. And the operation of the diversity device is stopped until a new synchronization signal is input.

[0011]

According to the present invention, there are provided a plurality of antennas, and a synchronization detector for receiving a video signal output from a television receiver connected thereto and outputting a component synchronization signal and a vertical synchronization signal. Detection switching means for performing antenna output level sampling and maximum level antenna detection and switching operation based on these signals, and when it is determined that there is no video signal based on the synchronization signal, any one of the above antennas is set to a television. And a control circuit having an operation stopping means for stopping the operation until a new synchronization signal is input by connecting to the antenna input. A series circuit of a synchronous level clamp circuit and an amplifier circuit, and a component having the output of the amplifier circuit as an input. And it constitutes a a parallel circuit of Component synchronizing signal separating circuit and a vertical synchronizing signal separating circuit.

[0012]

The diversity apparatus according to the present invention receives a plurality of antennas mounted on an automobile and a video signal output from a television receiver connected thereto, and receives a series circuit of a synchronous level clamp circuit and an amplifier circuit; The output of this amplifier circuit is used to output a component synchronization signal and a vertical synchronization signal from the component synchronization signal separation circuit and the vertical synchronization signal separation circuit, respectively, and the control circuit uses these signals to control the antenna output level sampling and the maximum level of the antenna. When the control circuit determines that there is no video signal based on the synchronization signal and performs a detection and switching operation, connect any one of the specific antennas to the antenna input of the television and wait until a new synchronization signal is input. During this time, the operation is stopped.

[0013]

FIG. 1 is a block diagram of a synchronization detector according to an embodiment of the present invention. The present invention basically includes a plurality of antennas (not shown), a television receiver 1, and a synchronization detection circuit 3.
And a control circuit 8. The synchronization detection circuit 3 includes a synchronization level clamp circuit 4, an amplification circuit 5, a component synchronization signal separation circuit 6, and a vertical synchronization signal separation circuit 7. The output from the television receiver 1 is connected to a synchronization level clamp circuit 4, to which an amplifier circuit 5 is connected in series and connected to a parallel circuit of a component synchronization signal separation circuit 6 and a vertical synchronization signal separation circuit 7. Is done. The component synchronization signal separation circuit 6 and the vertical synchronization signal separation circuit 7 are connected to a control circuit.

Next, the operation will be described with reference to FIGS. 1, 2 and 3. The video signal 2 from the television receiver 1 has the same sync signal level in the video signal 2 by the sync level clamp circuit 4, and the amplitude is amplified by the amplifier circuit 5. The component synchronizing signal component 9 in the amplified video signal is taken out by the component synchronizing signal separating circuit 6, and the vertical synchronizing signal component 10 is converted into the vertical synchronizing signal separating circuit 7.
Remove by The component synchronizing signal 9 and the vertical synchronizing signal 10 extracted from the video signal 2 are both inputted to the control circuit 8, and the sampling of the antenna output level and the detection of the antenna of the maximum level and the detection of the antenna of the maximum level are performed during the vertical blanking period. It is used as a reference for the timing of the switching operation.

Next, referring to FIG.
When a normal (non-disturbed) video signal such as the input video signal 21 of (a) is input, the component synchronizing signal output 9 of the synchronizing detection circuit 3 outputs the TV repetition except for the vertical synchronizing signal period. A component synchronization output signal 22 that is regularly repeated at a period TH is output.
The vertical synchronizing signal output 10 outputs a vertical synchronizing output signal 23 that is regularly repeated at a vertical repetition cycle TV of the television.
Immediately after the vertical synchronizing signal within the vertical blanking period, sampling of the antenna output level, detection of the antenna of the maximum level, and switching to the antenna are performed.

The control circuit 8 performs a diversity operation every time a vertical synchronizing signal is input, and then performs the processing shown in FIG. 3A → b → c → d → e. That is, the control circuit 8
After performing the processing of step a, it is determined in step b whether or not the vertical interrupt is within a permissible range, and if it is within the permissible range, it is determined in step c whether or not there is a vertical interrupt. At step d, a vertical interruptless counter (not shown) is cleared, and the process is terminated at step e.
If it is not within the allowable range of the vertical interrupt in step b, the process is immediately terminated in step e.

Even if the vertical synchronizing signal is not detected due to a sudden change in the antenna reception level or the switching of the reception channel, the control circuit 8 keeps the same cycle (about 1/60 second) as the vertical repetition cycle TV. The processing of → b → c → f → g → h is performed, and thereafter the diversity operation is forcibly performed to prevent the antenna from being fixed to the low-level antenna for a long time. That is, the control circuit 8 performs step a
After performing the processing in step b, if it is within the allowable range of the vertical interrupt in step b, it is determined whether there is a vertical interrupt in step c. If there is no vertical interrupt, the counter without vertical interrupt is incremented in step f. ,
At step g, it is determined whether or not the value of the vertical interruption-free counter has reached a predetermined value.

When the antenna reception level is extremely low,
When a non-broadcast channel is being received, the television screen becomes a noise screen, a signal such as the input video signal 24 in FIG. 2A is input to the device, and the component synchronization signal output 9 and the component synchronization signal output 9 of the synchronization detection circuit 3 are output. Vertical sync signal output 1
0, random pulse signals 25 and 26 as shown in FIGS. 2B and 2C are output, respectively. At this time, the control circuit 8 determines the timing of a → b → c → d → e, a → b → c → f → g → h and a → b → d → e in FIG. Since any of the processes is performed and the diversity operation is performed, when the antenna reception level is recovered, the antenna can be switched to the antenna having the maximum reception level.

When the power of the television is turned off or the video input signal line from the television is not connected, the input signal to the diversity device changes completely like the input video signal 27 in FIG. And the component synchronization signal output 28 as shown in FIGS. 2 (b) and 2 (c).
And the vertical synchronizing signal output 29 does not change at all. At this time, the control circuit 8 forcibly performs the diversity operation for a certain time in the processing of a → b → c → f → g → h in FIG. When there is no output from the time when the power of the apparatus is turned on, the processing of a → b → c → f → g → i → j → k in FIG. 3 is performed and fixed to a specific antenna. That is, after performing the processing in step a, if the control circuit 8 is within the allowable range of the vertical interrupt in step b, the control circuit 8 determines whether or not there is a vertical interrupt in step c. After incrementing the counter without vertical interrupt in step g
Then, it is determined whether or not this vertical interruption-free counter has reached a predetermined value. If so, it is determined in step i whether or not the power is to be turned on. And the process ends in step k.

In other cases (in the case where the vertical synchronizing signal is output at first, but is not output completely in the middle), a → b → c → f → g → i → k in FIG. Is performed and the antenna is fixed to the antenna selected before the vertical synchronizing signal is no longer output. After these antennas are fixed, the diversity operation is stopped until the next vertical synchronization signal is detected. When the vertical synchronization signal is detected, the diversity operation immediately returns. The time for forcibly performing the diversity operation for determining which of the above states is obtained by the processing of step g in FIG. 3, and in this embodiment, the predetermined value is the count value 15 (about 0.25).
Seconds) is set. In the above-described operation example, the detection of the video signal being disconnected and the video signal being disconnected is performed by judging only the vertical synchronization signal output. However, in order to ensure the operation, the component synchronization signal output and the horizontal synchronization signal output are determined. Detecting a change in may be used in combination. In a diversity device having a synchronization detection circuit as shown in FIG. 4, an oscillation circuit (OS) when there is no video signal (including noise) is provided.
C) The above operation can be performed by detecting the difference between the natural transmission frequency of 16 or 17 and the horizontal frequency or vertical frequency of the television and determining that there is no video signal (including noise).

[0021]

According to the present invention, the following effects can be obtained. 1. Since there is no need to provide a power switch, the installation location is not limited. 2. When the power of the television receiver is turned off, the diversity operation is automatically stopped and no noise is given to the radio or the like. 3. After the operation of diversity is stopped, the operation of diversity is started immediately when a video signal is input. 4. Since a specific antenna is connected without connecting a video cord, it is possible to cope with a television having no video output. Further, no manual changeover switch is required, and no change in wiring is required. 5. The circuit can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a synchronization detection unit used in a diversity device of the present invention;

FIG. 2 is an output signal waveform diagram of each unit of the diversity device according to the embodiment of the present invention;

FIG. 3 is a flowchart of a diversity device according to the present invention;

FIG. 4 is a block diagram illustrating a synchronization detection unit used in a conventional diversity device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... TV receiver 2 ... Video signal 3, 11 ... Synchronization detection circuit 8, 18 ... Control circuit 9 ... Component synchronization signal 10 ... Vertical synchronization signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/10-1/14 H04B 7/00 H04B 7/02-7/12 H04B 15/00-15 / 06 H04L 1/02-1/06 H04N 5/38-5/46

Claims (2)

(57) [Claims] 1. A plurality of antennas, a synchronization detection unit that receives a video signal output from a television receiver connected thereto and outputs a component synchronization signal and a vertical synchronization signal, and an antenna output level based on these signals. If it is determined that there is no video signal by the detection and switching means and the synchronization signal that performs the operation of detecting and switching the antenna of the sampling and the maximum level, by connecting any specific antenna of the antenna to the antenna input of the TV, A diversity circuit comprising: a control circuit having operation stopping means for stopping the operation of detecting and switching the antenna until a new synchronization signal is input. 2. A series circuit of a synchronization level clamp circuit and an amplification circuit, wherein a synchronization detection unit inputs the video signal, and
2. The diversity device according to claim 1, comprising a parallel circuit of a component synchronizing signal separating circuit and a vertical synchronizing signal separating circuit to which an output of the amplifying circuit is input.