JPS63304728A - Reception antenna switching/selecting device - Google Patents

Abstract

PURPOSE:To attain the switching/selection of an antenna in a best receiving state by interlocking an antenna changeover switch section with a latch changeover switch section in response to a command from an antenna switching circuit and accumulating the result of noise count at every plural antennas to a corresponding latch and comparing them mutually. CONSTITUTION:An antenna changeover switch section 92 is interlocked with a latch changeover switch section 91 in response to a command from an antenna changeover circuit 8, the result of count of the noise at every plural antennas is stored to corresponding latches 61-64 and the result of count is compared mutually. Thus, an antenna in the best receiving state among the plural antennas 81-84 is switched and selected. Thus, a video signal with less noise is received suitably based on the diversity reception in, e.g., an on-vehicle television receiver.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a method for cutting off receiving antennas! A/i%! For example, in a vehicle-mounted television receiver, the present invention relates to a reception antenna switching/selection device that is capable of accurately receiving video signals with extremely low noise based on diversity reception. be.

[Prior Art] FIG. 3 is a block diagram showing a conventional receiving antenna switching/selection device, as disclosed in, for example, Japanese Patent Laid-Open No. 57-14224. In this Figure 3, (31) ~
(33) are antennas for receiving and receiving video signals, which are television high frequency signals. (34
) is a high frequency switch that connects multiple antennas (31
) to (33) depending on a certain predetermined level. (35) is a television receiver for receiving and receiving video signals switched/selected by the high frequency switch (34). (36) is a first peak hold circuit for storing the peak value of the horizontal synchronization equivalent pulse in the detected video signal. (3)) is a switch circuit for sampling video signals from each of the antennas (31) to (33). (38
) is the second peak hold circuit, and the switch circuit (
This is for storing the peak value of the level sampling signal from 37) and converting it into a corresponding DC voltage signal. Reference numeral (39) is a level comparison circuit for comparing the DC voltage signal from the second peak hold circuit (38) at a certain predetermined timing.

(30) is a control circuit, which is a high frequency switch (34).
), first and second peak hold circuits (36), (38)
, a switch circuit (37), and a level comparison circuit (3
9) to issue the necessary control signals.

Next, the operation of the above conventional example will be explained. antenna(
The video signals received by 31) to 33 are guided to a high frequency switch (34). In this high frequency switch (34), after the vertical synchronization signal in the video signal at a certain point in time, under the control of the control circuit (30), the antennas (31) to (
The video signals from 33) are sequentially switched and input to the television receiver (35).

A first peak hold circuit (38) is provided at the rear stage of the television receiver (35), and this first peak hold circuit (36) detects the peak value of the horizontal synchronization equivalent pulse in the detected video signal. After being reset by a reset signal from the control circuit (30) whose period matches that, the signal retains the peak value of the next horizontal synchronization equivalent pulse. It is configured to output toward the switch circuit (37). The switch circuit (37) is under the control of the control circuit (30),
It is for sampling the level of the video signal from each antenna (31) to (33), and exists within the duration of a predetermined pulse signal for sampling the level of the received/detected video signal. The peak value level of the horizontal synchronization equivalent pulse is always sampled. The level sampling signal obtained in this manner is applied to the second peak hold circuit (38), where its peak value is stored and converted into a corresponding DC voltage signal. Each antenna (31) to (33)
The DC voltage signals converted in this way are applied to the level comparison circuit (39) for each of the horizontal synchronization equivalent pulses in the video signal from . The one with the highest level among them is selected as the ON signal, and the others are O
It becomes an FF signal. These ON and OFF signals are once taken into the control circuit (30) and combined with a drive signal for level sampling, and this combined signal is applied to the high frequency switch (34).
The levels of the video signals from (33) are compared, and the antenna receiving the video signal of the desired level is selected.

[Problems to be Solved by the Invention] The conventional reception antenna switching/selection device is configured and operated as described above, and the level of the horizontal synchronization equivalent pulse in the video signal received from each antenna is However, even if the received video signal contains noise, it is difficult to accurately deal with it. The problem was that it couldn't be done.

This invention was made to solve the above-mentioned problems. For example, it is possible to accurately receive video signals with extremely low noise based on diversity reception in a vehicle-mounted television receiver. An object of the present invention is to obtain a receiving antenna switching/selecting device that is configured to have the following characteristics.

[Means for Solving the Problems] A reception antenna switching/selection device according to the present invention is configured to switch/select the optimum one among a plurality of antennas by a diversity function, a synchronization separation circuit that separates and extracts a synchronization signal within a vertical blanking period from the video signal obtained by the video signal, a video signal amplification circuit that amplifies the video signal, and extracts a certain group of equivalent pulses from the synchronization separation circuit. an equivalent pulse extraction circuit that generates a predetermined gate signal based on the output signal from the equivalent pulse extraction circuit; and a gate signal generation circuit that generates a predetermined gate signal based on the output signal from the equivalent pulse extraction circuit; A digital count circuit that sequentially counts pulsed noise included in a plurality of time periods within a certain time period for an output signal from the circuit, and a digital count circuit that sequentially counts pulse noise contained in a plurality of time periods within a certain time period; Based on a plurality of latches for storing a plurality of sequentially outputted count results in correspondence with each other via a latch changeover switch section, and a predetermined gate signal from the gate signal generation circuit, Comprising a comparison circuit that compares and determines the magnitude relationship between the count results stored in a plurality of latches, and an antenna switching circuit that sequentially switches a plurality of antennas according to the output signal from the comparison circuit. It is.

[Operation] In the present invention, the antenna changeover switch unit is operated in conjunction with the latch changeover switch unit in response to a command from the antenna changeover circuit, and the noise count results for each of the plurality of antennas are sent to the corresponding latch. By accumulating and comparing these count results with each other, the antenna with the best reception condition is switched/selected among the plurality of antennas.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a partial block diagram showing one embodiment of the present invention.

In FIG. 1, (1) is a synchronization separation circuit, which separates and extracts a synchronization signal contained in a video signal as a television high frequency signal. (2)
is an equivalent pulse extracting circuit, and the receiver is for extracting only a certain group of equivalent pulses from the input synchronizing signal.

(3) is a gate signal generation circuit, which generates a required gate signal based on the output signal from the equivalent pulse extraction circuit (2). (4) is a video signal amplification circuit, which performs necessary amplification operations on the input video signal. (5) is a digital count circuit,
Based on a predetermined gate signal from the gate signal generation circuit (3), pulse noise generated in a plurality of specific time periods in the output signal from the video signal amplification circuit (4) is divided into individual time periods. It is counted for each band. (
61) to (64) are first to fourth latches, respectively, which accumulate count values of pulse noise occurring in a plurality of specific time periods in the output signal. . Note that each of the digital count circuit (5) and the first to fourth latches (61) to (64) is a latch changeover switch section (in the changeover switch (9)).
91), the connections are sequentially switched and connected. (7) is a comparison circuit, and gate signal generation circuit (3)
Based on a predetermined gate signal from the antenna switching circuit (8), the magnitude relationship of the count values accumulated in the first to fourth latches (61) to (64) is compared and determined. The first to fourth antennas (81) to (84) depend on the comparison judgment result in the comparison circuit (7).
The selection is made by switching sequentially. Also, (9)
is a changeover switch, which includes a latch changeover switch section (91) and an antenna changeover switch section (92), which operate in conjunction with a predetermined command signal from the antenna changeover circuit (8). This is how it is done.

FIG. 2 is a diagram illustrating waveforms for explaining the operation of the above embodiment. In this Figure 2, Figure 2 (a) shows the video signal applied to the sync separation circuit (1), and Figure 2 (b) shows the various synchronization pulses within the vertical blanking period of the video signal. FIG. 2(e) is a diagram illustrating the waveform of the subsequent equivalent pulse group in the vertical blanking period.

Next, the operation of the above embodiment will be explained with reference to the above-mentioned section 11' and FIG. 2. First, a video signal (a) is transmitted from the first antenna (81) among the first to fourth antennas (81) to (84) to the synchronization separation circuit (1) and the video signal amplification circuit (4). It is being

In this video signal (a), a required video signal to be displayed on the television receiver is inserted between the horizontal synchronizing pulses HS, forming one line. Normally, one field is formed by 262.5 lines, and there is a vertical blanking period VR between one field and the next field. The vertical blanking period VR includes a vertical synchronizing pulse VS period, a preceding equivalent pulse period EQI and a subsequent equivalent pulse Itl1 interval EQ2 sandwiching the vertical synchronizing pulse VS period. Further, over the vertical blanking period VR, horizontal synchronization equivalent pulses ES are inserted so as to alternate with the horizontal synchronization pulses H3.

Then, in the synchronization separation circuit (1), after it is detected that the vertical synchronization pulse vS period in the vertical blanking period VR has ended, in the equivalent pulse extraction circuit (2),
Extraction of the horizontal synchronizing pulse H3 and the horizontal synchronizing equivalent pulse ES (hereinafter collectively referred to as equivalent pulse) included in the subsequent equivalent pulse period EQ2 is started. In order to detect the end of the vertical synchronization pulse VS period, an appropriate integrator is provided in the synchronization separation circuit (1), and the various synchronization pulses are applied to this integrator to obtain a predetermined integration. Detection can be easily performed by performing an operation.

On the other hand, the video signal amplification circuit (4) constantly amplifies the received video signal, and its output signal is applied to the digital count circuit (5). In addition, the equivalent pulse in the subsequent equivalent pulse period EQZ extracted by the equivalent pulse extraction circuit (2) is sent to the gate signal generation circuit (3).
are applied sequentially to In this gate signal generation circuit (3), the digital count circuit (5) and the comparison circuit (7
), and the corresponding gate signals are applied to the digital count circuit (5) and the comparison circuit (7), respectively.

It is now assumed that the period of the vertical synchronizing pulse VS has ended and the subsequent equivalent pulse period EQ2 has started.

At this time, the gate signal generation circuit (3) outputs a predetermined gate signal to the digital count circuit (5) in response to the end of the period of the vertical synchronization pulse (2). Here, the digital count circuit (5) starts operating,
Pulse noise within a period A from the start of the operation until the first equivalent pulse is extracted for the first time is counted, and the count value is accumulated in the corresponding latch. In this case, anything that exceeds either the positive threshold value THI or the negative threshold value T if 2 will be counted as pulse noise. When the period A1 ends, a noise count value corresponding to the noise level of the video signal received from the corresponding antenna has been accumulated in the corresponding lunch. Note that here, since the video signal is being received from the first antenna (81), the first latch (81) corresponding to this first antenna is received.
61), the noise count value is accumulated.Next, in response to the switching command signal from the antenna switching circuit (8), the latch changeover switch section (91) in the changeover switch (9) and Antenna selector switch section (
92) operate in conjunction to select the second latch (62) and select the second antenna (82). A period B, until the second equivalent pulse occurs, is now started, and similarly as described above, this period B1
While counting the pulse noise generated in the antenna, it is accumulated in the corresponding second latch (62).The same operation is continued, and the first to fourth antennas (81) to
(84) The magnitude of the number of noises that will occur when reception is made from each of the corresponding first to fourth
It will be stored in latches (61) to (64). When such a series of operations is completed, a predetermined gate signal is output from the gate signal generation circuit (3) to the comparison circuit (7). In this comparison circuit (7), the magnitude of the noise accumulated in the first to fourth latches (61) to (64) is compared with each other, and based on the comparison result, the antenna switching circuit A necessary command signal is issued to (8). For example, if it is assumed that the number of noises in the third latch (63) is the minimum, a corresponding command signal is issued, and the third antenna (83)
) is selected, and video signals from this point onwards are received.

At this point, the third latch (63) corresponding to the third antenna (83) is connected to the digital count circuit (5), so the next operation for noise capture and comparison is performed. is this third antenna (
83).

Now, looking at the vertical blanking period VR, no intentional signals are input during this period, except for various synchronization pulses and equivalent pulses. Therefore, a plurality of portions in the vertical blanking period VR are individually associated with a plurality of antennas, and the magnitude of noise in each portion is examined. Therefore, it is possible to accurately select the antenna with the best reception conditions in a short time. In the above embodiment, the noise count for the corresponding antenna starts immediately after the vertical synchronization pulse VS period ends. However, the present invention is not limited to this; for example, after the second equivalent pulse is taken into the gate signal generation circuit,
It is also possible for said counting to be started.

This is effective when the integrator included in the synchronization separation circuit has a slow fall during discharge.

[Effects of the Invention] As described above, according to the present invention, in the receiving antenna switching/selecting device configured to switch/select an i-suitable antenna from a plurality of antennas using a diversity function,
In response to a command from the antenna switching circuit, the antenna selection switch section is operated in conjunction with the latch selection switch section, and the noise count results for each of the plurality of antennas are accumulated in the corresponding latch, and these count results are By comparing the antennas with each other, the one with the best reception condition among the plurality of antennas is selected. Therefore, the antenna with the lowest noise can be switched accurately in a short time. The effect of being able to choose is achieved.

[Brief explanation of the drawing]

FIG. 1 is a partial block diagram showing an embodiment of the present invention;
FIG. 2 is a waveform example diagram for explaining the operation of the above embodiment, and FIG. 3 is a partial block diagram showing a conventional example. (1) is a synchronous separation circuit, (2) is an equivalent pulse extraction circuit,
(3) is a gate signal generation circuit, (4) is a video signal amplification circuit, (5) is a circuit to digital run 1, (61) to (
64) are the first to fourth latches, (7) is the comparison circuit, (8)
is the antenna switching circuit, (81) to (84) are the first to fourth antenna switching circuits.
Antenna, (9) a selector switch, (91) a latch selector switch section, and (92) an antenna selector switch section. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. 6. Contents of amendment Procedural amendment written March 23, 1988

Claims (4)

[Claims] (1) In a receiving antenna switching/selection device that uses a diversity function to switch/select the optimal one among multiple antennas, the synchronization signal within the vertical blanking period is separated from the received video signal. a synchronous separation circuit for extracting a certain group of equivalent pulses from the synchronous separation circuit; a video signal amplification circuit for amplifying the video signal; an equivalent pulse extraction circuit for extracting a certain group of equivalent pulses from the synchronous separation circuit; a gate signal generation circuit that generates a predetermined gate signal based on an output signal; and a gate signal generation circuit that generates a predetermined gate signal based on the output signal; A digital count circuit that sequentially counts pulsed noise included in multiple time periods for each time period, and a latch switch for the multiple count results sequentially output from the digital count circuit. The count results accumulated in the plurality of latches are mutually connected via a switch section based on a plurality of latches for accumulation in correspondence with each other and a predetermined gate signal from the gate signal generation circuit. and an antenna switching circuit that sequentially switches a plurality of antennas in accordance with an output signal from the comparison circuit, and in response to a command from the antenna switching circuit, The antenna changeover switch section is operated in conjunction with the latch changeover switch section, the noise count results for each of the plurality of antennas are accumulated in the corresponding latches, and these count results are compared with each other. 1. A reception antenna switching/selection device characterized in that the receiving antenna switching/selecting device switches/selects the antenna with the best reception condition among the antennas. (2) The specific equivalent pulse group is included in a subsequent equivalent period following a vertical synchronizing pulse period within a vertical blanking period in the video signal. Receiving antenna switching/selection device. (3) The equivalent pulse is comprised of a horizontal synchronization pulse and a horizontal synchronization equivalent pulse that alternately exist within the vertical blanking period. Receiving antenna switching/selection device. (4) The reception antenna switching/selection device according to claim 1, wherein the latch changeover switch section and the antenna changeover switch section constitute a changeover switch.