JPH05145799A - Antenna selection controller of tv diversity receiver - Google Patents

Abstract

PURPOSE:To improve a picture quality by reducing a ghost and a noise at the time of mobile reception. CONSTITUTION:A synchronizing separator circuit 2 separates a video signal from an input terminal 1 into horizontal/vertical synchronizing signals, a gate pulse generating circuit 3 generates gate pulses (a)-(u), and a gate circuit 4 extracts a signal of a vertical blanking period therefrom, and outputs it to a 1H delay line 5, and gate circuits 6-1a-6-3. Outputs of the 1H delay line 5 and the gate circuit 4 are allowed to pass through the gate circuits 6-1a, 1b and a ghost noise is detected by ghost noise detecting circuits 7-1a, 1b. Subsequently, in sample holding circuits 8-1a, 8-1b, signals of a one-line portion are compared by a comparing circuit 9-1, inputted to a switch 11-1 and one output signal is selected by a result of comparison, signals from gate circuits 10-1-3 are sent to an antenna switching control signal circuit 14 through an OR circuit 12 and a serial-parallel converting circuit 13, and an antenna switching control signal is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TV diversity receiver, and more particularly, it extracts a noise component containing a ghost from a video signal received by a plurality of antennas and selects an antenna having the minimum noise component. The present invention relates to an antenna selection control device suitable for the receiver that performs control.

[0002]

2. Description of the Related Art A diversity system is used in which, of the four antennas, the antenna having the maximum reception level is selected when mobile reception of broadcast radio waves from a TV station is performed.
FIG. 7 shows a configuration example of a conventional antenna selection control device based on the diversity method. In the figure, 21 is an antenna switching unit, 22 is an antenna selecting unit, 23 is a noise detecting unit, and 24 is a control unit. For example, four antennas 25 are connected to the antenna switching unit 21, and these antennas are selected. RF switches 21-1 to 21-4 and an antenna selector 21- for selectively operating the switches
It has 5 etc.

The noise detecting section 23 detects noise from a video signal above a certain threshold and outputs a diversity operation signal to the control section 24. The control unit 24 controls the antenna selector 24 based on the diversity operation signal by providing a control signal at a timing synchronized with the horizontal / vertical synchronization signal from the video signal.
Output to -5.

The antenna selection unit 22 is for selecting the antenna having the highest input level from the four antennas and fixing it for one field. The antenna selection unit 22 samples the reception level from the video signal and sequentially samples the received values. Are compared and the maximum level antenna detection signal is obtained from the comparison result and sent to the antenna selector 24-5. The antenna selector 25-5 controls the RF switches 25-1 to 25-4 based on the control signal and the antenna detection signal, selects the antenna with the highest reception level, and fixes it for one field.

[0005]

In this conventional method, since the reception level, that is, the electric field strength is used as a criterion for switching the antennas, the antenna having a lot of ghost or jump noise even if the electric field strength is high may be selected. Erroneous detection due to an excessive ghost, for example, when there is a negative ghost with a high frequency phase difference ψ = 180 ° at the position of the detected signal of a certain antenna, even if the other antenna has a higher electric field strength, this There may be situations such as selecting an antenna. In particular, when driving in an urban area where multipaths frequently occur, ghosts are very noticeable and cause a great deal of deterioration in image quality. Therefore, selecting an antenna with a high electric field strength is not always a good method.

An object of the present invention is to select an antenna with the least ghost or jump noise from a plurality of antennas.
In the diversity system for receiving, it is intended to improve the image quality when a ghost or noise is conspicuous when receiving a TV movement or the like, particularly when driving in an urban area.

[0007]

In order to achieve the above object, the present invention detects the levels of video signals received from a plurality of antennas and, based on the detection results, obtains the signals with less noise components. In an antenna selection control device of a TV diversity receiver for selecting and controlling an antenna, control signal generating means for generating a predetermined control signal based on horizontal / vertical synchronization component signals of the received video signal, and based on the control signal Signal extracting means for extracting a signal in the vertical blanking period from the received video signal, first delay means for delaying and outputting the extracted signal by at least one line, and the first delay means based on the control signal. And a noise component extraction means for obtaining each noise component signal included in one line of the output signal of the signal extraction means, Line signal output means for detecting a line and outputting a signal for each line corresponding to the detected level, level comparison means for comparing the signals for each line to obtain a comparison result, and the first delay Means for delaying at least one line each output signal from the means and the signal extracting means, and selecting either of the output signals from the second delay means based on the comparison result. 1 selection means, and 2nd selection means for selecting each output signal of said 1st delay means and said 2nd delay means based on said predetermined control signal and outputting to said noise component extraction means; and said level Selection control means for controlling, based on the comparison result of the comparison means, for each line during the vertical blanking period, control for selecting an antenna for obtaining a received video signal having a low noise component signal level. To.

[0008]

A predetermined control signal is generated on the basis of the horizontal and vertical sync component signals which are synchronously separated from the received video signal. A signal in the vertical blanking period is extracted from the received video signal based on this control signal, and further delayed by one line to extract a noise component signal for one line of each output signal. The signals of one line of the levels of the noise component signals are compared, and at least one of the output signals is
The line-delayed signal is output, and one of the delayed output signals is selected based on the comparison result. An antenna for obtaining a received video signal having a low noise component signal level is selected for each line during the vertical blanking period based on the comparison result.

[0009]

Embodiments of the present invention shown in the drawings will be described below.
FIG. 1 shows an embodiment of an antenna selection control device for a TV diversity receiver according to the present invention. In the figure, 1 is a received video signal input terminal, 2 is a sync separation circuit, 3 is a gate pulse generation circuit, and these circuits constitute the control signal generation means. Reference numeral 4 is a gate circuit which constitutes the signal extracting means. Reference numeral 5 is a 1H delay line, which constitutes the first delay means.

7-1a, 7-1b, 7-2a, 7-2
b, 7-3a and 7-3b are ghost noise detecting circuits, respectively, and these circuits constitute the noise component extracting means.
8-1a, 8-1b, 8-2a, 8-2b, 8-3a,
Reference numerals 8-3b respectively denote sample and hold circuits, which constitute the line signal output means. Reference numerals 9-1, 9-2 and 9-3 respectively denote comparators, which constitute the level comparing means. 5-
1a, 5-1b, 5-2a, 5-2b, 5-3a, 5-
Reference numerals 3b are 1H delay lines, respectively, which constitute the second delay means. 6-1a, 6-1b, 6-2, 6-3 are gate circuits, which constitute the second selecting means. 10-1 to 10-3
Is a gate circuit respectively, and 11-1 to 11-3 are switches respectively, and these constitute the first selecting means. 12
Is an OR circuit, 13 is a serial-parallel conversion circuit, 14
Is an antenna switching control circuit, and these circuits constitute the selection control means. Reference numeral 15 is a ghost noise minimum line output terminal.

Various information such as character multiplex broadcasting data, ghost canceller GCR signals, other test signals, equalization pulses, etc. are provided during the vertical blanking (return line elimination) period of TV radio waves transmitted from a broadcasting station. Is included, but 4H in the odd field and 5H in the even field
There is no signal part over the section. Therefore, it is appropriate to detect the ghost and noise in this non-signal section. The signals in the vertical blanking period are shown in FIG. In the figure, OD
10 to 13H of D (odd field) and 272 to 276H of EVEN (even field) are non-signal sections,
Of these, 10 to 13H and 273 to 276H will be represented by Vn hereinafter. Antenna switching, ghost, and noise detection are performed in this Vn section.

Next, the operation of the embodiment shown in FIG. 1 will be described. Figure 1
In the figure, one of the received video signal input terminals 1 is connected to the sync separation circuit 2 and the other is connected to the gate circuit 4. In the sync separation circuit 2, a horizontal sync signal (H
D) and the vertical synchronizing signal (VD) are separated and input to the gate pulse generating circuit 3, respectively. The gate pulse generation circuit 3 forms the gate pulses A to F shown in FIG.

The gate circuit 4 extracts the Vn section which is a vertical blanking period from the received video signal. The gate circuit 4 may be omitted, but it is necessary when checking whether the Vn section is surely extracted.
One of the output signals of the gate circuit 4 is a gate circuit 6-1a,
The other is input to the 1H delay line 5. The output of the 1H delay line 5 is further input to the gate circuit 6-1b. Now, assume that the input received video signal is as shown in FIG. Figure 3 is OD
D line number LINE No. Although (horizontal scanning period number) is shown, EVEN operates similarly. The same applies to the following, and 10 to 13H are EVEN 273 to 2 respectively.
Equivalent to 76H.

Antenna numbers ANT. No. (Corresponding to one diversity antenna each), and G represents a ghost. The output of the gate circuit 6-1 is the gate pulse B (1H) of FIG.
(D), except for the HD,
It becomes like (e). That is, the 11th signal and the 10th signal are simultaneously input to the 1H delay line 5-1 and the ghost noise detection circuits 7-1a to 3b. Since the ghost and noise components have both positive and negative polarities as shown in FIG. 3A, after the absolute value of the ghost noise component is taken, the peak
Hold. There are an absolute value circuit and a differentiation circuit as a circuit for taking an absolute value. After taking the absolute value, the peak value is held by the peak hold circuit until the end of 11H. The detection circuits 7-1a to 3b include this peak hold circuit.

The output signal of 7-1 is as shown in FIGS. 3 (f) and 3 (g). The sample hold circuit 8-1 samples the value immediately before the end of the 11th H and then holds it for the next 1H. The output signal of the sample hold circuit 8-1 is shown in FIG.
(H) and (i), and the comparator 9-
Input to 1. The output signal of the comparator 9-1 is 11
Since we have information from the second half of the Hth to the end of the 12th H,
The gate circuit 10 uses this as information only for the 1H section.
-1. At the positions of the input terminals α and β of the switch 11-1, the signals of FIGS. 3D and 3E are at the 12th position by the 1H delay line 5-1. If the switch 11-1 is connected to the α side when the output signal of the gate circuit 10-1 is at “H” level, the output of the switch 11-1 is as shown in FIG.
The 11th signal in (a) is selected (FIG. 3 (l)).
That is, in the signal flow up to this point, the received video signal of 10H
The ghost components of the eye and the 11th eye are compared, and the 11th eye having the smaller level is selected.

The signal selected by the switch 11-1 is the ghost noise detection circuit 7-2a and the 1H delay line 5 in the next stage.
-2a, but at the same time, the portion other than the 12th horizontal sync signal HD of the received input signal is also detected by the noise detection circuit 7-2.
b and 1H delay line 5-2b. The gate circuit 6-2 extracts the portion excluding the horizontal synchronizing signal HD from the 12th H, and uses the pulse (j) ′ from which the shaded portion in FIG.

After this, the same operation as when comparing the 10th H and 11th H is performed, and this time the 1st HH and the 1st H of the received video signal.
By comparing the 11th H obtained in 1-1, the output of the gate circuit 10-2 is "L" (Fig. 4 (o)), and the output signal of the switch 11-2 is the 11th H (Fig. 4 (p)). Is obtained. Further, by the same operation, in the state of FIG. 4A, the switch 11-is activated in the section corresponding to the 14th H of the received video signal.
13H with minimum ghost level as output signal of 3
The eye information (FIG. 4 (t)) is obtained as "H" (FIG. 4 (s)) as the output signal of the gate circuit 10-3. The output signals (k), (o), and (s) are input to the 3-input OR circuit 12, and the output signal of the OR circuit 12 (FIG. 4 (u)) is serially input.
Input to the parallel conversion circuit 13. If the sections corresponding to 12H, 13H, and 14H of the received video signal of (u) are [A], [B], and [C], respectively, the result shown in FIG. 5 is obtained. For example, [A] = L, [B] = L, [C] =
LINE with minimum ghost noise component when H
No. Is the 13th H and is [A] = H, [B] = L,
It is the 11th H when [C] = L. From these results, when [C] = H, 13H (ANT. No. # 4),
When [B] = H and [C] = L, 12H (the same # 3),
When [A] = H and [B] = [C] = L, 11H (same #
2), 10H when [A] = [B] = [C] = L (same #
It can be determined that 1) has the minimum ghost noise component. Therefore, by matching the phases of [A], [B], and [C] in the serial-parallel conversion circuit 13, the ANT. No. (Or LINE No.) can be known.

The antenna switching control circuit 12 switches the receiving antenna every 1H in the section where the gate pulse A in FIG. 3B is "H", and then the ghost noise component selected by the serial-parallel conversion circuit 13 It serves to switch to the smallest antenna. The output of the antenna switching control circuit 12 is connected to four RF switches (not shown) for turning on / off the four antenna input signals.
Temporarily, the antenna with the smallest ghost and noise is # 2.
When changing from # 3 to # 3, the output signal of the antenna switching control circuit 12 becomes as shown in FIG. 4 (w) (when (w) is “H”, the connected antennas are selected respectively. ). In FIG. 4 (w), # 2 is selected until the field before the antenna switching timing (9th H in ODD), and 10H
Select # 1 with the eyes, # 2 with the 11H eyes, # 3 with the 12H eyes, # 9 with the 13H eyes, and compare the ghost noise components.
As a result of the determination, only # 3 becomes “H” in the section corresponding to the 14th H, indicating that this is held in the next field (ODD 15H-).

FIG. 6 shows another embodiment in which the embodiment of FIG. 1 is simplified. 6, 1 to 11 and 13 to 15 have the same circuit configurations as 1 to 11 and 13 to 15 of FIG. 1, respectively, and operate in the same manner. The switch of FIG. 6 is 11H of the received video signal.
The section corresponding to the eyes is connected to the X side, and the sections corresponding to the 12H and 13H are connected to the Y side. The control signal for this switch is output from the gate pulse generation circuit 3. If the received video signal is as shown in FIG. 3A, the output signal of the gate circuit 10 is the same as that of FIG. 3U, and the output signal of the antenna switching control circuit 14 is also the same as that of FIG. 4W.

As described above, in the embodiment of FIGS. 1 and 6, the antenna having the minimum ghost and noise components is
It can be selected for each field (1 / 60s).
If the vehicle speed is 50 km / h, the vehicle moves only about 14 cm in 1/60 seconds, so there is no sudden change in the ghost state, and the antenna switching timing is 1
/ 60s is sufficient.

The output terminal 15 shown in FIGS. 1 and 6 outputs ghost and noise components and may be omitted. Further, in particular, the 1H delay line 5-3a, 5-3b, the switch 11-3, and the output terminal 15 of FIG.
It is necessary when the output signal of is used as a control signal for ghost cancellation or the like. In each of the above-described embodiments, the video signal is delayed by 1H for the determination of the minimum value of the ghost noise component, and the comparison is performed each time. However, as another method, 10H is 3H, 11H is 2H, and 12H. May be delayed by 1H to perform comparison / judgment at once.

[0022]

As described above, according to the antenna selection control device of the present invention, ghost noise and the like can be greatly reduced, and the image quality can be improved especially in TV mobile reception.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram showing signals in a vertical blanking period in the ODD and EVEN fields of a video signal.

FIG. 3 is a timing chart for explaining the operation of the embodiment.

FIG. 4 is a timing chart for explaining the operation of the embodiment.

FIG. 5 is an operation explanatory diagram of the embodiment.

FIG. 6 is a block diagram showing another embodiment of the present invention.

FIG. 7 is a block diagram showing an antenna selection control device of a conventional TV diversity receiver.

[Description of Codes] 1 Received Video Signal Input Terminal 2 Sync Separation Circuit 3 Gate Pulse Generation Circuit 4 Gate Circuits 5, 5-1a to 5-3b 1H Delay Line 6 Gate Circuits 7-1a to 7-3b Ghost Noise Detection Circuit 8-1a to 8-3b Sample and hold circuit 9-1 to 9-3 Comparator (comparator) 10-1 to 10-3 Gate circuit 11-1 to 11-3 Switch 12 OR circuit 13 Serial-parallel conversion circuit 14 Antenna switching control circuit 15 Ghost / minimum noise line output terminal

Claims (1)

[Claims] 1. An antenna selection control device for a TV diversity receiver, which detects the levels of video signals received from a plurality of antennas, and selects and controls the antenna from which the signal with less noise components is obtained based on the detection results. A control signal generating means for generating a predetermined control signal based on a horizontal / vertical synchronization component signal of the received video signal, and a signal for extracting a signal of a vertical blanking period from the received video signal based on the control signal Extraction means, first delay means for delaying and outputting the extracted signal by at least one line, and one line of output signals of the first delay means and the signal extraction means based on the control signal. Noise component extraction means for obtaining each noise component signal, and a level of each of the noise component signals for detecting the level of each noise component signal At least one output signal from each of the first delay means and the signal extraction means, a line signal output means for outputting a signal for IN, a level comparison means for comparing the signals for each one line to obtain a comparison result A second delay means for line-delaying and outputting; a first selecting means for selecting one of the output signals from the second delay means based on the comparison result; and a predetermined control signal, During the vertical blanking period, based on the comparison result of the second selection means for selecting each output signal of the first delay means and the second delay means and outputting it to the noise component extraction means, and the level comparison means. An antenna for a TV diversity receiver, comprising: selection control means for controlling, for each line, selection of an antenna for obtaining a received video signal having a low noise component signal level.択制 control device.