JP3360963B2 - Diversity control type TV receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity control type TV receiver used in vehicles and the like. 2. Description of the Related Art FIG. 4 is a block diagram schematically showing a diversity control circuit 40 in a conventional diversity control type TV receiver. In the figure, A to D indicate antennas, and the antennas A to D are connected to a high frequency switching circuit 41. The high frequency switching circuit 41 is a TV tuner 42
And an output terminal 42a of the TV tuner 42.
Outputs an audio signal, and outputs a video signal from an output terminal 42b.
The audio signal is input to a synchronization signal generation circuit 44, and the audio signal is passed through an audio detection circuit 45 to a noise canceller circuit 48.
To be entered. Level detection comparison circuit 4
3 timing through the detection comparison result output lines 43 _A ~ 43 _D Control - is connected to Le circuit 46. From the synchronization signal generating circuit 44 vertical drive signal V _D timing control - are input to the Le circuit 46.
Timing control - Le circuit 46 gate - Toparusu noise canceller via the output lines 46a - is connected to the circuit 48 is connected to the switching control circuit 47 via the control line 46 _A -46 _D, the switching control circuit 47 and it is connected to a high-frequency switching circuit 41 through the switching control line 47 _a to 47 _D are. The diversity control circuit 40 configured as described above operates as follows. For example, it is assumed that the signal is currently being received by antenna A. After the audio signal and the video signal are extracted from the broadcast wave received by the antenna A in the TV tuner 42, the audio signal is output to the audio detection circuit 4.
5, and the video signal is supplied to a level detection / comparison circuit 43.
And a synchronization signal generation circuit 44. Vertical drive signal V _D on the basis of the vertical sync pulse of the synchronizing signal generating circuit 44 the video signal is created, timing controller - input Le circuit 46. Vertical drive signal V timing when _D receiving the control - In le circuit 46, selects the large antenna best reception sensitivity by sequentially switching the antennas A~D every time a predetermined time elapses while maintaining a reception by the antenna A principle The sampling mode is started. Then, if there is an antenna that can receive with a higher electric field strength than when receiving with the antenna A, the receiving antenna is switched from the antenna A to the antenna with the higher electric field strength when the sampling mode ends. When the antennas A to D are sequentially switched in the sampling mode, diver noise is generated in the audio signal output from the audio detection circuit 45 due to the antenna switching. On the other hand, a gate pulse having a predetermined pulse width is output from the timing control circuit 46 at the same time when the antenna is switched, and the diver noise is removed in the noise canceller circuit 48. The method of removing the diver noise will be briefly described with reference to FIGS. 5 (a) and 5 (b). [0005] In FIG.
5 shows an audio signal output from the control unit 5. Time t
Receive antennas at ₀ is switched from the antenna A to the antenna B, and the receive antenna at time t ₁ is switched from the antenna A to the antenna C, receive antenna at time t ₂ is assumed to be switched from the antenna A to the antenna D, O - The time t ₀ , t ₁ ,
Each diver at t ₂ - noise 52 to 54 is generated. On the other hand, from the timing control circuit 46, a predetermined pulse width (the time width during which the receiving antenna is switched from the antenna A to the antenna B, or the antenna C, or the antenna D) at times t ₀ , t ₁ and t ₂ . The gate pulses 55 to 57 are output to the noise canceller circuit 48. Noise canceller circuit 4
8, while the gate pulses 55 to 57 are being output,
Waveform shaping is performed on the audio signal 51 to remove diver noises 52 to 54. [0006] However, as shown in FIG. 5C, the antenna input signal is supplied to the high-frequency switching circuit 41.
A phase shift α determined by the input level (electric field strength) occurs before the signal is input to the noise canceller circuit 48 via the TV tuner 42 and the audio detection circuit 45, but the gate pulses 55 to 57 Since the signal is output when the antenna is switched, the diver noises 52 to 5 are output.
4 and the gate pulse 55-57, a time lag of .alpha. As can be seen from FIG. 5C, it is impossible to perform waveform shaping on the audio signal 51 and remove the diver noises 52 to 54 to such an extent that the influence thereof can be ignored. In the case of the diversity control circuit 40, the time lag is corrected by a predetermined (50).
Only done for field strengths (around dB). Therefore, in the conventional diversity control circuit 40,
There is a problem that the diver noises 52 to 54 cannot be sufficiently removed depending on the magnitude of the electric field intensity (when the electric field intensity changes from the predetermined electric field intensity). The present invention has been made in view of the above problems, and can automatically correct the phase difference between the diver noise and the gate pulse even if the electric field strength changes, and can reduce the magnitude of the electric field strength. It is an object of the present invention to provide a diversity control type TV receiver capable of eliminating diver noise. [0008] In order to achieve the above object, a diversity control type TV receiver according to the present invention comprises a plurality of antennas, a plurality of antennas, and a high frequency switch for switching the antennas. retrieving a circuit, an audio signal and a video signal from the received broadcast wave TV Ju - a Na,
Every predetermined time based on the vertical sync pulse of the video signal
Perform switching of the antennas, the highest reception sensitivity magnitude
In a diversity control type TV receiver for selecting an antenna , based on the vertical synchronization pulse,
The noise generated in the audio signal when the antenna is switched
Outputs a gate pulse for removing the inverter noise
A timing control circuit and the gate pulse are output.
While the power is being applied, the audio signal is shaped into a waveform.
Bar - a noise canceller for removing noise - circuit and, before
Timing control for obtaining the time required from the reception of the broadcast wave to the input to the noise canceller circuit based on the electric field strength of the audio signal, and delaying the output timing of the gate pulse based on the time. Means. The TV of the diversity control system according to the above configuration
In the receiver, by the timing control means, prior
Based on the electric field strength of the audio signal extracted from the broadcast wave.
The noise cancellation after the broadcast wave is received.
The time required for input to the ceramic circuit is determined,
The output timing of the gate pulse is delayed based on the obtained time . This makes it possible to make the generation timing of the diver noise coincide with the output timing of the gate pulse, and it is possible to always remove the diver noise regardless of the electric field strength of the input signal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A diversity type T according to the present invention will be described below.
An embodiment of a V receiver will be described with reference to the drawings. FIG. 1 is a block diagram schematically illustrating a diversity control circuit 10 in a diversity-controlled TV receiver according to an embodiment. The diversity control circuit 10 shown in FIG.
Is different from the configuration of the diversity control circuit 40 shown in FIG.
Reference numeral 6 designates a timing control circuit 11 in the diversity control circuit 10, and a level conversion circuit 1 between the voice detection circuit 45 and the timing control circuit 11.
2 and the level comparison circuit 13 are interposed.
Further, the timing control circuit 11 has a data indicating the relationship between the phase difference generated in the input signal and the electric field strength from the reception to the input to the noise canceller circuit 48.
This is a point that a memory 11a for holding the data is internally provided.
Other configurations are the same. The level conversion circuit 12 is constituted by an A / D converter or the like, and outputs a signal S outputted from the sound detection circuit 45.
The meter signal is converted into a digital signal. The level comparison circuit 13 is composed of a comparator or the like that compares a reference voltage corresponding to the electric field strength with a level output from the level conversion circuit 12, and outputs several levels (for example, _four of S _{1 to} S ₄ ). The level control circuit 12 transmits to the timing control circuit 11 the level of the S-meter signal, which has been converted into a digital signal by the level conversion circuit 12, into which of the above-mentioned steps. For example, the S menu - data signal level of When entering the phase of S _3, only S ₃ lines of output line goes high, other lines B - is maintained at a level. The operation of the diversity control circuit 10 configured as described above will be described with reference to FIGS. FIG. 3 is a flow chart showing a method for determining the output timing of the gate pulse in the timing control circuit 11.
FIG. 2 is a timing chart showing an antenna switching operation in the timing control circuit 11 when switching from the antenna A to the antenna B. In the timing chart shown in FIG. 2, signal (1) is a timing chart showing a vertical blanking period when a scanning field shifts from an even field to an odd field. The signal (2) is a timing chart showing the vertical blanking period when the scanning field shifts from the odd field to the even field. Also,
(DA) to (DD) indicate diver switching input data signals, (QA) to (QD) indicate antenna control output signals for switching antennas, S-
A) to (SD) denote S (sample) / H (hold) switch control output signals for controlling on / off of a diver switching input data signal, and Rst denotes a reset signal. Note that, in FIG. 2, the edges of the circles, triangles, and squares are synchronized. [0015] diversity - When Citi control is performed, first, the sampling mode on the basis of the vertical synchronizing pulses V _P in the vertical blanking period - vertical drive signal V _D indicating the start of de is created. Predetermined time after launched vertical drive signal V _D (e.g., 100 [mu] s) after a lapse of a reset signal Rst is turned on, diversity - switching input data - data signal (D-A) ~ (D -D) is L level It is settled. Next, the antennas are sequentially switched from A every predetermined time. In the case of the embodiment, since the antenna A is receiving, the control output signal (QA) of the antenna A remains on. Next, diversity among the S / H switch control output signal at the time of the lapse of 133μs since launched vertical drive signal V _D (S-A) is turned on, had dropped to L level - switching de - (DA) of the data input signal is turned on. Then, the vertical drive signal V _D of the antenna control output signal at the time of the lapse of 160μs from when launched (Q-B) at the same time is turned on (Q-A) off, selection antenna temporary Is switched from antenna A to antenna B. Then, the level detection / comparison circuit 43 compares the electric field strength between the case where the signal is received by the antenna A and the case where the signal is received by the antenna B. As a result, when the electric field strength when received by the antenna B is higher, as shown in FIG. 2, the S / H switch control output signal (165 μs elapses after the rise of the vertical drive signal V _D ). As soon as SB) is turned on, the diver switching data input signal (DA) becomes L
On the other hand, (DB) is raised to the H level. Then, in synchronization with the turning off of the antenna control output signal (QB), (QA) is set to the H level again, and the selected antenna is returned from antenna B to antenna A. The S / H switch control output signal (S-H) is synchronized with the turning off of the antenna control output signal (Q-B).
B) is also turned off. Next, when 192 μs elapses after the rise of the vertical drive signal V _D , the antenna control output signal (QC) is turned on, and at the same time, the antenna control output signal (QA) is turned off. The selected antenna is temporarily switched from antenna A to antenna C. And
In the level detection / comparison circuit 43, the electric field strength when received by the antenna B and the electric field strength when received by the antenna C are compared. Diver Consequently, when the electric field intensity when received by the antenna B is large, also S / H switch control output at the time since it was raised vertical drive signal V _D has elapsed 197μs (S-C) is turned on The H level state of the switching data input signal (DB) and the L level state of other diver switching data input signals are held. The antenna control output signal (QA) is synchronized with the turning off of the antenna control output signal (QC).
Is turned on again, and the selected antenna is returned from antenna C to antenna A again. In addition, the antenna control output signal (Q
The S / H switch control output signal (S-C) is also turned off in synchronization with the turning-off of -C). Next, when 224 μs elapses after the rise of the vertical drive signal V _D , the antenna control output signal (QD) is turned on, and at the same time, the antenna control output signal (QA) is turned off. The selected antenna is temporarily switched from antenna A to antenna D. And
In the level detection circuit 43, the electric field strength when received by the antenna B and the electric field strength when received by the antenna D are compared. As a result, when the electric field intensity when received by the antenna B is large, also S / H switch control output signal at the time of the lapse of 229μs since launched vertical drive signal V _{D (S-D)} is turned on The H level state of the diver switching data input signal (DB) and the L level state of other diver switching data input signals are held. Then, in synchronization with the turning off of the antenna control output signal (Q-D), the S / H switch control output signal (S
-D) is turned off, the diver switching data is read, the antenna control output signal (QB) is turned on, and the selected antenna is switched from antenna D to antenna B. At this point (at the time it was 234μs elapsed since launched vertical drive signal V _D) sampling mode - de is finished, Bruno - Malmö - return to de. Thereafter, reception is performed by the antenna B having the largest electric field strength. As described above, in the diversity control type TV receiver according to the embodiment, a predetermined time (32 μm) is required.
The antenna is switched every s), and the antenna having the highest electric field strength is selected. However, when the switching is performed, diver noise is generated in the audio signal (audio signal). In order to eliminate the noise, a gate pulse is output at the same time as the switching, and the diver is generated in the noise canceller circuit 48. Noise is removed. Simultaneously with the switching of the working example the antenna a timing chart of FIG. 2 - after the lapse of 160μs since launched vertical drive signal V _D in terms of the bets, after the lapse of 192 us, gate Upon expiration 224Myuesu - Instead of outputting the gate pulse, the output of the gate pulse is delayed by a predetermined time τ in accordance with the electric field strength of the input signal. Gate based on the flowchart shown in FIG.
A method of determining the output timing of the pulse (timing control means) will be described. First, in step 1, it is determined whether or not the mode is the sampling mode. If the mode is not the sampling mode, this processing is not performed. In the case of the sampling mode, the process proceeds to step 2, where the level of the S-meter signal received from the audio detection circuit 45 via the level conversion circuit 12 and the level comparison circuit 13 and the electric field strength held in the memory 11a And the data indicating the relationship between the phase difference and the phase difference τ of the input signal (when the input signal is the TV tuner 42,
A noise canceller circuit 48 via an audio detection circuit 45
Is required until the data is input to the server. In step 3, the vertical drive signal V _D is output gate - from Toparusu the reference time to output (= with vertical drive signal V _D is output, the antenna control output signal is turned on antenna It is determined whether or not the time obtained by adding the time τ to the time until the switching is completed has elapsed. When the time obtained by adding the time τ to the reference time elapses, a gate pulse is output to the noise canceller circuit 48. As described above, the diver according to the embodiment is
In a TV receiver of the city control system, a gate pulse is not output immediately when an antenna is switched, but rather a TV tuner 4 is received after an antenna input signal is received.
2. The game is delayed by a time τ required for input to the noise canceller circuit 48 via the voice detection circuit 45.
Therefore, the output timing of the gate pulse with respect to the diver noise can be adjusted, and the diver noise can be sufficiently removed regardless of the magnitude of the electric field intensity. As described in detail above, in the diversity control type TV receiver according to the present invention, regardless of the electric field strength of the antenna input signal, the audio signal is changed with the switching of the antenna. The diver noise generated in the above can be sufficiently removed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram schematically illustrating a diversity control circuit in a diversity control type TV receiver according to an embodiment of the present invention. FIG. 2 is a timing chart showing the operation of the diversity control circuit in the diversity control type TV receiver according to the embodiment. FIG. 3 is a flowchart showing a method of outputting a gate pulse in a timing control circuit. FIG. 4 is a block diagram schematically illustrating a diversity control circuit in a conventional TV receiver of a diversity control method. FIG. 5 is a schematic diagram showing the relationship between the generation timing of the diversity noise and the output timing of the gate pulse in the conventional diversity control type TV receiver. [Description of Signs] 10 Diversity control circuit 11 Timing control circuit 11a Memory (data holding means) 12 Level conversion circuit 13 Level comparison circuit 14 S-meter detection unit 41 High frequency switching circuit 42 TV tuner 43 Level detection comparison circuit 44 Synchronization signal generation circuit 45 Audio detection circuit 47 Switching control circuit 48 Noise canceller circuits A, B, C, D Antenna

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/44 H04B 7/08

Claims (1)

(57) [Claims 1] A plurality of antennas, a high-frequency switching circuit for switching the antennas, and a device for extracting an audio signal and a video signal from a received broadcast wave.
V Ju - a Na, based on the vertical sync pulse of the video signal, a predetermined time interval
Perform switching of the antennas, the highest reception sensitivity magnitude
In a diversity control type TV receiver for selecting an antenna, switching of an antenna is performed based on the vertical synchronization pulse.
The diver noise generated in the audio signal is removed accordingly.
Control for outputting gate pulse for
And the audio signal is output while the gate pulse is being output.
A noise key that removes the diver noise by shaping the waveform
The time required from the reception of the broadcast wave to the input to the noise canceller circuit is determined based on the canceller circuit and the electric field strength of the audio signal, and the output of the gate pulse is determined based on the time. A diversity control type TV receiver, comprising: timing control means for delaying timing.