JPH0353775A - Television signal receiver - Google Patents

Abstract

PURPOSE:To surely discriminate kinds of a television signal before it is led to a signal processing circuit by extracting a signal spectrum of the television signal with 1st and 2nd band pass filter means and using a discrimination means to discriminate whether a broadcast is a 1st broadcast or a 2nd broadcast with a discrimination means. CONSTITUTION:A discrimination circuit 10 discriminates whether a broadcast is a current television broadcast or a High Vision television broadcast from a signal spectrum of a television signal demodulated by an FM demodulator 22. Moreover, the discrimination circuit 10 outputs a signal in response to the result of the discrimination to control the internal connection state of changeover switches 28a, 28b respectively. For example, when a signal representing the current television broadcast is outputted from the discrimination circuit 10, the internal connection state of the changeover switches 28a, 28b is set so that an output signal from a 525-line signal processing circuit 23 is sent to a circuit of the next stage. Thus, the kind of the television signal is discriminated before the processing by the processing circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television signal receiver, and particularly to a television signal receiver having a scanning line count of 525 and a television signal receiver having a scanning line count of 1125.
This invention relates to a shared receiver that can receive high-definition television broadcasts.

[Prior Art] In the current television signal of television broadcasting, one frame consists of 525 scanning lines.

Recently, with the demand for improved image definition, high-definition television broadcasting using television signals composed of a larger number of scanning lines, 1125 in one frame, has also been carried out. Therefore, common receivers that can be applied to both current television broadcasting and high-definition television broadcasting have been put into practical use.

FIG. 5 is a schematic block diagram showing the power of a shared receiver.

Referring to the figure, the broadcast receiving antenna 21 has a frequency of 12 GHz.
IGH, which is an intermediate frequency, receives radio waves broadcast on the
Convert to Z band. The modulated television signal received by the broadcast reception antenna 21 and subjected to frequency conversion is subjected to FM detection and UI modulation by the FM demodulator 22 in the shared receiver 200. The signal processing circuit 23 for 525 lines is
It operates to reproduce the three primary color signals R, G, and B, in which one frame consists of 525 scanning lines, and the vertical/horizontal synchronization signal from the television signal demodulated by the FMui modulator 22. The resulting signals are output to changeover switches 28a and 28b.

Similarly, the 1125 line signal processing circuit 24 converts the television signal demodulated and replayed by the FM demodulator 22 into three primary color signals R, G, and B, in which one frame consists of 1125 scanning lines, and vertically. / Operates to re-input the horizontal synchronization signal and transfers the resulting signal to the selector switch 28.
a and 28b.

The selector switch 28g is set to 5 depending on its internal connection state.
3 primary color signals from the signal processing circuit 23 for 25 lines or 11
One of the three primary color signals from the 25-line signal processing circuit 24 is applied to the video amplification circuit 25. Similarly, the changeover switch 28
b is the synchronizing signal from the 525-line signal processing circuit 23 or the 1125-line signal processing circuit a1, depending on the internal connection state.
One of the synchronization signals from circuit 24 is applied to deflection circuit 26.

The video amplification circuit 25 amplifies the three primary color signals from the 525 signal processing circuit 23 or the three primary color signals from the 1125 signal processing circuit 24 and provides them to the CRT display 27 via the changeover switch 28a.

The deflection circuit 26 controls the deflection coil of the CRT display 27 in response to the synchronous signal No. 43 from the signal processing circuit 23 for 525 lines or the synchronization signal from the signal processing circuit 24 for 1125 lines, which is applied via the changeover switch 28b. A current is applied to 29.

In the CRT display 27, the video amplification circuit 25
An electron beam having an intensity corresponding to the three primary color signals from the screen scans the screen while being deflected by a deflection coil 29, and an image is projected on the screen.

The internal connection state of the changeover switches 28a and 28b is set, for example, by the user manually switching an external switch (not shown) so that a normal image is displayed on the screen of the CRT display. Further, the internal connection state of the changeover switches 28a and 28b is such that, for example, the output signal of the one of the 525-line signal processing circuit 23 and the 1125-line signal processing circuit 24 that outputs a normal synchronization signal is the changeover switch 28a. In some cases, the setting is automatically made so that the output signal is output from 28b and 28b.

[Problem to be solved by the invention]

As described above, in the conventional shared receiver t=m, the output signal of the circuit for processing the current television signal and the circuit for processing the television signal of high-definition television broadcasting, which are in the operating state, is used. , the signals given to the CRT display are switched. In other words, CR
The selection of the signal to be given to the T-display involves indirectly determining the type of signal received via the antenna (whether it is a television signal of current television broadcasting or a television signal of high-definition television broadcasting). It is done by doing. Through such indirect determination, it is difficult to accurately determine the type of received signal. As a result, if an erroneous determination is made, a signal from a processing circuit that does not correspond to the actually received signal is given to the CRT display, and normal reception is not performed.

Therefore, an object of the present invention is to solve the above-mentioned problems, automatically and more accurately determine the type of received signal, and perform normal image and audio reproduction from any type of signal. To provide a television signal receiver capable of

[Means for Solving the Problems] In order to achieve the above-mentioned objects, a television signal receiver according to the present invention frequency-detects and demodulates a television signal received through an antenna. a first bandpass filter means including both a first signal spectrum of the first television broadcast and a second signal spectrum of the second television broadcast; and a discriminating means for discriminating between the first broadcast and the second broadcast in response to the outputs of the first and second band filter means. In addition,
The number of scanning lines in the second television broadcast is greater than the number of scanning lines in the first television broadcast.

[Operation] Since the television signal receiver according to the present invention is configured as described above, the signal spectrum of the television signal received via the antenna is different from the first and second signals.
is extracted by a filter means. Furthermore, it is determined from the outputs of the first and second .:1} band filter means whether the television signal received via the antenna is of the first broadcast or of the second broadcast. Therefore, the type of television signal received via the antenna can be reliably determined before being guided to the signal processing circuit.

[Embodiment] FIG. 1 is a schematic block diagram of a shared receiver showing an embodiment of the present invention.

Referring to the figure, a shared receiver 100 includes, in addition to the functional units included in the conventional shared receiver shown in FIG. Contains 10.

The other functional parts of the shared receiver f: machine 100 and the functions of the antenna 21 are similar to those described above.

The determination circuit 10 determines from the signal spectrum of the television signal demodulated by the FM demodulator 22 whether the signal is in the current television broadcast or in the high-definition television broadcast. Furthermore, the discrimination circuit 10 outputs a signal according to the discrimination result to control the internal connection state of each of the changeover switches 28a and 28b.

When the discrimination circuit 10 outputs a signal indicating that the signal received by the antenna 21 is in the current television broadcast, the internal connection state of the changeover switches 28a and 28b changes to the 525 signal processing given to each switch. The output signal of the same path 23 is set to be transmitted to the next stage circuit.

Conversely, when the discrimination circuit outputs a signal indicating that the signal received by the antenna 21 is a high-definition television broadcast, the changeover switches 28a and 2
The internal connection status of 8b is given to each 1125
The output signal of the main signal processing circuit 24 is set to be transmitted to the next stage circuit.

As described above, according to the present embodiment, either the output signal of the processing circuit for processing the television signal of current television broadcasting or the output signal of the processing circuit for processing the television signal of high-definition television broadcasting can be output. by CR
How to operate the T display 27 is different from the conventional method.
It is determined from the television signal before it is processed by these processing circuits.

FIG. 2 is a schematic block diagram showing an example of the internal configuration of the discrimination circuit 10.

Referring to the figure, a discrimination circuit 10 detects the respective levels of the signals extracted by bandpass filters (hereinafter referred to as BPFs) 1 and 2 that extract signals in different frequency bands, and BPFI and BPF 2. and comparators 5 and 6 that compare the DC potentials outputted from the detection circuits 3 and 4 with predetermined reference levels, respectively, and an inverter that inverts the output of the comparator 6. 7, and a two-man power AND gate 8 which receives the output of the comparator 5 and the output of the inverter 7 as inputs.

The comparator 5 receives the output of the detection circuit 3 at its non-inverting input terminal, receives a predetermined reference potential Refl at its inverting input terminal, and outputs a high-level signal when the output potential of the detection circuit 3 is higher than the reference potential Refl. In the opposite case, a low level signal is output. Similarly, the comparator 6 receives the output of the detection circuit 4 at its non-inverting input terminal and receives a predetermined reference potential at its inverting input terminal, and when the output potential of the detection circuit 4 is higher than the reference potential Ref2, the comparator 6 goes high. In the opposite case, a low level signal is output.

Reference potentials Refl and Ref2 in comparators 5 and 6 are set to values corresponding to boundaries between the presence and absence of signals passing through BPFI and 2, respectively.

The output signal of the AND gate 8 and the output signal of the comparator 6 are sent to the selector switch 2 as output signals of this discrimination circuit.
8a and 28b.

When the above circuit is used as the discrimination circuit 10 in FIG. 1, the changeover switches 28a and 28b are
5 when the output signal of AND gate 8 is high level.
The output signal of the signal processing circuit 23 for 25 lines is given to the next stage circuit, and when the output signal of the comparator 6 is at high level, the output signal of the signal processing circuit 24 for 1125 lines is given to the next stage circuit. When both signals are at a low level, the output signal of either processing circuit is operated so as not to be applied to the next stage circuit.

Before explaining the specific operation of the discrimination circuit shown in FIG. 2, the bands extracted by BPFI and BPF2 will be explained.

Figure 3 shows the bandwidth of the current television signal for television broadcasting (when the number of scanning lines in one frame is 525) and the television signal for high-definition television broadcasting (when the number of scanning lines in one frame is 1125). FIG. 3 is a diagram showing bands extracted by BPFI and BPF2.

In the figure, the horizontal axis represents frequency f and the vertical axis represents gain. As shown in Figure 3(a), the current television signal is 4
．． 5. a video signal having a band of 2 MHz; 7MHz
The subcarriers of PSK (phase shift
PCM (plus code modulation) obtained by modulating the
on) audio signal. On the other hand, the television signal of high-definition television broadcasting is composed of a video signal having a band of 8, IMHz, with a PCM audio signal inserted in the vertical planking period, as shown in FIG. 3(b). Ru. Next, referring to FIG. 3(c), BPFI
The band extracted by BPF2 is set within the band of the current television signal, and the band extracted by BPF2 is set within the band specific to the television signal of high-definition television broadcasting.

Next, the operation of the discrimination circuit shown in FIG. 2 will be explained. In the explanation, also refer to FIG. 4.

FIG. 4 is a diagram showing the relationship between the type of received signal and the presence or absence of output signals from the BPFI and BPF2.

First, if there is no received signal from either the current television broadcast or the high-visibility television broadcast, no output signal is obtained from either the BPFI or the BPF 2, as shown in FIG. 4(a).

Therefore, the output potential of the detection circuit 3 is lower than the reference potential Ref1 in the comparator 5, and the output potential of the detection circuit 4 is also lower than the reference potential Ref2 in the comparator 6. Therefore, a low level potential is applied from the converter 5 to one of the input terminals of the AND gate 8. Therefore, the output potential of AND gate 8 becomes low level.

In other words, when there is no received signal in any of the above, the potential level of the two output signals of the separate circuit III becomes low level. Therefore, in this case, neither of the signal processing circuits 23 and 24 in the The output signal is also not given to the next stage circuit, and no image is displayed on the CRT display 27.

If the received signal is a current television signal, as shown in FIG. 4(b), an output signal is obtained from the BPFI, but no output signal is obtained from the BPF2. Therefore, although the output potential of the detection circuit 3 is higher than the predetermined reference potential Refl in the comparator 5,
Output of detection circuit 2? The i-position is lower than the predetermined reference potential Ref2 in the comparator 6. Therefore, one of the input terminals of the AND gate 8 is given a high-level potential from the comparator 5, and the other input terminal of the AND gate 8 is given a high-level potential that is an inversion level of the output potential level of the comparator. is given from the inverter 7. Therefore, the output potential of AND gate 8 becomes high level. That is, when receiving a current television signal, the high level signal output from the converter 5 is directly applied to the changeover switch via the AND gate 8. Therefore, in this case, an image is displayed on the CRT display 27 by the output signal of the 525-line signal processing circuit.

Conversely, if the received signal is from high-definition television broadcasting, as shown in FIG. 4(C),
When output signals are obtained from both PFI and 2, the output potential of the detection circuit 3 is higher than the uQ potential Ref1 in the comparator 5, and the output potential of the detection circuit 4 is also higher than the reference potential Ref2 in the comparator 6. Therefore, the high level potential from the comparator 5 and the low level potential from the inverter 7 are applied to the input terminal of the AND gate 8 . Therefore, in this case, only the output of the comparator 7 becomes high level. Also,
If the received signal is a high frequency band signal in high-definition television broadcasting, an output signal is obtained only from the BPF 2, as shown in FIG. 4(d). Therefore, the output potential level of comparator 6 becomes high level as in the previous case, and the output potential level of comparator 5 becomes low level. For this reason, AND gate 8
is given a low level potential from the comparator 5 and inverter 7, and outputs a low level signal as in the previous case.

As described above, when receiving a television signal of high-definition television broadcasting, the potential level of the output signal of the AND gate 8 becomes high level regardless of the output potential level of the converter 5. In other words, by operating the inverter 7 and the AND gate 8, the high level signal output from the comparator 5 is not given to the changeover switch.
Only the high level signal output from the converter 6 is given to the changeover switch. Therefore, in this case, an image is displayed on the CRT display 27 based on the output signal of the 1125 Honkawa signal processing circuit.

As described above, the discrimination circuit in this embodiment is a BPF that directly extracts the characteristics of the signal spectrum of each television signal.
In other words, the AND gate 8
is configured so that the output signal does not go high.

Therefore, according to this embodiment, whether the received signal obtained through the antenna is from current TV broadcasting or Ivision TV broadcasting, it is possible to perform stable operation with a simple circuit configuration. The discrimination circuit makes the discrimination more accurate than before.

Note that the configuration of the discrimination circuit and the configuration of the changeover switch are not limited to the present embodiment, and the configuration of the changeover switch may be any configuration that matches the output signal format of the discrimination circuit.

[Effects of the Invention] As described above, according to the television signal receiver according to the present invention, the type of received signal can be automatically determined by directly extracting the characteristics of the signal spectrum included in each received signal. Ru. Therefore, the connection state inside the receiver is automatically and accurately set to adapt to the type of actual received signal. Therefore, images and sounds can be reproduced more reliably than before in accordance with the type of received signal.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a shared receiver showing an embodiment of the present invention, FIG. 2 is a schematic block diagram showing a specific example of the discrimination circuit in FIG. 1, and FIG. FIG. 4 is a diagram for explaining the extracted frequency bands, and FIG. 4 is a diagram for explaining the operation of the discrimination circuit shown in FIG. 2. In the figure, 1 and 2 are BPFs, 3 and 4 are detection circuits, 5 and 6 are comparators, 7 is an inverter, 8 is a two-manufactured AND gate, 10 is a discrimination circuit, 21 is an antenna, 22 is an FM demodulator, 23 is a signal processing circuit for 525 lines,
24 is a signal processing circuit for 1125 lines, 25 is a video amplification circuit, 26 is a deflection circuit, 27 is a CRT display, 28a
and 28b is a changeover switch, 29 is a deflection coil, and 10
0 and 200 are Cogawa receivers. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A television signal receiver capable of receiving a first television broadcast and a second television broadcast having a number of scanning lines greater than the number of scanning lines of the first television broadcast, , demodulating means for frequency detecting and demodulating a television signal received through an antenna, a first signal spectrum of the first television broadcast, and a second signal spectrum of the second television broadcast. a first bandpass filter means including both a signal spectrum of the signal; and a second bandpass filter means including the second signal spectrum; and in response to outputs of the first and second bandpass filter means; A television signal receiver comprising a discrimination means for discriminating between a first broadcast and the second broadcast.