JP2000269842A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient reception level in the case of channel selection and to keep a selected channel in a good state in the case of usual reception. SOLUTION: An input signal is fed to a gain control(GC) amplifier 41, from which an output signal is fetched, this output signal is fed to a level comparator circuit 42, where the level is compared with, e.g. a level of the signal at a position of a horizontal synchronizing signal. Then the comparison output is fed to a control terminal of a gain control amplifier 41 through a low pass filter circuit 43 and an amplifier 44. Thus, automatic gain control(AGC) is conducted and this response speed is controlled by a cut-off frequency of the lower pass filter circuit 44 and a gain of the amplifier 44. Then the cur-off frequency and the gain are set by a setting value (digital value) of a register 45 controlled by, e.g. a controlling microcomputer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus suitable for use, for example, for receiving digital television broadcasts. In detail, for example, when detecting a reception channel by tuning or searching, by changing circuit characteristics such as the response speed of the automatic gain control operation, good tuning and detection of the reception channel are performed, and stable detection is performed. In such a case, the reception of the message is maintained.

[0002]

2. Description of the Related Art The configuration of a digital television broadcast receiving apparatus is, for example, as shown in FIG. In FIG. 4, an antenna device 7 such as a parabolic antenna is shown.
1 is supplied to a tuning and intermediate frequency circuit (TU / IF) block 72 which forms the front end of the receiving device. Further, the tuning and intermediate frequency circuit block 7
The signal tuned in step 2 and converted into an intermediate frequency (IF) is supplied to a demodulation circuit block 73 for demodulating the received digital signal.

[0003] A microcomputer 74 for control is provided. The microcomputer 74 controls the operations of the tuning and intermediate frequency circuit block 72 and the demodulation circuit block 73. Further, the digital signal demodulated by the demodulation circuit block 73 is, for example, M
The demodulated audio and video signals supplied to the PEG decoder circuit block 75 and decoded are supplied to a speaker 76 for sound emission and a picture tube (CR) for display, respectively.
T) 77.

In this way, for example, the antenna device 71
Tuning and intermediate frequency circuit (TU / IF) block 72
Of the digital television broadcast received by the demodulation circuit block 73 and demodulated by the demodulation circuit block 73.
5 is supplied. And this decoder circuit block 75
Are supplied to a speaker 76 and a picture tube (CRT) 77, respectively, and are emitted and displayed, respectively.

In such a receiving apparatus, for example, the tuning and intermediate frequency circuit block 72 and the demodulation circuit block 73 are tuned in such a manner that the influence of multipath and the like is minimized so that no demodulation error occurs. Automatic gain control (AG) to keep the channel in good condition
C) is being performed. In this case, such characteristics of the automatic gain control are set by the microcomputer 74 when the power is turned on, for example, and are thereafter fixed at the set values.

On the other hand, in a digital television broadcast receiving apparatus, for example, first, all channels are searched to start receiving, a receiving channel having a signal is detected, and only this receiving channel is stored in a nonvolatile memory or the like. A function called a program is regarded as one of the most important functions. Therefore, performing this operation reliably is a factor that facilitates the subsequent operation of the device and improves the reliability of the device.

That is, in this automatic program, for example, first, the reception of the microcomputer 74 is started.
For example, the tuning frequency in the tuning and intermediate frequency circuit block 72 is continuously changed from the lowest frequency to the highest frequency in the reception band. During this search, the demodulated circuit block 73 detects the demodulated channel of the signal, and the detected channel number and the like are stored in the microcomputer 74.

At the time of normal reception, reception is performed according to the channel number and the like stored in the microcomputer 74 described above. Thereby, for example, by not selecting a channel that has not been demodulated, the operation of the device at the time of channel selection can be performed smoothly, and noise generated by receiving a signal that cannot be demodulated can be reduced. Sound emission and display of meaningless screens can be prevented, and the reliability of the device can be improved.

[0009]

However, in the above apparatus, the automatic gain control is performed in the tuning and intermediate frequency circuit block 72 and the demodulation circuit block 73.
This automatic gain control prevents the level of the received signal from fluctuating abruptly. Therefore, for example, in the above-described auto program, the search may proceed before the reception level of each channel is not sufficiently increased. In this case, the demodulation of the signal in the demodulation circuit block 73 is unstable and the reception channel May not be detected.

For this reason, a process such as reselecting a channel is performed on a channel in which signal demodulation is unstable, and there is a possibility that the entire search takes a long time. On the other hand, the automatic gain control (AGC) in the tuning and intermediate frequency circuit block 72 and the demodulation circuit block 73 described above
It is indispensable in normal reception for the purpose of keeping the selected channel in a good state, such as minimizing the influence of multipath and the like so as not to generate a demodulation error.

The present invention has been made in view of the above points, and the problem to be solved is that the conventional apparatus keeps the channel selected in a good state during normal reception. It is important to make sure that you can obtain a sufficient reception level even at high speed search when selecting a channel or during auto programming, which is one of the most important functions. It was an issue.

[0012]

Therefore, according to the present invention, at the time of channel selection or detection of a reception channel by search, automatic gain control at least in the tuning and intermediate frequency circuit block and / or the demodulation circuit block is performed. The response speed of the operation is made faster than usual,
According to this, a sufficient reception level can be obtained even in a high-speed search at the time of channel selection or in an auto program which is one of the most important functions of a digital television broadcast receiving apparatus, and a normal reception of the program can be obtained. In this case, the selected channel can be maintained in a good state.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a receiving apparatus in which at least various characteristics of a tuning and intermediate frequency circuit block and a demodulation circuit block are controlled by a built-in microcomputer. The microcomputer controls the response speed of the automatic gain control operation in the circuit block and / or the demodulation circuit block to be faster than the response speed when the reception state is maintained. As a result, a sufficient reception level can be obtained even in a high-speed search at the time of channel selection or in the case of an auto program which is one of the most important functions of a digital television broadcast receiving apparatus. Can keep the selected channel in a good state.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an example of a receiving apparatus to which the present invention is applied.

In FIG. 1, a signal from an antenna device 1 such as a parabolic antenna is supplied to a tuning and intermediate frequency circuit (TU / IF) block 2 constituting a front end of a receiving device. This circuit block 2 is tuned (TU)
The circuit 21 includes a circuit 21 and an intermediate frequency (IF) circuit 22. The intermediate frequency circuit 22 includes a gain control amplifier (not shown) described later.
Is provided. As a result, an intermediate frequency (IF) signal tuned and received by the tuning and intermediate frequency circuit block 2 is extracted at a predetermined level.

The output signal of the tuning and intermediate frequency circuit block 2 is supplied to a demodulation circuit block 3 for demodulating a received digital signal. In this circuit block 3,
An internal automatic gain control (AGC) circuit 31 to be described later is connected to the input terminal.
The signal from the automatic gain control circuit 31 is supplied to the time reproduction circuit 32. Then, for example, a timing signal of a horizontal synchronizing signal from the time reproducing circuit 32 is supplied to an automatic gain control circuit 31, and automatic gain control (AG) is performed so as to keep the signal level at the position of the horizontal synchronizing signal constant.
C) is performed.

The output signal of the automatic gain control circuit 31 is supplied to an external automatic gain control (AGC) circuit 33. This automatic gain control circuit 33 is also supplied with, for example, a timing signal of a horizontal synchronization signal from the time reproduction circuit 32. Then, a control signal for performing automatic gain control (AGC) is formed so as to keep the signal level at the position of the horizontal synchronization signal constant, and the control signal is supplied to a gain control amplifier (not shown) provided in the intermediate frequency circuit 22 described above. ).

Further, if the signal passed from the automatic gain control circuit 31 through the time reproduction circuit 32 has a possibility that, for example, a digital broadcast signal and an analog broadcast signal may be present on the same channel, the digital broadcast signal may be disturbed. For removing analog broadcast signals (NTSC)
The signal is supplied to the SC signal removal circuit 34. Further, an equalizer (EQ) for detecting and compensating for a ghost of the received signal and a change in the frequency characteristic is used as a signal from the removing circuit 34.
The signal is supplied to the circuit 35.

The signal from the equalizer circuit 35 is supplied to a digital signal error correction circuit 36, and the received digital signal is demodulated and taken out from the demodulation circuit block 3. Further, the digital signal demodulated by the demodulation circuit block 3 is supplied to a decoder circuit block 5 of, for example, an MPEG system, and the decoded audio and video demodulated signals are respectively output to a speaker 6 for sound emission and a speaker for display. The picture is supplied to a picture tube (CRT) 7.

Here, the above-mentioned internal and external automatic gain control (AGC) circuits 31, 33 are in principle the same circuit, and for example, the configuration as shown in FIG. 2 is used. That is, in FIG. 2, an input signal is supplied to a gain control (GC) amplifier 41, and an output signal is extracted. The output signal is supplied to a level comparison circuit 42, for example, a timing signal of a horizontal synchronizing signal is supplied to the level comparison circuit 42, and the signal level at this position is compared with an arbitrary set level.

Further, the comparison output is supplied to a low-pass filter circuit 43, and the signal from which the high frequency component has been removed is supplied to a control terminal of a gain control amplifier 41 through an amplifier 44. Thereby, for example, automatic gain control (AGC) is performed so that the signal level at the position of the horizontal synchronization signal has a predetermined relationship with an arbitrary set level. The response speed of the automatic gain control (AGC) is controlled by, for example, the cutoff frequency of the low-pass filter circuit 43 and the gain of the amplifier 44.

That is, for example, the low-pass filter circuit 43
, The response speed of the automatic gain control (AGC) is increased, and the gain of the amplifier 44 is increased to increase the automatic gain control (AGC).
The response speed of C) can be increased. However, if the response speed of the automatic gain control (AGC) is increased in this manner, for example, during normal reception, it is likely to be affected by noise, and stability during reception reception is impaired.

On the other hand, in a device in which digital control is performed, for example, the characteristics and the like of each circuit provided inside are controlled by a digital value set in a register. Therefore, the cutoff frequency of the low-pass filter circuit 43 and the gain of the amplifier 44 are controlled by, for example, a digital value set in a register 45, and further, a set value (digital value) of the register 45 is set.
However, for example, there is provided a configuration that is set by the control microcomputer 4.

In the microcomputer 4, for example, control as shown in the flowchart of FIG. 3 is performed. That is, in FIG. 3, when the control is started, it is first determined in step [1] whether or not a channel is being selected. Here, when the channel is not being selected (NO), it is determined that the reception is being held. Then, the process returns to the step [1], and the current state is maintained by repeating the step [1].

When the channel is being selected in step [1] (YE
In S), the register value for the channel selection operation is set in the next step [2], and the set value (digital value) of the register 45 increases the cutoff frequency of the low-pass filter circuit 43, for example. By increasing the gain of the amplifier 44, control is performed to increase the response speed of automatic gain control (AGC). Then, in step [3], tuning is started.

When the channel selection is completed in step [4], a register value for receiving and holding is set in step [5], and the set value (digital value) of the register 45 is
For example, the cut-off frequency of the low-pass filter circuit 43 is set to a predetermined value necessary for holding the normal reception.
By setting the gain of No. 4 to a predetermined value necessary for holding the normal reception, the response speed of the automatic gain control (AGC) is controlled to the normal value. Then, the process returns to step [1].

As described above, in the above-described apparatus, when selecting a channel, the response speed of the automatic gain control operation in the tuning and intermediate frequency circuit block 2 and / or the demodulation circuit block 3 is changed to the response speed when the reception state is maintained. Control to make it faster
This can be performed by the microcomputer 4. As a result, a sufficient reception level can be obtained even in a high-speed search at the time of channel selection, and the channel selection channel can be maintained in a good state during normal reception.

Further, in the above-described apparatus, the microcomputer 4 controls the tuning and intermediate frequency circuit block 2 described above.
Is also controlled. Therefore, for example, the tuning frequency in the tuning and intermediate frequency circuit block 2 is continuously changed from the lowest frequency to the highest frequency of the receiving band by a control signal from the microcomputer 4 at the beginning of reception, for example. During the search, the demodulated circuit block 3 detects the demodulated channel of the signal, and the detected channel number and the like are stored in the microcomputer 4.

At the time of normal reception, reception is performed in accordance with the channel number and the like stored in the microcomputer 4 described above. Thus, for example, by not selecting a channel that has not been demodulated, the operation of the device at the time of channel selection can be performed smoothly, and noise generated by receiving a signal that cannot be demodulated can be reduced. Sound emission and display of a meaningless screen can be prevented, and the reliability of the device can be improved.

Also at this time, at the time of tuning, the response speed of the automatic gain control operation in the tuning and intermediate frequency circuit block 2 and / or the demodulation circuit block 3 is made faster than the response speed when the reception state is maintained. Is performed by the microcomputer 4 so that a sufficient reception level can be obtained even in a high-speed search at the time of channel selection, and a received signal can be detected easily and reliably. Can be maintained in a good state.

Further, in the above-described apparatus, a first set value for obtaining a response speed of a predetermined automatic gain control (AGC) operation necessary for holding a normal reception, and a first set value for obtaining a faster response speed. The second set value is, for example, the cutoff frequency of the low-pass filter circuit 43 and the amplifier 4
The above-described control can be performed extremely easily by storing the gain of 4 in a memory (not shown) of the microcomputer 4 and switching these as necessary.

Therefore, in this apparatus, when detecting a reception channel by tuning or searching, the response speed of the automatic gain control operation in at least the tuning and intermediate frequency circuit block and / or the demodulation circuit block is set to be higher than that in the normal state. By increasing the speed, it is possible to obtain a sufficient reception level even in a high-speed search, when selecting a channel or in an auto program, which is one of the most important functions of a digital television broadcast receiving apparatus, and to obtain a normal reception level. In this case, the selected channel can be maintained in a good state.

As a result, in the conventional apparatus, it is possible to keep the channel selected in a good state during normal reception, and to perform the automatic program at the time of channel selection or one of the most important functions. According to the present invention, it is possible to easily solve these problems, while it was an important problem to achieve a sufficient reception level even with a high-speed search. You can do it.

In the above-described apparatus, the control that can be switched between the time of channel selection and the time of holding reception is not only the switching of the response speed of the automatic gain control operation described above, but also, for example, multipath interference and adjacent channel interference. On the other hand, for example, the NTSC signal removal circuit 34 and the equalizer (EQ)
By controlling the characteristics of the circuit 35, it is possible to adjust between the time of tuning and the time of holding reception.

Thus, according to the above-described receiving apparatus, at least various characteristics of the tuning and intermediate frequency circuit block and the demodulation circuit block are controlled by the built-in microcomputer. A microcomputer controls the response speed of the automatic gain control operation in the circuit block and / or the demodulation circuit block to be faster than the response speed when the reception state is held, thereby selecting a channel or receiving a digital television broadcast. In the case of an auto program, which is one of the most important functions, a sufficient reception level can be obtained even with a high-speed search, and a good channel can be maintained during a normal reception. Things.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0037]

Therefore, according to the first aspect of the present invention, when a reception channel is detected by tuning or searching,
By making the response speed of the automatic gain control operation at least in the tuning and intermediate frequency circuit block and / or the demodulation circuit block faster than usual, one of the most important functions in channel selection and digital television broadcast receivers is achieved. In this automatic program, a sufficient reception level can be obtained even with a high-speed search, and a good channel can be maintained during normal reception.

As a result, in the conventional apparatus, the channel selected is maintained in a good condition during normal reception, and the channel is selected and the auto program, which is one of the most important functions, is performed. According to the present invention, it is possible to easily solve these problems, while it was an important problem to achieve a sufficient reception level even with a high-speed search. You can do it.

According to the second aspect of the present invention, the response speed of the automatic gain control operation in the tuning and intermediate frequency circuit block and / or the demodulation circuit block during the search is made faster than the response speed when the reception state is maintained. By performing the control by the microcomputer, a sufficient reception level can be obtained even in a high-speed search at the time of channel selection, and the reception signal can be easily and reliably detected. Can be maintained in a good state.

Further, according to the third aspect of the present invention, the first set value for obtaining the response speed of the predetermined automatic gain control (AGC) operation necessary for holding the normal reception and the faster response speed are set. The control can be performed very easily by storing the second set value to be obtained in the memory of the microcomputer and switching these as necessary.

According to the fourth aspect of the present invention, the first set value for obtaining the response speed of the predetermined automatic gain control (AGC) operation required for holding the normal reception, and the faster response speed By setting the second set value to obtain the cut-off frequency of the low-pass filter circuit and the gain of the amplifier in the automatic gain control circuit, the control can be performed very easily.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a receiving device to which the present invention is applied.

FIG. 2 is a configuration diagram of an embodiment of a main part thereof.

FIG. 3 is a diagram for explaining the operation.

FIG. 4 is a configuration diagram of a conventional receiving device.

[Explanation of symbols]

1. Antenna device, 2. Tuning and intermediate frequency circuit (TU /
IF) block, 21 tuning (TU) circuit, 22 intermediate frequency (IF) circuit, 3 demodulation circuit block, 31 internal automatic gain control (AGC) circuit, 32 time reproduction circuit, 3
3: external automatic gain control (AGC) circuit, 34: NTSC
Signal removal circuit, 35 ... Equalizer (EQ) circuit, 36
... Error correction circuit for digital signals, 4 ... microcomputer, 5 ... MPEG decoder circuit block, 6 ...
Speaker, 7 ... CRT (CRT)

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Makoto Kurahashi 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 5C025 AA15 AA17 AA24 AA27 BA27 DA04 5C026 BA14 5K061 AA11 BB06 BB07 CC11 CC20 CC23 CC52 CD02 CD04 JJ07

Claims (4)

[Claims] 1. A receiving device in which at least various characteristics of a tuning and intermediate frequency circuit block and a demodulation circuit block are controlled by a built-in microcomputer, and at least at the time of channel selection, the tuning and intermediate frequency circuit block and / or demodulation. A receiving device, wherein the microcomputer controls the response speed of an automatic gain control operation in a circuit block to be faster than the response speed when a reception state is maintained. 2. The receiving apparatus according to claim 1, wherein the microcomputer is used to search a tuning frequency of the tuning and intermediate frequency circuit block between a highest frequency and a lowest frequency of a receiving band, and to detect a receiving channel therebetween. When performing the control, at least the control to make the response speed of the automatic gain control operation in the tuning and intermediate frequency circuit block and / or the demodulation circuit block during the search faster than the response speed when the reception state is held is performed. A receiving device, which is performed by a computer. 3. The receiving device according to claim 1, wherein the microcomputer has a response speed of an automatic gain control operation in the tuning and intermediate frequency circuit block and / or the demodulation circuit block when the reception state is maintained. A first set value for setting and a second set value for setting a response speed of the automatic gain control operation in the tuning and intermediate frequency circuit block and / or the demodulation circuit block at the time of the tuning. A memory for storing is provided. At the time of the tuning, the response speed of the automatic gain control operation in the tuning and intermediate frequency circuit block and / or the demodulation circuit block is first set using the second set value, The response speed of the automatic gain control operation in the tuning and intermediate frequency circuit block and / or the demodulation circuit block using the first set value after the tuning is completed. Set to the receiving device, characterized in that for normal operation. 4. The receiving apparatus according to claim 3, wherein the first and second set values set a control frequency range and / or a control gain of an automatic gain control operation to first and second values, respectively. A receiving device, characterized in that: