JP2906921B2 - Satellite broadcast receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite broadcasting receiver for supplying a driving voltage of a converter superimposed on an antenna cable.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing an example of a conventional satellite broadcast receiving apparatus. The conventional satellite broadcast receiving apparatus will be described with reference to FIG. In FIG. 4, a converter 2 for converting a 12 GHz band radio wave to an intermediate frequency of a 1 GHz band is provided near an antenna 3 for catching a satellite broadcast radio wave. Since the converter 2 is attached to the antenna 3, it is desirable that the converter 2 be small in size and does not include a power supply circuit. The power supply for driving the converter 2 is a converter power supply unit 7 built in the satellite broadcast receiver 1.
Therefore, the voltage of DC15V is superimposed on the antenna cable 4 and supplied to the converter 2.

[0003] Whether power is supplied to the converter 2 is determined by
The following processing is performed. First, the power supply voltage superimposed on the antenna cable 4 and the AGC voltage in the channel selection demodulation unit 5 are input to separate voltage comparators 9 and 10, respectively, and the comparison result is supplied to the control unit 8. The control unit 8 makes a determination based on the comparison result, and performs on / off control on the converter power supply unit 7. The signal demodulated by the channel selection demodulation unit 5 is subjected to required signal processing in a signal processing unit 6. The signal (s) sent from the control unit 8 to the channel selection demodulation unit 5
2) is used for transmitting a tuning signal according to the channel operation and for the control unit 8 to determine whether to supply power to the converter 2. The signal (s1) sent from the control unit 8 to the converter power supply unit 7 is
For on / off control.

The reference voltage Vrf1 of the voltage comparator 9 is set to a lower limit voltage value necessary for operating the converter 2, and the reference voltage Vrf2 of the voltage comparator 10 is set to a threshold of a satellite broadcast television signal. Set to voltage. Each of the voltage comparators 9 and 10 outputs an “H” level when the comparison voltage is lower than the reference voltage, and outputs an “L” level when the comparison voltage is higher than the reference voltage.

Next, the control operation of the converter power supply unit 7 in the control unit 8 will be described. First, the satellite broadcast receiver 1
Is turned on, and before the converter power supply unit 7 is turned on, a signal for selecting all the broadcasting channels is sent from the control unit 8 to the channel selection demodulation unit 5. The voltage comparators 9 and 10 compare the input voltage and the reference voltage for all the satellite broadcast channels.

(1) When both of the comparison results of the voltage comparators 9 and 10 are at the “L” level: The power supply voltage is superimposed on the antenna cable 4 and the demodulation operation is performed in the channel selection demodulation unit 5. It is determined that power is being supplied to converter 2 from another satellite broadcast receiving device (not shown), and a command to hold power off in converter power supply unit 7 is sent from control unit 8 to converter power supply unit 7. . (2) When the comparison result of the voltage comparator 9 is “H” level and the comparison result of the voltage comparator 10 is “L” level Although the power supply voltage is not superimposed on the antenna cable 4, the channel selection demodulation operation is performed. Therefore, for joint reception, it is determined that power is being supplied to the converter 2 from a booster (not shown) or the like, and an instruction is given to the converter power supply unit 7 to hold the converter 2 off.

(3) When the comparison results of voltage comparators 9 and 10 are both at “H” level: No power supply voltage is superimposed on antenna cable 4,
Since the channel selection demodulation operation is not performed, it is determined that power is not supplied to the converter, and the converter power supply unit 7 is determined.
To start power supply. (4) When the comparison result of the voltage comparator 9 is “L” level and the comparison result of the voltage comparator 10 is “H” level Although the power supply voltage is superimposed on the antenna cable 4,
Since the channel selection demodulation operation is not performed, it is determined that the reception is abnormal or the channel is empty. FIG. 5 summarizes the on / off control of the converter power supply unit 7 in the control unit 8 described above.

A current detector 11 built in the satellite broadcast receiver 1 detects a state of a current flowing through the antenna cable 4 and sends a result of the detection to the controller 8 to turn on / off the converter power supply 7. Control. For example, when the current supply is started from another satellite broadcast receiver to the converter 2 in a state where the power supply unit 7 for the converter is turned on and the current is being supplied to the converter 2, the overcurrent is detected by the current detection. The detection result is sent to the control unit 8, and the control unit 8 sends a command to the converter power supply unit 7 to stop the current supply. Also, when the antenna cable 4 is short-circuited, the current detection circuit 11 detects a change in the state, and performs processing such as sending a command to stop the current supply from the control unit 8 to the converter power supply unit 7. I have.

[0009]

In the conventional satellite broadcast receiving apparatus, the control unit 8 issues an ON command to the converter power supply unit 7.
After that, when a short circuit or the like occurs on the current transmission path, the current detection unit 11 for detecting the short circuit is required. In the case of a joint receiving system in which UHF and VHF signals are also superimposed on the antenna cable 4, UHF,
Although the power of 30 V AC is supplied to the amplifier for amplifying the VHF signal via the antenna cable 4, a conventional circuit in which the DC current is detected and controlled by the current detection unit 11 cannot detect an AC overcurrent or the like. There was a problem that sometimes. Therefore, the present invention provides a satellite broadcast receiving apparatus, which can always detect the power supply voltage superimposed on the antenna cable, regardless of whether the converter power supply unit is on or off.
An object of the present invention is to reliably detect a change in the state of an antenna cable such as an overcurrent and control the converter power supply unit even when an AC voltage for UHF and VHF signals is superimposed on the antenna cable.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides a converter for converting radio waves captured by an antenna into a predetermined intermediate frequency, a converter from a power supply section for the converter to an antenna cable. In a satellite broadcast receiving apparatus that supplies a power supply voltage in a superimposed manner, a voltage comparator that compares a voltage value superimposed on the antenna cable with a lower limit voltage value required to operate the converter, And a control unit for inputting a comparison result of the voltage comparator and performing on / off control of the converter power supply unit, wherein the control unit compares the comparison result of the voltage comparator with a commercial power supply.
Sampling at a cycle sufficiently shorter than the cycle , and reading for a period of an integral multiple of one cycle of the commercial power supply, and determining whether a power supply voltage is superimposed on the antenna cable by detecting majority decision of a plurality of read comparison results. , The con
An object of the present invention is to provide a satellite broadcast receiving device that performs on / off control of a power supply unit for a barter .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a satellite broadcast receiving apparatus according to the present invention will be described.
This will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of a satellite broadcast receiving apparatus of the present invention, FIG. 2 is a flowchart for explaining the operation of the control unit of the present invention, and FIG. 3 is a diagram for explaining a current waveform in an antenna cable. In addition,
1, the same parts as those of FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, a converter power supply unit 7 includes:
It is built in the satellite broadcast receiver 20 and supplies the voltage of the converter power supply 7 to a voltage comparator 21 also built in the satellite broadcast receiver 20. The voltage comparator 21 compares a reference voltage Vrf, which is a lower limit voltage value required for operating the converter 2, with a voltage of the converter power supply unit 7. When the voltage of the converter power supply unit 7 is lower than the reference voltage Vrf, the control unit 22 is supplied with the “H” level, and when the voltage is high, the “L” level.

In the control unit 22, the antenna cable 4
Considering the case where AC 30 V for HF and VHF signals is also superimposed, the following processing is performed. As shown in FIG.
A cycle sufficiently shorter than the cycle of the commercial power supply (50 Hz to 60 Hz)
The power supply voltage of the converter 2 is supplied to the antenna cable 4 by reading the comparison result of the voltage comparator 21 sampled in the period for one period or an integral multiple of the period and performing a majority decision on the comparison result. Is determined, and an ON / OFF command for the converter power supply unit 7 is determined.

Next, the operation of the present invention will be described with reference to FIG. First, when the converter power supply unit 7 is turned off as an initial state, the control unit 22
The comparison result of the voltage comparator 21 is read a plurality of times [S1
1]. When the input voltage is higher than the reference voltage Vrf, that is, when the “L” level is output as the comparison result, the number of the “L” levels is counted and set to M [S12].
For example, in the case as shown in FIG. 3A, M = 3. Similarly, when the value is low, that is, when the “H” level is output as the comparison result, the number of “H” levels is counted and set to N [S13]. In the case of FIG. 3A, N = 1
0.

Next, it is determined whether or not M <N [S1
4]. Otherwise (No), that is, as shown in FIG. 3 (B), when both the AC component for the UHF and VHF signals and the DC component for the converter exist, the antenna cable 4 is required to drive the converter. Since a high voltage is superimposed, the control unit 22 sends to the converter power supply unit 7 a command to suspend the supply of current to the converter 2 while keeping it off [S15]. When M <N, as shown in FIG. 3A, when only the AC component has no DC component for the converter, the voltage necessary for driving the converter is not superimposed on the antenna cable 4, so that the control is performed. The unit 8 sends a command to the converter 2 to start supplying current to the converter power supply unit 7 [S16].

As described above, the antenna cable 4 is connected to the UH
Even when the AC voltages for the F and VHF signals are superimposed, the control unit 22 keeps the period sufficiently shorter than the cycle of the commercial power supply.
By reading the comparison result of the voltage comparator 21 sampled at a predetermined cycle for a period of one cycle or an integral multiple of the cycle , and performing a majority decision on the comparison result, the converter cable is converted to the antenna cable 4. It is possible to determine whether or not the power supply voltage is supplied.

When the converter power supply 7 is turned on, the same processing as described above is performed. In this case, however, the operation as a result of the determination is different from that described above. First, it is determined whether or not M <N [S17]. Otherwise, the voltage necessary for driving the converter is superimposed on the antenna cable 4 and the current is normally supplied.
Thereafter, a command to keep the converter 2 supplying current is sent to the converter power supply unit 7 [S18]. Also, M <N
At this time, since the voltage required for driving the converter is not superimposed on the antenna cable 4, the antenna cable 4 may be short-circuited. Therefore, the control unit 22 issues a command to stop the supply of current to the converter 2. It is sent to the converter power supply unit 7 [S19].

Thereafter, when the converter power supply unit 7 is turned off, the subroutine processing is performed and then the processing is performed again from step 14, and when the converter power supply unit 7 is on, the subroutine processing is performed and the processing from step 17 is performed. The operation of being performed again is repeated.

[0019]

As described above in detail, the satellite broadcast receiving apparatus according to the present invention uses a voltage comparator for detecting a power supply voltage superimposed on an antenna cable and a software processing by a control unit to provide a converter power supply unit. Irrespective of the ON or OFF state, the state of the antenna cable can always be detected, so that the current detection circuit is unnecessary and the circuit can be simplified. In addition, the control unit reads the comparison result of the voltage comparator a plurality of times and performs on / off control of the converter power supply based on majority decision, so that the AC voltage for the UHF and VHF signals is superimposed on the antenna cable. Even in such a case, it is possible to reliably detect a change in the state of the antenna cable such as an overcurrent and to control the converter power supply unit, which is an extremely excellent effect in practical use.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a satellite broadcast receiving apparatus of the present invention.

FIG. 2 is a flowchart for explaining the operation of the present invention.

FIG. 3 is a diagram illustrating a current waveform in an antenna cable.

FIG. 4 is a block diagram illustrating an example of a conventional satellite broadcast receiving device.

FIG. 5 is a flowchart for explaining a conventional operation.

[Explanation of symbols]

 Reference Signs List 2 converter 3 antenna 4 antenna cable 5 channel selection demodulation unit 6 signal processing unit 7 converter power supply unit 20 satellite broadcast receiving device 21 voltage comparator 22 control unit

Claims (1)

(57) [Claims] 1. A converter for converting a radio wave captured by an antenna into a predetermined intermediate frequency, from a converter power supply unit to
In a satellite broadcast receiving device that supplies a power supply voltage by superimposing the power supply voltage on an antenna cable, a voltage comparator that compares a voltage value superimposed on the antenna cable with a lower limit voltage value required to operate the converter, A control unit that inputs a comparison result of the voltage comparator and performs on / off control of the power supply unit for the converter, wherein the control unit sets the comparison result of the voltage comparator to a cycle sufficiently shorter than a cycle of a commercial power supply. in samples, and loading an integer multiple of the period of one cycle of the commercial power source, by majority decision of a plurality of comparison results of reading, to detect whether the power supply voltage to the antenna cable is superimposed, the co
A satellite broadcast receiving apparatus for performing on / off control of an inverter power supply unit .