JPH07143015A - Transmitter - Google Patents

Abstract

PURPOSE:To obtain a transmitter in which coaxial cable length can be extended by performing the automatic control of the power of a high frequency part in a transmitter used in the mobile relay of television or sound. CONSTITUTION:The transmitter is constituted of a control part 10, one coaxial cable 20, and the high frequency part 40, A voltage comparator 36 level- compares a DC voltage from the control part 10 separated by a branching filter 31 with a reference voltage from a reference voltage source 37. When the cable length of the coaxial cable 20 is extended and the input DC voltage of the voltage comparator 36 is decreased lower than the reference voltage due to heat loss by the coaxial cable 20, a control signal is sent out to a control circuit 38. The control circuit 38 decreases a power supply voltage supplied from a regulator power source 35 to a power amplifier circuit 34 in a high frequency circuit 38 by the signal, and decreased the power consumption in the high frequency circuit 33. In this way, a capacity margin can be obtained for a power source circuit 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter, and more particularly to a transmitter used for mobile relay of television or voice.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing an example of a conventional transmitter. This transmission device is applied to a transmission system of an FPU device which is a coaxial single unit among FPU (Field Pickup Unit) devices which are external microwave transmission / reception devices used for signal transmission of mobile relay of television or voice. The transmitting device includes a control unit 10, a high frequency unit 30, and a single coaxial cable 20 that connects them. The control unit 10 frequency-multiplexes a DC voltage from the power supply circuit 11 and an intermediate frequency signal (IF signal) related to video and audio input via the input terminal 12 by the demultiplexer 13, and the frequency-multiplexed signal is coaxial cable. It is supplied to the high frequency unit 30 via 20.

The high frequency unit 30 separates the frequency multiplexed signal into a DC voltage and an IF signal by a demultiplexer 31, inputs the separated DC voltage to a regulator power supply 35, and outputs the separated IF signal to an intermediate frequency circuit 32. input. The output voltage of the regulator power supply 35 is applied to each part of the high frequency unit 30 as a power supply voltage. On the other hand, the intermediate frequency signal that has passed through the intermediate frequency circuit 32 is input to the high frequency circuit 33, where it is up-converted to the transmission frequency, and further the power amplification circuit (PA).
After the power is amplified to a required level by 34, it is output to the output terminal 39 for transmission.

In such a conventional transmitter, as the length of the coaxial cable 20 increases, the power consumed by the coaxial cable 20 (heat loss due to the resistance of the coaxial cable 20) increases, and the power reaches the high frequency section 30. The voltage and power are reduced. On the other hand, the power consumption in the high frequency unit 30 is not controlled except when the output power is manually reduced.
Therefore, in the conventional transmitter, the DC voltage is sent from the control unit 10 to the high frequency unit 30 at a predetermined level in consideration of the voltage drop due to the connectable coaxial cable 20 and the power consumption of the high frequency unit 30.

[0005]

As described above, in the conventional transmitter, the control unit 10 considers the power consumption in the high frequency unit 30 and the loss in the coaxial cable 20, and the power supply circuit 11
Since the capacity of the coaxial cable is determined, the maximum drivable length of the coaxial cable is limited. However, since the high frequency unit 30 is installed in a place apart from the control unit 10, it is desirable that the coaxial cable 20 be as long as possible in order to increase the degree of freedom of the installation place.

However, in the conventional transmitter, when the coaxial cable 20 having a length exceeding the maximum extension length is used, the DC voltage input to the high frequency section 30 needs to be a predetermined value or more. The output DC voltage of the power supply circuit 11 must be increased, and as a result, the sum of the power consumption in the high frequency unit 30 and the power loss in the coaxial cable 20 exceeds the capacity of the power supply circuit 11 in the control unit 10. The efficiency of the power supply may deteriorate, and in the worst case, the power supply may stop.

The present invention has been made in view of the above points,
An object of the present invention is to provide a transmitting device that can lengthen a coaxial cable by automatically controlling the power consumption of a high frequency section.

[0008]

In order to achieve the above-mentioned object, the present invention generates a frequency-multiplexed signal of a power supply voltage and an information signal to be transmitted by a control unit, and a high-frequency unit via one coaxial cable. And the high-frequency section operates by the power supply voltage separated from the input frequency-multiplexed signal, and the information signal separated from the input frequency-multiplexed signal is converted into the high-frequency signal in the transmission band in the high-frequency circuit and then transmitted. In the above, the voltage comparator and the control means are provided in the high frequency section.

Here, the voltage comparator compares the power supply voltage separated from the input frequency multiplex signal of the high frequency section with a preset reference voltage. Further, the control means lowers the power supply voltage to the high frequency circuit when the comparison result that the separated power supply voltage is equal to or lower than the reference voltage is obtained from the voltage comparator.

[0010]

According to the present invention, when the voltage comparator detects that the power supply voltage input to the high frequency section from the control section through the single coaxial cable is equal to or lower than the above reference voltage, the control section controls the high frequency. Since the power supply voltage to the circuit is lowered, it is possible to automatically suppress the power consumption of the high frequency circuit, that is, the power consumption of the entire high frequency unit, from becoming unnecessarily large.

Further, in the present invention, the above-mentioned control means is means for controlling a DC voltage supplied from the regulator power supply operating by the separated power supply voltage to the final stage transistor of the power amplification circuit in the high frequency circuit. Therefore, the power consumption of the power amplifier circuit, which occupies most of the total power consumption of the high frequency unit, can be suppressed.

[0012]

Next, an embodiment of the present invention will be described.
FIG. 1 shows a block diagram of an embodiment of the present invention. In FIG.
The same reference numerals are given to the same components as. In FIG. 1, the transmission device of the present embodiment is a transmission device applied to a transmission system of a coaxially integrated FPU device, and includes a control unit 10 and a high frequency unit 40, and one coaxial unit connecting them. It is similar to the conventional transmitting device in that it is configured with the cable 20, but the configuration of the high frequency unit 40 is different from that of the conventional high frequency unit 30.

That is, the high frequency section 40 of the present embodiment has a demultiplexer 31, an intermediate frequency circuit 32, a high frequency circuit 33 and a regulator power source 35, and further has a voltage comparator 36,
The configuration has a reference voltage source 37 and a control circuit 38. Here, the voltage comparator 36 is the demultiplexer 31.
The DC voltage separated by is compared with the reference voltage from the reference voltage source 37 in level, and an output signal having a logical value corresponding to the level comparison result is generated.

The control circuit 38 is linked to the regulator power supply 35, and from the regulator power supply 35 to the drain of the field effect transistor (not shown) at the final stage of the power amplification circuit (PA) 34 in the high frequency circuit 33. It controls the applied power supply voltage (drain voltage). However, the control circuit 38 does not control the power supply voltage output from the regulator power supply 35 other than the drain voltage. This is because the power consumption of the power amplifier circuit 34 accounts for most of the power consumption of the entire high frequency unit 40.

Next, the operation of this embodiment will be described.
The frequency multiplex signal of the intermediate frequency signal and the DC power supply voltage relating to the information signal (video signal, audio signal, etc.) to be transmitted, which is generated in the demultiplexer 13 of the control unit 10, is passed through one coaxial cable 20. The signal is input to the demultiplexer 31 of the high frequency unit 40, and is again separated into the information signal (intermediate frequency signal) to be transmitted and the DC power supply voltage. The information signal to be transmitted (intermediate frequency signal) is input to the high frequency circuit 33 via the intermediate frequency circuit 32, where it is frequency-converted into a high frequency signal in the transmission band, and then power amplified by the power amplifier circuit 34.
It is output to the output terminal 39 as a transmission signal.

On the other hand, the DC power supply voltage separated from the input frequency multiplexed signal by the demultiplexer 31 is the regulator power supply 3
Input to 5. The regulator power supply 35 performs a required operation when the DC power supply voltage is equal to or higher than a predetermined value, and outputs the stabilized DC power supply voltage having a predetermined value to each unit of the high frequency unit 40 as a power supply voltage. The DC power supply voltage separated from the input frequency multiplexed signal by the demultiplexer 31 is supplied to the voltage comparator 3
6 and the level is compared with the reference voltage from the reference voltage source 37.

Here, when the coaxial cable 20 has a relatively short cable length, the electric power consumed by the coaxial cable 20 is small, so that the voltage drop of the frequency-multiplexed signal input from the control unit 10 to the high-frequency unit 40 is small. At this time, the voltage comparator 37 determines that the input DC power supply voltage is higher than the reference voltage, and outputs a control signal having a logical value to that effect to the control circuit 38. At this time, the control circuit 38 does not reduce the DC power supply voltage (drain voltage) supplied from the regulator power supply 35 to the drain of the field effect transistor at the final stage of the power amplification circuit 34, and does not decrease the normal value by the regulator power supply 35 alone. Hold on.

However, when a coaxial cable having a long cable length longer than the maximum drivable length in the related art is used as the coaxial cable 20, since the power consumption by the coaxial cable 20 is large, the frequency higher than that of the control unit 10 is generated. The voltage drop of the frequency-multiplexed signal input to the unit 40 is large, and at this time, the voltage comparator 37 determines that the input DC power supply voltage is equal to or lower than the reference voltage, and notifies the control circuit 38 of a control signal of a logical value indicating that fact. Is output.

As a result, the control circuit 38 controls the drain voltage supplied from the regulator power supply 35 to the final stage field effect transistor of the power amplification circuit 34 from a normal value to a predetermined value. However, as described above, the control circuit 38 does not reduce the DC voltage other than the drain voltage to the power amplification circuit 34 in the DC power supply voltage output from the regulator power supply 35.

This is because, as described above, most of the total power consumption of the high frequency section 40 is due to the power amplifier circuit 34. Therefore, in order to reduce the power consumption, only the power consumption of the power amplifier circuit 34 is reduced. This is because the purpose can be achieved with. As a result, the influence of the fluctuation of the DC power supply voltage on other circuit parts of the high frequency part 40 can be eliminated as much as possible.

In this way, when the coaxial cable 20 has a long cable length, the drain voltage of the power amplifier circuit 34 is lowered, so that the transmission output is slightly lowered to such an extent that there is no problem in practical use, but the high frequency section 40. The overall power consumption will be suppressed. As a result, even if the power loss in the coaxial cable 20 increases, the power consumption of the high frequency unit 40 can be reduced. Therefore, the sum of the power loss of the coaxial cable 20 and the power consumption of the high frequency unit 40 is equal to or less than a predetermined value. Therefore, it is possible to suppress the increase in the load of the capacity of the control unit 10 on the power supply circuit 11.

Therefore, according to this embodiment, the power supply circuit 11
The maximum drive length of the coaxial cable 20, which is limited by the capacity of, can be made longer than the conventional capacity even with the same capacity.

The present invention is not limited to the above embodiment, and for example, in order to reduce the power consumption of the high frequency section 40, the power supply voltage of the other high frequency section internal circuit section including the power amplifier circuit 34 is simultaneously lowered. However, it is also possible to provide a plurality of voltage comparators and a plurality of reference voltage sources in parallel to reduce the power supply voltage of the high frequency unit 40 in a plurality of steps in principle.

[0024]

As described above, according to the present invention,
When the voltage comparator detects that the power supply voltage input to the high-frequency unit is equal to or lower than the reference voltage, the control unit lowers the power-supply voltage to the high-frequency circuit to reduce the power consumption of the high-frequency circuit, that is, the high-frequency unit. Since the overall power consumption is automatically suppressed, the power loss due to the coaxial cable can be compensated.

Therefore, according to the present invention, a margin can be provided for the capacity of the power supply circuit of the control unit, so that the maximum extension length of the coaxial cable can be made longer than before, and particularly in the transmission system of the FPU device. When the present invention is applied, the degree of freedom of the installation place of the high frequency part can be improved more than before.

Further, according to the present invention, by reducing the power consumption by controlling the DC voltage supplied from the regulator power supply operating by the separated power supply voltage to the final stage transistor of the power amplifier circuit in the high frequency section, Since the power consumption of the power amplifier circuit, which occupies most of the total power consumption of the high frequency section, is suppressed, the power consumption of the high frequency section can be suppressed when the coaxial cable is long, and the high frequency section other than the power amplifier circuit can be suppressed. It is possible to minimize the influence of power supply voltage fluctuations on the circuit.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram of a conventional example.

[Explanation of symbols]

 10 Control Unit 11 Power Supply Circuit 13, 31 Splitter 20 Coaxial Cable 32 Intermediate Frequency Circuit 33 High Frequency Circuit 34 Power Amplifier Circuit (PA) 35 Regulator Power Supply 36 Voltage Comparator 37 Reference Voltage Source 40 High Frequency Section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical indication H04N 5/38

Claims (2)

[Claims] 1. A frequency multiplex signal of a power supply voltage and an information signal to be transmitted is generated by a control unit and input to a high frequency unit via one coaxial cable, and the high frequency unit is separated from the input frequency multiplex signal. In a transmitting device configured to operate by a power supply voltage and convert an information signal separated from an input frequency multiplex signal into a high frequency signal in a transmission band in a high frequency circuit and then transmitting the same, a power supply separated from the input frequency multiplex signal of the high frequency unit A voltage comparator for comparing a voltage with a preset reference voltage, and a power supply for the high frequency circuit when a comparison result in which the separated power supply voltage is less than or equal to the reference voltage is obtained from the voltage comparator. A transmitting device comprising: a control unit for lowering a voltage, which is provided in the high frequency unit. 2. The control means is means for controlling a DC voltage supplied from a regulator power supply which operates by the separated power supply voltage to a final stage transistor of a power amplification circuit in the high frequency circuit. Claim 1
The transmission device described.