JPH10257349A - Fpu transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a microwave frequency band power radiation and to radiate a stable frequency component by detecting the level and the frequency of an external IF input and controlling the power of a transmission powere amplifier, according to the detection outputs. SOLUTION: When an IF transmission mode is selected by a change-over circuit 4, an external IF input 2 is supplied to BPF(band limiting filter) 9 with a buffer (buffer amplifier) 8, A BPF output is respectively inputted to a frequency detecting part 10 and a level detecting part 11, and the frequency and the level are detected. The detection results are inputted to a PA control part 12 for controlling the power of a power amplifier part 61. The PA control part 12 controls the supply of the power of the power amplifier part 61, in accordance with the two detection results and displays the detection results in a display part 13. Thus, reliability against obstruction to an adjacent channel caused by the quality of an external IF input signal is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FPU (Field Pickup).
-up Unit) An FPU that monitors a transmission device, in particular, wirelessly transmits a television video signal and an audio signal using a microwave band.
It relates to a transmission device.

[0002]

2. Description of the Related Art In a conventional FPU transmitting apparatus of this type, various methods are employed for stabilizing a transmission frequency.
Among them, a method of stabilizing a transmission frequency to which an automatic frequency control circuit is added has been widely adopted. These frequency stabilization methods generate an IF (intermediate frequency) signal inside the FPU transmitting apparatus, and it is a great premise that a signal of an appropriate level in an IF band within a rating is input to an RF (high frequency) circuit. It has become.

[0003] One of the operation modes of the FPU transmission apparatus is an operation mode in which an IF component is input from the outside, the frequency is converted into a microwave band based on the input, and power is radiated. This is generally called an IF transmission mode.

In this IF transmission mode, the center frequency and level of an IF component input from the outside are defined as ratings. However, due to factors such as the IF signal supply side,
When the center frequency of the IF component deviates or the level decreases, the FPU transmitting apparatus generates a power radiation component in the microwave band based on the IF component, so that the frequency and level fluctuate in the microwave band. And the like, the quality of the line may be significantly reduced. In particular, the shift of the transmission frequency poses a problem because it interferes with an adjacent channel.

Japanese Patent Application Laid-Open No. 60-81927 discloses an example of stabilizing a transmission frequency signal for a microwave transmitting / receiving device. According to this, for the purpose of stabilizing the transmission frequency, a method of controlling the frequency of the transmission output signal based on the frequency of the reception input signal has been adopted. By this method, the transmission frequency is stabilized.

For this purpose, two frequency converters having the same modulation frequency shift amount must be prepared. However, since the control for equalizing the respective shift amounts is not performed, good characteristics are constantly obtained. Is unknown. This is because the technique disclosed in this publication aims to simplify the circuit configuration, and does not take an approach from the viewpoint of improving line quality.

[0007] In the case of the FPU device, the device connected to the external IF input terminal is not particularly limited, the frequency shift of the radiated microwave band is strictly specified, and particularly, there is no influence on adjacent channels. However, special conditions are required for circuit reliability.

[0008] Against this background, the conventional technology uses FPU.
The external IF input terminal of the transmitting device is only urged to input the component of the IF band within the rated range, and the monitoring of the IF band is only performed by the device operator,
The FPU transmitting apparatus itself does not have a monitoring function for these.

FIG. 4 is a block diagram showing an example of a conventional FPU transmitting apparatus. The baseband input signal 1 is modulated into an IF band by the IF modulator 3 (in an internal modulation mode).
In another system, a terminal for inputting the component of the external IF input 2 is provided, and the IF switching circuit 4 selects between the internal modulation mode and the IF transmission mode. The selected output of the IF switching circuit 4 is applied to the IF amplifier 5 and the RF circuit 6
Is converted to a microwave band frequency by PA
(Power amplification) The power is amplified by the unit 61 and the SFH output terminal 7
Power is radiated as microwaves.

When the operation mode of the FPU transmitting apparatus is the internal modulation mode, the frequency is stabilized by using a method such as automatic frequency control in the IF modulation section 3. However, in the IF transmission mode, the IF input is determined only by the rating, and the function of monitoring the IF component is not provided therein.

[0011]

The first problem is that the external I
If an IF component whose center frequency is shifted or out of the specified level is input at the time of F input, a component which is converted into a microwave band through the frequency conversion of the RF unit and radiated power is converted into an IF component. That is, it is affected in proportion to the variation, and may cause interference to an adjacent channel.

The reason is that there is no means for monitoring the external IF input and controlling the power emission in the microwave band.

A second problem is that the apparatus operator cannot know whether the external IF input is proper or not by the FPU transmitting apparatus alone. The reason is that the FPU transmitting apparatus is not provided with a means for displaying the monitoring of the status of the IF component.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an FPU transmitting apparatus capable of monitoring microwave external power input and controlling microwave power emission to emit more stable frequency components.

[0015]

According to the present invention, there is provided an FPU transmitting apparatus for wirelessly transmitting a television video signal and an audio signal in a microwave band, and detecting means for detecting the level and frequency of an external IF input, respectively. And a control means for controlling the power of the transmission power amplifier in accordance with the detected outputs.

According to the present invention, a modulating means for modulating a television video signal and an audio signal and converting the modulated signal into an IF band, a switching means for selectively deriving the modulated output and an external IF input, An FPU transmitting apparatus including an IF amplifier for amplifying a selected output by a switching unit and a power amplifier for power-amplifying the amplified output, wherein a detecting unit for detecting a level and a frequency of a selected output of the switching unit, Control means for controlling the power supply of the power amplifier in accordance with the equal detection output.

The control means supplies power to the power amplifier when the frequency detection and the level detection are each in a predetermined detection state, and the control means comprises: A display unit for displaying a detection state of the detection means.

Further, the detecting means includes a frequency / voltage converter for converting the frequency of the input IF signal into a voltage, an integrator for integrating the converted output, and a comparator for comparing the integrated output with a predetermined threshold. Wherein a frequency detection output is generated in accordance with the result of the comparison, wherein the detection means comprises a fixed attenuator for attenuating the level of the input IF signal, and an output terminated with the attenuated output as an input. And a comparator that compares the automatic gain control voltage with a predetermined threshold value, and generates a level detection output according to the comparison result.

The operation of the present invention will be described. Added a monitoring function to monitor the frequency and level for the external IF input,
It is possible to prevent the influence on the microwave band due to the quality of the supplied external IF signal. Therefore, it is possible to expect an improvement in the reliability against the interference to the adjacent channel, and it is possible to notify the operator of the apparatus of the problem by displaying the state of the external IF signal.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and the same parts as those in FIG. 4 are denoted by the same reference numerals. In addition to the conventional configuration shown in FIG. 4, in the present invention, a function of monitoring the frequency and level of the external IF input 2 is added. That is, the output of the switching circuit 4 is supplied to a buffer (buffer amplifier) 8.
Is supplied to a BPF (Band Limiting Filter) 9 via the.

The BPF 9 is a band-pass filter having a narrow band with a rated IF as a center frequency. The output of the BPF whose band is limited is input to a frequency detector 10 and a level detector 11, respectively. Detection is performed. These detection results are input to the PA control unit 12 that controls the power of the power amplification unit 61.

The PA control unit 12 controls the power supply of the power amplifying unit 61 according to these two detection results, and instructs the display unit 13 to display the detection results. The other configuration is the same as that of FIG. 4, and the description is omitted.

FIG. 2A is a diagram showing an example of the frequency detector 10 of the block shown in FIG. 1. The FV converter 101 converts the frequency of the IF signal into a voltage, and the integration circuit 102 integrates the output. And a comparison conversion circuit 103 that compares the integrated output with a reference voltage 104 that is a predetermined threshold and outputs a comparison result at, for example, a logic level.

The output of the BPF 9 passes through the FV conversion circuit 101 and the integration circuit 102, whereby the frequency energy in the IF band is converted into a DC voltage. This DC voltage is compared with a preset reference voltage 104, and pass / fail information as to whether or not the frequency component is compatible is output by the comparison conversion circuit 103. If the output is a logic level, a high level is generated in the case of frequency adaptation, and a low level is generated in the case of non-conformity.

FIG. 2B is a diagram showing an example of the level detector 11 of FIG. 1, and shows a fixed attenuator 1 for attenuating an IF signal.
11, an AGC (automatic gain control) system 112 to which the attenuated output is input, a terminating resistor 117 for terminating a signal passing through the AGC system, and a drive circuit 115 for inverting the polarity of the AGC voltage of the AGC system and leading the AGC voltage. And a comparison conversion circuit 116 that compares the drive output with a predetermined reference level, which is a threshold, and outputs a comparison result at, for example, a logic level.

The fixed attenuator 111 is set to an attenuation of, for example, about 20 dB.
AGC (comprising F amplifier 113 and negative feedback circuit 114)
System 112 operates to compensate. Therefore, this AGC
The amount of AGC compensation (DC voltage) of the system 112 is inversely proportional to the level of the IF signal.

Therefore, the amount of AGC compensation is calculated using the feedback circuit 11.
4, a DC voltage proportional to the IF level can be obtained by inverting the polarity in the drive circuit 115. This output is compared by a comparison conversion circuit 116.
IF level within the rated input range (for example, 0 to +4 dB
m) A comparison is made to determine whether the AGC compensation amount is considerable, and a high level is generated if the determination result is appropriate, and a low level is generated if the determination result is inappropriate.

The PA control unit 12 calculates the logical product of the logic levels of these detection results, and supplies power to the power amplification unit 61 only when the frequency of the IF band is appropriate and the level is also appropriate. I do. The control of the power supply is performed in such a manner that the power supply to the drain terminal of the field effect transistor which is the active element of the power amplifying unit 61 is controlled, but is not limited to this.

Further, by controlling the display section 13 to display the detection result, it is possible to notify the operator of the monitoring result.

FIG. 3 is a block diagram of another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals. In this example, the FPU transmitting apparatus is separated into a control section 30 in the preceding stage and a high-frequency section 40 in the subsequent stage.
The present invention is applied to the configuration connected by.

In the preceding control section 30, the IF modulation section 3
And a switching circuit 4 are provided.
Switches between the internal modulation mode and the IF transmission mode. This switching output is amplified by the IF amplifier 5A for compensating for the signal loss due to the coaxial cable 50, and is combined with the DC power supply 31 by the multiplexer 32 and output. This DC power supply is used as an operation power supply for the high-frequency unit 40 in the subsequent stage, and is supplied to the subsequent stage via the cable 50 together with the IF signal.

Therefore, in the latter stage 40, the DC power is separated by the demultiplexer 41 and the power is supplied to each unit from the power supply circuit 42. In FIG. Just show it to supply.

The configuration of the high frequency section 40 at the subsequent stage is equivalent to that of FIG. It is clear that such a configuration also has the same operation and effect as the previous embodiment.

[0035]

As described above, since the external IF input is monitored inside the device and the microwave power emission is controlled based on the result of the monitoring, the reliability of the device with respect to adjacent channel interference in the IF transmission mode is reduced. There is an effect of improving.

In addition, by displaying the monitoring result, the status of the external IF input can be notified to the apparatus operator, so that it is easy to find the cause when a failure occurs.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

2A is a diagram illustrating an example of a frequency detection unit 10 in FIG. 1, and FIG. 2B is a diagram illustrating an example of a level detection unit 11.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a block diagram of a conventional FPU transmission device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 baseband input 2 external IF input 3 IF modulation section 4 switching circuit 5, 5A IF amplifier 6 RF circuit 7 SHF output 8 buffer 9 BPF 10 frequency detection section 11 level detection section 12 PA (power amplification) control section 13 display section 61 Power amplifier

Claims (6)

[Claims] 1. An FPU transmitting apparatus for wirelessly transmitting a television video signal and an audio signal in a microwave band, comprising: detecting means for detecting the level and frequency of an external IF input; Control means for controlling the power supply of the credit power amplifier.
U transmission device. 2. Modulation means for modulating a television video signal and an audio signal to convert them into an IF band, switching means for selectively deriving the modulation output and an external IF input, and selective output by the switching means. An FPU transmission apparatus including an IF amplifier for amplifying the amplified output and a power amplifier for power-amplifying the amplified output, wherein the detection means detects the level and frequency of the selected output of the switching means, respectively, Control means for controlling the power supply of the power amplifier. 3. The FPU according to claim 1, wherein said control means supplies power to said power amplifier when frequency detection and level detection are each in a predetermined detection state. Transmission device. 4. The apparatus according to claim 1, wherein the control unit has a display unit for displaying a detection state of the detection unit.
3. An FPU transmitting apparatus according to any one of to 3. 5. The detecting means includes a frequency / voltage converter for converting the frequency of an input IF signal into a voltage, an integrator for integrating the converted output, and a comparator for comparing the integrated output with a predetermined threshold. 5. A frequency detection output is generated according to the comparison result.
The FPU transmitting apparatus according to any one of the above. 6. The detection means comprises: a fixed attenuator for attenuating the level of an input IF signal; an automatic gain control circuit having an output terminated with the attenuated output; and comparing the automatic gain control voltage with a predetermined threshold. 6. The FPU transmitting apparatus according to claim 1, further comprising: a comparator configured to generate a level detection output according to a result of the comparison.