JPS61163729A - Transmitting power monitoring and controlling system - Google Patents

Abstract

PURPOSE:To detect and control easily a transmitting output with regard to a discontinuous wave, as well, by deriving the respective transmitting output levels of plural carrier waves by a time division processing, and inputting a desired set transmitting level of each carrier wave to a digital processor. CONSTITUTION:A part of an output signal of a transmitting device 2 is made to branch by a directional coupler 5 and inputted to an output detecting part 4. In the output detecting part 4, said signal is converted to an intermediate frequency again by a frequency converter 41, and thereafter, a necessary signal component is extracted by a band pass filter 42, and an envelope of its signal component is detected by a detector 43. This detected output is brought to sampling by a sample holding circuit 44 at a prescribed time or time interval, and its sample value is held. The sample value held by the sample holding circuit 44 is converted to a digital value by an A/D converter 45, and led to a signal processing circuit 31 of a signal processing part 3. The signal processing circuit 31 compares an output of the A/D converter, and set transmitting output information which is set in advance or suitably from a parameter input terminal 6, and outputs their difference as an error signal to an output control part 1.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a method for monitoring the output level of a transmitting device used in a wireless line, and is particularly effective when applied to a transmitting device that commonly amplifies a plurality of carrier waves. Related to transmission power monitoring and control methods.

(Prior art and its problems) In a transmitter used for a wireless line, it is important to transmit the transmission output at a predetermined level in order to maintain the line stably. In particular, when a single transmitter outputs multiple carrier waves at the same time, such as in satellite communications, it is important for operation to accurately detect the output level of each carrier wave and to maintain the output level of each carrier wave constant. It is also important from Conventionally, this type of technology has involved arranging filters in parallel to the output of a transmitting device corresponding to each carrier wave, extracting each carrier wave using these filters, and monitoring its level individually.

In the above-mentioned conventional technology, when the number of carrier waves increases,
A corresponding number of filters is required, which makes the filter circuit complicated. In particular, when a waveguide is used for microwaves, millimeter waves, etc., the filter circuit becomes physically large. Furthermore, a major drawback is that it is not possible to flexibly cope with an increase in the number of carrier waves, and in particular, when the number of filters prepared in advance is exceeded, it may become impossible to cope with the increase in the number of carrier waves.

(Objects and Features of the Invention) The present invention has been made in view of the drawbacks of the above-mentioned prior art.
It is an object of the present invention to provide a transmission power monitoring and control method that can monitor the output levels of a large number of carrier waves and control the transmission output to a constant level using digital signal processing means.

To achieve this objective, the transmission power monitoring and control method of the present invention uses a digital processor to control a variable frequency local oscillator using a digital processor to time-divisionally convert all carrier waves to the same frequency. The output level of the plurality of carrier waves is detected by inputting the signal into a plurality of filters, selecting and detecting the necessary signals in a time-division manner, and combining this detection output with a set transmission level set in advance in the digital processor. A variable attenuator provided on the input side of the transmitter corresponding to each of the plurality of carrier waves is time-divisionally controlled so that the detection level becomes the set transmission level. It is characterized by controlling the output level of.

According to the present invention, the transmission output level of each carrier wave can be controlled to the set transmission level by determining the transmission output level of each of a plurality of carrier waves by time-sharing processing and inputting the desired set transmission level of each carrier wave to a digital processor. .

(Structure and operation of the invention) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram for explaining the principle of the signal output control method of the present invention. In the figure, ■ is an output control section consisting of a variable attenuator 11 and a control circuit 12, 2 is a transmitter consisting of a frequency converter 21 including a local oscillator and a transmitter 22, and 3 is a transmitting device consisting of a transmitter 22.
4 is a signal processing section consisting of a signal processing circuit 31 and a display 32, and 4 is a frequency converter 41.4 including a local oscillator. The band is 42. Detector 43° Sample and hold circuit 44
5 is a directional coupler, 6 is a parameter input terminal, and 7 is a sample signal input terminal.

Hereinafter, the principle operation of the present invention will be explained with reference to FIG.

The input signal in the intermediate frequency band is guided to the transmitting device 2 after passing through the output control section 1, where it is converted to a desired transmission frequency by the frequency converter 21, and then amplified to a predetermined power by the transmitter 22. It is then guided to an antenna (not shown).

A part of the output signal of the transmitter 2 is branched by the directional coupler 5 and sent to the output detector 4 manually. In the output detection unit 4, the frequency converter 41 converts the signal into an intermediate frequency again, a bandpass filter 42 extracts a necessary signal component, and a detector 43 detects the envelope of the signal component. This detection output is sampled at a predetermined time or time interval by a sample hold circuit 44, and the sampled value is held. The operation of this sample hold will be explained in detail later. The sample value held by the sample hold circuit 44 is converted into a digital quantity by the A/D converter 45 and guided to the signal processing circuit 31 of the signal processing section 3 . The signal processing circuit 31 compares the output of the A/D converter 45 and the setting transmission output information set in advance or appropriately from the parameter input terminal 6, and outputs the difference between them as an error signal to the output control section l. . Further, the setting transmission output information and the error signal level are displayed on the display 32 at all times or when necessary. The output control section 1 controls the attenuation amount of the variable attenuator II using the control circuit 12 in accordance with the error signal from the signal processing section 3 so that the error signal becomes zero. Signal processing circuit 31
can be configured with a microprocessor.

In the above-described operation, the degree of coupling of the directional coupler 5 and the gain of the output detector 4 are different, and the correspondence between the output level of the transmitter 2 and the output value of the A/D converter 45 is known in advance. Therefore, if a value corresponding to a desired output level is set from the parameter input terminal 6 to the signal processing circuit 31 based on the correspondence relationship, the attenuation amount of the variable attenuator 11 can be set so that the output level of the transmitting device 2 is always at the desired level. will be controlled.

Here, the operation of the above-mentioned sample and hold will be described. It is necessary to consider two cases of input signals: continuous waves and discontinuous waves. In other words, there are waves that are continuous in time like normal FM waves, and discontinuous waves that are transmitted only in the time period allocated to the own station like TDMA (time division multiple access) waves. It's a wave. In the configuration of FIG. 1, when the input signal is a continuous wave, there is no time restriction on the sampling operation of the sample and hold circuit 44, so the sample signal is generated from the signal processing circuit 31, and when the input signal is a discontinuous wave, the sample signal is generated from the signal processing circuit 31. Since it is necessary to perform a sampling operation while the transmission wave is being transmitted, a sample signal is supplied from the terminal 7 from a separately provided known TDMA synchronization circuit or the like. The sampling period of the sample and hold circuit 44 is a matter to be determined based on the relationship between the output stability of the transmitter 2 and the level stability required for the transmitted wave.

(Example) The above describes the basic configuration of the present invention by taking as an example the most basic case where the transmitted wave is one wave, but in satellite communication, various bands and bands are used depending on the amount of information to be transmitted. The transmission power is allocated to a number of transmission waves. In the embodiment of the present invention described below, a large number of transmitted waves are processed by one signal processing section, and a transmission power control function is also added.

First, in this embodiment, the output detection section 4' and signal processing section 3' for detecting the output level of a multi-wave signal will be explained with reference to FIG.

In FIG. 2, 50 is a frequency converter, 60 is a local oscillator consisting of a synthesizer that supplies a locally oscillated frequency wave to the frequency converter 50, 71-73 are hybrids, 81-8
4 is a band pass filter (BPF) with different pass bands.
), 91 to 94 are amplifiers, 100 is a switch circuit, 1
10 is a detector, 120 is a sample and hold circuit, 130
1 is an A/D converter, 140 is a signal processing circuit composed of, for example, a microprocessor, and 150 is a parameter input terminal.

The aforementioned large number of transmitted waves are commonly amplified by the transmitter 2, and the output thereof is branched by the directional coupler 5 and input to the frequency converter 50. For convenience, let these transmission waves be f++ fit h+ f4+ fs. The signal processing circuit 140 transmits the transmission waves f1 to f in a predetermined order according to a preset program, for example,
The oscillation frequency of the local oscillator 60 is controlled so that it is sequentially converted to an intermediate frequency fi (i is 1 to 5). For example, f
fit for l signal and f for f2 signal
Set Jz. In this case, the time interval (To) for switching from frequency fJ+ to fJz is the time constant of the detector 110,
When controlling the number of transmission waves and furthermore the transmission power, it is determined by taking into consideration the time constant of the control loop, etc. The signal converted to an intermediate frequency by the frequency converter 50 and the local oscillator 60 is transmitted to all BPFs by the hybrid 7I.
91 to 94 are input. These BPP 91-94
The human power is guided to the switch circuit 100 via amplifiers 91 to 94, and the switch circuit 100 selects the output of the BPF suitable for the transmitted wave to be detected under the control of the signal processing circuit 140, and transmits the output to the detector. Lead to 110. The output of the detector 110 is sampled by a sample and hold circuit 120 and then converted into a digital quantity by an A/D converter 130 and input to a signal processing circuit 140.

Here, the reason for the BPF that should be prepared will be explained with reference to FIG. 3 in relation to the previous operations.

FIG. 3(a) shows an example of the frequency array and signal spectrum of signal waves f, to f5. In the figure, the frequency interval between two adjacent waves f#+f@al is Δf, 5°, , and the frequency interval of f m'+ f,,-1 is Δf
Ill+1I-1, and each signal f
Let each bandwidth of m + fsLI + L-1 be δ'',,δ
f...

Let it be expressed as δf1-1. As mentioned above, f1
The signals of ~f are commonly amplified by the transmitter 2, and a portion thereof is input to the frequency converter 50. This frequency converter 50
In this case, a local oscillation frequency wave with a frequency fl+ to fls is generated from the local oscillator 60 with a repetition period T, where the processing time of one wave is To.
t (Figure (b)).

Correspondingly, the output side of the frequency converter 50 is shown in FIG.
As shown in C), the signal waves f1 to f sequentially change to the intermediate frequency f.
, appears as . B according to the timing of Figure 3(C)
The one having the optimum bandwidth is selected from among PF+ to BPF4. A requirement for the BPF to be selected is the bandwidth δf of the signal f1 to be detected.

It has a wider bandwidth and does not mix with adjacent signal components. That is, when extracting the signal f1, if the bandwidth of the BPF is B, then B>δf,
------------ If a BPF that satisfies the condition (2) is already prepared, that BPF can be used in common. In the example of the frequency array in FIG. 3A, it is easy to see that three BPFs with different passbands may be provided by sharing fl, rs, and ft+f4, for example.

(However, the example in FIG. 2 is for explaining the operation,
(4 BPFs are available). In this way, when the BPF can be used in common, the signal shown in FIG. 3C can be processed by storing this information in the signal processing circuit 3 and switching the switch circuit 100 at that timing. For example, in satellite communications, since a large number of signals with different bandwidths are not arranged adjacent to each other, four BPFs are practically sufficient.

The sharing of BPF has been described above. The above sharing method is
A BPF with a fixed passband width is assumed. However, in recent years, surface acoustic waves (surface acoustic waves)
With the advent of ic Wave (hereinafter abbreviated as SA-) filters, it has become possible to easily control the passband.

If such an SA-filter is applied to the present application, one BPF is sufficient, and the pass band of the SIV filter is changed to the signal processing unit 3 at the above-mentioned BPF switching timing.
You can control it from With such a configuration, it is possible to flexibly deal with changes in bandwidth due to an increase in the communication capacity of transmitted waves, and the effectiveness in terms of maintenance and operation can be further improved.

Note that the signal processing circuit 140 in FIG. 2 is the A/D converter 130.
The output can be displayed as the current transmission power value, or the error value can be displayed by comparing it with the setting transmission output information given from the outside via the parameter input terminal 150.

Furthermore, it is of course possible to control the transmission power using the error value, similar to the principle configuration shown in FIG. 1, and an example of this will be shown and explained in FIG. 4.

FIG. 4 shows a configuration example in which the input signal has four waves, and it is assumed that the input signal has already undergone frequency conversion from an intermediate frequency to a radio frequency. The output control sections 81a to 84a are basically the same as the embodiment shown in FIG. The amount of attenuation can be controlled by changing . Output control section 81a~
84a is prepared for each input signal, and their outputs are combined by the hybrids 74 to 76 and commonly amplified by the transmitter 9. The output level detection section 4' uses the output detection section explained in FIG.

The signal processing unit 3 is composed of a microprocessor, and controls the transmission power in a time-division manner as described above with reference to FIG.

The digital signal from the output detection section 4' is output in synchronization with the sample signal from the signal processing section 3.

The signal processing unit 3 calculates the average value from the signal power in N samples in l signal output period T0, and uses this as a detection output.

An example of a sample signal is shown in FIG. FIG. 3D shows an example in which five sample pulses are used within the T0 period to obtain a highly accurate average value, and the same applies to other T0 periods. Since this average value processing is performed in the signal processing section 3, T and length are To
It is necessary to set it so that calculation of the average value can be completed within the period with sufficient margin.

The signal processing unit 3 inputs a predetermined transmission output level input via the parameter input terminal 6, for example from a keyboard,
A comparison with the transmitter output is performed to obtain an error, which is output to the output controllers 81a to 84a. This series of operations is performed sequentially within 10 intervals for each signal, and after one round, the process returns to the original state and repeats this process. Therefore, if the number of input signals is M, the series of repetitive control periods T is T. It becomes M. It is clear that this value is sufficiently small compared to the output fluctuation period of the transmitter 9, and no problem occurs with time-division control.

The digital control signal from the signal processing section 3 is sent to the output control section 81.
It is input to the control circuits a to 84a. This circuit converts the input digital N (amount of error) into an analog amount and applies a change in bias current corresponding to this to the PIN diode forming the variable attenuator.

Although the above description has been made regarding the application of continuous waves such as FM waves to human input signals, the present invention can also be applied to signals transmitted intermittently such as TDMA waves. Figure 5(a) shows the PSK signal (
Phase 5hift Keying) “1”, “
Phase modulated by a digital signal of 0”.TDM
In the A method, signals from each country are amplified on a satellite without overlapping each other on the time axis, and then transmitted to the ground. For this reason, the signal format transmitted from each earth station is a burst signal that repeats at a fixed period.
It is not a continuous wave like an FM signal. Therefore, the signal processing section 3 that is manually input to the sample and hold circuit of the output detection section 4'
The sample signal from the source must be input in synchronization with the burst signal to be transmitted. Reference numeral 52 in FIG. 5(b) indicates a sample signal sent from the terminal station to the TDM, which is synchronized with the TDM^ signal 51. Therefore, when applying the present invention to the TOMA signal, the output detection section 4' in FIG. It may be processed by the signal processing device 3 in the same way as continuous waves such as.

It should be noted that for burst signals such as continuous waves and TDMA waves, it is necessary to input and use the program in the signal processing section 3.

When a TDM^ signal and a continuous wave (for example, FM) are mixed, the sample signal for the TDMA signal is output to the TDM^DMA terminal in synchronization with the TDMA burst signal, so the sample signal is input when switching from continuous wave to TDMA. Out-of-sync occurs in the signal. As a means to prevent this, it is sufficient to synchronize the sample signal and the local oscillation change timing for the continuous wave with the TtlMA burst signal. Normally, the repetition period of TDMA (TDMA frame) is 1/8 KHz (12
5μ5ec), so the sample pulse and local oscillator change timing should be adjusted to synchronize with this.
It may be created by referring to the TDMA frame from the DMA terminal station.

As described above, the present invention can be applied to signals that are transmitted intermittently in the same way as for continuous waves by separately preparing a sample signal that is synchronized with the signal from the terminal station that creates this signal. be able to.

Therefore, the sample signal synchronized with the TDMA burst is also input to the signal processing section 3.

As described above, in transmission power control, the attenuation amounts of the output control units 81a to 84a are controlled so as to achieve the set transmission output set in the signal processing unit 3.

Therefore, it is clear that by changing the set transmission output information via the parameter input terminal, the output of the transmitter 9 can be controlled in accordance with the change in the set amount.

As an application of this control operation, a transmission power control method for rain can be considered. This will be explained below. Conventionally, the 674 GHz band has been used in satellite lines, but recently, frequency bands of 10 GH2 or higher have been introduced. In such frequency bands, radio waves are attenuated by rainfall. Therefore, as will be described later, by measuring the amount of rainfall attenuation in the downlink using a beacon signal from a satellite and inputting this amount to the signal processing section 3, the above-described transmission power control can be easily realized.

That is, for example, the amount of rainfall attenuation is estimated using a beacon signal from a satellite, and this is set as x (dB).

If the frequency ratio of uplink and downlink is y, then 10 to 3
Since the amount of rain attenuation with respect to frequency increases in dB approximately to the square of the frequency between 0GH2O, the set transmission power P1 is as follows.

Pr (dB) −Pc +x−y ” (dB) where PC is the transmission power (dB) in clear weather. In reality, these settings can be achieved quite easily when using a processor. In this case, the only new information required is the amount of downhill rainfall attenuation, and in the example of FIG. 4, the reception level (or C/N) of the beacon signal is input to the signal processing unit 3. The beacon reception level (or C/N) is input into the processor in advance, and the amount of rainfall is estimated from the difference between the two within the processor according to a program.

(Effects of the Invention) As detailed above, according to the present invention, the transmission output of not only continuous waves but also discontinuous waves such as TDMA waves can be easily detected and controlled, and maintenance and The operational effects are significant.

Furthermore, when the present invention is applied to a communication system at a frequency that is subject to rain attenuation, it is possible to automatically perform control corresponding to the amount of rain attenuation, thereby preventing deterioration in line quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a block diagram showing an example of a signal processing section used in an embodiment in which the present invention is applied to the basic configuration of FIG. 1, and FIG. 3 (a) (
bl (cl (di) is a schematic diagram for explaining the conditions of a band waver used in the present invention, FIG. 4 is a block diagram showing another embodiment of the present invention, and FIG. 5 is a diagram in which the present invention is applied to TDMA waves. 2 is a time chart for explaining the operation in this case.

Claims (1)

[Claims] By controlling the variable frequency local oscillator using a digital processor, the output of the plurality of carrier waves is time-divisionally converted so that all the plurality of carrier waves have the same frequency and inputted to the plurality of filters to generate the necessary signal. Detecting the output level of the plurality of carrier waves by selecting and detecting them in a time-division manner, and comparing the detected output with a set transmission level set in advance in the digital processor, and determining that the detected level is the set transmission level. Transmission power monitoring characterized in that the output levels of the plurality of carrier waves are controlled by time-division control of variable attenuators provided corresponding to each of the plurality of carrier waves on the input side of the transmitter so that control method.