JPH0478232A - Transmission power controller - Google Patents

Abstract

PURPOSE:To attain transmission power control even with a beacon signal subject to modulation by measuring separately total power sum of a carrier and noise and noise power so as to obtain a signal power to noise power ratio C/N of a reception signal. CONSTITUTION:An antenna 1 receives a beacon signal fed from a satellite and the signal is reproduced at a receiver 4 through a low noise amplifier 2 and a reception frequency converter 3. A BPF 14 extracts a carrier and a signal in the vicinity of it from the reception signal, and a power meter 15 measures the sum of the total power of the carrier and the total power of the noise. A BPF 16 extracts only the noise from the reception signal and a power meter 17 measures the noise power. A C/N computing element 7 calculates and outputs the C/N of the reception signal from the output of the power meters 15,17. As a result, since the carrier power is always constant regardless of modulation/nonmodulation, the transmission power is controlled even from the modulated beacon signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transmission power control device used in satellite communication earth station equipment to compensate for transmission power attenuation due to rain.

[Conventional technology]

Figure 2 is a configuration diagram of a conventional transmission power control device that estimates and compensates for uplink attenuation from downlink attenuation. a noise amplifier; 3 a reception frequency converter that converts the frequency of the received signal; 4 a receiver; A phase detector that detects waves with 7
is the C/N of the received signal from the average variance of the output of the phase detector 6.
8 is a downlink attenuation calculator that estimates the downlink attenuation from the fluctuation of the CN of the received signal; 9 is an uplink attenuation calculator that estimates the uplink attenuation from the downlink attenuator. 10 is a transmitter, 11 is a variable attenuator that changes the amount of attenuation according to the output of the uplink attenuation amount calculator 9;
12 is a transmission frequency converter, and 13 is a power amplifier.

Next, the operation will be explained. A signal transmitted from the satellite is transmitted from an antenna 1 to a low noise amplifier 2. The signal passes through a reception frequency converter 3 and is reproduced by a receiver 4. In the phase detector 6, the receiver output is subjected to in-phase detection by the reference frequency oscillator 5. The C/N calculator 7 calculates the average and variance of the output of the phase detector, and calculates the signal power to noise power ratio C/N of the received signal. The downlink attenuation calculation unit 8 compares the received C/N with the C/N under clear weather and estimates the rain attenuation in the downlink from the difference.

The uplink attenuation calculator 9 estimates the uplink rain attenuation from the downlink rain attenuation using the frequency correlation of the rain attenuation. The transmitter 10 always outputs a signal at a constant level, but the attenuation of the variable attenuator changes according to the output of the uplink attenuation calculator. In other words, when the uplink rain attenuation is large, the attenuation of the variable attenuator 11 is made small;
Conversely, when the uplink rain attenuation is small, the variable attenuator 11
The attenuation amount is increased (by this, the transmission power output from the antenna 1 through the transmission frequency converter 12 and power amplifier 13 is controlled.

[Problem to be solved by the invention]

Since the conventional transmission power control device is configured as described above, there is a problem in that the received signal must be an unmodulated signal.

This invention was made to solve the above problems, and even if the received signal is modulated, the received C
An object of the present invention is to obtain a transmission power control device that can control transmission power by measuring fluctuations in /N.

[Means for Solving the Problems] A transmission power control device according to the present invention calculates the C/N from the sum of the carrier wave power and the noise power of the received signal and the noise power, and calculates the rainfall attenuation amount of the uplink from the fluctuation thereof. is estimated and the transmission power is compensated.

[Effect]

Since the C/N calculation in this invention is performed based on the ratio of the total power of the carrier wave of the received signal and the noise power, the C/N can be calculated accurately even for a signal subjected to phase modulation or frequency modulation.

〔Example〕

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

FIG. 1 shows a transmission power control device according to an embodiment of the present invention. In the figure, numeral 1 is an antenna, 2 is a low-noise amplifier that amplifies the signal received by antenna 1, 3 is a reception frequency converter, and 4 is a reception 5 is a reference oscillator that emits a reference signal for the receiver 4; 14 is a first bandpass filter that extracts a signal in a certain band including a carrier wave; 15 is a first power that measures the output level of the bandpass filter 14; 16 is a second bandpass filter that extracts a signal in a certain band that does not include a carrier wave; 17 is a second wattmeter that measures the output level of the bandpass filter 16; 7 is a wattmeter 15.17
a C/N calculator that calculates the C/N of the received signal from the output of the
8 is a downlink attenuation calculator that estimates downlink attenuation from fluctuations in the received signal C/H; 9 is an uplink attenuation calculator that estimates uplink attenuation from downlink attenuation; lO is a transmitter; 11 12 is a variable attenuator that changes the amount of attenuation according to the output of the uplink attenuation amount calculator 9; 12 is a transmission frequency converter; 13
is a power amplifier.

Next, the operation will be explained. An antenna 1 receives a beacon signal sent from a satellite, and a low noise amplifier 2. The signal passes through a receiving frequency converter 3 and is reproduced by a receiver 4. The bandpass filter 14 extracts the carrier wave and signals in its vicinity from the received signal, and the power meter 15 measures the total power of the carrier wave and the total power sum of the noise. The bandpass filter 16 extracts only the noise portion from the received signal, and the power meter 17 measures the noise power. The C/N calculator 7 calculates the C/N of the received signal from the outputs of the wattmeter 15 and the wattmeter 17 and outputs it.

In the conventional system, the C/N of the received signal was determined by phase detection of the received signal and the average and dispersion of the output, so it was not possible to control the transmission power for a modulated signal. However, when using the method of this embodiment, the power of the carrier wave is always constant regardless of modulation 9 or non-modulation, so it is possible to control the transmission power even for a modulated beacon signal.

The downlink attenuation calculation unit 8 compares the received signal C/N with the received signal C/N on a clear day to estimate the downlink rain attenuation.

The uplink attenuation amount calculator 9 estimates the uplink rain attenuation amount from the downlink rain attenuation amount. The transmitter 10 controls transmission power by transmitting a signal at a constant level and changing the attenuation amount of the variable attenuator 11 according to the output of the uplink attenuation amount calculator.

In the above embodiment, the outputs of the bandpass filters 14 and 16 were input to separate wattmeters 15 and 17 to measure the power of the carrier wave and noise, but as shown in FIG. A changeover switch 18 is provided at the input of the power meter 15, and the changeover switch is switched between the bandpass filter 14 side and the bandpass filter 16 side according to the timing signal from the C/N calculator 7, and the output of the wattmeter 15 is changed over again by the changeover switch 19 between the carrier wave power input and the noise. The power input may be divided into power inputs and input to the C/N calculator 7, and the same effect as in the above embodiment can be obtained.

Also, instead of inputting the receiver output directly to the bandpass filter, as shown in FIG. 15 in total, the total power of the carrier wave and noise is input to the C/N calculator 7, and then the signal from the C/N calculator is used to switch to the local oscillator 22 for frequency conversion, which is then input to the bandpass filter. Noise may be input, and the power meter 15 may measure the power of the noise and input it to the C/N calculation unit W7 via the changeover switch 19, and the same effect as in the above embodiment can be obtained. It will be done.

[Effects of the Invention] As described above, the transmission power control device according to the present invention is configured to obtain the C/N of a received signal by separately measuring the total power sum of the carrier wave and noise and the noise power. Therefore, it is now possible to control the transmission power even for modulated beacon signals.

[Brief explanation of the drawing]

The first circle is a block diagram showing a transmission power control device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional transmission power control device, and FIGS. 3 and 4 are other embodiments of the present invention. FIG. In the figure, 1 is an antenna, 2 is a low noise amplifier, 3 is a receiving frequency converter, 4 is a receiver, 5 is a reference oscillator, 6 is a phase detector, 7 is a C/N calculator, and 8 is a downlink attenuation amount. 9 is an uplink attenuation calculator, 10 is a transmitter, 11 is a variable attenuator, 12 is a transmission frequency converter, 13 is a power amplifier, 14 is a first band pass filter, 15 is a first power 16 is a second bandpass filter, 17 is a second wattmeter, 18.19 is a changeover switch, 20 is a frequency converter, 21 is a first local oscillator, and 22 is a second local oscillator. The same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Among the equipment at the satellite communication earth station, the transmission power control device that compensates for the attenuation of transmission power due to rain captures the received signal output from the satellite and measures the power of the noise part where there is no carrier wave. A device that captures the received signal and measures the power in a certain band including the carrier wave; A device that measures the signal-to-noise power ratio (C/N) of the received signal from the measurement results of the noise power and the power of the sum of the carrier wave and noise. ) to find C/N
A computing unit, a downlink attenuation computing unit that calculates the downlink rain attenuation from the C/N variation of the received signal, and an uplink attenuation computing unit that estimates the uplink rain attenuation from the downlink rain attenuation. A transmission power control device comprising: