JPS62188438A - Transmission power control system - Google Patents

Abstract

PURPOSE:To control the power by controlling a level control means so as to increase the transmission power of a transmission system by alphaXdB (alpha is a constant) higher than a reference transmission power at a fine weather thereby using a reflected signal only of the transmission of its own station without using a beacon signal. CONSTITUTION:A pilot signal is relayed by a satellite and converted into an intermediate frequency, amplified in common by an intermediate frequency amplifier 9 and the result is fed to a pilot reception section 11 via a distributor 10 and used as an AGC and AFC reference signal. The detection output 102 of the pilot reception section 11 is fed to a control circuit 12, where the signal is converted into a digital signal, which is compared with a reference voltage set in a memory in advance to obtain the level reduction XdB of the reception level. Then the ratio alpha of rainfall attenuation of an up-link to a down-link is multiplied with the value X, a digital signal 103 set to a value lower than the reference attenuation of a digital attenuator 4 by alphaXdB is sent, the rainfall attenuation of the up-link is compensated and the reception power of the satellite is kept to the same value as at a fine weather.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transmission power control method, and particularly relates to a transmission power control method, and particularly relates to a transmission power control method, and is particularly applicable to uplink rain control systems at earth stations that use frequencies above the sub-millimeter wave band, where rainfall attenuation is large. This invention relates to a transmission power control method used to compensate for attenuation.

[Conventional technology]

For satellite communication earth stations that use frequencies above the sub-millimeter wave band (Ka, Ku band) where rain attenuation is large,
When the rain attenuation is large, transmission power control is required to increase the earth station's transmission power to compensate for the uplink rain attenuation. Hashira's method has been proposed for this transmission power control, which measures downlink rainfall attenuation using beacon signals sent from satellites, and estimates uplink attenuation from this measured value. Send that amount'1
An estimated control method that increases the power, and a pilot signal sent from the own station receives a return signal relayed by a satellite.
The received level or carrier-to-noise power ratio (C/N') of this return signal and the beacon signal sent from the satellite is compared, and the transmission power is controlled so that the relationship between the two always maintains the same relationship as on a clear day. Loop control method (Unexamined Japanese Patent Publication No. 58-8
4547) is used.

[Problem that the invention seeks to solve]

The conventional transmission power control methods described above all use a beacon signal from a satellite, so there is a problem that stable transmission power control cannot be performed when the output of the beacon signal fluctuates.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems and provide a transmission power control method that can be controlled using only a return signal transmitted from the own station without using a beacon signal.

[Problem fa: Means to solve]

The transmission power control method of the present invention is a transmission power control method used in an earth station of a satellite communication system to compensate for uplink rain attenuation, and the transmission system of the earth station uses a control signal to control the gain or The receiving system of the earth station is provided with a level control means for changing the amount of attenuation, and the receiving system of the earth station is provided with return receiving means for returning and receiving one of the transmission signals constantly transmitted from the earth station via the satellite, and the return receiving means is Amount of level decrease from the standard reception level in clear weather set in advance from the output
dB is calculated, and the four transmitters of the transmission system are αX dB (α is a constant) compared to the predetermined standard transmission power in clear weather.
The level control means is configured to control the level control means to increase the level.

[Effect]

The amount of increase in propagation loss (value expressed in dB) due to rainfall on the satellite communication propagation path, that is, the rain attenuation t, is approximately proportional to the square of the frequency, and the amount of rain attenuation ΔLu on the uplink and the rain on the downlink for the same propagation path are It is known that a constant proportional relationship holds between the amount of attenuation ΔLu and the amount of rainfall.

Now, if ΔLu/ΔLD-α and the amount of increase in transmission power due to transmission power control is ΔP, then the amount of decrease in the reception level of the own station's transmission signal relayed by the satellite and returned is expressed by equation (1). .

X = - (ΔF - ΔLu - ΔLn) ... - (1) In order to compensate for uplink rain attenuation by transmission/1 power control, it is sufficient to set ΔP = ΔLu, and such control was performed. According to equation (1), X in this case becomes X=ΔLu.

Therefore, it is sufficient to control ΔP so that ΔP=αΔLo=αX.

This condition is the same as the control condition when controlling the transmission power by estimating the amount of rain attenuation in the uplink from the amount of reduction in the reception level of the beacon signal. Therefore.

The control circuit of the transmission power control method of the present invention can be realized with a configuration similar to that of the conventional estimation control method.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, showing a case where an earth station transmitting a 5CPC viroft signal returns and receives its own pilot signal to perform transmission power control. Referring to FIG. 1, a pilot signal generated by a pilot estrus section 1 is combined with a communication transmission signal 101 in a combiner 2, and then a digital attenuator 3. Up converter 4. ' is transmitted from the antenna 6 via the force amplifier 5. This pilot signal is relayed by the satellite, and the returned signal is sent to the antenna 6° and the low noise amplifier 7 along with other communication reception signals.
．． After being converted to an intermediate frequency through a down converter 8, it is commonly amplified by an intermediate frequency amplifier 9, and then a distributor 10.
is sent to the pilot receiving section 11 via AGC and AF.
It is used as a C reference signal. The detection output 102 of the pilot receiver 11 is applied to the control circuit 12, where it is converted into a digital signal, and compared with a reference voltage (detection output of the pilot receiver on a clear day) set in memory in advance to determine the reception level. The level reduction amount XdB is determined.

Next, a digital signal 103 that multiplies X by the ratio α of rain attenuation between the uplink and downlink and sets the value to a value αXdB lower than the attenuation standard of the digital attenuator 4 is sent out, and the rain attenuation of the uplink is is compensated for, and the received power of the satellite is kept almost the same as on a clear day.

FIG. 2 is a block diagram of another embodiment of the present invention.
The difference from the diagram is that a pin diode attenuator 13 is used for level control of the transmission system, and a part of the output of the power amplifier 5 is branched to a level detector 15 via a directional coupler 14, where n is detected. The detected voltage vD is compared with the reference voltage Va in a control circuit 16, and the bin diode attenuator 13 is controlled so that the two match and VD=Va.

S, reference voltage vR is the reference voltage Vo for controlling the transmission power to the reference power in clear weather, and the pilot receiving unit 11
Correction voltage V for rain attenuation compensation obtained from the amount of 0 level decrease
c, and is configured to prevent fluctuations in transmission power and increase uplink transmission power during rain in the same control loop.

In any of the above embodiments, gain fluctuations in the earth station receiving system cannot be distinguished from rain attenuation and become a factor that changes the transmission power, so it is necessary to maintain good stability in the receiving system. Therefore, when the fluctuation is large, a gain control signal is inserted into the input side of the low-noise amplifier via a directional coupler.
It is desirable to take measures such as configuring a control loop that keeps the output constant.

In the above embodiment, a case where control is performed using a 5CPC pilot signal has been explained, but if the signal is always input to the transmitter system combiner at a constant level, it cannot be used as a pilot signal (transmission signal for communication). It can also be controlled using @
, it is also possible to control using an FM system carrier wave instead of the 5cpc system.

〔Effect of the invention〕

As explained in detail above, according to the transmission power control method of the present invention, uplink transmission power can be controlled without using beacon signals, so even earth stations with a simple configuration that are not equipped with a beacon receiver can transmit data. This has the effect of enabling power control.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the invention, and FIG. 2 is a block diagram of another embodiment of the invention. 1...Biloft transmitter, 2...Synthesizer, 3...Up converter, 4...
Digital attenuator. 5...Power amplifier, 6...Antenna,
7...Low noise amplifier, 8...Down converter, 9...Intermediate frequency amplifier, 10...
...Distributor, 11...Pilot receiving section, 1
2, 16... Control circuit, 13... Pin diode attenuator, 14... Directional coupler, 1
5...Level detector.

Claims (1)

[Claims] In a transmission power control method used to compensate for uplink rain attenuation in an earth station of a satellite communication system, the transmission system of the earth station is provided with a level control means for changing the gain or attenuation amount by a control signal, The receiving system of the station is equipped with a return receiving means for returning and receiving one of the transmission signals constantly sent from the own station via a satellite, and from the output of this return receiving means, it is possible to calculate the signal from the preset standard reception level in clear weather. Transmission power characterized in that the level reduction amount XdB is determined and the level control means is controlled so that the transmission power of the transmission system is increased by αXdB (α is a constant) from a predetermined reference transmission power in clear weather. control method.