JPS6313377B2 - - Google Patents

Abstract

PURPOSE:To correct the rainfall attenuation of an up link without wasting the transmitting electric power of a satellite and increasing the scale of a ground station by allowing a subordinate station to receive a pilot signal from a master station and controlling the transmitting electric power of the subordinate station individually according to the received level. CONSTITUTION:When a maximum received level on a fine weather condition is PA, it is the set level of this circuit. At the master station, a common-circuit (CSC circuit) carrier received level from each subordinate station is sampled and a level comparison is made to transmit the pilot signal by increasing the transmitting electric power up to the received level of a station having the highest received level. Since the effective isotropic radiation electric power (EIRP) of the satellite is constant without reference to rainfall attenuation near the master station, i.e. transmitting station, each subordinate station controls its transmitting electric power so that the received level of its own radio wave is equal to that of a pilot signal received by itself, thus making the EIRP constant without reference to the rainfall attenuation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission power control system for an earth station in satellite communications.

In general, in satellite communications, particularly in satellite communications that use a sub-millimeter wave band of approximately 10 to 20 GHz, radio waves are attenuated significantly due to rainfall, and compensation is usually performed in some way. As a compensation method for the downlink from the satellite to the ground station, a site diversity method or a control method in which the earth station is given a margin in advance to compensate for attenuation is used. on the other hand,
For uplinks from earth stations to satellites, site diversity methods and methods that control the earth station's transmission power according to rainfall attenuation are used. This method of providing a margin in advance for rain attenuation of radio waves in the case of uplink will waste transmission power by that amount on clear skies, so it is not effective from the point of view of effective use of transmission power to the satellite. Very disadvantageous. For this reason, EIRP on normal satellites
A method is used to control the earth station's transmission power according to the uplink rainfall attenuation so that the effective isotropic radiated power (Equivalent Isotropic Radiated Power) is always constant. This method is generally referred to as the earth station transmission power control method. As this transmission power control method, multiple earth stations use a CSC (Common Signaling Channel) line of a random access method such as the ALOHA method to transmit SCPC (Single Channel).
DAMA (Demand) by Per Carrier)
There was a problem when using the Assignment Multiple Access) method.

Conventionally, the transmission power control method of this type of _satellite communication earth station has been as _shown in Figure 1. This return signal is divided into (S/N) ₁ of the pilot signal received by A ₁ station and (S/N) 1 of the pilot signal transmitted from B ₁ station and received by A ₁ station.
N) There is a method to control the transmission power of one station so that _A2 is equal to _A1 . Also, as shown in Figure 2,
There was a method of controlling the transmission power between the earth station _A2 and the satellite 1 using the telemetry value of the satellite reception power. However, since the method shown in FIG. 1 uses two waves as pilot signals, it is necessary to use satellite transmission power accordingly, which is disadvantageous from the point of view of effective use of satellite transmission power. Furthermore, the method shown in FIG. 2 requires a satellite telemetry receiving device, which has the disadvantage of increasing the size of the earth station.

An object of the present invention is to eliminate these drawbacks and provide a transmission power control method for a satellite communications earth station that corrects uplink rain attenuation without wasting satellite transmission power or increasing the scale of the earth station. There is a particular thing.

The transmission power control method of a satellite communication earth station according to the present invention is such that when a plurality of earth stations including a master station and a slave station are operated through a common control line in random access satellite communication, the master station Sequentially requests uplink transmission to slave stations,
In response to this transmission request, each of the slave stations sends a transmission output, and the master station receives these transmission outputs, detects each received carrier level, and becomes equal to the maximum level of these received carrier levels. The transmission power of the pilot signal of the master station is controlled and transmitted so that the pilot signal of the master station is received by the slave station, and the transmission power of each slave station is controlled according to the reception level of the pilot signal. Accordingly, the uplink radio wave attenuation is compensated for.

The present invention will be explained in detail below with reference to the drawings.

FIGS. 3a and 3b are transmission level diagrams illustrating the transmission power control of the present invention. Figure 3a shows the arrangement of each burst from station A to station H sent out to the CSC line at the request of the master station, and Figure 3b shows the sequence of bursts sent to the CSC line at the master station's request.
Indicates the receiving carrier level of the line. here
Assuming that P _A is the maximum reception level under clear skies,
This is the setting level for this line. Here, at the master station, the CSC line carrier reception level from each slave station is sampled, and after passing through an integrating circuit with a fixed time constant, the levels are compared, and the reception level is compared with that of the station with the highest reception level. Control is performed to increase the transmission power of the pilot signal to the same level and transmit it. Since the pilot signal controlled in this way has a constant EIRP at the satellite regardless of rain attenuation near the master station, which is the transmitting station, each slave station can adjust the reception level of its own radio waves to the pilot signal received by its own station. By controlling the transmitting power of the local station so that it is at the same level as the signal receiving level, the satellite transmits power is not affected by rain attenuation.
EIRP can be made constant.

Satellite communication is generally used over a wide area, but the rainy area is said to be within a range of several tens of kilometers, and it is thought that it is rare for all earth stations to experience rain attenuation. Transmission power control is fully possible.

FIGS. 4a and 4b are block diagrams showing a master station and a slave station according to an embodiment of the present invention. In the figure, 2 is an antenna,
3 is a low noise amplifier into which the received signal is input, 4 is a receiving frequency converter, and 5 and 7 are on the receiving and transmitting sides.
AGC amplifier, 6 is AGC/AFC control device, 8 is transmitting frequency converter, 9 is high power amplifier, 10 is IF
Signal splitter, 11 is IF signal combiner, 12, 17
is a CSC demodulation and modulation device, 13, 19 is a channel selection device, 14 is a DAMA device, 15, 16
19 is a channel demodulation and modulation device, 19 is a level detector, 20 is a level comparator, 21 is a CSC line carrier detection circuit, and 22 is a pilot carrier detection device.

The operation of this embodiment is as follows.

First, in the case of the master station, the carrier level of the CSC line is detected at the output of the reception frequency converter 4. That is, the master station receives a timing signal synchronized with each earth station from the DAMA device 14, extracts the burst signal level from each earth station, and compares the highest reception level with the reception level of the pilot signal through each integration circuit. Then, control is performed so that the maximum reception level and the reception level of the pilot signal are equal. For this purpose, a CSC line carrier detection circuit 21 that extracts the output of the reception frequency converter 4, a sampling identification circuit 19 that synchronizes this carrier detection circuit 21 with the DAMA device 14, and a maximum level of the output of this identification circuit 19 are provided. It is constructed by adding a comparison circuit 20 for comparison and an AGC amplifier 7 for controlling the transmission level based on the output of this comparison circuit.

Next, in the case of a slave station, the carrier detection circuit for the pilot signal detects the carrier level of the pilot signal from the output of the receiving frequency converter 4, and the received carrier level of the own station radio wave when transmitting the own station, and then outputs the signal to each AGC. Control is performed through each integrating circuit included in the amplifier 7 so that the reception level of the pilot signal and the reception level of the local radio wave are equal.

As described above, according to the present invention, an economical and reliable satellite communication earth station transmission power control function can be obtained by adding a simple circuit and without increasing the scale of the earth station.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of conventional pilot and telemetry satellite communications earth station transmission power control systems, and Figures 3a and 3b illustrate the burst arrangement of each slave station and the master station to explain the present invention. FIGS. 4a and 4b are block diagrams of a master station and a slave station according to an embodiment of the present invention. In the figure, 1...Artificial satellite, 2...Antenna,
3...Low noise amplifier, 4...Reception frequency converter,
5, 7...AGC amplifier, 6...AGC/AFC control device, 8...Transmission frequency converter, 9...High power amplification device, 10...IF signal splitter, 11...IF signal combiner , 12...CSC demodulator, 13...channel selection device, 14...DAMA device, 15...
... Channel demodulation device, 16 ... Channel modulation device, 17 ... CSC modulation device, 18 ... Channel selection device, 19 ... Level detector, 20 ... Level comparator, 21 ... CSC line carrier detection circuit, 22 ...Pilot carrier detection circuit.

Claims (1)

[Claims] 1. When a plurality of earth stations including a master station and a slave station are operated through a common control line in random access satellite communication, the master station sequentially requests uplink transmission to the slave stations in a non-communicating state,
In response to this transmission request, each of the slave stations sends a transmission output, and the master station receives these transmission outputs, detects each reception carrier level, and adjusts the level so that it becomes equal to the maximum level of these reception carrier levels. control the transmission power of the pilot signal of the master station and send it out, receive the pilot signal of the master station at the slave station, and control the transmission power of each slave station according to the reception level of the pilot signal. A transmission power control method for a satellite communication earth station, characterized in that the uplink radio wave attenuation is compensated for by: