JPS6033747A - Large power transmission system having transmission power control function - Google Patents

Abstract

PURPOSE:To improve the reliability and to reduce power consumption by controlling the number of power amplifiers operated in parallel depending on weather. CONSTITUTION:Only the 1st power amplifier 113 is activated at fine weather and the 2nd power amplifier 114 is not activated and the amplifier current and voltage are interrupted. The transmission output at fine weather is stored in a power amplifier control section 143 in advance comprising a microprocessor, and the control is performed by detecting a part of the output branched by a coupler 140 connected to an output terminal 112 by a detector 141, converting it by a detected current converter 136 and returning it to a power amplifier control section 143 via an A/D converter 142. When the attenuation due to rainfall is large, the 1st power amplifier 113 is operated up to the saturated output and the level does not reach a required rainfall margin, the 2nd power amplifier 114 turned on in advance is operated at a certain rainfall attenuation level and switching devices 117, 118 are connected to the position B to attain parallel operation.

Description

Detailed Description of the Invention (Technical Field) The present invention is a transmitting device used in a frequency band where rainfall attenuation is large, and when the weather is clear, the transmission output is sufficient to obtain the line standard value, and the transmission is performed according to the amount of rain attenuation. The present invention relates to a high power transmission system having uplink transmission power control to increase device output.

(Background technology) As geostationary satellite orbits in the microwave band conventionally used for satellite communications become congested, rainfall attenuation is large.
The use of frequency bands above 0 GHz is becoming popular. The problem with such frequency bands is that they require a tight rain margin, which results in the need for a high-power transmitter.

To explain using the example of the 50/20GH2 band, where rainfall attenuation is severe, large attenuation that can cause line disconnections occurs, for example, 0 per year.
．． Only about 5tI6 occurs, and the remaining 995% of the time can be said to be in a state with almost no attenuation (clear weather).

Therefore, constantly transmitting high power is disadvantageous in terms of earth station power consumption and the lifespan of the transmitter.

In addition, in the two-satellite system interference path diagram of FIG. 1, the orbital interval O between the desired satellite 2 and the interfering satellite 3 on the geostationary satellite orbit 1 needs to be a large value unless transmission power control is performed. That is, when communication is performed between the desired earth station (transmission) 4 and the desired earth station (reception) 5, rain 6 occurs on the desired earth station (transmission) 4, and the desired signal wave 9 is attenuated. On the other hand, the interfering earth station (transmission) accessing the interfering satellite 6
Let us consider a case where there is no rain above the interfering earth station (transmitting) 7 with a line between the interfering earth station (receiving) 7 and the interfering earth station (receiving) 8. In such a state, the interference wave 10 directed toward the desired satellite 2 from the interfering earth station (transmission) 7 is not attenuated, so the value of the desired wave to interference wave power ratio (C/I) at the desired satellite 2 is a small value. Therefore, in order to avoid this, the orbital spacing (0) between the two satellites must be a large value. If used in this way, the C/I will deteriorate by the rain margin (for example, 15 to 2 odB), and the orbit will deteriorate. Effective utilization becomes difficult to achieve.

It is necessary to control the transmission power at the earth station.

Conventionally, such transmission power control can be achieved by changing the amount of attenuation of the F-band variable attenuator 61 on the input side of the frequency converter 62 connected before the power amplifier 63, as shown in FIG. However, power amplifiers always operate with constant current and voltage, and the power consumption of the device is constant.

In addition, as shown in FIG. 5, the conventional technology related to the power combining method is to arrange a first power amplifier 71 and a second power amplifier 72 in parallel, a power divider 73 on the input side, and a power combiner on the output side. 74 are arranged to perform power synthesis. However, the current and voltage of the power amplifiers 71.72 are fixed so that they can always transmit saturated outputs, and the two power amplifiers 71.
Generally, 72 units operate at the same time. To this end,
The lifespan of a power amplifier is determined by the time determined by the conventional MTBF, and in the case of an electron tube, etc., this must be replaced, increasing the cost of the earth station. Moreover, it also has the disadvantage that the amount of electricity used is large annually.

(Problems to be solved by the invention) The present invention is intended to improve the drawbacks of the conventional technology.
The probability of heavy rainfall occurring in the 0GH2 zone is 0.5-1%.
During the rest of the time (90 to 95%), rain attenuation is almost small, and the earth station transmitter does not need a large output all the time. When the sky is clear, the number of lines (for example, one line) is sufficient to obtain the line standard value for clear weather, and the power amplifier current (for example, the collector current of a traveling wave tube) is sufficiently lowered to reduce interference and improve reliability. It is characterized by improving performance and reducing power consumption. In addition to increasing the above-mentioned current etc. according to the amount of rainfall, the power of the variable attenuator in the IF stage is changed to increase the transmission power, and if even greater transmission power is required, the remaining power amplifier is operated, It is characterized by gradually increasing its transmission output according to the amount of transmission, obtaining large transmission power, improving equipment reliability, reducing costs, and providing efficient and highly accurate uplink transmission power control functions. The objective is to realize a high-power transmission system with a high power transmission method.

(Structure and operation of the invention) In order to solve the problems described in the prior art, the present invention does not transmit all the power as the transmission output of the earth station transmitter in clear weather, and the clear weather line standard (for example, code Error rate (Pe
) -10-8), the output is sufficiently lowered to obtain a signal-to-noise power ratio (C/N) value that satisfies A transmission power control method is used. As a method to increase or decrease the transmission power,
Multiple power amplifiers are used, and they are used depending on the magnitude of the rain attenuation slippage.

FIG. 4 shows an embodiment of the present invention, and describes an example in which two power amplifiers are combined using a switch. In the figure, 111 is an input terminal, 112 is an output terminal, 113
, 114 is a power amplifier, 117°, 118 is a switch, 11
9 is a power divider, 120 is a power combiner, 121 is an amplitude variable circuit, 123 is a phase variable circuit, 125 is an IF stage amplitude variable circuit, 126 is a transmission frequency converter, 128 is an excitation amplifier, 16o is an IF stage amplitude variable circuit control circuit, 131,
132 is a power amplifier collector current control circuit, 166 is a detection current converter, 140 is a coupler, 141 is a wave detector, 142 is an A/D converter, 143 is a power amplifier control unit,
144 to 147 are D/A converters, and 148 is a beacon receiver.

To operate this, the power amplifier is used differently depending on the amount of rain attenuation as described below.

(7) During clear weather, only the first power amplifier 113 is left in operation, the second power amplifier 114 is not operated, and the amplifier current and voltage are turned off. All contacts of the switch 117 and 118 are connected to the A side, and the information signal is configured to pass only through the first power amplifier.

The transmission output during clear weather, which is determined by the line design, is stored in advance in the power amplifier 1liil control section 146 consisting of a microprocessor. This method of adjusting the predetermined transmission output is performed using a coupler 140 connected to the output terminal 112 side.
A part of the branched output is detected by the detector 141, converted by the detection current converter 166, and returned to the power amplifier control unit 143 through the A/D converter 142. If the output does not match the predetermined output, the difference is calculated. Calculate the collector current control circuit 13
1. Control the IF stage amplification variable circuit 130.

For example, increase or decrease the collector current in steps of 1 mA, and then finely adjust the IF stage amplitude variable circuit control circuit 1.
The configuration is such that it is controlled by 60.

To enable such operation, power amplifier 113 .
When the collector current or the like of 114 is changed, it is necessary that the frequency characteristics remain so flat even if the output power changes. Examples of commonly used traveling wave tubes include coupled cavity type TWTs and edge type TWTs. The former obtains a flat frequency characteristic by superimposing the tuning characteristics of multiple cavities in a staggered manner, so if the current or voltage parameters such as the collector current change, the flat characteristics cannot be maintained due to the difference in the tuning characteristics. . On the other hand, the latter helical TWT has good frequency characteristics. For example, the outline of the output power vs. frequency characteristic when the collector current of a helical TWT is changed shows that a flat frequency characteristic may be obtained over 2 to 3 GH2). As a result, it can be said that sufficient characteristics can be obtained for the bandwidth of the transmitter (100 to 600 MH2 in the shaded area) that is currently being widely used. Furthermore, similar characteristics can be expected from a transistor amplifier using a transmission line with a low residual Q such as an IJ tube line.

However, the way the collector current vs. output current changes is not necessarily linear, and the same collector current 1 m
With respect to changes in A, there are parts where the output power changes significantly and parts where it does not change much, making it impossible to increase or decrease the output power with high precision. In order to make this fine adjustment, the IF stage amplitude variable circuit 125 may be changed to increase or decrease the input power to the power amplifier to finely adjust the output power. As a result, only one power amplifier 116 is operated at a sufficiently low level during sunny weather, resulting in further savings in power consumption.

If rain attenuation occurs, 20GH2 band beacon reception 11
Measure the attenuation of the beacon level or C signal level at 4B, and increase the 30GHz band transmitter output according to this value. Generally, there is a certain correlation between rainfall attenuation values in the 20730GH2 band. According to one example of measurement, as shown in FIG. 6, it has been revealed that attenuation approximately twice as much as the lower line (20GH2 band) occurs in the upper nine lines. Taking this into consideration, the signal from the 20GH 2-band beacon receiver 148 is input to the power amplifier 2 headquarters 146, and based on this value, the control amount is calculated by the processing section of the power amplifier control section 146, and the result is The collector current control circuit 161 and the IF stage variable amplification control circuit 130 are operated through the /A converters 44 and 45,
The output of the output terminal 112 is adjusted.

If the rain attenuation is large and the first power amplifier 116 operates to the saturation output and the required rain margin is not yet reached, the second power amplifier 116, which has been turned on in advance when a certain rain attenuation level is reached, is activated. 114 is operated.

To operate this second power amplifier 114, 20
Based on the information from the GH2 band vicon receiver 148, it is detected that the power amplifier 114 needs to be operated, and the collector current control circuit 132 is controlled to set the collector current to a predetermined value. Switchers 117 and 118 are still connected to the B side so that power can be combined.

The phase characteristics etc. of the power amplifiers 113 and 114 to be used are measured in advance and stored in the power amplification control unit 143, but since there may be slight changes over time, the phase characteristics etc.
Through the adjustment in step 6, the output power is detected by the coupler 140, the detector 141, etc., and adjusted so that the output power is maximized. As a result, an output approximately twice that of the amplifier output when operating with one amplifier can be obtained.

The amount of time the second power amplifier operates is related to device reliability. For example, if an example of the distribution curve of the attenuation amount due to typical rainfall in Japan in the 30GH2 band is shown in Figure 7, the design target point for the annual uplink unavailability rate is set to, for example, 0 point 1so (0.2%). In the case of 0 point 151, the transmission power decreased by approximately 3 dB when operating with one power amplifier.
Even so, the uplink downtime rate only increases by about 0.1 factor. This can be said to be a short time of 0.1% (ie, about 8 hours) of the operating time of the second power amplifier 114 per year. As a result, the reliability of the second power amplifier 114 becomes very good.

When the amount of rain attenuation decreases, the signal level of the 20 GHz band vicon receiver 148 increases, so the output power is decreased following the reverse process described above.

In addition, it is possible to remedy a power amplifier failure without installing a standby device as in the past. In other words, if the first power amplifier 113 fails, switching the switch 118 to the B side will cause the power combiner to have a magic
When using T etc., the output is the second power amplifier 114
An output is obtained at the output terminal 112, although the output is approximately 3 dB lower than the saturated output. Since the probability that a failure occurs at the same time as rain is sufficiently small compared to the annual downtime rate, there is a high probability that communication will be possible even with a sufficiently low output power during a failure, and the line will not reach all locations. It is possible to replace the failed first power amplifier 116 while the second power amplifier is operating, and repair can be performed without disconnecting the line.

In the configuration method explained in FIG. 4, the IF stage amplitude variable circuit 125 is used for fine adjustment of the transmission output, but the amplitude variable of this fine adjustment is performed using the RF
If a band amplitude variable device is inserted, the output can also be finely adjusted.

(Effects of the Invention) As explained above, in sunny weather, only one power amplifier tube is used, and the collector current and current are sufficiently reduced, so the power consumption of the power amplifier device can be extremely reduced. can.

Furthermore, since the second power amplifier tube is used only a very small percentage of the year (for example, 0.1% per year, about 8 hours), it contributes to extending the life of the device.

Since the earth station transmission output is sufficiently reduced during clear weather, unnecessary interference with other satellite systems can be reduced, and the orbit spacing can be reduced, allowing effective use of orbits. . In addition, interference with other services such as terrestrial wireless systems can be reduced, and the adjustment range in which stations can be placed can be expanded.

In addition, since the device is configured using two power amplifiers with half the output, the power amplifier is easy to make, has good efficiency, can have a large gain, and can simplify the protection circuit, etc., making the device smaller and simpler. High efficiency can be achieved.

In addition, if the first power amplifier fails, the conventional method installs a backup device and switches to it, but in the present invention, by using the second power amplifier, the annual During Inugyo's time, he can provide disability relief.

In the description of the present invention, a traveling wave tube is mainly shown as an example of a power amplifier, but the present invention can also be applied to a solid-state amplifier using an FET element or the like.

Although the description is still based on a satellite communication system in the 30720 GHz band, it is also possible to apply it to other frequency bands such as the 14/11 GH2 band, and to other services such as broadcasting satellites and terrestrial radio.

Furthermore, in a wireless transmission system using a frequency band without rain attenuation, it can also be used, for example, for a system that changes transmission output according to traffic, a system that temporarily increases transmission power, etc.

[Brief explanation of the drawing]

Fig. 1 is an interference model diagram with other satellite communication systems, Fig. 2 is a diagram showing the conventional transmission power control method, Fig. 6 is a diagram showing the conventional power combining method, and Fig. 4 is the device of the present invention. Transmission power 11) High power transmitter with control function, Figure 5 is an example of the frequency versus traveling wave tube output characteristics when changing the collector current of the traveling wave tube, Figure 6 is for the quasi-millimeter wave band. Figure 7 shows the correlation between upstream and downstream lines of rainfall attenuation for 30GH.
It is a figure which shows an example of the time rate which exceeds the value with respect to the rain attenuation amount pair of z band. 1: Geostationary satellite orbit, 2: Satellite of own system, 6: Satellite of other system, 4.5: Earth station of own system, 7.8:
Earth station of other system, 6: Rainfall, 9: Own system uplink, 10: Other system uplink 1 line, 61: IF band variable attenuator, 621 frequency converter, 66゛ power amplifier, 71.
72: Power amplifier, 73: Power divider, 74 Lightning single power combiner, 111: Input terminal, 112: Output terminal, 113
: first power amplifier, 114: second power amplifier, 11
7.118: Switcher, 119: Power divider, 120: Power combiner, 121: Variable amplitude circuit, 123: Variable phase circuit, 125: IF stage variable amplitude circuit, 126: Transmission frequency converter, 128: For excitation Amplifier, 130: IF
Stage amplitude variable circuit control circuit, 131, 132: Collector current control circuit of power amplifier, 136: Detection current balancer, 1
40: Coupler, 141: Detector, 142: A/D converter, 145: Power amplifier control section, 144.145,1
46,147: D/A converter, 148: 20 GHz band V = +7 receiver, 150: C point, 151: ]) point Patent applicant Nippon Telegraph and Telephone Public Corporation patent agent Megumi Yamamoto - Figure 5 f, fz f- v: tl, Iff, ((rHi) #6 Figure/7q?-Jy immediately loses (d8) Act 7 Concave 7 axis i Moe b Time key (%)

Claims (1)

[Claims] In transmission power equipment used in satellite communication frequency bands where rain attenuation is large, first and second power amplifiers are arranged in parallel, and a power divider is installed on the input side of each amplifier, and a power combiner is installed on the output side of each amplifier. The system is installed in a configuration where power can be combined using the first and second power amplifiers, and when the weather is clear, only the first power amplifier is turned on and the second power amplifier is turned off to satisfy the line standard values during fine weather. In order to obtain a transmission output of 100%, the parameter value that affects the transmission output of the first power amplifier is lowered, and the first power amplifier is operated at a transmission output lower than the saturation output of the power amplifier, and a variable amplitude in the IF band is set. Finely adjust the transmission output by adjusting the attenuation of the RF band variable amplification attenuator installed in front of the attenuator or power divider to obtain the required transmission output in clear weather, and then increase the amount of rain attenuation. In this case, increase the collector current of the first power amplifier to increase the transmission power, and reduce the amount of attenuation of the variable amplitude attenuator in the IF band to make fine adjustments to achieve the required transmission output. When the transmission output reaches a large attenuation that cannot be covered by the first power amplifier, the second power amplifier, which was turned on in advance when a certain rain attenuation value is reached, is switched on to the first power amplifier. Connect it so that it is combined with the power amplifier of A high-power transmission method having a transmission power control function that performs control such that the transmission power is increased.