JPH04269018A - Radio transmitter - Google Patents

Abstract

PURPOSE:To realize the inexpensive radio transmitter for a satellite communication earth station with small size, light weight and less power consumption. CONSTITUTION:A burst signal detector 4 being a detection means of a transmitter 2 detects a burst signal sent from a time division multiplexer 1. A burst signal to match the timing of a control signal from the detection means is delayed by a burst signal delay device 5, a frequency to be sent by a transmission frequency converter 6 is converted and the result is inputted to a power amplifier 7. The power amplifier 7 is controlled by a power supply control unit 8 so that it is in the operating state when the burst signal is in existence and it is in the non-operating state when the burst signal is not in existence.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmitter, and more particularly to a radio transmitter for a satellite communications earth station in a time division multiple access system.

0002

2. Description of the Related Art Generally, in a time division multiple access system using a satellite, an earth station transmits signals in bursts only during a certain allocated time. Therefore, the proportion of the signal transmission time in the repetition period (frame period) is extremely small, ranging from a fraction of a fraction to a thousandth of a fraction. A traveling wave tube amplifier (T
WTA: Traveling Wave Tube
Amplifier) and solid state power amplifiers are used.

[0003] As a method for amplifying signals in a transmitting device, there is a common amplification method in which signals are amplified in common by one high-power amplifier device, and a traveling wave tube amplifier is used for this method. Furthermore, there is an individual amplification method in which a large power amplifier with a relatively small output is used for each of a plurality of transmitted waves, and the outputs are combined in power, and a solid state power amplifier is used in this method.

0004

[Problems to be Solved by the Invention] However, although traveling wave tube amplifiers can be expected to have high output and high efficiency, they are large in size and use a high voltage, making the power supply configuration complicated.
In addition, there is a problem in terms of deterioration of the life of the traveling wave tube. On the other hand, solid-state power amplifiers do not have performance deterioration or longevity factors, and operate at a voltage of 10V or less, making maintenance easier, making the power supply smaller and lighter, and potentially making the amplifier smaller. However, at frequencies used for satellite communications, such as 14 GHz or 30 GHz, solid-state power amplification elements have a relatively small output and low efficiency. In order to obtain high output in a solid-state power amplifier, it is necessary to combine the outputs of multiple solid-state amplifier elements, which further reduces efficiency and generates a large amount of heat.
Weight also increases significantly.

[0005] Furthermore, the solid-state power amplifiers currently used in satellite communication earth stations have an amplifier class rating of class A or A.
There is a problem in that the power amplifier is in an operating state even when not transmitting a signal due to class B operation, and consumes power.

FIG. 5 shows a signal transmitted in bursts and the operating state of a conventional solid-state power amplifier. The figure (A) shows a signal sent out in bursts, and the figure (B)
) indicates the operating status of the solid-state power amplifier. In the figure, even when the radio frequency is not being output as shown in (A), the solid-state power amplifier is always in an operating state in (B) of the figure. As mentioned above, in the state shown in the figure, the signal transmission time occupies a very small proportion of the frame period, and most of the consumed power is converted into heat without being emitted as a transmission signal. For this reason, there is a drawback that the amount of heat generated is large, and the power equipment becomes large, heavy, and expensive due to equipment for heat dissipation and countermeasures against large amounts of power.

The present invention has been made in view of the above points, and an object thereof is to provide a wireless transmitter for a satellite communication earth station that is small, lightweight, consumes low power, and is inexpensive.

[0008]

[Means for Solving the Problems] In a radio transmitter for an earth station using a time division multiple access system that amplifies and transmits burst signals, the presence or absence of a burst signal input from a time division multiplexer is identified, burst signal detection means for generating a control signal depending on the identification state; delay means for delaying the burst signal sent out from the burst signal detection means by a predetermined time and inputting the delayed signal to the amplifier; and burst signal detection means for indicating the presence of a burst signal. and power supply control means for controlling power supply to the amplifier to put the amplifier into an operating state only when the control signal is applied.

[0009]

[Operation] The present invention converts a signal into a time-division multiplexed signal and controls transmission at an earth station for a satellite communication system in which a repeater on a satellite is used time-division multiplexed by transmitting/receiving devices of a large number of earth stations. When a time division multiplexed burst signal is sent to an amplifier from the device to a satellite, the presence or absence of the burst signal is detected by a burst signal detection means, the burst signal is delayed, and the signal is input to the amplifier depending on the presence or absence of the burst signal. The power supply to the amplifier is controlled by the control signal from the burst signal detecting means for the time period during which the amplifier is in an operating state, and when there is no signal, the amplifier is in an inactive state to suppress power consumption. The amplifier amplifies the input signal and transmits it. This results in
Transmission power amplifiers for satellite communication earth stations can be made smaller, lighter, consume less power, have higher reliability, and become more economical. Additionally, small earth stations will be able to achieve high burst output.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. The configuration of this embodiment includes a time division multiplexing device 1, a transmitting device 2, and a cable 3 connecting the time division multiplexing device 1 and the transmitting device 2. The transmission device 2 includes a burst signal detection device 4, a burst signal delay device 5, a transmission frequency converter 6, a power amplifier 7, and a power supply control unit 8. Note that the operation of the time division multiplexing device 1 requires reception of control signals and the like from a base station that controls the entire system, but this will be omitted since it does not affect the explanation of the operation of the present invention.

Next, the operation of this embodiment will be explained. The plurality of transmission signals are input to a time division multiplexing device 1, which becomes a time division multiplexed signal (a) to be transmitted to a satellite, and sent to a transmission device 2 via a cable 3. The burst signal detection device 4 of the transmitting device 2 detects the time division multiplexed signal (a), and generates a control signal (b) for controlling the power amplifier 7 in synchronization with the time division multiplexed signal (d), which will be described later. , and sent to the power supply control unit 8.

The burst signal delay device 5 delays the input time division multiplexed signal (a) by a time t1 and outputs it as a time division multiplexed signal (d). For example, in a system in which the frequency of the time-division multiplexed signal (a) is 140 MHz as the intermediate frequency, a delay circuit on the order of microseconds can be easily constructed using a surface acoustic wave (SAW) element or the like. In this burst signal delay circuit 5, at time t1, after the burst signal detection device 4 detects the time division multiplexed signal (a), it sends out a control signal, controls the power supply control unit 8, and stabilizes the power amplifier 7. It is set to the time until it can operate.

The transmission frequency converter 6 converts the time division multiplexed signal (
Converting the frequency of d) to a transmission frequency. Furthermore, the power amplifier 7 amplifies this time division multiplexed signal (d) and outputs it from the transmitter 2.

FIG. 2 is a time chart showing the time division multiplexed signal, control signal, and operating state of the power amplifier of the present invention before and after delay. In the same figure, (a), (b), (d)
Each signal indicated by corresponds to each signal in FIG. In Figure 2 (
(a) shows the time division multiplexed signal sent out from the time division multiplexing device 1, (b) shows the control signal sent out from the burst signal detection device 4, and (c) shows the control signal sent out by the control signal (b). (d) shows the time division multiplexed signal sent out from the burst signal delay device 5.

The time division multiplexed signal (a) is synchronized burst 2
1 and 22, and a data burst 23, all of which are signal modulated bursts. Synchronous burst 21, 2
Data burst 23 is transmitted at regular intervals regardless of the presence or absence of transmission information, and data burst 23 is transmitted only when there is transmission information.

The control signal (b) is always a time division multiplexed signal (
It rises later than a) by time t2, and at time t3
It only falls behind. The time t2 is the time required from when the burst signal detection device 4 detects the time division multiplexed signal (a) until it sends out the control signal (b). time t
3 is the time from the end of the burst of the time division multiplexed signal (a) until the operation of the power amplifier 7 is stopped; It is set in consideration of the detection accuracy.

The operating state (c) of the power amplifier 7 is such that the operation of the power amplifier 7 is controlled by the control signal (b) and switched between operating and non-operating. Thereby, the power amplifier 7 can amplify the time division multiplexed signal (d), which will be described later, without damaging it. The time-division multiplexed signal (d) consists of synchronization bursts 27, 28 and data bursts 29, which are similar to the bursts 21, 22, 22, and 22 in the time-division multiplexed signal (a), respectively.
23 is delayed by the time t1.

Further, in FIG. 2, the control signal (b) is
It is a constant detection signal that always rises with a delay of time t2 and falls with a delay of time t3 from the time division multiplexed signal (a), but as a control signal (b), the rise and fall of this detection signal are Even in the case of a configuration in which only synchronized triggers are output, the power supply control unit 8 in Figure 1
By adopting a circuit configuration in which the power amplifier 7 is driven by trigger control, the operation of the power amplifier 7 in FIG. 1 can be controlled based on the same principle.

FIG. 3 shows the configuration of a power amplifier 7 according to an embodiment of the present invention. The power amplifier 7 is composed of an amplifier circuit 31 and a power supply 32. Of these, the amplifier circuit 31 is a small signal amplification section 33
and a power amplification section 34. The power supply 32 includes a small signal amplification section power supply 35 and a power amplification section power supply 36. The small signal amplifying section 33 is supplied with power from the small signal amplifying section power supply 35, and because of its low power consumption, it operates continuously regardless of the burst signal of the time division multiplexed signal (d). The power amplification unit 34 is supplied with power from a power amplification unit power supply 36, and this power amplification unit 34
FET (field effect transistor) is a solid-state amplification element.
The drain voltage of is turned on and off according to the control signal (b).

The synchronization bursts 27 and 28 in FIG. 2 are transmitted for a period of approximately 1/1000 of the frame interval, and the data burst 29 is transmitted for a period of approximately 1/200 to 1/4 of the frame interval depending on the transmission signal. Ignoring the difference between t2 and time t1 and time t3, the power amplification section 34 is approximately 1/10
It is on for about 1/4 of the period from 00, and is off for the rest of the period. Therefore, the power consumption of the power amplifier 7 is significantly reduced.

FIG. 4 shows the configuration of another embodiment of the present invention. In the figure, the same components as those in FIG. In the embodiment shown in FIG. 2 described above, the burst signal detector 4 and the burst signal delay device 5 are installed closer to the time division multiplexer 1 than the transmission frequency converter 6, but as shown in FIG. The burst signal detector 4 and the burst signal delay device 5 may be installed on the power amplifier 7 side. In this case, the transmission signal is input to the time division multiplexing device 1, the time division multiplexed signal (a) is sent to the transmission device 2, and the time division multiplexed signal (a) is sent to the transmission frequency converter 6 of the transmission device 2. a) is converted into a transmission frequency and sent to the burst signal detection device 4.

The burst signal detection device 4 detects the time-division multiplexed signal and sends it to the burst signal delay device 5, and also generates a control signal (b) for controlling the power amplifier 7 and sends it to the power supply control unit 8. Send to. The burst signal delay device 5 transmits the input time division multiplexed signal (a) at time t1.
The signal is delayed by 10 seconds and sent to the power amplifier 7 as a time division multiplexed signal (d). As a result, the same result as the configuration shown in FIG. 1 can be obtained.

Furthermore, it is clear that similar results can be obtained even if the drain voltages of all FETs of the power amplifier 7 are turned on and off. Alternatively, it is clear that similar results can be obtained by installing the burst signal detection device 4 and the burst signal delay device 5 between the small signal amplification section 33 and the power amplification section 34 of the power amplifier 7 shown in FIG. be. Furthermore, FET
In this case, it is not the drain voltage but some or all of the FE.
The FET may be turned on and off by controlling the gate voltage of T.

[0024]

As described above, by using the transmitting device for a satellite communication earth station according to the present invention, the power consumption of the power amplifier can be significantly reduced, and as a result, the power amplifier can be made smaller and lighter. Further, since the heat generation of the power amplifier is reduced to 1/2 or less, a cooling facility can be easily provided, so that the power amplifier can be made smaller and more economical.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing time division multiplexed signals and control signals before and after delay, and the operating state of the power amplifier in the present invention.

FIG. 3 is a diagram showing the configuration of a power amplifier according to an embodiment of the present invention.

FIG. 4 is a diagram showing the configuration of another embodiment of the present invention.

FIG. 5 is a diagram illustrating burst-sent signals and operating states of a conventional solid-state power amplifier;

[Explanation of symbols]

1 Time division multiplexer 2 Transmitter 3 Cable 4 Burst signal detector 5 Burst signal delay device 6 Transmission frequency converter 7 Power amplifier 8 Power supply control unit 21, 22, 27, 28 Synchronous burst 23, 29
Data burst 31 Amplification circuit 32 Power supply 33 Small signal amplification section 34 Power amplification section 35 Small signal amplification section power supply 36 Power amplification section power supply

Claims (1)

[Claims] Claim 1: A radio transmitter for a time division multiple access earth station that amplifies and transmits a burst signal, which identifies whether or not the burst signal is input from a time division multiplexer, and according to the identification state. burst signal detection means for generating a control signal; delay means for delaying the burst signal sent from the burst signal detection means by a predetermined time and inputting the delayed signal to an amplifier; and detecting the presence of the burst signal by the burst signal detection means. a power supply control means that controls power supply to the amplifier to put the amplifier into an operating state only when indicated by the control signal.