JPH04355527A - Transmission power control system - Google Patents

Abstract

PURPOSE:To make the transmission output stable by keeping an input of a detector detecting an RF output level constant at all times so as to implement AGC amplification and to control the transmission power. CONSTITUTION:The system is provided with variable gain IF amplifiers 1A-1C of a transmitter whose output level varies with a control signal received from each control terminal and receiving plural carrier signals respectively, an RF amplifier 7B synthesizing outputs of the variable gain IF amplifiers and sending the result through common amplification after frequency conversion, a gain control circuit in which level information of plural carrier signals received by an opposite receiver is returned to the transmitter and applying a 1st control signal to an external terminal of the variable gain IF amplifiers 1A-1C based on the level information and an RF amplifier means controlling the RF amplifier 7B so as to make the gain constant regardless of the level change in the RF output signal by using the 2nd control signal of the gain control circuit.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission power control system, and more particularly to a transmission power control system for controlling the power of a transmitter of an opposing station for each carrier in accordance with the received input level of a multicarrier.

0002

2. Description of the Related Art Conventionally, this type of transmission power control system uses a modulator for each carrier, as shown in FIG. The modulated signal sent from the transmitting device 3A
After being amplified by the variable gain IF amplifiers 1A, 1B, and 1C in the respective variable gain IF amplifiers 1A, 1B, and 1C with a gain corresponding to the control voltage from the gain control circuit 13, the signals are combined by the power combiner 4. The synthesized IF signal is converted to an RF frequency by a frequency converter 5 consisting of a local oscillator 5B and a mixer 5A, amplified by a fixed gain RF amplifier 7A, and transmitted.

On the other hand, in the receiving device 2B facing this, after the received signal is amplified by an RF amplifier 8, it is converted to an IF frequency by a frequency converter 6 consisting of a local oscillator 6B and a mixer 6A, as in the case of transmission. Then, this IF signal is branched into three by the power divider 12, and then split into branch filters 9A, 9B,
At 9C, modulated waves for each carrier are extracted. Each carrier is connected to a variable gain IF amplifier 10A, 10B, 10
C, and a detector 11A that detects its output power level and provides a gain control voltage for the variable gain IF amplifiers 10A to 10C.
, 11B, and 11C perform AGC amplification for each carrier. A transmitter (TX) captures the detected voltages of the detectors 11A, 11B, and 11C as reception input level information of each carrier and transmits them in the opposite direction.
Input level information sending circuit 1 that sends data to 3B
It has 4. The transmitted input level information is received by the receiving device 2B of the opposite station, and is sent to the gain control circuit 13 to control the gain control voltages of the variable gain IF amplifiers 1A, 1B, and 1C.

0004

[Problems to be Solved by the Invention] In this conventional transmission power control system, the power of the modulated wave for each carrier is controlled and synthesized at the intermediate frequency (IF) stage, and then the power of the modulated wave is controlled at the radio frequency (RF) stage after frequency conversion. Since the amplification is performed at a fixed gain,
The transmission output level could not be stabilized sufficiently. usually,
A transmitter that does not perform transmission power control uses radio frequency (RF)
) stage, a variable gain amplifier is used to amplify the output level, and automatic gain control (AGC) amplification is performed to detect the output level and control the gain of the variable gain amplifier to maintain a constant level, thereby stabilizing the transmission output. There is. However, in the transmission power control method that controls the transmission power for each carrier in a multi-carrier system, the total output power changes depending on the control of the carrier power, so the transmission output for each different transmission power is Transmission was performed in a state where automatic gain control (AGC) could not be simply performed at the full output power level as in the past for stabilization.

[0005]

[Means for Solving the Problems] The transmission power control system of the present invention includes a variable gain IF amplifier in which a transmitting device inputs a plurality of carrier signals respectively and whose output level is varied by control signals input from each control terminal. , an RF amplifier that combines the outputs of the variable gain IF amplifiers, performs frequency conversion, and then commonly amplifies and transmits the same, and level information of each of the plurality of carrier signals received by the opposing receiving device is sent to the transmitting device. and a gain control circuit that supplies a first control signal to an external terminal of the variable gain IF amplifier based on the level information that is sent back, and a second control signal of the gain control circuit. RF
The RF amplifier includes RF amplification means for controlling the RF amplifier so as to keep the gain constant regardless of changes in the level of the output signal.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
The same reference numerals as in FIG. 2 have the same functions and configurations. That is, compared to FIG. 2, which is a block diagram of a transmission power control system in a conventional multicarrier system, the embodiment shown in FIG. After that, the power of the three carriers is controlled by voltage-controlled variable attenuators 17A, 17B, and 17C, and then recombined by a power combiner 16.
5 controls the variable gain RF amplifier 7B to detect the level and keep the detected voltage at a constant level. In other words, the voltage controlled variable attenuators 17A, 17B, 17C have variable gain I
Contrary to the gain changes of the F amplifiers 1A, 1B, and 1C, for example, if the variable gain IF amplifier 1A lowers the power by 10 dB, the voltage-controlled variable attenuator 17A is controlled to reduce the attenuation by 10 dB, and the power combiner 16 is always activated. The output of the detector 15 is held constant, and the same detected voltage as before is outputted from the detector 15. Therefore, a constant bias voltage is applied to the RF amplifier 7A, and the gain is kept constant.

[0007]

As explained above, the present invention provides an output level detection system of an RFAGC amplifier circuit of a transmitting device with a voltage controlled attenuator that performs power control equal to the amount of power controlled by the IF by transmitting power control. By reversing the control of the attenuator, the input of the detector that detects the RF output level is always kept constant and AGC amplification is performed, thereby stabilizing the transmission output and controlling the transmission power. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a transmission power control method according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional transmission power control method.

[Explanation of symbols]

1A, 1B, 1C Variable gain IF amplifier 2, 2A
, 2B Receiving device (RX) 3, 3A, 3B
Transmitter (TX) 4 Power combiner 5, 6 Frequency converter 7A, 8 RF amplifier 7B Variable gain RF amplifier 9A, 9B, 9C Branching filter 10A, 10B
, 10C variable gain IF amplifiers 11A, 11B,
11C Detector 12 Power divider 13 Gain control circuit 14 Input level information sending circuit 15 Detector 16 Power combiner

Claims (2)

[Claims] Claim 1: A transmitter comprises a variable gain IF amplifier into which a plurality of carrier signals are respectively input and whose output level is made variable by control signals input from each control terminal; and a variable gain IF amplifier which combines the outputs of the variable gain IF amplifier, and , the level information of each of the plurality of carrier signals received by the RF amplifier that commonly amplifies and transmits after frequency conversion and the opposing receiving device is sent back to the transmitting device, and the variable gain is adjusted based on the level information. Connect the first terminal to the external terminal of the IF amplifier.
and a gain control circuit that supplies a control signal, the RF amplifier is controlled by a second control signal of the gain control circuit to keep the gain constant regardless of level changes of the RF output signal. 1. A transmission power control system comprising RF amplification means. 2. The RF amplification means includes a variable gain RF amplifier, and a voltage-controlled variable attenuator that branches the output signal of the variable gain RF amplifier and makes the amount of attenuation variable by external control for each corresponding carrier signal. , comprising a combiner for recombining the branched carrier signals, and a detector for detecting the combined output, and the output of the detector is fed back to the variable gain RF amplifier. Transmission power control method.