JPH06205381A - Temperature compensation method - Google Patents

Abstract

PURPOSE:To control a transmission gain of a signal accurately against temperature fluctuation of a transmission line. CONSTITUTION:The temperature compensation method is adopted for a relay amplifier 15 comprising an equalizer 16 in which various characteristics of a television signal and a data signal sent through a transmission line 14 of a data transmission system for high frequency analog signal transmission are compensated and comprising an amplifier 17 in which the result is amplified and adjusts the transmission gain to compensate the temperature against a line loss caused by temperature fluctuation in the transmission line 14. In this temperature compensation method, the equalizer 16 equalizing a line loss is identified by a control circuit 21, the line loss quantity is decided by an equalization quantity of the equalizer 16 and the transmission gain with respect to the line loss is obtained based on the line loss quantity by the control circuit 21 and temperature information of the transmission line 14 from a temperature sensor 20 and the gain adjustment circuit adjusts the gain depending on the change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensation method used in a relay system used in a transmission system for high frequency analog transmission, for example, a CATV system.

[0002]

2. Description of the Related Art Conventionally, in a CATV system, as shown in FIG. 3, a center 1 having a supervisory control function in the system is used.
0 and a plurality of sub-centers 11 to which a plurality of subscriber terminal devices 12 are connected are bidirectionally connected by a transmission line 13 such as a coaxial cable or an optical fiber cable, and further via a transmission line 14 such as a coaxial cable. There is one that transmits a necessary video signal and various electric signals to the subscriber's terminal equipment 12 connected to the sub-center 11. Further, a plurality of relay amplifiers 15 are connected to the transmission line 14, and compensate for losses such as attenuation and distortion of the television signals and data signals on the transmission line 14 to transmit the television signals and data signals. Subscriber terminal equipment 1
I was transmitting to 2.

Generally, the relay amplifier 15 is, as shown in FIG. 4, an attenuator (ATT), an equalizer (EQ), a pseudo line (BON), etc. that equalize the loss of each television signal and data signal due to the transmission line 14 and the like. 2 has an equalizer 16 and an amplifier 17, and the relay amplifier 15 uses a temperature compensation method in which the temperature in the vicinity of the transmission line 14 is detected and the transmission gain is controlled according to the temperature. In this temperature compensation method, assuming that the temperature coefficient is α and the reference fixed gain of the amplifier 17 is G, the transmission gain G (t) due to temperature is G (t) = G (1 + α), and in general, the temperature coefficient is α is determined according to the detected temperature fluctuation amount, and this temperature coefficient is used to obtain the change in transmission gain with temperature.

[0004]

However, the fluctuation amount of the line loss due to the temperature fluctuation depends on the relay interval L of the relay amplifier.
In the above temperature compensation method, since the line loss is fixed, the transmission gain controlled by the system becomes excessive and deficient with respect to the temperature fluctuation amount of the line loss to be controlled, and the level fluctuation is large. There was a problem that it might be.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a temperature compensation method capable of accurately controlling the transmission gain with respect to temperature fluctuations.

[0006]

In order to achieve the above object, the present invention compensates various characteristics of a data signal such as a television signal transmitted through a transmission line of a high frequency analog transmission system with an equalizer and further an amplifier. In the temperature compensation method, which is used in an amplification section that amplifies with, the line loss caused by the temperature fluctuation of the transmission line is adjusted by adjusting the transmission gain to perform temperature compensation, the equalizer is identified, and the equalizer is equalized. There is provided a temperature compensation method for determining a line loss amount based on the amount and controlling a transmission gain for the line loss based on the determined line loss amount and the temperature of the transmission line.

[0007]

The equalizer equivalent to the line loss is identified by the control circuit, the line loss amount Ll is determined by the equivalent amount Leq of the equalizer, and the control circuit determines the line loss based on the line loss amount and the temperature of the transmission line. The transmission gain is controlled to be adjusted by the gain adjusting circuit. Therefore, the transmission gain can be accurately adjusted with respect to the temperature fluctuation amount of the line loss.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings of FIGS. FIG. 1 is a block diagram showing a circuit configuration of a relay amplifier in the downlink direction (from the subcenter to the subscriber terminal device). The relay amplifier 15 includes an equalizer 16 that equalizes line loss of each television signal and data signal by the transmission line 14,
An amplifier 17, a gain adjustment circuit 18 that adjusts the transmission gain of each television signal or data signal from the amplifier 17, and an output amplifier 19 that amplifies each television signal or data signal and outputs it to each subscriber terminal device 12. A temperature sensor 20 provided near the transmission line 14, and a control circuit 21 for controlling the gain adjusting circuit 18 based on the equivalent amount information of the equalizer 16 and the temperature information from the temperature sensor 20. There is.

The type and equivalent amount of the equalizer 16 are determined according to the transmission line 14, and output a voltage value corresponding to the type and equivalent amount to the control circuit 21, for example. The control circuit 21 is for executing the temperature compensation method according to the present embodiment, obtains the temperature variation amount based on the temperature information from the temperature sensor 20, and determines the temperature coefficient α according to the temperature variation amount.
To decide.

The control circuit 21 detects the equivalent amount Leq of the equalizer 16 based on the voltage value output from the equalizer 16, and the line loss from the equivalent amount Leq and the reference fixed gain G of the amplifier 17. Find the quantity Ll. That is, the control circuit 21 obtains the line loss amount Ll from the relational expression of G-Leq = Ll. The maximum value of Ll is the value of the fixed gain G.

Further, the control circuit 21 obtains the transmission gain G (t) including the line loss amount Ll using the line loss amount Ll thus obtained and the determined temperature coefficient α. That is, in the control circuit 21, the equation including the line loss amount Ll is set to G (t) = G (1 + α · Ll / G) (1), and the fixed gain G, the temperature coefficient α and the line are added to the equation (1). The transmission gain G (t) is obtained by substituting the loss amount Ll, the transmission gain change amount is obtained based on the obtained transmission gain, and a gain control signal corresponding to the change amount is output to the gain adjustment circuit 18 for transmission. Adjust the gain.

Therefore, in the present embodiment, the transmission gain of the television signal and the data signal from the sensor 10 and the sub-center 11 is controlled according to the line loss amount of the transmission line 14 which needs temperature compensation in the relay amplifier. Level fluctuations due to the line loss and the gain to be controlled match, the transmission gain of the entire system does not become excessive or deficient, the gain level is stabilized, and the television signal or the data signal is sent to each subscriber terminal device 12
Can be output to.

FIG. 2 is a block diagram showing the circuit configuration of a relay amplifier in the upstream direction (from the subscriber terminal device to the sub-center). 2 is different from FIG. 1 in that the amplifier 17
Is the opposite direction, and the input amplifier 22 is connected instead of the output amplifier 19. Similar to the embodiment of FIG. 1, this embodiment also calculates the line loss amount of the transmission line 14 that needs temperature compensation based on the equivalent amount of the equalizer 16 in the relay amplifier, and the line loss amount and the temperature from the temperature sensor 20. Since the transmission gain of the television signal or the data signal from each subscriber terminal device 12 is controlled according to the information, the level fluctuation due to the actual line loss and the controlled gain match, and the transmission gain of the system as a whole is exceeded. There is no shortage, the gain level is stabilized, and the TV signal and the data signal are sent to the sub-center 11.
And can be output to the center 10.

[0014]

As described above, according to the present invention, an amplifying section for compensating various characteristics of a television signal or a data signal transmitted through a transmission line of a high frequency analog transmission system with an equalizer and further amplifying with an amplifier. For the line loss caused by the temperature fluctuation of the transmission line, in the temperature compensation method of performing temperature compensation by adjusting the transmission gain, the equalizer is identified, and the line loss is based on the equivalent amount of the equalizer. While determining the amount, the transmission gain for the line loss is controlled based on the determined line loss amount and the temperature of the transmission line.
The transmission gain can be controlled accurately with respect to temperature fluctuations.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a downstream relay amplifier.

FIG. 2 is a block diagram showing a circuit configuration of an upstream relay amplifier.

FIG. 3 is a diagram showing a system configuration of a CATV system.

FIG. 4 is a diagram for explaining a line loss that varies depending on a relay interval L.

[Explanation of symbols]

 10 center 11 sub center 12 subscriber terminal equipment 13, 14 transmission line 15 relay amplifier 16 equalizer 17, 19, 22 amplifier 18 gain adjusting circuit 20 temperature sensor 21 control circuit

Claims (1)

[Claims] 1. Compensating various characteristics of a data signal transmitted through a transmission line of a high frequency analog transmission system with an equalizer,
Further, in a temperature compensating method which is used in an amplifying section for amplifying by an amplifier and performs temperature compensation by adjusting a transmission gain with respect to a line loss caused by a temperature fluctuation of the transmission line, the equalizer is identified, and the equalizer is identified. The line compensation amount is determined on the basis of the equivalent amount of the above, and the transmission gain for the line loss is controlled based on the determined line loss amount and the temperature of the transmission line.