Modern Automation Technologies Professional Magazine


НаименованиеModems for Multichannel Data Transmission via High-Voltage Lines


This article focuses on modems for transmitting data via high-voltage electric lines and other analog communications channels.

Automation in the energy sector and other industries to a great extent depends on the communications infrastructure. The digital communications technologies that are used extensively in the West are not applicable in Russia due to this country's widely dispersed energy system and the lack of an advanced telecommunications infrastructure. As a result, Russian power companies rely on analog channels for data transmission over high-voltage lines. Resolving the data-transmission issue to introduce automation (for example, for emergency alerts or power metering) would require either implementing new communications channels, which is too expensive, or expanding the use of current channels, which has not been practical with the technologies available in the past.

However, the authors' approach meets the requirements for a modem that can address this issue, offering a multi-channel, universal, easy-to-use and reliable solution. The TsMT-3 modem developed by PROSOFT-E uses the 16-bit ADSP-2181 digital signal processor (DSP) from Analog Devices. Capable of 30-40 MIPS, with 16K words of RAM and 16K words of data RAM, as well as advanced input-output ports, the processor is capable of simultaneously handling three to four channels without additional hardware support. All the monitoring, service and signal processing, including for voice, is done using software on the chip.

The TsMT-3 includes the DSP, a discrete signals interface, an analog signals interface, a computer interface, a display and control unit and a power unit. The processor performs all the basic signal processing functions, including modulating signals, dividing the spectrum into speech and data channels, demodulating data and transmitting test signals.

The interface module on the microcontroller allows configuration data for the modem to be read from a computer and stored in nonvolatile memory. Users can change the TsMT-3's configuration by simply connecting it to any computer via the serial port and using the Windows-based interface software to set the necessary parameters. When the power is turned on, the configuration data loads into the DSP and automatically boots the modem.

The display and control unit offers light indicators for outgoing and incoming signals and allows the modem to be put in test mode. The modem is housed in a metal case with the display and control buttons on the front.

The TsMT-3 can handle up to three discrete input/output channels. Transmission speed in the ultrasonic spectrum at 2400-3400 Hz is 100-600 baud, or 300-1200 baud in the 300-2100 Hz range.

The TsMT-3 could find its most immediate and promising application in power facilities requiring additional data transmission channels, such as for automated energy metering at remote substations, as is being done now at Tyumenenergo, or at major substations where higher speed data transmission is required.

Click to enlarge! 

Multifunctional TsMT-3 modem

By Gennadiy Chirkov and Yurii Chirkov

Gennady Chirkov,  Yuri Chirkov