Reduce wiring and maintenance costs — this new solution uses existing power lines for data and voice communication

by Brianna Crandall — October 4, 2017 — Renesas Electronics Corporation, a global supplier of advanced semiconductor solutions for a broad range of applications, recently announced a new voice-over-power line communication (PLC) solution that enables both data communication and voice communication capabilities over existing power networks. The PLC solution reduces the amount of internal wiring required in buildings, enabling reduced implementation and maintenance costs for public address (PA) systems and security systems.

The new solution consists of Renesas’ PLC software modem (R9A06G037), which manages the PLC communications, and the RX651 microcontroller (MCU), which controls the audio codec processing. The new solution enables system manufacturers to enhance security systems by incorporating voice capabilities to an existing installation at low cost. For a new installation that includes various sensors as well as voice communication, wiring costs can be reduced by approximately 60 percent, while installation and maintenance costs can be reduced up to 40 percent.

Voice communication graphic

The Renesas PLC solution enables voice communication over power lines.

Renesas notes that facilities such as office buildings have a variety of management systems installed including climate control systems, lighting, sensors of various types, building PA systems, and security systems. In the past, each of these systems would have required their own dedicated wiring. Recently, trends have shifted toward utilizing existing direct current (DC) power lines in configurations where these communication lines are shared with the power system.

However, earlier attempts to use power lines for voice communication have led to poor audio quality due to fluctuations in the delay time, according to Renesas. To resolve this issue, the new voice-over-PLC solution uses priority control during audio transmission to virtually eliminate delay fluctuations in voice communication, even in cases where signal control communication and voice communication operate over the same power lines. The company says this ensures stable audio quality at all times.

In addition, it combines the audio priority control feature with Renesas’ low-bandwidth PLC technology in an optimized manner to allow the use of signal lines exceeding 1 kilometer (km) in length without using repeaters. By making it possible to combine data communication and voice communication over existing power networks, the new solution is said to significantly reduce the amount of wiring required for building management systems and contribute to lower maintenance costs.

Main features of the voice-over-PLC solution

Achieves priority control during audio transmission to suppress delay variation, ensuring stable audio quality

In a PLC system, where multiple devices use power lines as a common communication medium, it is essential to avoid data collisions. This is similar to collision-avoidance functions used in wireless communication where data is transmitted once it is confirmed that no other device is communicating. Renesas’ voice-over-PLC solution is utilizing an optimized collision-avoidance feature that gives priority to devices that are performing “voice” transmission. This minimizes fluctuations in the communication delay, which reportedly ensures stable voice communication without dropouts.

Support of long-distance transfers over wiring lengths exceeding one kilometer without relays, for wide-range coverage within each installation

PLC systems usually include repeating (hopping) mechanisms in order to extend distance coverage. However, these mechanisms also cause increased fluctuation during data transfers. The R9A06G037 PLC chip integrates an analog front-end circuit with a wide dynamic range, variable amplifiers for transmission and reception, as well as ADC and DAC peripherals. In addition, Renesas has boosted the operating frequency of the DSP for PHY layer processing and added special instructions for PLC processing. These enhancements provide improved sensitivity with very small signals and better immunity to noise generated by power lines, which ensure long-distance communication, says the company. The new voice-over-PLC solution has been tested and proven to support greater than 1 km distance on DC powerlines with more than 128 nodes connected, without the need of repeaters.

Easy-to-implement software stack shortens time required for system development

The new solution is paired with a flexible and configurable software stack running on Renesas’ RX651 MCU. This software stack allows the user to easily select and implement an audio codec with the desired characteristics, which greatly shortens the time required for system development.


The solution is expected to be available from October 2017.

For more information, visit the Renesas Web site.