A German company operates a radio broadcast load balancing and ripple control system for electrical power distribution networks. Short telegrams are used to control street lights, heaters, tariff switching etc.

The subscribers control their equipment by sending messages to the central computer of service provider. The central computer forwards the messages to transmitters in Frankfurt am Main (DCF49, 129.1 kHz) and Burg (DCF39, 139.0 kHz).

Transmissions are 200 Bd ASCII FSK with a shift of 340 Hz.

The transmission format is based on DIN-19244, i.e., start bit, 8 data bits, parity bit and stop bit. The length of the data frame is variable; therefore a length field is required. The frames consist of a start character, followed by the length information, which is sent twice. The fourth byte is the start character again. Bytes five to seven are message number, address field A1 and address field A2. After a maximum of 16 data bytes, a checksum is transmitted and finally the stop character. The checksum is an addition of the message number, address and data fields without considering carry bits. Messages are sent twice to increase transmission security.

Two user data protocols are in use, Semagyr-TOP and Versacom. As messages do not contain a protocol identifier both formats are displayed together with the raw data string in hexadecimal format. Using Options/Display Mode... the display may be toggled between All frames and Error free frames.

If messages are not at hand, EFR periodically transmits time signals which allow the receivers to synchronize their internal clock. From time to time, a test signal is transmitted containing the name of the transmitter, e.g., DCF49.