2.3 PTM 200 Radio Telegram
For the transmission of the telemetric signals, EnOcean has defined a new dynamic radio data
telegram that is adapted to the individual application. It is optimized to the essential features
of energy autarkic radio sensors:
•
Minimal energy demand
•
Possibility of operating hundred of senders within the same radio cell
•
Maximum transmission reliability
•
Wide transmission range
•
Easy extensibility
•
Suitable for uni- and bi-directional communication
•
Flexibility for adaptation of different data structures and data quantities
•
Data encryption option
2.3.1 Frequency range
The EnOcean technology operates the 868.3 MHz radio channel (868.0 – 868.6 MHz), which is
exclusively released for short-time data transmission in Europe. Timing conditions can be
found in chapter 3.5 of this paper.
Because of the very low radiated field strength on average, the 868.3 MHz EnOcean radio
technology can be approved in the USA and in Canada. Timing conditions can be found in
chapter 3.6 of this paper.
2.3.2 Modulation process
As modulation process, EnOcean uses incoherent amplitude modulation (ASK). Digital
amplitude modulation enables the implementation of very efficient energy-saving transmitters
because only the “1”-bits are transferred. At the same interference signal level, the
transmission security of the alternative FSK method is identical to that of the ASK method
(Reference: Pehl, Digitale und analoge Nachrichtenübertragung, Hüthig 2001).
2.3.3 Transmission timing
The transmission timing of the radio device PTM 200 has been developed to avoid possible
collisions with data packages of other EnOcean transmitters as well as disturbances from the
environment.
With each transmission cycle, at least three identical subtelegrams are transmitted. The
transmission of a subtelegram lasts approximately 0.7 ms. To optimize data security, each
telegram is repeated twice within about 20 ms, whereas the delay between the second and the
third transmission burst is effected at random. If some residual energy is available after
transmission of three subtelegrams, up to 2 further subtelegrams are sent.
©EnOcean GmbH, A. Anders
Page 13 of 22
PTM 200 User Manual V1.1
