Funk-Electronic Piciorgros GmbH
RTU-810
V2.30 - Page 47 of 126
3.2.5
Timeslot operation
The RTU-810 fully supports time slot operation mode. For TS
mode, each minute is divided into fixed slices of 6 seconds,
staring with second 0. This is giving in total 10 time slots (TS
1-10).
Each 6 second time slot can be divided into 4 sub-timeslots
with 1.5 seconds each, which is pretty sufficient for running a
point-to-point-connection.
The time slot method fully fulfills the requirements for
operation on the time slot frequencies in Germany.
In other countries the time slot operation can mainly be used
to run multiple radio networks on the same frequency and
within the same range. As the time slots are synchronized to
fixed parts of a minute, networks on different time slots will
not collide with each other.
Time slot operation requires a precise time source to synchronize the internal time base
of the RTU-810. Possible sources are:
SNTP: A SNTP time server which is available via Ethernet- or GSM connection
GPS via PTS-100: This is a time server module which includes a GPS antenna
for time synchronization. The connection to the RTU-810 is a DCF-77 coded
signal, hence it requires the DCF or PTS option at the RTU-810
DCF-77: The DCF option is a hardware option and includes a socket for an
active DCF-77 antenna and the antenna itself. The range of the DCF-77
reception is up to 1000km around Frankfurt/Germany.
The PTS option includes only the socket, which can be used to connect a PTS-
100 for generating the time sync information from a GPS signal.
If both, SNTP and DCF time sources are available, the RTU-810 uses SNTP first. When
a sync with SNTP is not successful, it'll use the DCF source. After selecting a sync
source it will use this source as long as a synchronization fails, it'll then try to use the
other source.
The RTU-810 will automatically calibrate its internal time base to the time source,
which gives it a 3 days buffer in case all time sources will fail. During this reserve time
the time slot is continuously capped at its start and stop to ensure that the deviation will
not collide into neighbor time slots.
The time source is also used to set the internal battery buffered real time clock.
However, the RTC does not maintain the precision to maintain the precise time base
during power down. After a power down or device reset the RTU-810 must have a valid
time sync to continue time slot operation.
