SATEL-TR489
Integration Guide, Version 0.9
29
6.5
Power Save Mode
The Power save mode performs an automatic, self-adjusting receiver wake-up/sleep cycle.
It is designed for applications which base on one-way communication with relatively constant
TX interval and, in which the data packet separation is > 200 ms.
When enabled, the unit makes the
transmission interval study
basing on four (4) successfully
received data packets. The shortest time between transmitted packets is measured (
t
min
).
Measured value is updated after each successfully received data packet, so that possible
changes in the message length becomes noted.
Ensuring that the complete messages will be received even if there occur little variation in
transmission interval, some safety margin (
t
marg
) is left into Ready to receive from RF mode time.
Safety margin is calculated by dividing the shortest time between transmitted packets (
t
min
, in
ms
) with 8 and by adding 60 ms to this result:
t
marg =
tmin
+ 60 ms
8
The length of the whole sleeping period (
t
sleep
) is calculated by decreasing the shortest time
between transmitted packets (
t
min
) with safety margin (
t
marg
) and transmission time of the
original message (
t
TX
):
t
sleep
= t
min
−
t
marg
−
t
TX
Transmission interval study is started over always after 100 successful sleep/wake-up cycles
and, if the expected receiving slot (
t
RX slot
) with enhanced overlap margin (
t
overlap
) has been missed.
In latter case the package is considered to be lost.
t
overlap
= t
marg
+ 100 ms
t
RX slot, min
= t
min
- t
marg
t
RX slot, max
= t
min
+ t
overlap
