Campbell Scientific RF401-series and RF430-series Spread Spectrum Data Radios/Modems - Manual (Page 119)

Appendix L. RF401/RF411 Average Current Drain Calculations
EXAMPLE #7 (Remote RF401/RF411 in “<0.4 mA, 4 sec Cycle” standby mode )
The RF401/RF411s in this example are configured for the lowest possible
average standby mode current (Advanced Setup Menu selection 7). The same
amount of data are collected as in Example 1, however the frequency of
collection is extended to once an hour.
It = Is + Id + Ir + Ii
Calculating each term:
Is = table mA value = 0.4 mA
It ≈ 0.43 mA
SUMMARY
Choosing a lower current standby mode does not always result in an overall
lower average current for the base RF401/RF411 because, by selecting a lower
current standby mode, the base RF401/RF411 must generate a longer “long
header” which involves more transmit time at 73 mA. However, the remote
site will normally benefit from a lower standby mode current since it does not
usually transmit a “long header.”
If the remote station is doing call-backs, then the remote RF401/RF411 must
initiate the connection by sending a “long header” so the remote
RF401/RF411’s average current drain may be higher than that of the base
RF401/RF411. Data collection may be a mixture of scheduled calls and call-
backs (possibly event driven).
As collection intervals become longer, the effects of “time of inactivity to
sleep” and data amount lessen and the average current drain approaches the
stated standby mode current.
mA 0.001 mA 73
ms 3,600,000
ms 65
mA 73
(ms) T
(ms)] N 2 (ms) 45 [
Id = Ч = Ч
+
=
mA 0.0001 mA 24
(ms) 3,600,000
(ms) 20
Ir = × =
mA 0.033 mA 24
(ms) 3,600,000
ms 5000
Ii = × =
L-9