Campbell Scientific RF401-series and RF430-series Spread Spectrum Data Radios/Modems User Manual

Page 114

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Appendix L. RF401/RF411 Average Current Drain Calculations

EXAMPLE #2 (Base RF401/RF411 in default standby mode)

The base RF401/RF411 in the above example does more receiving and less

transmitting than the remote RF401/RF411 so you might expect less average

current drain, however, the amount of data being transmitted per minute is

small, and the long header required is significant. Here are the results:

It = Is + Ih + Iq + Ir + Ii

Calculating each term:

Is = table mA value = 4 mA

It 6.9 mA

As in Example #1, the standby mode current, long header, and the “time of

inactivity to sleep” currents dominate the average RF401/RF411 current drains,

so the calculated values for remote and base RF401/RF411s are nearly equal.

Larger data collections would make the Ir contribution more significant.

ms)

700

length

header"

long

"

(default

mA

0.875

mA

73

ms

60,000

ms

700

73

(ms)

T

(ms)

L

Ih

=

=

Ч

=

Ч

=

mA

mA

0.025

mA

73

(ms)

60,000

(ms)

20

Iq

=

×

=

mA

0.026

mA

24

(ms)

60,000

ms]

20

(ms)

45

[

Ir

=

×

+

=

50)

sleep"

to

inactivity

of

time

"

default

(using

mA

2

mA

24

(ms)

60,000

ms

5000

Ii

=

=

×

=

L-4

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