Campbell Scientific CC640 Digital Camera - Manual (Page 33)

CC640 Digital Camera
11.1 Standalone Operation
In standalone mode the camera operates as a self-contained image logger.
The current draw of the camera while in low power quiescent mode is 250uA.
When the camera wakes up to take a picture, operating current draw increases
to a maximum of 250 mA for approximately 30 seconds. In order to calculate
the daily power usage of the camera, both the quiescent and operating power
consumptions need to be calculated.
The quiescent power consumption in Amp-Hours is calculated as follows:
P
quiescent
= 250x10 -6 Amps * 24 Hours = 0.006 Amp-Hrs / Day
The operating power usage per picture in Amp-Hours is calculated as follows:
P
operating
= 0.250 Amps * (30Sec. / 3600 Sec./Hr) = 0.00208 Amp-Hrs / Picture
The daily power usage will depend on the number of pictures taken per day.
The power usage can be calculated using the following formula:
P
usage
/ Day = 0.006 Amp-Hrs + (0.00208 Amp-Hrs * Number of Pictures Per
Day)
The following table shows the power usage versus the number of pictures taken
per day:
TABLE 7. Standalone Operation Power Usages
Number of Pictures Per Day Power Usage Per Day
1 (Every 24 Hours) 0.008 Amp-Hrs
4 (Every 6 Hours) 0.014 Amp-Hrs
12 (Every 2 Hours) 0.031 Amp-Hrs
24 (Every 60 minutes) 0.056 Amp-Hrs
48 (Every 30 minutes) 0.106 Amp-Hrs
96 (Every 15 minutes) 0.206 Amp-Hrs
288 (Every 5 minutes) 0.606 Amp-Hrs
1440 (Every minute) 3.006 Amp-Hrs
11.2 Operation with Communication
If the camera is operating in a standalone mode, the time the camera is
operational in this mode is typically 30 seconds. The power calculations are
more complicated when communication are involved, as the amount of time
the camera is in operating mode is increased by the amount of time it takes for
the camera to transfer an image.
The transfer times are influenced by two main factors, the size of the image
and the transfer speed used to send the image. The amount of time the camera
is on will be increased as the size of the image becomes larger or as the
communication rate slows down.
To properly determine the power consumption while communicating, the
additional time the camera stays in operating mode needs to be accounted for.
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