Trying to make some battery budget calculations, I would like to know how many transmission bursts (577 us) are typically needed to send one SMS message?
Listening to the audible noise while the SMS message is transmitted, it seems to be something like 5 to 10 bursts. I believe it is exactly described somewhere in the ETSI GSM standards, but wonder if someone has the exact information available by heart.
ETSI doesn’t describe how many GSM bursts are needed to send an SMS. The consumption can vary depending on the network conditions.
With a module connected to a Radio Communication Tester with PCL5 and 900MHz band, to perform the transmission of one SMS, it needs a period long about 6.2sec. The energy to accomplish this activity is proportional to 0,085 mAh with a mean value of 49.5mA.
This gives me a good estimate to start with. Maybe I will later on test it more thoroghly on some application, over a longer time period.
If your goal is optimizing battery budget, then what you are actually looking for are energy consumption values or measurements. Energy is measured in joules (j) = watts x seconds (Ws) = amperes x volts x seconds (AVs).The best public source I found for such kind of values or measurement is the University of Aalborg. Please start here http://mobiledevices.kom.aau.dk/research/energy_measurements_on_mobile_phones/As a quick start, you can assume that a basic SMS costs typically between 2 and 3 joules.
thanks a lot for this information, I was not aware of such research activity. Looks interesting, not only being limited to GSM.
And sure, energy counts finally, not current. But as a first approximation, one could assume a nominal voltage at 3.8 Volts, and then current x time makes a pretty good estimate. Especially in the case of SMS, where I was curious to know how many "expensive" 2 A (or more) spikes will be needed to carry out the transmission, in addition to the basic 20 mA or so continuos current flow. But Cosmin nicely put this into a frame already.
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