Re:One wolf's migration across Europe
by michaelt on Sunday August 10, 2014 @01:24PM
(#8160172)
Ah, spotted an error there. If you were using 0.66 milliwatt-hours per day and had two 20,000 milliwatt-hour batteries, it would of course last for 60,606 days. Which is 160 years not 4 years.
Of course, you'd also need to power the radio module to send the SMS, and presumably wolves spend time in remote regions with poor cell phone coverage Products like the Quectel M10 can use as much as 2 watts while transmitting [1] (or as little as a fifth of that). To make 40,000 milliwatt-hours of batteries last for 5 years would only give you a budget of 21 milliwatt-hours (75 joules) per day. That would let your run a 2 watt transmitter for about 37 seconds a day - so to make 8 transmissions a day you'd have to power on, join the network, transmit, and power down again in less than 5 seconds.
On the other hand, according to [2] it takes between 1.5 and 5.5 joules to send an SMS, allowing us to send several in a budget of 75 joules per day. They don't make much mention of signal strength or the energy cost of connecting to the network, unfortunately.
So I guess it all comes down to how long you have to have your radio module turned on in order to get a message off.
There are also tracking collars with solar cells [3].
Of course, you'd also need to power the radio module to send the SMS, and presumably wolves spend time in remote regions with poor cell phone coverage Products like the Quectel M10 can use as much as 2 watts while transmitting [1] (or as little as a fifth of that). To make 40,000 milliwatt-hours of batteries last for 5 years would only give you a budget of 21 milliwatt-hours (75 joules) per day. That would let your run a 2 watt transmitter for about 37 seconds a day - so to make 8 transmissions a day you'd have to power on, join the network, transmit, and power down again in less than 5 seconds.
On the other hand, according to [2] it takes between 1.5 and 5.5 joules to send an SMS, allowing us to send several in a budget of 75 joules per day. They don't make much mention of signal strength or the energy cost of connecting to the network, unfortunately.
So I guess it all comes down to how long you have to have your radio module turned on in order to get a message off.
There are also tracking collars with solar cells [3].
[1] http://arduino.cc/en/uploads/Main/Quectel_M10_datasheet.pdf [2] http://mobiledevices.kom.aau.dk/research/energy_measurements... [3] http://www.rvc.ac.uk/SML/People/awilson/Wildlife-tracking-co...