Forgive me for my simplicity–I am really new to GPS technology and don’t know much about it, but I am interested and trying to learn.
My question is is there a way to remotely awake a hibernating receiver using a remote computer and have it send its position back to that computer? What type of hardware would be required for the gps module? Or is there a way to intercept the code as it obtains a lock on its position? The reason I want the receiver hibernating is to conserve on power consumption. I only want the receiver to track its position when I remotely request it. Their would be no need to have it save its last position so it would be a cold start.
Next question: how long would a 3.3 v button cell battery last when power consumption during hibernation is approx 20 uA (according to siRFstarIV chipset)?
Again, sorry if I am not making much sense–my knowledge and technical lingo is limited.
You don’t really say if this GPS receiver will be accessed wirelessly or via some kind of wired network. However, considering it’s GPS, I’m assuming you want wireless.
This implies you have a cellular or other wireless transceiver, and that’s what is going to eat your power. A coin cell isn’t going to cut it. You’re looking at a fairly large li-poly battery to get something that can stay in the lowest power mode possible, but still reachable via SMS or GPRS, and last even a full week without recharging.
If you tell us more about your exact requirements or scenarios I might have some suggestions on a good approach for building something feasible.
[quote="This implies you have a cellular or other wireless transceiver, and that’s what is going to eat your power. A coin cell isn’t going to cut it. You’re looking at a fairly large li-poly battery to get something that can stay in the lowest power mode possible, but still reachable via SMS or GPRS, and last even a full week without recharging.
[/quote]
Thanks for the quick reply. Yes it will be accessed by wireless. What I am looking to build is a relatively small GPS receiver that will be able to use a small LiPo or coin cell battery. I was thinking to have the GPS receiver stay in sleep mode until awakened by a sms or cellular signal.
However, it seem that a transceiver will draw a lot of power. Is that what your saying? What if the GPS unit was programed to track or fix a position once every 15 minutes and send transmit that to a remote PC instead of once/second? Is that possible? Would that use any less power?
My point is that I am not going to be able to charge the GPS receiver battery for long periods at a time and I need it to use as least power as possible using the smallest battery. What about SparkFun’s 3.7 100mAH Poly Lithium battery? Too small?
No matter how you you look at it, the power consumption by the cellular module will drive your battery requirements. You can certainly implement an aggressive power sleep strategy for both the cellular and GPS chips, but shutting down cellular means there are times you won’t be able to contact the device.
At the hobbiest level, you’re going to have a hard time beating the standby life of an average cell phone, which has a 1000-1800mAh battery. And that typically lasts 3-5 days with very little usage.
Take a look here for discussions on the actual components you’d need for such a system: viewtopic.php?t=19526
Hopefully this doesn’t come off as negativity towards your project! Personally, I find it amazing that the technology has come to a point where we (hobbyists and small businesses) can actually build these GSM and GPS systems using COTS technology. They are a lot of fun!
If you want to post more details (either here or via PM) about your exact project requirements and goals, there may be some workarounds that would get you closer to you goals.