15135Re: [tracker2] Replacing Older OT1m System
- Jan 16, 2013Hi Scott,
I'll go over my notes on the weekend when I get home and send you through some info.
I'm about 300mi from home at the moment out in the country side with my trusty laptop, 3G wireless internet modem & embedded development system literally writing and debugging code in a farmers paddock... it's just tipped over +42degC in the shade today :)
Anyway more soon.
MatthewOn 17 January 2013 15:54, Scott Miller <scott@...> wrote:
I think you've shared some of the documentation with me before, but it's
been a while and I don't remember the details. I'd be happy to look
over it again and see if I can incorporate some of that into the T3 and
maybe the T2. Turns out one compiler optimization wasn't enabled and I
have something like 800 bytes to work with on the T2 now!
Scott> <mailto:ve6srv@...>> wrote:
On 1/16/2013 8:23 PM, Matthew Cook wrote:
> I've already stumped the pennies into a T2 + Alinco HT for my yacht at
> least. The scripts were easily written, mind you took me a while to debug.
> To solve this GPS Power/APRS tracker problem I've been working on a
> MSP430 that sits between the T2 and the GPS. The MSP430 puts the GPS
> (ublox) into binary low power mode (hot start) and implements a variable
> GPS polling period (based upon speed) and then simply tells lies to the
> T2 every second by sending fake NMEA sentances. The MSP430 currently
> adds 2mA to my overall consumption. I've down to 25-27mA depending on
> how to look at the AVO.
> The MSP430 sits there and polls the GPS and watches the speed. If the
> speed starts to change then the GPS polling period is varied, this
> should sound familiar? Yes I've simply copied the SmartBeaconing(TM)
> algorithm again.
> Anyway if we could get a T3 that can read any one of the GPS units in a
> low power (and if necessary binary) mode and poll the GPS for a position
> before transmit then I'd certainly be looking for such a unit.
> Programming my MSP430 is a PITA, since I've got to copy the
> SmartBeaconing parameters out of the T2 and feed them into my software.
> It works but it's certainly not production ready, nor do I wish to
> release/develop this further. Was just trying to solve the same problem
> as Marc.
> I hope that the ideas above gives Scott some thoughts as to how this low
> power GPS mode could be useful.
> I've found the hot start mechanism in the Atmel ublox is pretty good,
> meaning the positions when polled are coming out as expected. The
> prolific chipsets I had no end of trouble with in general. They were
> not as well supported as the ublox in terms of others having used them.
> With regard to the GPS, having a unit that can mount on the deck of the
> boat and sends serial back (hockey puck style) would be preferable to
> say a GPS module within the T3. An internal module would require an
> external antenna with active preamp to get around the cable loss and NF
> issues, which adds 10-12mA to the overall current consumption; this will
> blow your power budget.
> The HT and T2 I've hidden under the deck using the HT rubber duck. I've
> found that this gets into the local APRS system well when the boat is on
> the hard and isn't too shabby when out to sea. I'm luck that my boat is
> plywood/fibreglass so no issues with faraday shields etc. External 2m
> marine antennas aren't easily obtainable here in Australia, I'm
> certainly interested in any suggestions other APRS yachties might have,
> especially dual band inc 70cm :)
> On 16 January 2013 15:10, James Ewen <ve6srv@...
> On Tue, Jan 15, 2013 at 8:42 PM, Matthew Cook vk5zm@...> into aprs.fi <http://aprs.fi>, you can simply send the parameters> <mailto:vk5zm%40bistre.net>> wrote:
> > Scott if you were to look at low power modes then it would be worth
> > switching to the binary protocol and looking for a GPS module
> with hot start
> > capabilities. I think it wouldn 't be too hard to then put in a
> > that allowed us to switch profiles when the boat starts to move,
> which then
> > switches from a 30min update rate to a smart beaconing routine
> taylored for
> > yachts/power boats.
> We already have the scripting capability, profile switching based on
> speed, and fixed rate/SmartBeaconing. Using the binary protocol
> however would mean that you would be limited one one specific GPS, or
> series of GPS as each one will have a proprietary communications
> protocol. NMEA is a common language.
> > It's then just a simple matter of switching the HT at
> > the appropriate time. It would also be nice if we could somehow
> get the
> > PARAM information into the TNC so that APRS.fi can give us pretty
> graphs of
> > battery volts etc.
> You can do that with scripting right now. Not many places display the
> telemetry parameters. If you are only wanting to get the parameters> once, and they will
> "stick" for a very long time.
> > I'd certainly be willing to buy/build/test such a unit.
> > I've got two boats to test it on (yes I'm greedy and likes my
> > boating/fishing), and a mate of mine has a shiny new sports car
> that sits in
> > his garage that wants one also. Definitely food for thought.
> Pony up the pennies... you've got 95% of what you are asking for
> sitting on the shelf!
> The OT+ will do everything you want except talk in a proprietary
> binary mode to the GPS of your choice, and poll it for a position.
> 0487 653 245
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