Wednesday, January 06, 2010

APRS phone

I finally succumbed to the idea of using a mobile phone for APRS. It arrived today. The phone is an HTC Touch Pro Windows Mobile phone. It isn't the latest model, but it's one that I knew would run the APRS software I wanted, APRSISCE by KJ4ERJ, and I got it for a very good price from Expansys. Though not visible in the photograph, it's one that has a real (if small) QWERTY keyboard that slides out from the back. So apart from APRS it will also be useful sending and receiving email and surfing the web when I am out.

Unfortunately my phone company 3 UK's account servers were down today so I was unable to log in and add unlimited internet to my package. I had to do it over the phone. This worked out rather well, as because I have had my account for more than 18 months and have not taken advantage of a free upgrade phone they gave me the internet add-on for free. So I have all the minutes and texts I could ever use, plus "unlimited" internet, for £15 a month, which I think is quite a good deal.

Unfortunately I don't think the internet package will start until 15th January (I had a bit of difficulty understanding the Indian gentleman who took my call) so I won't be able to use the internet (and the APRS software) out and about until then. But the phone can use wi-fi so I was able to install the software and get it running from inside the shack.

I was very impressed with the performance of the phone's GPS, which picked up signals from several satellites from inside the shack. APRS text messaging works really well - faster than ordinary mobile phone text messaging in fact. It is also faster and more reliable than APRS text messaging over amateur radio, which always seemed a bit hit and miss.

I do feel a bit of a cheat doing APRS this way, but the functionality is just so much better using the phone. The map display of the APRSISCE software is far more useful than the display of the VX-8E, and the compact self contained phone is much more convenient than using a portable GPS linked to an APRS tracker and separate radio.

Since the mobile network will relay my position reports to the internet I can be tracked and receive messages anywhere, not just when in range of an APRS digipeater or gateway. I no longer need to run a (cough, unattended) Internet gateway in order to connect myself to the APRS network. And that simplifies things in the shack a good deal. I have already released the FT-817ND from 2m duty and returned to using the K3 and transverter. So it's smiles all round.

If you have APRS capability feel free to send a text message to G4ILO-12.

6 comments:

Maurice.G4DVM said...

This looks an interesting phone, Julian. Once you have your internet package up and runningm could you post your findings on battery life from a full charge?
You may even get me into APRS activity!
73 Maurice G4DVM

Lynn (D) said...

I'm anxious to read your BLOG after your first outing with APRSISCE on the Windows Mobile phone. With automatic OpenStreetMap.org maps coming onto the screen as you drive and visibility to APRS stations as you drive by, it's pretty neat.

A few friends and I play "APRS tag". If you drive by a beaconing station, and are yourself beaconing, drop a note on their windshield (windscreen?) with your callsign, date, and time.

Also, on the battery life, my experience and that of others using the APRSISCE client is that you'll really want portable power in your mobile to keep the phone alive. The GPS really eats up the battery. For instance, my AT&T Tilt gives:

2-3 hours Full Tracking w/GPS
4-6 hours GPS Off, APRS-IS on
2-3 Days Client closed

That final line also has all other data-related applications closed like not even polling for e-mails via Windows Mobile Messaging.

Oh, and I also have an extended battery on the phone just to get that much useful time.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile

PS. Those times are estimates based on my (many times faulty) memory, but are probably more pessimistic than optimistic.

Lynn (D) said...

Oh, and I just remembered that APRSISCE sends the current battery state as telemetry! This is automatically graphed by aprs.fi and can give you a way to see your own battery consumption. Check out my phone at:

http://aprs.fi/telemetry/KJ4ERJ-12

The Bit sense also shows when you are on A/C and/or charging...Hm, maybe I'll put 0/1 values into the battery transition telemetry so this is also graphed on the "spare" charts...

Lynn (D) - KJ4ERJ - AT&T Tilt (HTC TyTN II) with extended battery

g4ilo said...

Thanks for the comments, Lynn, and especially for answering Maurice's questions about battery life. I think your AT&T Tilt is a rebadged HTC TyTN which is similar to my Touch Pro so I guess the battery life would be similar.

I want to use this while out walking and would need at least 6 hours of battery endurance whilst tracking. I don't know if any commercial solutions exist for an external battery pack that plugs in the bottom or whether I would have to make something up. Otherwise I guess I'll have to buy a couple of spare batteries and change them en route.

I suppose it wouldn't be possible to implement a sort of walker's economy mode where the application turns off the GPS and the data connection for a user defined interval? When you are walking in the mountains, you aren't going very fast so the app could probably sleep for 4 minutes in 5 or even 9 out of 10 without major consequences.

Lynn (D) said...

I quite often take my phone GeoCaching and hiking and biking. To do that, my son has created a USB power port device that runs on 7.2v LiON batteries. I hook up a miniUSB cable to my USB power port and have 2 swappable external cells running the whole thing.

Basically, if you can find a 12v cigarette plug/USB charger with a low drop-out regulator, it will work from a 7.2v rechargable pack and provide 5v to the phone for a LONG time.

With my pair of 7.2v LiON rechargables and the phone battery itself, I've gone 8-10 hours of walkabout with full tracking and APRS-IS monitoring. I have learned to start with a full charge on the phone and keep the "external" power connected until the batteries run down. Charging the phone with full GPS tracking takes a LONG time and really drains the external batteries quickly. (Not to mention how hot the phone gets doing that also!).

You can do your own "walker" mode by simply turning off the Enable/GPS and only toggle it back on during rest breaks. I've found that the GPS locks on quicker (especially under tree cover) while not moving.

A friend of mine (KJ4HPQ) is working on APRS-IS for the BlackBerry and has his GPS in a quasi-power-save mode, but the accuracy and drift suffer IMHO.

I'll add a "walker" mode to my ToDo list. If the interest is great, it may happen sooner rather than later.

Lynn (D) - KJ4ERJ

2W0PWR Blog said...

Hi Julian,

Firstly I'd like to say well done at the website, it's really good. I have stumbled across it more than once and it always impresses me.

I run iBCNU which is an APRS App for the iPhone.

I have been wanting to get onto APRS for some time now and with no igate repeaters locally it's pointless even buying the radio that can do this.

It's good to know that there is an App for a windows phone so if I ever wanna swap phones at some point I know where to look... :-)

73 de Dave
2W0PWR
www.dmrk.co.uk