Re: APRS-IS client - quick questions


Kevin Jensen <ktjensen@...>
 

Thanks Lynn - once again showing that Hams are genius material.

On 10/16/09, Lynn W. Deffenbaugh <KJ4ERJ@...> wrote:
Kevin Jensen wrote:
Lynn,

I know you are busy. My background is electrical engineering so I am
very curious about the application. Yes I will read more about it in
the groups.yahoo page; but am at work where I do not have access. So
hope you do not mind a couple questions.
If you don't mind random delays in getting answers, I certainly don't
mind answering them! I hope you don't mind that I copied the answer to
the group so that others might benefit.
1) My cellphone will go into battery save mode after a minute. Will
the APRS-IS client still keep sending beacon points? When I look on
the APRS GOOGLE map of my activity (I am N1KCG-12) it looks like it
stopped after I got on the highway, after about two or three minutes.
In my experience, when the phone turns "off" in battery save mode, the
GPS is also turned off. My application doesn't muck at all with power
settings, so beaconing will stop, but incoming APRS-IS updates will
continue.
2) How rapidly will my battery get drained running APRS-IS? Any data
on its effect on power in a typical cellphone with a GPRS circuit, and
data connectivity?

The battery with GPS and APRS-IS active will drain quite quickly. I
always plug my phone into a power adapter in the car and only turn off
the power savings timer when I KNOW I want to continue tracking. Once
in power saver with only a modest-radius APRS-IS feed active, it'll last
longer, but still MUCH less than if the client itself were closed or
APRS-IS disabled.

The client also transmits battery level telemetry. You can see mine at:

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

The week view has some good days in it and the month or year view shows
just how mean I've been to my battery. I'm now running an extended
capacity battery on my AT&T Tilt. I'm happy with the battery life (3-4
hours with full APRS-IS and GPS, 6 hours with only APRS-IS), but I don't
like the fact that it no longer fits in my belt clip.
3) I assume that the APRS-IS client needs a GPS circuit in the
cellphone, and a unlimited data connection. Is that true?

Yes, the client relies on a GPSapi-supported GPS unit and sends/receives
lots of data so an unlimited plan is highly recommended.
4) Since I am running WM6 on my cellphone, will the APRS-IS client
run in the background, while I use the phone for other activities?
Can I receive phone calls? Supposing it depends on the cellphone, but
that most that can run the APRS-IS client under WM6 might be able to
handle the multitasking.

The application will continue to run in the background, but the ability
to maintain a data connection while receiving calls is up to the
cellular provider and the infrastructure around you. I've had calls go
straight to voice-mail in some cells. I've had the data connection stop
when the phone rang and resume when I terminated the voice call. And
I've had the data connection continue operating while talking on the
phone. And these were all on the SAME phone, just in different
geographical areas.

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


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