REFLECTOR: APRS amateur radio tracking

David Staten Dastaten at earthlink.net
Wed Jul 23 22:55:40 CDT 2008


Brett,
   While you replied privately, the answer I have for you is good for 
the whole group, and there's not anything "private" I can see in your 
message.

The site aprs.fi saves the overlay information for up to  6 months. Go 
look me up, either as K5EFD or MSMOT2 or MSMOT7 (the latter two are 
tactical call signs I used in recent MS150 events). There should be data 
tracks accessible in the menu on the right for up to 6 months.

Things to keep in mind. My installation this year had lots of noise 
issues and reception issues so they should not be taken to indicate 
unreliability of APRS itself. Thats why even though I beaconed every 3-5 
mins there was relatively few collected beacons. Also, flexible antennas 
(rubber duckies, whips) in the slipstream have issues with remaining 
vertical at 50 mph.. I would consider them unusuable at airplane speeds 
unless internal in the cabin, or a purpose built slipstream antenna.

K5EFD is my ham call sign/license. You MUST broadcast your call sign 
every 10 minutes of a conversation or event, or use at the conclusion of 
your conversation if not 10 mins long. When I use the tactical call 
signs for events, my legal call sign is broadcast in embedded comments 
that are viewable when you click on my APRS track, or if a viewing party 
decodes it on their radio's control head/computer screen.

I would recommend using the plane's call sign (N number) as your beacon 
ID, and your ham call in the comments. Beacon a MINIMUM of every 10 mins 
(or at least set the beacons that contain your comment/call sign every 
10). Every 5 really should do fine.

There is a parameter that controls how many times your beacon is 
repeated. Currently ground mobiles tend to set this parameter (path) to 
WIDE 2-2 at the worst.. that means the packet is repeated 2 times down 
stream in all directions. In a plane, you could cover half of Louisiana 
or Oklahoma from 10,000 feet  In a plane, you could set this to WIDE 1-1 
and still saturate the area with no problem. Since the ARPS 
infrastructure (amatuer owned) is geared towards ground xmitters, the 
receivers and "digipeaters" tend to be located up high.. 100-200' agl 
antennae or higher. Keep this in mind when beaconing. Also keep in mind, 
from a good neighbor perspective that there is a finite limit to the 
amount of traffic a given area can support at once. So beaconing every 
minute or every 2 minutes is wasteful and impolite. Even when I tried to 
beacon every 3 during an event, I was operating for short term in a 
special event on a dedicated, nonstandard channel. 144.39 is the defacto 
nationwide APRS freq in the US.

Using Byonics tiny trak, there are a few algorhythms built in such as 
smart beaconing, corner pegging and proportional pathing. If your 
position isnt changing, proportional pathing changes the rate and path 
of your beacons so that you arent broadcasting lots of duplicate data.  
Corner pegging causes a beacon to go off when you change course a 
certain number of degrees and maintain that for more than a specified 
number of seconds. Works great for planes because you can set the beacon 
to go every 10 mins, but if you change course, the turn point is 
beaconed right then and there.

One caveat.. the Byonics boxes are VERY sensitive to RFI. I had probs 
with a 30 watt radio radiating less than 12 inches from the brain box, 
and causing feedback fits/chirped transmissions. Encasing the byonics TT 
box in something metal would be adviseable, and again, in airborne apps, 
anything more than 10 watts is severe overkill. Airborne coms tend to be 
12 watts or less and the ground antennae they talk to are 20 feet AGL at 
most.

Good luck.
Dave

Brett Ferrell wrote:
> Dave,
>
> Thanks for all of the great information!  I've ordered hardware from Byonics and
> plan to install this in my plane as soon as I can pass the exam.
>
> One thing that wasn't totally clear to me, the google earth tracking like on
> aprs.fi, it collects the information from all iGates, and maintains it for some
> period of time?  So the end user would go there, enter my N# and date of the
> trip, and they'd see all of the position reports for that day, for example, and
> that trip data is stored for say 30 days?  Thanks again!
>
> Brett
>
> Quoting David Staten <Dastaten at earthlink.net>:
>
>   
>> Milton Mersky wrote:
>>     
>>> Will radio tracking work in an auto?
>>>
>>> How much does it cost?
>>> Milt
>>>
>>>
>>>
>>>       
>> It will work on a car, truck, motorcycle, boat, bicycle, SAR dogs, or
>> anything you can attach a power source, GPS puck, xmitter and TNC to.
>>
>> HAM 2m (144 mhz) radios can be had at a "hamfest" used for $1-200 bucks.
>> New for $2-400. Can buy online. Can buy equipment without a license. The
>> majority of US domestic APRS use happens on 144.39.
>>
>> The MS150 bike ride in Houston and Dallas both utilize APRS extensively
>> for route management and asset tracking. Tour officials, supply
>> vehicles, medics, motorcycle escorts, SAG vehicles.. All of em. The main
>> limitations is the term (and code) for APRS is trademarked/held by one
>> individual, who stipulates its only used for non-profit non-commercial
>> purposes. The advantage of APRS on a Ham Net is that signal gets out and
>> is propagated even when everything else fails.. cell, etc..
>>
>> You can get into things with a cheap used handheld, a TNC, cable and GPS
>> puck from Byonics (www.byonics.com  $100 bux approx) and an external
>> (internal ok if glass plane) VHF air band or ham band antenna on the
>> plane (vertical polarity)
>>
>> Dave
>>
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