> >> Are you limiting the equipment used in the chase to just the radio,
> >> OT2, and Nuvi350? Will you have a laptop along as well?
> > I'd rather just use the nuvi 350 and t2-301, otherwise what's the
> > advantage of the t2-301 nuvi combo? If I need a laptop I might as
> well just
> > run soundmodem on the laptop and attach that to a radio.
> You tell me what the advantage is... The only advantage I see is less
> equipment in the vehicle, but you are limited to the capabilities of
> the equipment chosen. I love the OpenTracker line. I have over a dozen
> OTUSB/OT2/OT3 units, and an R-Trak HAB as well... they all have their
> own specialized purposes. However I run my Kenwood D710 and AvMap G6
> in the truck because the capabilities available in those devices
> provide me with the desired functionality. I also run a TH-D72 as my
> handheld unit. The two Kenwood devices and the AvMap give me
> everything I need to be able to chase and recover HAB payloads. I
> can't achieve the same level of functionality with the OT line and the
> When chasing balloons however, I add on the laptop (or WebDT366) so
> that I get an even larger screen, a historic track of the payload
> path, packet logs, and a bunch more functionality that I can't get out
> of the Kenwood and AvMap G6.
> > What about using some creative scripting on the t2 to limit what
> the nuvi
> > sees? Any possibilities there?
> Not that I can think of. We don't have access to manipulating the
> incoming data stream. That would take a fair bit of processor power,
> and a lot of memory to be able to provide enough commands to parse out
> packets and manipulate them based on your own criteria.
> >> You could get the altitude of the payload displayed on an AvMap GPS
> >> connected to the OT2 though.
> > AvMap? what are you referring to?
> Uh, the AvMap GPS line... The current production model is the AvMap
> G6. http://www.geosat.us/
It is a GPS built in Italy, but it has
> firmware custom designed to support APRS built in. No other GPS
> manufacturer supports APRS. The closest anyone else comes is Garmin,
> and that's only because Scott has manipulated their Fleet Management
> Interface into believing that APRS data is FMI data. We all know how
> interested Garmin is in making the FMI mode work properly to support
> live data from the APRS network.
> The AvMap G6 is the latest in the AvMap line to support APRS. The G4
> and G5 units also supported APRS functionality. With the G6, I can
> tell the unit to follow a specified target (the balloon payload), and
> I can have three windows open on the map screen showing me specific
> data on that payload (I like speed, heading, and altitude when
> chasing). I can tell the GPS to calculate a route to the payload (not
> a good idea while the balloon is in flight, you want to head to where
> it is going to land, not where it is currently), but when the payload
> is on the ground, the GPS can direct you to the area.
> >> If you attach a laptop, and run APRSISCE/32, you can have everything
> >> you want, and have it displayed on a much larger screen.
> > I'll consider that as an option, but then doesn't that defeat the
> > point of the nuvi/t2-301 combo?
> That all depends on what the point of the T2-301 and Nuvi is... If you
> want a small minimal component count APRS station with the ability to
> see incoming icons on the screen, and the ability to send and receive
> messages on screen, then you've probably got the right package.
> If you want to be able to limit the incoming display to just a single
> specific station, or group of stations, and to be able to see the
> altitude of a specific station on screen, then you probably don't have
> the right package.
> Ham radio is a niche market. APRS is a niche market in the ham radio
> niche market. HAB tracking is a niche market in the APRS niche market
> of the ham radio niche market. Most manufacturers aim to position
> their products to hit the largest market possible. The fact that AvMap
> is producing a product that supports APRS is amazing, and then they
> also have features that cater to the HAB niche is even more amazing.
> You can't sit in a rowboat in the middle of a corn field in Nebraska
> and wonder why you're not flying to London. Sometimes you need
> specialized equipment to perform a specialized task. :)
> As Brian suggested, perhaps using a unique frequency would give you
> the ability to limit the stations heard. Hopefully you are aware that
> once your payload is aloft, there is no need to run an outgoing path.
> With the payload over 1000' AGL, asking for digipeats is a waste of
> time. Your payload will transmit much further than any ground based
> digipeater around. Moving to a frequency with no digipeaters available
> does not affect your ability to track. You can have ground based
> stations switch to the unique frequency and i-gate your packets so
> they appear on the APRS-IS stream.
> Many HAB groups run paths at altitude, which just causes all kinds of
> unnecessary noise on the ground. Dozens to hundreds of digipeaters end
> up repeating packets that are easily copied by every station on the
> ground already. Even worse people run with WIDE1-1 as a path request,
> causing not only every digipeater to act upon the packet, but every
> home fill-in digipeater as well.
> If you are running a quality HAB APRS tracking payload, you'll have
> the ability to change paths based on profile switching. Set up your
> profile switching to use no path on one profile, and then once the
> payload has dropped below something like 5000 feet, add an outgoing
> path to ask for help from the digipeaters. If you land somewhere a
> long distance from an i-gate, and your chase teams have managed to not
> keep up with the payload, a digipeat *might* help you get closer.
> Many people feel that if the payload can't be heard on the ground via
> the APRS-IS stream, that there's no possible way of recovering the
> payload. That is not the case. We've had payloads stop being gated at
> 20,000 feet AGL and still been able to find them on the ground. You
> simply extrapolate the flight path based on the winds seen on the way
> up and go to the projected area. If need be set up a search grid and
> search until you can hear your payload.
> If you have a frequency agile payload, you can have the unit switch
> back and forth between your unique frequency and 144.390, and get the
> best of both worlds.