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Re: RTrak-HAB antenna thoughts

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  • Jason R
    Lynn, Unless a receiver was added and interfaced to the input section of the OpenTracker on the RTrak-HAB, there is no carrier detection and the tracker will
    Message 1 of 36 , Sep 6, 2012
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      Lynn,

      Unless a receiver was added and interfaced to the input section of the OpenTracker on the RTrak-HAB, there is no carrier detection and the tracker will transmit "in the blind". This is another reason to always run a NO PATH situation when above a certain altitude threshold.

      Jason Rausch - KE4NYV
      RPC Electronics, LLC
      www.rpc-electronics.com

      --- In RTrak@yahoogroups.com, "Lynn W. Deffenbaugh (Mr)" <ldeffenb@...> wrote:
      >
      > One more thought. If the balloon's tracker was set to listen for
      > carrier before transmitting, that could also explain the black-out
      > period. It may not have transmitted due to getting into line of sight
      > with some really powerful and busy set of digipeaters. Calculate your
      > footprint from a 100,000 foot altitude and draw that circle on a map.
      > If it covers some major metropolitan areas (and a 90,000 footprint
      > doesn't) that could 'splain the lack of packets from the higher altitudes.
      >
      > But I still think you need to track down (no pun intended) why the
      > balloon's tracker didn't get a single packet through any other stations
      > for the entire flight.
      >
      > Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
      >
      > On 9/6/2012 1:25 PM, airsix73 wrote:
      > >
      > >
      > > I apologize if I come off as ignorant. I've been a ham for about 60
      > > days or so and barely know which way is up at this point.
      > >
      > > Between 100,000ft and 123,000ft I had a 36 minute black-out. That was
      > > a long nail-biting half-hour. Meanwhile I was having no trouble
      > > picking up other digipeated APRS traffic from all around the region.
      > > During that 1/2 hour in which I could not receive my tracker I would
      > > have expected it to be picked up by one of the digipeaters within
      > > range of my ground station. Even if it was picked up by a digipeater
      > > beyond my range to receive by RF I would expect that digipeater would
      > > have got it to someone's igate.
      > >
      > > We don't have heavy APRS traffic in Eastern Washington, but we do seem
      > > to have a decent digipeater and igate coverage.
      > >
      > > --- In RTrak@yahoogroups.com <mailto:RTrak%40yahoogroups.com>, James
      > > Ewen <ve6srv@> wrote:
      > > >
      > > > So where's your proof that no digipeaters handled the packet? Did you
      > > > have stations located near every digipeater for 500 miles around? That
      > > > would be the only definitive way of knowing that no digipeater handled
      > > > the packet.
      > > >
      > > > Let me guess, you're basing this opinion on data gleaned from the
      > > > APRS-IS stream where only a small portion of the data is available.
      > > >
      > > > Your payload was being heard direct by dozens of i-gates all racing to
      > > > get the packet to the internet first. After that the digipeaters got a
      > > > chance to act on the packet, and then finally i-gates hearing a
      > > > digipeated packet would get gated. There's little chance that a
      > > > digipeated packet can get to the internet before one heard direct.
      > > >
      > > > The APRS-IS stream is not a reliable tool to use for network monitoring.
      > > >
      > > >
      > > >
      > > > On 9/6/12, airsix73 <ben.messinger@> wrote:
      > > > > Thanks James & Jason,
      > > > > Here is a cut and paste of a packet (pulled from aprs.fi)
      > > > >
      > > > > 2012-09-01 18:32:09 UTC:
      > > > >
      > > KC7PUC-1>APOTC1,WIDE2-1,qAR,KF7VZR-1:!4632.56N/11931.92WO322/019/A=124524
      > > > > 07.4 13C M&M Space Prog.
      > > > >
      > > > > So "WIDE2-1" should have been a good 1-hop path, right? Thank you for
      > > > > correcting me on that as well as the repeater/digipeater slip up.
      > > I did
      > > > > notice right from the get-go aprs.fi was flagging it with a path
      > > warning due
      > > > > to the path/altitude combination (even at very low altitude). Are
      > > > > digipeaters filtering out packets they think have a bad path?
      > > > >
      > > > > Regarding the doughnut hole: Tried moving the antenna to the side
      > > of the
      > > > > vehicle to no effect and it was a van with about a 4ft square door
      > > (good
      > > > > ground plane). Perhaps we just never got the vehicle oriented
      > > properly in
      > > > > relation to the balloon.
      > > > >
      > > > > Ben
      > > > >
      > > > > --- In RTrak@yahoogroups.com <mailto:RTrak%40yahoogroups.com>,
      > > James Ewen <ve6srv@> wrote:
      > > > >>
      > > > >> As Jason has mentioned, WIDE2-1 would be a valid path request. APRS
      > > > >> packets will not activate repeaters, but rather digipeaters.
      > > > >>
      > > > >> Digipeaters listen on 144.390 capture packets and forward those
      > > > >> packets back out on the same frequency if a valid path alias is seen
      > > > >> by the digipeater.
      > > > >>
      > > > >> As for being in the doughnut hole, the simple solution is to not get
      > > > >> into the hole. If you find yourself in the hole, simply taking you
      > > > >> antenna off the roof and moving it to the side of your vehicle will
      > > > >> work. Obviously this is easiest with a magmount where you can
      > > stick it
      > > > >> to the door or other panel. A fold over mount can be folded to
      > > aim the
      > > > >> pattern upwards. You can also just bend an antenna over to get the
      > > > >> pattern skyward.
      > > > >>
      > > > >>
      > > > >>
      > > > >> On 9/6/12, Jason R <lists@> wrote:
      > > > >> > Ben,
      > > > >> >
      > > > >> > Glad to hear you have a successful first flight!
      > > > >> >
      > > > >> >> One thing I'm scratching my head over is that although I
      > > configured
      > > > >> >> it for "WIDE2,1" it was not picked up by a single repeater.
      > > > >> >
      > > > >> > Was this a typo or did you actually put in WIDE2,1?
      > > > >> >
      > > > >> > If so, that is the problem, the path should have been WIDE2-1. The
      > > > >> > comma
      > > > >> > would have made the path look like alias WIDE2 and then alias 1 to
      > > > >> > everything on the network. The dash would have made the alias
      > > WIDE2-1
      > > > >> > and
      > > > >> > that would have given you a single hop.
      > > > >> >
      > > > >> > Keep in mind, with altitude control, you can have the path be
      > > something
      > > > >> > like
      > > > >> > WIDE2-1 below a certain threshold and then go to no path above that
      > > > >> > threshold. This is a very popular option with balloons since
      > > once they
      > > > >> > achieve a certain altitude, there is typically no need for a
      > > path and
      > > > >> > it
      > > > >> > just results in network congestion.
      > > > >> >
      > > > >> > Jason Rausch - KE4NYV
      > > > >> > RPC Electronics, LLC
      > > > >> > www.rpc-electronics.com
      > > > >> >
      > > > >> >
      > > > >> > --- In RTrak@yahoogroups.com <mailto:RTrak%40yahoogroups.com>,
      > > "airsix73" <ben.messinger@> wrote:
      > > > >> >>
      > > > >> >> Just wanted to follow up and let everyone know we pulled off a
      > > > >> >> successful
      > > > >> >> 1st balloon project. The RTrak-HAB performed well. In fact it
      > > survived
      > > > >> >> a
      > > > >> >> very hard landing. I didn't mess around with profile or frequency
      > > > >> >> switching just to be safe.
      > > > >> >>
      > > > >> >> One thing I'm scratching my head over is that although I
      > > configured it
      > > > >> >> for
      > > > >> >> "WIDE2,1" it was not picked up by a single repeater. I used
      > > APRSISCE
      > > > >> >> running on my laptop with a Verizon mobile wifi hotspot to act
      > > as an
      > > > >> >> iGate
      > > > >> >> from my chase-vehicle. That worked great, but I'm puzzled that
      > > it was
      > > > >> >> ignored by the rest of the APRS community. There are plenty of
      > > > >> >> repeaters
      > > > >> >> around that certainly heard it.
      > > > >> >>
      > > > >> >> I ended up going with a vertical dipole which worked very well
      > > until
      > > > >> >> roughly 100,000ft at which point we couldn't get out from
      > > under the
      > > > >> >> doughnut and started missing packets. We were roughly 12 miles
      > > off to
      > > > >> >> the
      > > > >> >> side, but that was no longer enough distance. Our highest-altitude
      > > > >> >> packet
      > > > >> >> came in at 124k and change. Based on our rate of climb at that
      > > point
      > > > >> >> and
      > > > >> >> the time-stamp on the video we hit a bit over 126,000ft roughly 3
      > > > >> >> minutes
      > > > >> >> later.
      > > > >> >>
      > > > >> >> Here is a bit of video from the last 1:30 before burst. Thanks
      > > for the
      > > > >> >> help with antenna design!
      > > > >> >>
      > > > >> >> http://www.youtube.com/watch?v=GRqrnh_ySNs&feature=g-upl
      > > > >> >>
      > > > >> >> -Ben
      > > > >> >>
      > > > >> >>
      > > > >> >> --- In RTrak@yahoogroups.com <mailto:RTrak%40yahoogroups.com>,
      > > "airsix73" <ben.messinger@> wrote:
      > > > >> >> >
      > > > >> >> > Hello,
      > > > >> >> > I'm preparing my first balloon launch and trying to decide on
      > > > >> >> > antennas
      > > > >> >> > for the mobile ground station as well as the balloon. I'm a
      > > new ham,
      > > > >> >> > and
      > > > >> >> > nervous about keeping a strong enough signal over 25-30
      > > miles with
      > > > >> >> > just
      > > > >> >> > 350mw transmit power and random orientation. Suggestions?
      > > > >> >> >
      > > > >> >> > For best front-to-back ratio there are some really neat antenna
      > > > >> >> > designs
      > > > >> >> > (patch, bi-quad with reflector, yagi, 2 and 3 element quad)
      > > but they
      > > > >> >> > aren't very conducive to balloon work!
      > > > >> >> >
      > > > >> >> > For those of you who've done this before, what are your
      > > > >> >> > recommendations?
      > > > >> >> > I'm sure I'm over-thinking it, so I'd love to hear what
      > > others have
      > > > >> >> > done
      > > > >> >> > with success.
      > > > >> >> >
      > > > >> >> > Thanks!
      > > > >> >> >
      > > > >> >> > Ben
      > > > >> >> >
      > > > >> >>
      > > > >> >
      > > > >> >
      > > > >> >
      > > > >> > ------------------------------------
      > > > >> >
      > > > >> > Yahoo! Groups Links
      > > > >> >
      > > > >> >
      > > > >> >
      > > > >> >
      > > > >>
      > > > >> --
      > > > >> Sent from my mobile device
      > > > >>
      > > > >> James
      > > > >> VE6SRV
      > > > >>
      > > > >
      > > > >
      > > > >
      > > > > ------------------------------------
      > > > >
      > > > > Yahoo! Groups Links
      > > > >
      > > > >
      > > > >
      > > > >
      > > >
      > > > --
      > > > Sent from my mobile device
      > > >
      > > > James
      > > > VE6SRV
      > > >
      > >
      > >
      >
    • Keith VE7GDH
      Ben KF7VZR (got that from a June 22 message) wrote... ... Deviation is important. If it s too high (within limits) nearby stations may still be able to decode
      Message 36 of 36 , Sep 6, 2012
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        Ben KF7VZR (got that from a June 22 message) wrote...

        > My documentation says nothing about TX audio level...
        > They've both been played with...

        Deviation is important. If it's too high (within limits) nearby stations
        may still be able to decode the tones. Distant ones where your signal
        is weaker may not be able to. You have probably heard this on a voice
        repeater or even on simplex. A distant and noisy station can be copied
        via a repeater if he backs off from the mic. If he starts shouting, the
        deviation goes up. More energy is outside the passband of the receiver
        and eventually the signal is too noisy to copy or the squelch might
        even close. If you are simplex, you can try opening your squelch. If
        you are on a repeater, you're out of luck. It's the same with packet.
        You are better off having the deviation set properly. It can be done
        by ear, but a deviation meter or service monitor would be better.
        Lacking one, just crank the deviation all of the way up and then
        start turning it down. When it starts to sound quieter, turn it down
        some more. It will get you in the ballpark, but checking the actual
        deviation would be better.

        Perhaps you could check the actual deviation before you change
        anything. So... could over-deviation explain why only one iGate
        heard you?

        73 es cul - Keith VE7GDH
        --
        "I may be lost, but I know exactly where I am!"
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