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Re: [GPSL] Re: request for advice: GPS units for ARHAB

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  • Ralph Wallio, W0RPK
    Joe -- This would be interesting information but it is anecdotal in nature, very time consuming to collect and very difficult if not impossible to maintain in
    Message 1 of 19 , Jan 22, 2008
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      Joe -- This would be interesting information but it is anecdotal in nature, very time consuming to
      collect and very difficult if not impossible to maintain in a complete balanced view. I would add
      brief results from specific lab testing which takes modes, bandwidths, power levels, radiation
      patterns, proximity, et al, into account. The complete story would have to be in group ARHAB web
      pages. -- Ralph W0RPK





      ----- Original Message -----
      From: "Joe" <nss@...>
      To: <GPSL@yahoogroups.com>
      Sent: Tuesday, January 22, 2008 08:56
      Subject: Re: [GPSL] Re: request for advice: GPS units for ARHAB



      Ralph? how about a sub catagory of the GPS list, that gives flight
      results. like i know we have the list of what ones work above "X"
      altitude. but maybe a list of what ones don't like certain modes or
      freqs. and or power levels etc?

      Joe
    • Joe
      ... I can understand that. ... Maybe a This is what happened area? Reason stating, is as soon as i made a comment about this GPS locking up, (probably
      Message 2 of 19 , Jan 22, 2008
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        Ralph Wallio, W0RPK wrote:

        >Joe -- This would be interesting information but it is anecdotal in nature, very time consuming to
        >collect and very difficult if not impossible to maintain in a complete balanced view.
        >
        I can understand that.

        > I would add
        >brief results from specific lab testing which takes modes, bandwidths, power levels, radiation
        >patterns, proximity, et al, into account.
        >
        Maybe a "This is what happened area?

        Reason stating, is as soon as i made a comment about this GPS locking
        up, (probably desence) Bill ELK knew that that unit does not like
        439.25 ATV. and it has failed on other flights with other groups when
        used on a video flight. It would be something that would have been good
        to know beforehand. that others have had problems with it, and it would
        pop up a red flag. as something to pay super close attention to. After
        45 flights this is the first time we have ever had a problem with any
        GPS unit we have ever used.

        Just a thought

        > The complete story would have to be in group ARHAB web
        >pages. -- Ralph W0RPK
        >
        >
        >
        >
        >
        >----- Original Message -----
        >From: "Joe" <nss@...>
        >To: <GPSL@yahoogroups.com>
        >Sent: Tuesday, January 22, 2008 08:56
        >Subject: Re: [GPSL] Re: request for advice: GPS units for ARHAB
        >
        >
        >
        >Ralph? how about a sub catagory of the GPS list, that gives flight
        >results. like i know we have the list of what ones work above "X"
        >altitude. but maybe a list of what ones don't like certain modes or
        >freqs. and or power levels etc?
        >
        >Joe
        >
        >
        >
        >
        >
        >Yahoo! Groups Links
        >
        >
        >
        >
        >
        >
        >
        >
      • Michael Gray
        Another contributing factor to jamming problems is an active antenna. Strong out of band signals can cause intermod problems with the antenna LNA. The higher
        Message 3 of 19 , Jan 22, 2008
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          Another contributing factor to jamming problems is an active antenna.
          Strong out of band signals can cause intermod problems with the antenna
          LNA. The higher voltage/current antennas generally perform better than
          the newer 3VDC low current antennas. It all comes down to the IP3 of the
          LNA. A good quality GPS antenna with filtering really helps. The $10
          Chi-Com specials are pretty poor.


          On Tue, 22 Jan 2008, Ralph Wallio, W0RPK wrote:

          > Joe -- This would be interesting information but it is anecdotal in nature, very time consuming to
          > collect and very difficult if not impossible to maintain in a complete balanced view. I would add
          > brief results from specific lab testing which takes modes, bandwidths, power levels, radiation
          > patterns, proximity, et al, into account. The complete story would have to be in group ARHAB web
          > pages. -- Ralph W0RPK
          >
          >
          >
          >
          >
          > ----- Original Message -----
          > From: "Joe" <nss@...>
          > To: <GPSL@yahoogroups.com>
          > Sent: Tuesday, January 22, 2008 08:56
          > Subject: Re: [GPSL] Re: request for advice: GPS units for ARHAB
          >
          >
          >
          > Ralph? how about a sub catagory of the GPS list, that gives flight
          > results. like i know we have the list of what ones work above "X"
          > altitude. but maybe a list of what ones don't like certain modes or
          > freqs. and or power levels etc?
          >
          > Joe
          >
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
        • Mark Conner
          While anecdotal, I think there seems to be enough evidence that the GPS-18 is more touchy than usual about RFI. I agree that for many units where boards,
          Message 4 of 19 , Jan 22, 2008
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            While anecdotal, I think there seems to be enough evidence that the GPS-18 is more touchy than 'usual' about RFI. I agree that for many units where boards, antennas, etc., may vary, it'd be too hard to track all the permutations. But for integral units like the all-in-one mice and handheld units, it'd be a worthwhile footnote to caution the operator to fully investigate RFI issues where they've been reported on multiple occasions.

            I didn't realize until reading the last few posts that the GPS-18 also suffered from problems due to UHF ATV transmissions. That paralleled my experience with degraded performance in proximity to a digital camera. I now have mine relegated to the backup payload in a somewhat more benign RF environment (appears infrequent 2m transmissions don't upset it). I'll definitely keep the UHF ATV experiences in mind with this unit. Probably would not be good to pair it with a 70cm simplex repeater anymore.

            73 de Mark N9XTN

            ----- Original Message -----
            From: Joe <nss@...>
            Date: Tuesday, January 22, 2008 9:55 am
            Subject: Re: [GPSL] Re: request for advice: GPS units for ARHAB
            To: GPSL@yahoogroups.com

            >
            >
            > Ralph Wallio, W0RPK wrote:
            >
            > >Joe -- This would be interesting information but it is anecdotal
            > in nature, very time consuming to
            > >collect and very difficult if not impossible to maintain in a
            > complete balanced view.
            > >
            > I can understand that.
            >
          • wb8elk@aol.com
            I ve had great luck with using the Motorola VP Oncore with 70 cm ATV....and the Garmin GPS-35 as well. However, the GPS-18 LVC takes some work to get it to
            Message 5 of 19 , Jan 22, 2008
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              I've had great luck with using the Motorola VP Oncore with 70 cm ATV....and the Garmin GPS-35 as well.  However, the GPS-18 LVC takes some work to get it to work in that environment.....we did manage to get it to work on the last UAH Balloonsat by putting it about 3 feet above the ATV transmitter section with aluminum foil between them....I wasn't able to check to measure just how much desense we were getting but it did perform well throughout that flight.
               
              The following output sentence might be helpful to determine if you have desense problems with your GPS receiver or antenna....see if the signal to noise values on the tracked satellites change dramatically when turning on other transmitters or equipment in your payload:
               
              The $GPGSV message field 7 gives you the signal to noise ratio on tracked satellites.
               
               
              In addition:
              The Garmin Specific $PGRMT sentence will give you the GPS unit's internal temperature....since the GPS unit is often placed right out in the open....this would be a good parameter to measure particularly if doing a night flight.
               
              - Bill WB8ELK
               




              Start the year off right. Easy ways to stay in shape in the new year.
            • Hank
              ... This whole thread about GPS performance is a real good one. Mike, Could you provide some context and specifics about the above two observations, please?
              Message 6 of 19 , Jan 22, 2008
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                > A good quality GPS antenna with filtering really helps. The $10
                > Chi-Com specials are pretty poor.

                This whole thread about GPS performance is a real good one.

                Mike,

                Could you provide some context and specifics about the above
                two observations, please?

                Anecdotes, whether this was something you or someone you know
                experienced, whether it was on board a balloon, stuff like that.

                Hank
              • Mike Manes
                Our GPS antennas are mounted inside the top of foamcore enclosures, and they do work. But we have observed some loss of signal quality - not enough to lose 3D
                Message 7 of 19 , Jan 22, 2008
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                  Our GPS antennas are mounted inside the top of foamcore enclosures,
                  and they do work. But we have observed some loss of signal quality -
                  not enough to lose 3D lock, however. Past performance does not
                  guarantee future results, however :=}. So I was reluctant to
                  suggest that, especially since we've not verified that an enclosed
                  GPS antenna/rcvr in fact does operate OK overnight.

                  73 de Mike W5VSI

                  PAUL VERHAGE wrote:
                  > 3/4" thick Styrofoam is transparent to GPS signals, so you can keep the
                  > GPS inside the capsule but near the top of it to stay warm.
                  >
                  > Paul
                  >
                  > >>> Mike Manes <mrmanes@...> 1/21/2008 5:49 PM >>>
                  > I'd think a CR123 LiSO2 cell would keep the GPS CMOS alive nicely even
                  > down to -40C, which shouldn't be too challenging an interior temp to
                  > stay above. The CR123's we use to power our NiCr cutdown burners have
                  > little thermal insulation and zero power dissipation inside the parachute
                  > canopy, and they've always fired over 5A on command.
                  >
                  > Whether the GPS will operate that cold is another issue. Although the
                  > GPS engine could be kept above its min ambient, a GPS patch with a
                  > preamp may not enjoy such a comfy environment, especially if it's
                  > mounted outside the payload housing. A passive antenna would be
                  > preferable, I'd think.
                  >
                  > 73 de Mike W5VSI
                  >
                  > Mark Conner wrote:
                  > > Ralph W0RPK maintains this page of GPS receivers that have passed or
                  > failed the 60kft test:
                  > > http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm
                  > >
                  > > One note regarding the GPS-18 is that it seems to be more sensitive
                  > to RFI. I flew one in the same payload as a digital camera and the
                  > camera desensed the GPS unit by around 10dB or so. The GPS-35 I use is
                  > practically unaffected by the camera, but the tradeoff is that it's an
                  > older design and more of a power hog (about 130 mA at 5V).
                  > >
                  > > The Motorola OnCore M12 is a pretty good board-level unit that works
                  > at 60kft+ and has good power consumption. The main issue is that you
                  > have to get the battery backup unit if you want it to power up with your
                  > configuration (output type, baud rate) intact. The default is their
                  > binary mode. This could be an issue in a long-duration flight where you
                  > may lose battery power at night and then regain it the next day with
                  > warming. The backup battery could fail too in such conditions.
                  > >
                  > > That actually is something you may want to fully test on any GPS for
                  > a long-duration flight - will it retain the desired settings if
                  > thorougly frozen and powered off? Most of us flying daytime flights
                  > don't fully exercise these conditions.
                  > >
                  > > 73 de Mark N9XTN
                  > >
                  > >
                  > >> --- In GPSL@yahoogroups.com, "K. Mark Caviezel" <kmcaviezel@...>
                  > >> wrote:>
                  > >>> All:
                  > >>> I haven't kept up with what the ARHAB state of the art
                  > >>> for airborne GPS units is. What units are being used
                  > >>> now days? Factors of merit: low power consumption,
                  > >>> cheap, lightweight, works at ARHAB altitudes,
                  > >>> integrated antenna.
                  > >>> I'm considering getting some Garmin 18LVCs which at
                  > >>> 5V/0.060A, $60, about 2 oz seems like a real contender
                  > >>> but I know that unit has been on the market for
                  > >>> several years now, maybe there is something better out
                  > >>> there. Notionally, I'm thinking about flights in the
                  > >>> 2-5 day range, so power consumption is a bigger driver
                  > >>> in this application than short duration sounding
                  > >>> balloon flights.
                  > >>>
                  > >>> Your detailed suggestions are welcome.
                  > >>>
                  > >>> - Mark ng0x
                  > >>>
                  > >
                  > >
                  > >
                  > > Yahoo! Groups Links
                  > >
                  > >
                  > >
                  > >
                  >
                  > --
                  > Mike Manes mrmanes@... Tel: 303-979-4899
                  > "Things should be made as simple as possible, but not more so."
                  > A. Einstein
                  >
                  >
                  >
                  > Yahoo! Groups Links
                  >
                  >
                  >
                  >

                  --
                  Mike Manes mrmanes@... Tel: 303-979-4899
                  "Things should be made as simple as possible, but not more so."
                  A. Einstein
                • Mike Manes
                  EOSS had the same problem when our 426.25 ATV xmtr shared the same enclosure as the GPS. Problem solved when we put em in separate packages separated by
                  Message 8 of 19 , Jan 22, 2008
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                    EOSS had the same problem when our 426.25 ATV xmtr shared the same
                    enclosure as the GPS. Problem solved when we put 'em in separate
                    packages separated by 10-15 ft of payload line. Steve KC0YA proved
                    that we could put GPS-derived data on the ATV downlink overlay using
                    a 900 MHz Zigbee link between the payloads - but 433 Mhz Zigbee went
                    belly up when the ATV was QRV, even 10 ft away.

                    We think the GPS QRM is 3rd harmonic or simple front end desense.

                    73 de Mike W5VSI

                    Joe wrote:
                    >
                    > saxdru wrote:
                    >
                    >> The GPS 18 LVC (OEM) has worked flawlessly out here in Maryland (we
                    >> have ~4 of them).
                    >>
                    >>
                    >>
                    > But, this all depends on the payload use. We here at NSS learned this
                    > the hard way last fall. This unit does NOT like 439.25 ATV signals. We
                    > found this out from others after the flight also.
                    >
                    > Ralph? how about a sub catagory of the GPS list, that gives flight
                    > results. like i know we have the list of what ones work above "X"
                    > altitude. but maybe a list of what ones don't like certain modes or
                    > freqs. and or power levels etc?
                    >
                    > Joe
                    >
                    >
                    >
                    > Yahoo! Groups Links
                    >
                    >
                    >
                    >

                    --
                    Mike Manes mrmanes@... Tel: 303-979-4899
                    "Things should be made as simple as possible, but not more so."
                    A. Einstein
                  • Mike Manes
                    Fortunately, ATV QRM to GPS can generally be evaluated on the deck by looking at the NMEA strings that show signal quality. Compare that data with ATV on and
                    Message 9 of 19 , Jan 22, 2008
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                      Fortunately, ATV QRM to GPS can generally be evaluated on the deck
                      by looking at the NMEA strings that show signal quality. Compare that
                      data with ATV on and off, in a reasonable replica of the flight config,
                      of course.

                      73 de Mike W5VSI

                      Mark Conner wrote:
                      > While anecdotal, I think there seems to be enough evidence that the GPS-18 is more touchy than 'usual' about RFI. I agree that for many units where boards, antennas, etc., may vary, it'd be too hard to track all the permutations. But for integral units like the all-in-one mice and handheld units, it'd be a worthwhile footnote to caution the operator to fully investigate RFI issues where they've been reported on multiple occasions.
                      >
                      > I didn't realize until reading the last few posts that the GPS-18 also suffered from problems due to UHF ATV transmissions. That paralleled my experience with degraded performance in proximity to a digital camera. I now have mine relegated to the backup payload in a somewhat more benign RF environment (appears infrequent 2m transmissions don't upset it). I'll definitely keep the UHF ATV experiences in mind with this unit. Probably would not be good to pair it with a 70cm simplex repeater anymore.
                      >
                      > 73 de Mark N9XTN
                      >
                      > ----- Original Message -----
                      > From: Joe <nss@...>
                      > Date: Tuesday, January 22, 2008 9:55 am
                      > Subject: Re: [GPSL] Re: request for advice: GPS units for ARHAB
                      > To: GPSL@yahoogroups.com
                      >
                      >>
                      >> Ralph Wallio, W0RPK wrote:
                      >>
                      >>> Joe -- This would be interesting information but it is anecdotal
                      >> in nature, very time consuming to
                      >>> collect and very difficult if not impossible to maintain in a
                      >> complete balanced view.
                      >> I can understand that.
                      >>
                      >
                      >
                      >
                      > Yahoo! Groups Links
                      >
                      >
                      >
                      >

                      --
                      Mike Manes mrmanes@... Tel: 303-979-4899
                      "Things should be made as simple as possible, but not more so."
                      A. Einstein
                    • Mike Manes
                      Mike Who? 73 de Mike W5VSI, EOSS ... -- Mike Manes mrmanes@gmail.com Tel: 303-979-4899 Things should be made as simple as possible, but not more so.
                      Message 10 of 19 , Jan 22, 2008
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                        Mike Who?
                        73 de Mike W5VSI, EOSS

                        Hank wrote:
                        >> A good quality GPS antenna with filtering really helps. The $10
                        >> Chi-Com specials are pretty poor.
                        >
                        > This whole thread about GPS performance is a real good one.
                        >
                        > Mike,
                        >
                        > Could you provide some context and specifics about the above
                        > two observations, please?
                        >
                        > Anecdotes, whether this was something you or someone you know
                        > experienced, whether it was on board a balloon, stuff like that.
                        >
                        > Hank
                        >
                        >
                        >
                        >
                        > Yahoo! Groups Links
                        >
                        >
                        >
                        >

                        --
                        Mike Manes mrmanes@... Tel: 303-979-4899
                        "Things should be made as simple as possible, but not more so."
                        A. Einstein
                      • Dan Wietchy
                        If you folks are interested in testing GPS performance in cold weather, let me know. I live in Fairbanks Alaska where the winter temperatures commonly go to
                        Message 11 of 19 , Jan 22, 2008
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                          If you folks are interested in testing GPS performance in cold weather, let me know. I live in Fairbanks Alaska where the winter temperatures commonly go to minus 40 below (-40F). I can open my front door and set a GPS down on my deck and monitor "real time" performance. Ditto for all kinds of battery life too. I can tell you exactly how something behaves during a 100K balloon flight while keeping both feet on the ground.

                          Dan

                          Mike Manes <mrmanes@...> wrote:
                          Mike Who?
                          73 de Mike W5VSI, EOSS

                          Hank wrote:
                          >> A good quality GPS antenna with filtering really helps. The $10
                          >> Chi-Com specials are pretty poor.
                          >
                          > This whole thread about GPS performance is a real good one.
                          >
                          > Mike,
                          >
                          > Could you provide some context and specifics about the above
                          > two observations, please?
                          >
                          > Anecdotes, whether this was something you or someone you know
                          > experienced, whether it was on board a balloon, stuff like that.
                          >
                          > Hank
                          >
                          >
                          >
                          >
                          > Yahoo! Groups Links
                          >
                          >
                          >
                          >

                          --
                          Mike Manes mrmanes@gmail. com Tel: 303-979-4899
                          "Things should be made as simple as possible, but not more so."
                          A. Einstein


                          Looking for last minute shopping deals? Find them fast with Yahoo! Search.

                        • Mike Manes
                          Dry ice (solid CO2) can get stuff down to -80C inside a beer cooler with a lot lower shipping cost. Thanks for offering, Dan, and keep your socks on! 73 de
                          Message 12 of 19 , Jan 22, 2008
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                            Dry ice (solid CO2) can get stuff down to -80C inside a beer cooler with
                            a lot lower shipping cost. Thanks for offering, Dan, and keep your socks
                            on!

                            73 de Mike W5VSI, EOSS

                            Dan Wietchy wrote:
                            > If you folks are interested in testing GPS performance in cold weather,
                            > let me know. I live in Fairbanks Alaska where the winter temperatures
                            > commonly go to minus 40 below (-40F). I can open my front door and set a
                            > GPS down on my deck and monitor "real time" performance. Ditto for all
                            > kinds of battery life too. I can tell you exactly how something behaves
                            > during a 100K balloon flight while keeping both feet on the ground.
                            >
                            > Dan
                            >
                            > */Mike Manes <mrmanes@...>/* wrote:
                            >
                            > Mike Who?
                            > 73 de Mike W5VSI, EOSS
                            >
                            > Hank wrote:
                            > >> A good quality GPS antenna with filtering really helps. The $10
                            > >> Chi-Com specials are pretty poor.
                            > >
                            > > This whole thread about GPS performance is a real good one.
                            > >
                            > > Mike,
                            > >
                            > > Could you provide some context and specifics about the above
                            > > two observations, please?
                            > >
                            > > Anecdotes, whether this was something you or someone you know
                            > > experienced, whether it was on board a balloon, stuff like that.
                            > >
                            > > Hank
                            > >
                            > >
                            > >
                            > >
                            > > Yahoo! Groups Links
                            > >
                            > >
                            > >
                            > >
                            >
                            > --
                            > Mike Manes mrmanes@... <mailto:mrmanes%40gmail.com> Tel:
                            > 303-979-4899
                            > "Things should be made as simple as possible, but not more so."
                            > A. Einstein
                            >
                            >
                            > ------------------------------------------------------------------------
                            > Looking for last minute shopping deals? Find them fast with Yahoo!
                            > Search.
                            > <http://us.rd.yahoo.com/evt=51734/*http://tools.search.yahoo.com/newsearch/category.php?category=shopping>
                            >

                            --
                            Mike Manes mrmanes@... Tel: 303-979-4899
                            "Things should be made as simple as possible, but not more so."
                            A. Einstein
                          • saxdru
                            We have never used ATV so I can not speak to the issues on 70cm. We have however used it in close proximity to 2m (APRS), 900 MHz, and 2.4 GHz signals along
                            Message 13 of 19 , Jan 24, 2008
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                              We have never used ATV so I can not speak to the issues on 70cm. We
                              have however used it in close proximity to 2m (APRS), 900 MHz, and 2.4
                              GHz signals along with some modern metal shelled cameras without issues.

                              -Dru KB3MRQ

                              --- In GPSL@yahoogroups.com, "saxdru" <dru@...> wrote:
                              >
                              > The GPS 18 LVC (OEM) has worked flawlessly out here in Maryland (we
                              > have ~4 of them). I'm sure its obvious, but cut most of the wiring
                              > off as it weighs about as much as the unit itself (Garmin will still
                              > RMA if you cut the wires).
                              >
                              > It seems to preform better than the other units we have tried as far
                              > as acquisition time, so it may be possible to turn it on for 3 min
                              > twice an hour and either sleep or unpower it for the other 90% of the
                              > flight. We have not used it in this capacity, but have a 15-20 hour
                              > flight this summer we are working towards.
                              >
                              > Also, it works great on 3 L91 lithium AA batteries.
                              >
                              > -Dru Ellsberry KB3MRQ
                              > MdSGC/BPP
                              >
                              > --- In GPSL@yahoogroups.com, "K. Mark Caviezel" <kmcaviezel@> wrote:
                              > >
                              > > All:
                              > > I haven't kept up with what the ARHAB state of the art
                              > > for airborne GPS units is. What units are being used
                              > > now days? Factors of merit: low power consumption,
                              > > cheap, lightweight, works at ARHAB altitudes,
                              > > integrated antenna.
                              > > I'm considering getting some Garmin 18LVCs which at
                              > > 5V/0.060A, $60, about 2 oz seems like a real contender
                              > > but I know that unit has been on the market for
                              > > several years now, maybe there is something better out
                              > > there. Notionally, I'm thinking about flights in the
                              > > 2-5 day range, so power consumption is a bigger driver
                              > > in this application than short duration sounding
                              > > balloon flights.
                              > >
                              > > Your detailed suggestions are welcome.
                              > >
                              > > - Mark ng0x
                              > >
                              >
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