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VR5000 for AO40?




Is anyone out there using the Yaesu VR5000 for receiving
AO40's downlink direct or with a downconverter?

If so, can you compare it to the reciever on an FT847/TS2000 style
transceiver?

Thanks,

Jon

Computing Center			Internet: jneher@darkwing.uoregon.edu
University of Oregon		        WWW http://darkwing.uoregon.edu/~jneher
Eugene, OR 97403-1212			Amateur Radio: N7WNX
Voice: (541) 747-5782
Fax: (541) 346-4397

On Wed, 31 Oct 2001, Bob Bruninga wrote:

> PCsat GPS Success!
>
> Background:  PCsat is in a phase of worst case eclipses (35 mins)
> (you can see it plotted on a link on http://www.ew.usna.edu/pcsat)
> so we cannot turn on the GPS for more than a 10 minute pass at a time.
> And we also have the 9600 baud UHF receivers off also to save power.
>
> On with the story:
> On today's GPS test pass, we got a late start and since the process in
> lower-power ops these days requires a four separate logon/logoff
> sequence to enable UHF receivers, then enable GPS, then Command GPS,
> then UHF and GPS off, we were only able to have the GPS on for about 3
> minutes or  less.  We had difficulty getting logged on for the final step
> to make sure the GPS and UHF receivers were both off...
>
> But in the last second, we did get the GPS-OFF command transmitted
> (though not confirmed).  The data file we captured was small, but we
> edited it up and sent it to the GPS engineers anyway..  The objective for
> the next and final pass of the day was to make certain UHF and GPS was
> off. (We now only get the later 3 passes during working hours.  The other
> three are between midnight and 4 AM).
>
> Good news, PCsat came over the horizon with both off, so we had been
> successful in getting everything off in time.  And as we sat there, the
> phone rang.  It was Sunny Leung from DLR in Germany.  He was excited,
> because the data we had sent him only an hour earlier confirmed that PCsat
> had AQUIRED 11 satellites and had a GPS FIX and good signal strengths up
> to 16 (the best we had on the ground after the goop disaster).
>
> In the three 1-per-30 second data packets we sent them, the first showed
> no lock, but the second showed 11 satellites and the final one showed
> all 12 channels in lock!
>
> Can't wait to tomorrow.
>
> We have developed an improvd procedure for the next GPS test orbit cycle:
> 1) The pass before, we will turn on the UHF 9600 baud receiver.
> 2) DUring the GPS pass, we only have to command on, then off the GPS
> 3) During the final pass we will turn off the UHF receiver.
>
> This reduces the logon process to only one process per pass, maybe 2,
> instead of 4.  THus greatly extending the time we can let the GPS be on
> and still have a margin of safety at the end.
>
> Here is the position data we received in XYZ coordinates:
> PCsat header & GPS time:     PCSAT-12>APRS,SGATE:F401138313275.0000013
> XYZ Coordinates:             +2873638.13 -5441977.29 +3687550.30
> XYZ Velocity:                +4193.65050 -1649.51147 -5694.28574
> GPS Mode (3D)                2
> Sats in Lock:                11
> PDOP:                        1.2
> Checksum:                    64
>
> WHile the GPS is on, you may hear some $GPGGA sentences from W3ADO-1 on
> the 145.825 while over Annapolis (one pass a day).  The reason this GPS
> commanding is not easy is because all of its engienering data comes down
> at 9600 baud on 144.39 over the command station and we have as much of a
> hard time hearing the data as anyone else listening to all the local QRM
> on 144.39...
>
> When we get back to full sun for 2 weeks in January, we may be able to
> leave the GPS on for full orbits at least twice a day...
>
> But anyway, this is the first lock we have gotten from the GPS, and mostly
> because this is only the second orbit when we have tried in a month since
> launch to upload a new set of keps to the GPS engine...
>
> Bob
>
>
>
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