[aprssig] PCSAT2 Downlink Challenge
Phillip B. Pacier
ad6nh at arrl.net
Sat Jul 30 12:53:25 EDT 2005
Whatever you end up with, send your PCSat2 9600 telemetry to
satgate.aprsca.net:20150
73
Phil - AD6NH
Robert Bruninga wrote:
>Unattended 9600 baud fixed antenna data capture:
>
>There are many variables at work here for optimizing data
>capture unattended from weak satellite signal. Remember
>with global APRS-Intenret links, the only thing that counts
>will be the SUM of everyone's efforts, so not any one station
>needs to get all data. In fact, a single fixed antenna and
>because of doppler, it is impossible to get all data without
>changing direction of beam or doppler. But we can each
>optimize our fixed station to make our best contribution.
>Even if only one pass a day.. There are many variables.
>
>1) Weakest signal near horizon must have beam
>2) But least doppler change is at horizon
>2) Strongest signal above 30 deg, but maximum doppler change
>3) 19" whip is excellent gain at 435 (7 dBi) but only for >30 deg
>4) But high doppler (over 8 KHz in 2 minutes) >30 deg
>5) Your latitude determines if most passes are north, south
> and your area might favor east or west.
>6) Also you might live on east coast or west coast. If on east
>coast, you should have fixed antenna to favor passes to east
>that no one else will hear, on west coast, favor to the west.
>
>Best combination will be different for everyone. Or, everyone
>just gets a small part on an OMNI and APRS network puts
>it all together into good total... hummh...
>
>
>
>>>>aprssig at ei7ig.org 07/30/05 7:01 AM >>>
>>>>
>>>>
>>1) You need to replace the antennas!
>>
>>
>No rotators here unfortunately, so a 19" Whip it will have to be
>then. Though from reading and re-reading Bob's post, and knowing
>that these stations will be un-manned should we just leave the rigs
>on the downlink frequency and hope to receive with little or no
>doppler at the centre of the pass, or should we tune/scan between the
>frequencies most likely at the beginning/end of the pass?
>
>
>>2) For work at 9600, you must tap the receive signal off the
>>radio's discriminator output
>>
>>
>
>Ok, I'll try the linux soundmodem interface again later... I think I
>hung the soundcard driver trying 9k6 last night, i have the cables
>already made up to interface to the FT-847.
>
>I did a bit of playing with the TH-D7 this morning and i have it
>running under Linux in Kiss mode. Though I've come across a few web
>pages that seem to suggest that its very unreliable at 9K6 in kiss
>mode. Has anyone had any experience of this? bearing in mind we are
>only trying to catch a few packets of data would this suffice for a
>9K6 downlink?
>
>I've got the machine time synced using ntp and this should give me
>the correct output, listen -t -p 70cm | tee PC2_$(date +%y%m%d_%H%M)
>_EI7IG.txt
>
>
>
>>3) The TS2000 appears,
>>
>>
>>
>So for the EI8JA's TS-2000, kiss mode and add 19" Whip, AGW (which he
>has) and AGW monitor. Excellent, one hopefulle sorted.
>
>
>
>>If you have a PC with sufficient "horsepower" (approximately
>>Pentium II 300 or higher) and a soundcard with a stereo line input,
>>the AGW PE softmodem can be configured to act as TWO TNCs, one on
>>the left channel and one on the right channel, emulating something
>>like a Kantronics 9612 dual-port.. You could set one to 1200 baud
>>connected to one radio via the speaker output, and one to 9K6
>>connected to the other radio via the discriminator output. Note
>>that you MUST have a line-level input to get the stereo input; the
>>mic input (often the ONLY input on laptops) is single-channel
>>(MONO) and can't use this feature of AGW PE.
>>
>>
>
>Thats a very interesting idea, I'll put that to John, as he could
>then use both rigs one on the 'big vertical' and one on the 19" Whip,
>
>Thanks for the reply.
>
>Regards
>de John
>EI7IG
>
>
>
>_______________________________________________
>aprssig mailing list
>aprssig at lists.tapr.org
>https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
>
>
>_______________________________________________
>aprssig mailing list
>aprssig at lists.tapr.org
>https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
>
>
>
>
More information about the aprssig
mailing list