[amsat-bb] Re: AO-73 Deaf again ????

Paul Stoetzer n8hm at arrl.net
Thu Mar 13 19:03:44 PDT 2014


Peter,

One other thing to keep in mind is that the satellite is out of
eclipse during the last 2-4 minutes of each evening pass at your
latitude now, so the transponder will switch off as it passes to the
north. This period will grow longer and longer as we move towards the
northern summer solstice.

This shows you how much transponder time you have on your evening
passes tomorrow night:

14.03.2014 E 19:09:00  81.3   0.6    156.0    677   3007   39  49   1551   -
14.03.2014 E 19:10:00  73.8   2.5    158.6    676   2783   38  52   1551   -
14.03.2014 E 19:11:00  65.0   4.1    161.3    675   2608   36  56   1551   -
14.03.2014   19:12:00  55.1   5.3    163.9    673   2494   34  59   1551   -
14.03.2014   19:13:00  44.6   5.7    166.5    672   2451   32  63   1551   -
14.03.2014   19:14:00  34.0   5.3    169.1    670   2482   29  66   1551   -
14.03.2014   19:15:00  23.9   4.2    171.8    668   2585   25  70   1551   -
14.03.2014   19:16:00  15.0   2.5    174.4    666   2751   20  73   1551   -
14.03.2014   19:17:00   7.2   0.6    177.0    664   2969   12  76   1551   -

14.03.2014 E 20:42:00 134.8   1.4    144.3    680   2907   20  32
1552   -
14.03.2014 E 20:43:00 131.4   5.1    146.9    680   2522   19  36
1552   -
14.03.2014 E 20:44:00 126.7   9.5    149.6    679   2151   18  40
1552   -
14.03.2014 E 20:45:00 119.9  14.8    152.2    678   1804   17  43
1552   -
14.03.2014 E 20:46:00 109.3  21.0    154.8    677   1499   15  47
1552   -
14.03.2014 E 20:47:00  92.8  27.5    157.5    676   1270   14  50
1552   -
14.03.2014 E 20:48:00  69.1  31.4    160.1    675   1163   13  54
1552   -
14.03.2014 E 20:49:00  43.7  29.4    162.7    674   1211   11  58
1552   -
14.03.2014   20:50:00  24.4  23.4    165.3    672   1400    9  61   1552   -
14.03.2014   20:51:00  12.0  16.8    168.0    671   1681    6  65   1552   -
14.03.2014   20:52:00   4.0  11.1    170.6    669   2016    3  68   1552   -
14.03.2014   20:53:00 358.7   6.4    173.2    667   2381  358  71
1552   -
14.03.2014   20:54:00 354.9   2.4    175.8    665   2762  352  75
1552   -

14.03.2014 E 22:18:00 185.9   0.9    140.5    681   2965  357  27
1553   -
14.03.2014 E 22:19:00 188.7   4.6    143.1    680   2573  356  31
1553   -
14.03.2014 E 22:20:00 192.5   9.0    145.8    680   2190  355  34
1553   -
14.03.2014 E 22:21:00 198.0  14.5    148.4    679   1823  354  38
1553   -
14.03.2014 E 22:22:00 206.5  21.4    151.0    678   1486  353  41
1553   -
14.03.2014 E 22:23:00 220.8  29.8    153.6    678   1206  352  45
1553   -
14.03.2014 E 22:24:00 245.3  37.5    156.3    677   1034  350  49
1553   -
14.03.2014 E 22:25:00 277.8  37.9    158.9    676   1024  349  52
1553   -
14.03.2014 E 22:26:00 303.4  30.6    161.5    674   1181  347  56
1553   -
14.03.2014   22:27:00 318.6  22.0    164.2    673   1452  345  59
1553   -
14.03.2014   22:28:00 327.6  14.9    166.8    672   1784  343  63
1553   -
14.03.2014   22:29:00 333.3   9.3    169.4    670   2149  340  66
1553   -
14.03.2014   22:30:00 337.3   4.7    172.0    668   2530  336  70
1553   -
14.03.2014   22:31:00 340.3   1.0    174.7    666   2921  331  73
1553   -

14.03.2014 E 23:59:00 252.1   1.4    149.8    679   2904  329  40
1554   -

The most obvious cause of deafness is certainly alligators though. The
satellite appears to be functioning fine. The FUNcube Handbook says
that the AGC range of the transponder is 43 dB. Perhaps someone more
knowledgeable about how transponders operate can put into perspective
how that translates in real-life usage.

73,

Paul, N8HM

On Thu, Mar 13, 2014 at 7:02 PM, Patrick STODDARD (WD9EWK/VA7EWK)
<amsat-bb at wd9ewk.net> wrote:
> Paul,
>
> I had replied directly to Peter earlier today, and we have had a nice
> exchange discussing what he reported and what I saw on passes last
> night.  I can expand on what I saw last night on two AO-73 passes...
>
> The pass you referenced was a 58-degree western pass around 0535 UTC.
> Unfortunately, I was the only one on the transponder (as W1AW/7), so
> I did more tests with my transmitter power.  I was able to cut my power
> down from 5W to 500mW and still hear myself loudly and clearly through
> the transponder.  And it was nice outside (around 68F/20C at 10.35pm
> local time).  The 145.935 MHz telemetry downlink sounded loud, but I
> did not copy it with the software (my laptop was not out with me).
>
> At 0401 UTC, an eastern pass with maximum elevation of 11 degrees
> where I lose the first 3 or 4 degrees in that direction due to mountains,
> I had a hard time getting through in the first couple of minutes.  I
> heard a QSO on the transponder, and one station was very loud.  I was
> able to finally hear myself at the center of the transponder, and make
> one QSO (as W1AW/7) with CO6CBF.  I didn't move around to find the other
> station, so my only QSO on that pass was with Hector.
>
> For both passes, I used a pair of FT-817NDs, transmitting at 5W to my
> Elk handheld 2m/70cm log periodic (except for part of the western pass
> where I cut my power to 500mW).
>
> The suggestion of trying VO-52 in particular is a good one.  If the
> setup works for VO-52, it should do fine with AO-73.  I'll be on at
> least one AO-73 pass this evening as W1AW/7 (0423 UTC, maximum
> elevation 19 degrees), and - if anyone will be up for the later pass -
> I will stick around for the 0559 UTC pass (maximum elevation 33
> degrees).  Or maybe I will swap antennas on the later pass, going with
> something other than the log periodic...
>
> 73!
>
>
>
>
> Patrick WD9EWK/VA7EWK
> http://www.wd9ewk.net/
>
>
>
>
> On Thu, Mar 13, 2014 at 3:20 PM, Paul Stoetzer <n8hm at arrl.net> wrote:
>
>> Peter,
>>
>> Not any evidence from Europe, but WD9EWK reported good downlink
>> signals from AO-73 on a westerly pass from his QTH in Arizona while
>> running just 500 mW to an Elk antenna last night.
>>
>> The AAR29 AO-73 log page also reports several QSOs from Europe today:
>> http://aar29.free.fr/sat/ao73/ao73log.php
>>
>> Have you checked VO-52 and AO-7 Mode B passes to rule out a problem on
>> your end?
>>
>> 73,
>>
>> Paul Stoetzer, N8HM
>> Washington, DC
>>
>>
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