Just tried to work through AO-73 (22:00) - managed to hear myself briefly, but way off the normal uplink frequency, I had to tune 11Khz higher than normal, then signal suddenly disappeared?
Did anyone else experience this?
Any ideas?
Peter
G8KEK
Hi Peter,
The AO-73 transponder shuts off as soon as it sees sunlight. That is why your signal suddenly disappeared.
Here is a readout from WinListen of the pass you were working:
29.04.2014 E 21:34:45 161.5 0.5 244.5 595 2818 6 29 2231 - 29.04.2014 E 21:35:00 161.5 1.3 245.2 595 2712 6 30 2231 - 29.04.2014 E 21:35:15 161.4 2.2 245.8 595 2607 6 31 2231 - 29.04.2014 E 21:35:30 161.4 3.2 246.5 595 2502 6 32 2231 - 29.04.2014 E 21:35:45 161.3 4.3 247.1 595 2397 5 33 2231 - 29.04.2014 E 21:36:00 161.3 5.4 247.8 595 2292 5 34 2231 - 29.04.2014 E 21:36:15 161.2 6.6 248.5 595 2188 5 35 2231 - 29.04.2014 E 21:36:30 161.1 7.9 249.1 595 2083 5 36 2231 - 29.04.2014 E 21:36:45 161.0 9.3 249.8 595 1980 4 37 2231 - 29.04.2014 E 21:37:00 160.9 10.7 250.4 595 1876 4 38 2231 - 29.04.2014 E 21:37:15 160.8 12.3 251.1 596 1773 4 39 2231 - 29.04.2014 E 21:37:30 160.7 14.1 251.7 596 1671 4 40 2231 - 29.04.2014 E 21:37:45 160.5 16.0 252.4 596 1569 3 40 2231 - 29.04.2014 E 21:38:00 160.3 18.1 253.1 596 1469 3 41 2231 - 29.04.2014 E 21:38:15 160.1 20.4 253.7 596 1370 3 42 2231 - 29.04.2014 E 21:38:30 159.8 23.1 254.4 597 1272 2 43 2231 - 29.04.2014 E 21:38:45 159.4 26.0 255.0 597 1177 2 44 2231 - 29.04.2014 21:39:00 158.9 29.5 255.7 597 1084 2 45 2231 - 29.04.2014 21:39:15 158.3 33.4 0.3 597 995 2 46 2232 - 29.04.2014 21:39:30 157.4 38.0 1.0 598 910 1 47 2232 - 29.04.2014 21:39:45 156.3 43.5 1.7 598 831 1 48 2232 - 29.04.2014 21:40:00 154.5 49.9 2.3 598 760 1 49 2232 - 29.04.2014 21:40:15 151.7 57.3 3.0 599 699 0 50 2232 - 29.04.2014 21:40:30 146.5 65.9 3.6 599 651 360 51 2232 - 29.04.2014 21:40:45 134.1 75.0 4.3 599 619 359 52 2232 - 29.04.2014 21:41:00 90.7 82.1 4.9 600 605 359 52 2232 - 29.04.2014 21:41:15 25.3 78.6 5.6 600 611 359 53 2232 - 29.04.2014 21:41:30 5.4 69.7 6.3 601 637 358 54 2232 - 29.04.2014 21:41:45 358.2 60.8 6.9 601 679 358 55 2232 - 29.04.2014 21:42:00 354.6 53.0 7.6 601 736 357 56 2232 - 29.04.2014 21:42:15 352.6 46.2 8.2 602 803 357 57 2232 - 29.04.2014 21:42:30 351.2 40.4 8.9 602 880 356 58 2232 - 29.04.2014 21:42:45 350.3 35.5 9.5 603 962 356 59 2232 - 29.04.2014 21:43:00 349.6 31.3 10.2 603 1050 355 60 2232 - 29.04.2014 21:43:15 349.0 27.7 10.9 603 1141 355 61 2232 - 29.04.2014 21:43:30 348.6 24.6 11.5 604 1236 354 61 2232 - 29.04.2014 21:43:45 348.3 21.8 12.2 604 1332 353 62 2232 - 29.04.2014 21:44:00 348.0 19.4 12.8 605 1431 353 63 2232 - 29.04.2014 21:44:15 347.8 17.2 13.5 605 1530 352 64 2232 - 29.04.2014 21:44:30 347.6 15.2 14.1 606 1631 351 65 2232 - 29.04.2014 21:44:45 347.5 13.4 14.8 606 1733 351 66 2232 - 29.04.2014 21:45:00 347.4 11.8 15.5 607 1836 350 67 2232 - 29.04.2014 21:45:15 347.3 10.2 16.1 607 1939 349 68 2232 - 29.04.2014 21:45:30 347.2 8.8 16.8 608 2042 348 69 2232 - 29.04.2014 21:45:45 347.1 7.5 17.4 608 2146 347 69 2232 - 29.04.2014 21:46:00 347.1 6.3 18.1 609 2251 346 70 2232 - 29.04.2014 21:46:15 347.1 5.1 18.7 609 2355 344 71 2232 - 29.04.2014 21:46:30 347.0 4.0 19.4 610 2460 343 72 2232 - 29.04.2014 21:46:45 347.0 3.0 20.1 610 2565 342 73 2232 - 29.04.2014 21:47:00 347.0 2.1 20.7 611 2670 340 74 2232 - 29.04.2014 21:47:15 347.0 1.2 21.4 611 2775 338 74 2232 - 29.04.2014 21:47:30 347.0 0.3 22.0 612 2879 337 75 2232 -
If there isn't an 'E' to the left of the time, the satellite is in the sunlight. As you can see, the satellite is into the sunlight nearly nine minutes before your LOS, so you only have a brief period to work through the transponder.
As far as the frequency instability, it's just a quirk of the satellite.
From what PA3WEG, the designer of the transponder, has stated, PLL
frequency generation was not possible within the power budget of a 1U CubeSat when the transponder was designed.
See: http://amsat.org/pipermail/amsat-bb/2013-December/047815.html
73,
Paul, N8HM
On Wed, Apr 30, 2014 at 6:10 PM, Peter Wilson [email protected]wrote:
Just tried to work through AO-73 (22:00) - managed to hear myself briefly, but way off the normal uplink frequency, I had to tune 11Khz higher than normal, then signal suddenly disappeared?
Did anyone else experience this?
Any ideas?
Peter
G8KEK
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Paul,
Many thanks for the detailed response - all understood.
It's easy to forget that at that altitude the sun comes into line of sight.
Peter
G8KEK
From: [email protected] [mailto:[email protected]] On Behalf Of Paul Stoetzer Sent: 01 May 2014 01:05 To: Peter Wilson Cc: AMSAT -BB Subject: Re: [amsat-bb] AO-73 over UK
Hi Peter,
The AO-73 transponder shuts off as soon as it sees sunlight. That is why your signal suddenly disappeared.
Here is a readout from WinListen of the pass you were working:
29.04.2014 E 21:34:45 161.5 0.5 244.5 595 2818 6 29 2231 -
29.04.2014 E 21:35:00 161.5 1.3 245.2 595 2712 6 30 2231 -
29.04.2014 E 21:35:15 161.4 2.2 245.8 595 2607 6 31 2231 -
29.04.2014 E 21:35:30 161.4 3.2 246.5 595 2502 6 32 2231 -
29.04.2014 E 21:35:45 161.3 4.3 247.1 595 2397 5 33 2231 -
29.04.2014 E 21:36:00 161.3 5.4 247.8 595 2292 5 34 2231 -
29.04.2014 E 21:36:15 161.2 6.6 248.5 595 2188 5 35 2231 -
29.04.2014 E 21:36:30 161.1 7.9 249.1 595 2083 5 36 2231 -
29.04.2014 E 21:36:45 161.0 9.3 249.8 595 1980 4 37 2231 -
29.04.2014 E 21:37:00 160.9 10.7 250.4 595 1876 4 38 2231 -
29.04.2014 E 21:37:15 160.8 12.3 251.1 596 1773 4 39 2231 -
29.04.2014 E 21:37:30 160.7 14.1 251.7 596 1671 4 40 2231 -
29.04.2014 E 21:37:45 160.5 16.0 252.4 596 1569 3 40 2231 -
29.04.2014 E 21:38:00 160.3 18.1 253.1 596 1469 3 41 2231 -
29.04.2014 E 21:38:15 160.1 20.4 253.7 596 1370 3 42 2231 -
29.04.2014 E 21:38:30 159.8 23.1 254.4 597 1272 2 43 2231 -
29.04.2014 E 21:38:45 159.4 26.0 255.0 597 1177 2 44 2231 -
29.04.2014 21:39:00 158.9 29.5 255.7 597 1084 2 45 2231 -
29.04.2014 21:39:15 158.3 33.4 0.3 597 995 2 46 2232 -
29.04.2014 21:39:30 157.4 38.0 1.0 598 910 1 47 2232 -
29.04.2014 21:39:45 156.3 43.5 1.7 598 831 1 48 2232 -
29.04.2014 21:40:00 154.5 49.9 2.3 598 760 1 49 2232 -
29.04.2014 21:40:15 151.7 57.3 3.0 599 699 0 50 2232 -
29.04.2014 21:40:30 146.5 65.9 3.6 599 651 360 51 2232 -
29.04.2014 21:40:45 134.1 75.0 4.3 599 619 359 52 2232 -
29.04.2014 21:41:00 90.7 82.1 4.9 600 605 359 52 2232 -
29.04.2014 21:41:15 25.3 78.6 5.6 600 611 359 53 2232 -
29.04.2014 21:41:30 5.4 69.7 6.3 601 637 358 54 2232 -
29.04.2014 21:41:45 358.2 60.8 6.9 601 679 358 55 2232 -
29.04.2014 21:42:00 354.6 53.0 7.6 601 736 357 56 2232 -
29.04.2014 21:42:15 352.6 46.2 8.2 602 803 357 57 2232 -
29.04.2014 21:42:30 351.2 40.4 8.9 602 880 356 58 2232 -
29.04.2014 21:42:45 350.3 35.5 9.5 603 962 356 59 2232 -
29.04.2014 21:43:00 349.6 31.3 10.2 603 1050 355 60 2232 -
29.04.2014 21:43:15 349.0 27.7 10.9 603 1141 355 61 2232 -
29.04.2014 21:43:30 348.6 24.6 11.5 604 1236 354 61 2232 -
29.04.2014 21:43:45 348.3 21.8 12.2 604 1332 353 62 2232 -
29.04.2014 21:44:00 348.0 19.4 12.8 605 1431 353 63 2232 -
29.04.2014 21:44:15 347.8 17.2 13.5 605 1530 352 64 2232 -
29.04.2014 21:44:30 347.6 15.2 14.1 606 1631 351 65 2232 -
29.04.2014 21:44:45 347.5 13.4 14.8 606 1733 351 66 2232 -
29.04.2014 21:45:00 347.4 11.8 15.5 607 1836 350 67 2232 -
29.04.2014 21:45:15 347.3 10.2 16.1 607 1939 349 68 2232 -
29.04.2014 21:45:30 347.2 8.8 16.8 608 2042 348 69 2232 -
29.04.2014 21:45:45 347.1 7.5 17.4 608 2146 347 69 2232 -
29.04.2014 21:46:00 347.1 6.3 18.1 609 2251 346 70 2232 -
29.04.2014 21:46:15 347.1 5.1 18.7 609 2355 344 71 2232 -
29.04.2014 21:46:30 347.0 4.0 19.4 610 2460 343 72 2232 -
29.04.2014 21:46:45 347.0 3.0 20.1 610 2565 342 73 2232 -
29.04.2014 21:47:00 347.0 2.1 20.7 611 2670 340 74 2232 -
29.04.2014 21:47:15 347.0 1.2 21.4 611 2775 338 74 2232 -
29.04.2014 21:47:30 347.0 0.3 22.0 612 2879 337 75 2232 -
If there isn't an 'E' to the left of the time, the satellite is in the sunlight. As you can see, the satellite is into the sunlight nearly nine minutes before your LOS, so you only have a brief period to work through the transponder.
As far as the frequency instability, it's just a quirk of the satellite. >From what PA3WEG, the designer of the transponder, has stated, PLL frequency generation was not possible within the power budget of a 1U CubeSat when the transponder was designed.
See: http://amsat.org/pipermail/amsat-bb/2013-December/047815.html
73,
Paul, N8HM
On Wed, Apr 30, 2014 at 6:10 PM, Peter Wilson <[email protected] mailto:[email protected] > wrote:
Just tried to work through AO-73 (22:00) - managed to hear myself briefly, but way off the normal uplink frequency, I had to tune 11Khz higher than normal, then signal suddenly disappeared?
Did anyone else experience this?
Any ideas?
Peter
G8KEK
_______________________________________________ Sent via [email protected] mailto:[email protected] . Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (2)
-
Paul Stoetzer -
Peter Wilson