Real Telemetry plots from AO-27 are present so users that don't have telemetry receiving equipment can get an idea of some of the technical aspects of the satellite. The Schedule for transmitter operation (The TOPR States) table is updated when we make changes to the programming on-board the satellite.
We ask that you only send pertinent questions to the control operators. If we receive too much e-mail we will not be able to respond to the real questions that users have. We can not tell you when the satellite will be on for a given location. Please try to find the information you need before e-mailing us. Thank you.
We need your help in logging TLM from AO27. Visit the Logging AO-27 Telemetry page for directions in getting started.
The Image on the left is AO-27 on the ASAP ring just before launch. The picture on the right is AO-27 suspended in the clean room in final launch configuration.
Current Time UTC => Wed May 14 13:45:25 2008
Schedule Time => 00:51:58
Current State => 7
Mode => OFF
Remaining => 00:48:50
Next Event UTC => Wed May 14 14:34:15 2008
State => 0
Mode => Digital Med
TOPR Epoch (UTC) = Sat Mar 8 06:07:03 2008
TOPR Epoch (ctime) = 1204956423
Schedule Period (sec) = 6048.670
State Start Time End Time Duration(sec) Mode
--------------------------------------------------------
0 00:00:00 00:00:20 20 Digital Med
1 00:00:20 00:07:20 420 Analogue Med
2 00:07:20 00:08:20 60 Digital Med
3 00:08:20 00:32:01 1421 OFF
4 00:32:01 00:33:01 60 OFF
5 00:33:01 00:33:21 20 OFF
6 00:33:21 00:33:41 20 OFF
7 00:33:41 01:40:48 4027 OFF
OFF = Transmitters are turned off
Analogue Low = 145.850MHz Uplink <==> 10mW 436.797MHz Downlink Analogue Med = 145.850MHz Uplink <==> 500mW 436.797MHz Downlink Analogue High = 145.850MHz Uplink <==> 4W 436.797MHz Downlink
Digital Low = NO Uplink ==> 10mW 436.797MHz AFSK Downlink Digital Med = NO Uplink ==> 500mW 436.797MHz AFSK Downlink Digital High = NO Uplink ==> 4W 436.797MHz AFSK Downlink
As soon as we have finished checking out the bird we should have the Analogue repeater back on the air. Please keep in mind that AO-27 is 13 years old and takes some work to keep it going.
- Michael N3UC
We have successfully reset the cpu on AO-27.
AO-27 is now commanable and is sitting at the bootloader. We are
beginning the process of uploading flight software. The transmitter was
very strong during our tests. This is very good news.
Data From 2004/Aug/10
Data From 2002/May/15 10:36:32 UTC
Until 2002/May/15 12:18:42 UTC
Data From 2002/May/11 10:50:02 UTC
Until 2002/May/11 12:34:12 UTC
On July 1st, 2007 during the 20:00 UTC pass over North America, AO-27 was again providing a new round of enjoyment for Amateur satellite experimenters. Thirteen years ago, AO-27, which coined the term "Easy Sat" by employing an FM bent pipe in space, provided many hams the ability to use a satellite without the expense of multi mode radios.
This time around, AO-27 was used to provide the first D-Star via Satellite contact between Michael, N3UC, FM-18 in Haymarket VA and Robin, AA4RC, EM-73 in Atlanta GA. Signals were reported as strong and easy to copy. Call signs were received digitally on both sides of the link. Communications were possible for most of the pass. Both Robin and Michael were surprised at just how well the digital link was received.
The Analogue repeater on-board AO-27 is well suited for D-Star work. The radios were designed to pass 1200-19200 baud GMSK data. The Analogue mode was not a primary mode of operation in the design. Using a free switch setting in the switching board, the design team hooked up the output of the receiver to the input the transmitter to create the Analogue mode. There is not the normal low frequency filtering that is found in normal FM Repeaters. This means the Analogue mode passes the low frequencies required by D-Star.
The equipment for the contact were IC-2200s on the Uplink at both N3UC and AA4RC, an IC-2820 on the downlink at N3UC, and an IC-91AD on the downlink at AA4RC. Doppler shift did prove to be a minor problem while using these radios. The D-Star signal would decode out to about 1.5 KHz in frequency error. The IC-2820 would only tune on 5 KHz spacing (the 6.25 KHz channels did not fall in the right locations to help.) so at times we could not decode the digital signals.
For others that want to try D-Star via Satellite we have a few things to keep in mind.
1) Remember that the FM users can't hear you on the bird.
They hear a strong "noise" but can't decode you. So please keep the D-Star transmitting short.
If you can monitor the FM side, you can time your transmitting as to not step on them.
Please try to schedule with other D-Star users instead of calling CQ for the entire pass.
2) Watch the doppler, at times you may not be able to decode a signal even if the other station can decode you.
Keep your uplink on 145.850 for the entire pass. Program your radio call signs the same as for simplex, AO-27
does not have a D-Star call sign. You don't need to set up your radio for repeater use.
3) Before using other satellites besides AO-27, please check with the control operators of those satellites. Every
FM satellite may not pass the D-Star signal nor may the control operators wish to have D-Star traffic on the bird.
4) If you hear us on the Bird, please give us a call. We would love to have as many D-Star users on AO-27 as possible.
The AO-27 Control Operators fully support and encourage the use of D-Star via Satellite on AO-27.
