The Home of AO-27 on the Web

ASAPHangingWelcome to the AO-27 Web site. This page contains the most up-to-date information on AO-27 that can be found. It is updated by the control operators who run the satellite.

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 AO-27 Status: Primary Bootloader

We have received a lot of e-mails about donations so we decided to add the following info:

  AO-27 Control Operators Assoc: 
 BTC: 12hd5EATm7Uy4WP2s7WGH9hRw3n6utGonn

-- NEWS --

Aug 1, 2015
Turned on low power during first pass. Had good tone, received a few TLM frames but then lost commanding of it as it came over the US. Seems to have major interference on uplink while over the US.
It faded mid pass and was not heard from for the rest of the pass. Sent off commands in the blind. Don't know if the TX turned off or not.
The good news is it was at least heard from after last weekend's problems.
- Michael, N3UC

July 26, 2015
Tried to turn on during both of the passes this morning. Nothing Heard. - Michael, N3UC

July 25, 2015
AO-27 Turned on today. Seems good on the bootloader
First pass went fine. Second pass while over the US we had major interference. Could not turn the TX off and it went over the horizon with the TX on High.
- Michael, N3UC
- Dan, KM4HZJ

June 28, 2015
AO-27 Turned on today. Seems good on the bootloader
If anyone has contacts into CelesTrak to get AO-27 back into the amateur.txt file it would help some of the control operators stations.
Our e-mails have gone unanswered.
- Michael, N3UC
- Dan, KM4HZJ
- James, N3UCC

April 18, 2015
AO-27 Turned on today. Uploaded Secondary boot loader
- Michael, N3UC

April 12, 2015
Turned on High power to check power output. Looks good.
- Michael, N3UC

Sept 23, 2014
AO-27 Turns 21 today. The controll team is in the process of writing a new BIOS and OS for the satellite.
- Michael, N3UC

June 14, 2014
Turn on to checkout Boot Loader. EveryThing is looking good for the next upload attempt.
- Michael, N3UC

March 31, 2014
Moved the website to another provider. Work is continuing on a new method to correct the hardware communications on the bird.
- Michael, N3UC

Dec 8, 2013
Finished uploading EOS 120 with fixes for RX Telemetry errors. Did not correct the problem. Seems outgoing packets are not being sent down after the first few.
EOS-120 locked up and to reset.
Download some debug blocks to try to understand what happened.

- Michael, N3UC

Dec 7, 2013
During the over head pass in the morning we uploaded the secondary bootloader and the Kernel.
During the upcoming passes we will be sending the first set of high level code that may contain a fix for the problems we have been seeing on the bird.

-Michael, N3UC

Nov 30th, 2013
First Morning pass uploaded 2/3 of EOS.
First Afternoon pass uploaded remainder of EOS.
Second Afternoon pass, Executed EOS. Locked up during first TLM cycle.
Recovered back to Primary bootloader.
Cleared Modem Tone Problem.
Downloaded DEBUG info from EOS.

-Michael, N3UC

Nov 29th, 2013
Uploaded Kernel during two afternoon passes.

- Michael, N3UC

Nov 17th, 2013
Turned on. Good tones
Turned on. Good tones. Uploaded 2k test file using secondary bootloader. Uploading went very well.
Turned on. Good tones. Low pass so only turned on then back off.
- Michael, N3UC

Nov 16th, 2013
Turned on on low power and tried to upload to it. It heard us but did not send anything we could decode.
Turned off ok.
Turned on on low power. Upload test worked great. Very little interference. Great Pass.
Turned off ok.
- James N3UCC

Nov 11th, 2013
Turned on High Power for the pass to try a software upload.
Uploaded code using the secondary bootloader. Went slow but made it. The interference is still a problem on the uplink.
STATUS: on Secondary bootloader, Software upload test complete.
- James, N3UCC

Nov 10th, 2013
Another good pair of passes gave a clean upload of the secondary bootloader.
Commanded back to the Primary. Modem came up with up without IDLE tones. Had to clear the modem lockup again.
Uploaded secondary. Changed to the secondary cleanly.
We still have heavy interference on the uplink.
- James, N3UCC

Nov 9th, 2013
Pass 2:
Heavy interference on the uplink.
Cleared modem lockup
Uploaded secondary bootloader
Executed secondary bootloader
STATUS: secondary bootloader, modem tone good (IDLE flags OK)

Pass 1:
The bird turned on first try and sounds good. Several commands went well. Not bad a a low pass. Next pass we will try to recover the modem from its lockup condition. This is a normal issue we deal with every time we recover the satellite so we expect it will go ok.
STATUS: primary bootloader, modem at single tone (no IDLE flags), commandable.
- James, N3UCC and Michael, N3UC

Oct 29th, 2013
Recovery operations are underway again for AO-27. We will try to keep the website up to date with any information.
- Michael, N3UC

Sept 23rd, 2013
Happy 20th birthday to AO-27.

Jan 6th, 2013
We are in the process of repairing the ground station and writing new code for the bird. It will still be several months before we know if it is possible to recover, we don't know yet.
We can command it just fine, we just can't run high level code until we find out why it keeps crashing. We will have news when there is some to report but right now there is just a lot of work going on behind the scenes.
- Michael, N3UC

Oct, 21th, Pass 5
EOS 118 ran for a few seconds before locking up. We were able to reset it back to the bootloader. Dumps indicate it is locking up while fetching telemetry from the hardware.
It does not look like there will be a quick resolution to this crash.
We will keep you posted.
- James, N3UCC and Michael, N3UC

Oct, 21th
The Kernal is uploaded. A new version of EOS is uploading. This version has more debug info in it to help us find out why it keeps crashing.
- Michael, N3UC

Oct, 18th
We tried to do a restart of the high level code today which did not work out. We left the transmitter on to drain the batteries in hopes of clearing any latch ups.
On the next pass, we could turn the bird back on so it survived the battery draining. The modem problem was back and we got that cleared.
Its back up on the secondary bootloader.
- Michael, N3UC

Oct 17, 2012 Pass 3
We have cleared the AFSK Modem problem again and are up on the secondary bootloader.
- Michael, N3UC

Oct 16, 2012 Pass 2
AO-27 has crashed again. Its back at the bootloader.

Oct 15, 2012
The command team has finished uploading the high level code to AO-27. EOS is now running and we are checking out the bird. The TOPR schedule will be on digital for the entire pass until we collect enough telemetry and finish the on-orbit checkout.
- Michael, N3UC

Oct 14, 2012
The AFSK modem problem has come back. After Working the night passes the last few nights we have recovered from that problem.
AO-27 is running on its secondary bootloader, this is the one we can upload high level code with.
We had a great commanding night and begun to upload the kernel today.
We can report than the entire kernel is now uploaded. EOS uploading will start next pass.
- Michael, N3UC and James N3UCC

Oct 12, 2012
The command team finished downloading memory from the bird and has begun uploading of the secondary bootloader.
- Dustin, KB3FNF

Oct 8, 2012
We continue to download segments of the memory from the bird looking for clues as to what happened.
Commanding is going slow due to interference. Please, if you can't hear the bird in Analogue mode, please don't transmit to it.
- Michael, N3UC

Oct 6, 2012
AO-27 is running on the primary Bootloader. Control operators were able to turn on the Transmitter for a short time.
We are working on the problem.
- James, N3UCC

Oct 5, 2012
It seems AO-27 is off-line.
- Michael, N3UC

Aug 11, 2012 UTC
Congratulations to James, KJ4KII for passing his General class and his new call sign, N3UCC.

Jul 04, 2012 UTC
Uploaded a new Schedule.

Dec 26, 2011 UTC
The website RAID drive was repaired and the website is back up.

Dec 2011 UTC
Uploaded a new Schedule

May 28, 2011 UTC
Uploaded a new Schedule

Feb 5th, 2011 UTC
Uploaded a new Schedule.

Dec 19th, 2010 UTC
James, KJ4KII uploaded a new Schedule.

Aug 28th, 2010 UTC
New Schedule Uploaded.

May 30th, 2010 UTC
New schedule uploaded.
Thanks N1AIA for the contact from Maine.
- Michael, N3UC

November 29th, 2009 UTC
New schedule uploaded.

Sept 14th, 2009 UTC
New schedule uploaded.

Aug 26th, 2009 UTC
New schedule uploaded.

May 15th, 2009 UTC
Happy Birthday to James, KJ4KII.
Thanks to Keith, W5IU for the Contact from Dayton Hamvention.
- Michael, N3UC

May 14th, 2009 UTC
We have uploaded a new schedule and it should now be correct.
Thanks to Jeff WB3JFS for letting us know it was so far off.
Thanks to KB1RVT on a handheld for the analogue check today. Great signal.

Mar 22nd, 2009 UTC
Thanks to our new control operator KJ4KII for updating the time and schedule on the bird. We have extended the data times to collect more information on the batteries and hope to use this added time for Analogue mode soon.
If you hear Jimmy, KJ4KII on the bird please give him a call. At seven years old, we believe he is the youngest Amateur Satellite Control Operator.
He would love to receive a QSL card from you.

Mar 6th, 2009 UTC
AO-27 is back to normal Analogue operation. The ground station automatically uploaded the new schedule at 12:35:21 Eastern time today.
The website files are also updated and should match the bird.

Mar 1st, 2009 UTC
Telemetry is looking good. During several passes over the US the control team turned on the Analogue Repeater. It was good to hear so many familiar calls on the bird.
This week we will continue the data download schedule to collect as much whole orbit data to check on the health of the batteries.
So far, it is looking like AO-27 will return to normal operations on or around March 7th.
Thanks goes out to Geoff, KJ4JWL for finishing the EOS configuration on Saturday.

Feb 28th, 2009 UTC
After several more attempts, the control team has managed to upload the high level software (EOS) to AO-27. We will spend the next week collecting data to check on the batteries and conduct an on-orbit-checkout before returning to analogue mode.

Dec 19th, 2008 UTC
Control team members continue to drain the batteries in the hopes of resetting the locked up modem. The bird has rebooted into the primary bootloader.

Oct 5th, 2008 UTC
After a bunch of work, AO-27 is now running on its secondary bootloader.
The batteries will take a while to recharge to the point where we can upload the high level software.

Sept 23rd, 2008 UTC
We are working on it.

Historic News

Listing of Satellite Events

Check the 24hr Listing for a list of the upcoming events.


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


-- Source for TOPR Listings --

Here is the source that is used to generate the schedules on this page.

The input files are Ephoc.txt and TOPR.txt.

These files are updated here when the schedule changes.

These programs were compiled under GNU C++ 2.95 on Linux. Their output is HTML used for the website but could be changed very easily.

Have a look at a great windows version of the Lister by Christopher Henry.
Updated by George Henry, KA3HSW
AO-27 Satellite Scheduler Please read the directions on his site, this program requires the Java Runtime to be installed.


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

TEPR States are no longer a valid method of Transmitter schedule for AO-27.
Chuck Wyrick, N1UC, provides an Explanation of TEPR States

AO-27 Control Operators Assoc. D-Star Repeaters

The AO-27 Control Operators Assoc. has put two D-Star repeaters in Haymarket, VA. (N 38 55, W 77 39)
Frequencies are:
N4USI Port C -> 145.45-


AO-27 does D-Star

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.

A shout goes out to ICOM for creating Radios for this Fun new Amateur mode of operation. Without their radios we could not have made this contact.

- Michael
AO-27 Control Operator

Screen shot of software running at AA4RC showing received D-Star call signs.

Image of IC-2820 at N3UC showing received D-Star call sign.
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