Author: SM0TGU

Som ni kan lsa nedan ppnas AO-51 fr trafik idag den 30:e juli. Det som kommer att testas r FM-repeatern.

AO-51 (AMSAT-Echo) will be turned on for general use in FM repeat mode on 30 July 2004 at about 0215 UTC. This will be for a trial period of about three weeks during which the command stations will be watching the power budget and adjusting the UHF transmitter B power as needed for good management of the battery. Initially, the transmitter will be running at about 1W. If power allows, it will be slowly increased during the trial period. We will also be adjusting settings on the satellite, so if the signal changes slightly from time to time, do not be alarmed. The TXB transmitter will be on 435.300 MHz, which is also a trial frequency. The original frequency of 435.225 MHz is now in regular use by GO-32, so the alternate is being tested to see if it can be used long term.

To work Echo in this mode you need the following information: Uplink: 145.920 MHz FM voice with 67 Hz PL. Downlink: 435.300 MHz FM voice. The downlink transmitter will come on when it hears an uplink signal with a 67 Hz PL tone for about 1 second. It stays on for 10 seconds after that signal goes away.

This operation is just like a terrestrial FM repeater with a 1 second kerchunk filter and a 10 second hang time.

The command stations will be watching the AMSAT-BB email reflector for report of how Echo is working. Please post your results there. We are most interested in hearing about how well Echo hears you and how well you hear it.

Note that Echo is still wobbling a great deal and the polarization sense of the downlink will vary. The B UHF TX is nominally RHCP in the northern hemisphere but this will change over the duration of a pass due to wobble and orientation relative to the ground station.

Transmitter A will generally continue to operate on 435.150 but may be at reduced power at times, or may be at about 1W only when the command stations are gathering Whole Orbit Data (WOD) telemetry. We will be analyzing the WOD for information about how much TX B is on and how the power system is behaving. Please note that the digital transponder and the store and forward BBS, are NOT yet open for general use. TX A may also switch to 38k4 from time to time to facilitate downloading large files.

We expect Echo will be heavily used in these first few days. Many stations will be trying to make a contact through Echo. It is good amateur practice and common courtesy to let everyone have a chance. Echo will hear you as well as or better than any previous amateur FM repeater satellite. With the downlink transmitter at 1W you will need a small directional antenna to hear it. Especially in these first few days, always listen first. Even though the downlink will only come on when it hears an uplink signal, with hundreds of stations trying it out we expect the transmitter to be on continuously when over populated areas. So again, listen first, and be courteous to let everyone have a chance at making a contact via AO-51.

And a reminder, this is a trial period of the FM voice repeat function. The digital portion of Echo is NOT yet open for use.

Echo Command Team Jim White, WD0E Mike Kingery, KE4AZN

Klla: ANS

The command team continues to work and test Echo. At the present time they are testing the satellite s software on the ground in preparation for general amateur use. The team continues reloading and testing software on the satellite. Telemetry data is also being collected when Echo is in the sun, to work on attitude determination.

The satellite has been in a low power mode while software is loaded. The 435.150 MHz downlink is being used for this task. There are a few more tests to complete before the satellite is opened up for use by the general amateur community. This step will not signify the completion of
commissioning by any means, but it has always been the goal of the command team to insure that the satellite s hardware is working properly first, and then open the satellite for everyone to use.

Much more work and testing is yet to be done. The command team, at various times, following general use, will disable the current operating mode to compete the necessary tests. This will occur without prior warning. When we begin this phase, please consider the satellite in experimental operation mode.

At the present time it is anticipated that Echo will be opened initially in 9k6 digital mode, via the BBS system. After running a few days in that mode the FM repeater may be enabled. All modes will start at low power and gather data while looking at the overall health of the satellite, – specifically the power consumption in each configuration. As the command team gains knowledge they will gradually increase the power, and again watch the data.

The command team asks at the present time, that you continue to NOT transmit to Echo. Your patience in that regard up to this point has been appreciated. When Echo is ready, a BBS message will be posted on the Satellite, as they have tried to do from time to time to inform the 9k6 digital group what is happening with commissioning. Also a bulletin through ANS and on the AMSAT website will be issued. So, please continue to show restraint and you will
be making your first contacts through Echo soon.

[ANS thanks Mike, KE4AZN for the above information]

Klla: ANS

Senaste nytt frn ANS om Echo. Nu brjar ven S-sndaren at testas:

Some stations have noted the S testing and reported results, which is appreciated by the command team. The command team has been watching the temperature closely when the S Tx is on. Since it is only about 30 percent
efficient a lot of power must be dissipated in the transmitter and its enclosure. So far the temperature rise, while quite noticeable, has not been a problem.

AO-51 continues to spin and tumble at a relatively rapid rate. In one axis it s about 15 seconds per rev. While these rates are high they are not a problem for the satellite. They do create some fades on the downlink that
will go away once the tumble is damped out. Because of the high rates it is likely to take a while for that stable mode to be achieved. The torq rod has also not yet oriented the satellite to the earth s magnetic field.

A new section of the telemetry archive will be open soon with whole orbit data that has been collected by the command stations. Some of it is at a rate of 3 seconds between samples. That high sample rate data is what has
been being used to determine the spin and attitude. Once on-line that section of the site will be available for anyone to download archived telemetry.
http://coloradosatellite.com/echo

Approximately 2500 launch campaign pictures are now available for browsing on the web thanks to Chuck Green, N0ADI. The pictures can be viewed at
http://bach.as.arizona.edu/gallery/echo

There has been some speculation about modes for future experimenter Wednesday. While AO-51 is a very flexible and capable spacecraft, it is still too early to determine exactly what the final operational parameters will be on Wednesdays or during normal operations.

Klla: ANS 199

Senaste nytt om Echo AO-51:

The remainder of this week is expected to be spent loading some new code, testing the S downlink and the UHF B TX. Note that the S downlink when in digital mode will always be at 38k4 or higher. It is not capable of 9k6 due to limitations involved in making it work properly at speeds up to 76k8. We are pleased so far with the strength of the 2.45W S downlink. At times the UHF A TX (.150) will be off or at very low power. We will also be testing
transmitters at higher data rates. Listeners should not be surprised or alarmed if the UHF A TX is not on or if they are unable to copy it at 9k6 during some orbits.

The Command Team is carefully checking off the tests and measurements that are part of the commissioning process. They ask everyone to be patient and again, AO-51 is not yet open for use. Any transmissions aimed at AO-51 by
other than command stations will slow down the process and delay the day when it is open for all to use.

The coloradosatellite.com/echo web site was off line for a few hours Sunday and Monday due to a data center move. Stations wishing to upload telemetry should find it on line now.

[ANS thanks Jim, WD0E for the above information]

Klla: ANS 195

Nu heter AMSAT Echo AMSAT-OSCAR-51, AO-51:
—
AMSAT-NA President Robin Haighton, VE3FRH has asked me to handle issuance of OSCAR numbers, and has written me requesting an OSCAR number for the Echo satellite. Therefore, in response to his communication, I hereby issue Echo the number AMSAT-OSCAR-51 (AO-51) to this exciting new amateur radio spacecraft. Thus, AO-51 joins a long line of amateur radio satellites beginning with OSCAR-1 launched in December, 1961.

I wish to congratulate everyone involved in the design, construction, testing, preparing for launch, launching and commissioning of this latest Amateur Radio spacecraft.

I trust that amateurs all over the world will have an opportunity to avail themselves of the many features offered by AO-51. May AO-51 have a long and productive life.

Best wishes and 73,
William (Bill) Tynan, W3XO

Klla: ANS

Mycket fakta om Echo AO-51 i denna notis. Fortfarande gller, snd ej till satelliten:

On the 06 July 2004, during the 0310 UTC pass, the SQRX was set to a VHF frequency and the antenna relay switched to the VHF whip. Once the various modulator/switch functions where set to the right configuration the SQRX
audio path proved to work fine. In an additional test of the SQRX the receiver was retuned to an L-band frequency and connected to the L-band antenna on the bottom of AO-51.

Testing has also been done on S-band using a frequency of 2401.200 MHz. The second 70cm transmitter has also been tested as well as the ability to command frequency changes to the transmitters should that be needed in the future. All transmitters have been confirmed to be operational.

Friday, 09 July 2004 the 38k4 digital downlink was enabled for the first time on the UHF A transmitter. Mike was able to copy packets at 38k4. Further testing will be done, and some WOD data will be downloaded at 38k4. The modulator settings for that mode will need to be tweaked as testing continues.

Mike, KE4AZN has taken some WOD data at 3 second intervals during daylight passes over his station to get a better look at the satellite s attitude. That data is being analyzed. When AO-51 is not in view of the command
stations, WOD at 30 second intervals is gathered continuously during the period from the time last time they see the satellite after a group of passes until their next AOS.

The EDAC count in Echo is not counting the actual number of physical memory errors, but the number of times the software detects a memory error while it is running. If the software loops through that section of memory a number
of times before the error is cleared, the EDAC count will increase by a large value. There is a routine that runs on a specific time interval to wash memory and clear any errors. Until that routine runs, if the program loops through that memory area, it will count an EDAC error.

With the file system now running, the downlink is going to show the BBS is open even though the BBS has NOT been made available for general use. Everyone is requested to please not transmit to ECHO until checkout and commissioning has been completed. Unexpected uplinks may cause delays in
verifying the proper operation of ECHO and delay the opening of the transponders to general use.

The commissioning and checkout activities are going very well. During this checkout period activities and plans are very dynamic and frequent mode and transmitter changes should be expected.

[ANS thanks Jim, WD0E and Mike, KE4AZN for the above information]

Klla: ANS 193