Author: SM0TGU

Lite nyheter om Echo AO-51, bla. dags fr PSK-tester:

The Mode L/S Experimenters Wednesday was a success. Reports from a number of amateur stations indicate that good signals were copied from the S Band transmitter. The data from Echo shows that the satellite worked fine and there was enough power to sustain Echo through Eclipse.

Until next Experimenters Wednesday we plan to run Echo with the FM repeater ON and the BBS OFF. During this time, command stations will work on the satellites solar panel power output.

Next Experimenters Wednesday, 8 September, we plan to run a PSK31 test. The satellite will be configured to receive on 28.140 mhz (10 meters) in USB mode and transmit on 435.300 mhz in FM mode. Only PSK31 mode may be operated during this test. I personally am not setup for this mode, so I would appreciate reports of how well (or not well) this mode worked sent to the amsat-bb.

You can check:

http://www.amsat.org/amsat-new/echo/

for the most up to date scheduling for Echo. I will post any changes to the schedule on this Web page. If the 435.150 mhz transmitter is ON then status info is sent in the PBP Broadcast message as well.

[ANS thanks the Echo Command Team for the above info]

AO-51 hemsida

Klla:

The following is the planned schedule for the next week and a half on AO-51. Please remember, we are still it an experimental/checkout phase of the satellite. Events like the software reload last weekend will happen from time to time. The schedule is subject to change. All times are
approximate.

25 Aug 0200 UTC to 26 Aug 0300 UTC
Experimenters Wednesday – Mode V/S FM Repeater Test.
S Band TX (2401.200) will be turned ON in FM voice mode, continuous transmission. The 145.920 VHF receiver (RX3) will be set to FM voice mode. No 67 hz Tone will be required during this test.

As this will be the first time the S Band transmitter has been allowed to run for an extended period, the WOD will be checked after the first pass. If all is well mode V/S will continue for the rest of Experimenters Wednesday.

Digial TXA (435.150) will be OFF except to download data over Command Station. FM TXB (435.300) will be OFF.

At the conclusion of Exp Wed normal FM repeater mode on TXB will return. After completing the download of data from the S Band test the BBS will be opened for an extended window of user operation. This will be at the current low power level of TXA. During this time AO-51 will be active in both FM repeat (145.920 FM up, 67 hz tone / 435.300 FM down at 0.60 watts) and 9k6 BBS (145.860 FM up / 435.150 down FM down at 0.40 watts) for the first time. Please check the Broadcast message on Echo, for a notice when the BBS is open.

26 Aug 0300 UTC
Digital TXA 9k6 BBS Closed
FM TXB repeater mode Active (at conclusion of Exp Wed)

26 Aug 0500 UTC to 31 Aug 0000 UTC
Digital TXA 9k6 BBS OPEN (Low Power Output)
FM TXB repeater mode Active

During this time the Command Team would again appreciate any telemetry capture and download to the website that they can get. If you are active on the BBS please take a couple of minutes to get a few Telemetry records during your pass.

Klla: ANS

AMSAT News Service Bulletin 214.08 From AMSAT HQ
SILVER SPRING, MD. Aug 2, 2004
To All RADIO AMATEURS
BID: $ANS-214.08

The 67 Hz PL tone must be transmitted continuously for a station to be heard through the FM repeater.

Unlike previous similar satellites the Echo PL tone decoder both turns on the downlink transmitter and gates the audio path. The tone must be present on a signal for the audio to get through. If a signal without a tone captures the receiver no audio will get through the decoder chip and the satellite will be transmitting a
signal without modulation. If that condition persists for 10 seconds the transmitter will go off until it again hears a signal with PL.

Multiple uplink signals can mix and cause no clear PL tone to be present at the decoder. During this time no audio is being repeated. What has been reported as a dead carrier is usually a result of this condition. It s not a carrier with no modulation on the uplink, but no valid PL on the
uplink because of mixing, resulting in no audio passing through the satellite. May we again note this is just like a terrestrial FM PL controlled repeater?

The PL decoder chip easily detects PL tone of 1 Khz deviation and is quite forgiving. It is neither necessary or desirable to increase the deviation of the PL tone you transmit above the nominal values. It will not work any better.

It is possible to turn off the PL function. But there is no COR (carrier operated relay) in the satellite. So without the PL function to control when the transmitter is on it would have to be on all the time. In the first few orbits in this mode, the B transmitter has been on about half the time. If it was on all the time it would have to be operated at a lower power level. There is only so much DC power available in the satellite and it is a zero sum game one orbit at a time. One of the major advantages
of the PL control mode is it keeps the transmitter off when not in use and therefore allows it to be at higher power when in use. Of course another is the satellite will not re-transmit signals not intended for it. It is
not possible for the PL tone to turn on the transmitter but not gate the audio.

We are watching the power usage closely and considering how to modify the software to allow higher transmitter powers when adequate DC power is available, and not pull the battery down to far for Echo to make it through the next eclipse, and not go to deep into the battery capacity,
etc. This three week (aprox.) trial period is for the purpose of measuring these performance parameters (and of course having some fun with this cool bird).

The trial move of the voice downlink frequency to 435.300 MHz does not limit Echo in any way or change the number of options available for various modes. All three Echo transmitters are frequency agile in their bands. 435.225 MHz was initially chosen and coordinated with the IARU on
the assumption GO-32 was not active. The reactivation of that satellite required Echo to move. 435.300 MHz was suggested by the IARU frequency coordination group. If feedback from users around the world indicates this is a usable frequency we will complete the coordination process and continue to use it.

The power level of the B transmitter on 435.300 MHz has been at about .5 Watts for a couple of days now. This is as high as we can go in the current mode without over stressing the batteries near the end of eclipse.

There is no beep generator in Echo so it is not possible to send a courtesy tone type beep when a valid PL goes away. We put the idea of sending a short 9k6 digital packet from time to time on the voice downlink on our todo list. It would have to interrupt any voice repeat going on at the time for about half a second due to the switching that it would entail, but at first glance seems doable.

There is nothing wrong with the sensitivity of the uplink receiver. In fact if anything it is too sensitive. In any event it cannot be changed. There is nothing about the orientation that is causing a reduction of sensitivity on the uplink. The uplink antenna is for all practical purposes omni-directional.

Jim White, WD0E

Klla: ANS

Portable PREDICT Plus r en portabel variant av programmet Predict. Portable PREDICT Plus innehller alla program man behver fr att spra satelliter och kra digital trafik, ryms p tv disketter, bootar upp p disketterna och kr en minimal variant av Linux.

Ls mer:

Announcing the release of Portable PREDICT Plus, a miniature distribution of Linux that includes several ham radio and OSCAR satellite communication applications.

Portable PREDICT Plus boots from a pair of floppy disks and runs entirely in RAM. There s no need to download huge CDROM images, install Linux, compile code, configure a kernel, or re-partition your hard disk to run this software. A third data disk is used to save configuration and home directory files, and can be used to import Keplerian orbital data into the system during setup.

Portable PREDICT Plus includes PREDICT, PB/PG, FODtrack, PacsatTools, MoonTracker, minicom, setserial, and a small collection of AX.25 applications and utilities including kisson, kissoff, kissattach, kissparms, listen, mheard, call, and beacon. There s even a program included to play audio CDs. 🙂

Portable PREDICT Plus is based on a Linux kernel version 2.6.7, and supports a total of eight virtual consoles , providing multiple login sessions that take full advantage of the multitasking and co-operative nature of the operating system and many of the included applications.

Portable PREDICT Plus is capable of supporting moonbounce, analog and digital (Pacsat) satellite operations (including the new ECHO satellite), satellite and terrestrial packet radio communications (including ISS operations), as well as the generation of APRS-style beacons. Portable PREDICT Plus supports KISS and 6pack mode terminal node controllers, and runs on 32-bit PCs from 386s on up.

Portable PREDICT Plus is available in two forms: One that builds the disk sets under Linux, and another that builds the disks under a DOS/Windows environment. The DOS/Windows version contains some extra tutorial information to assist those new to a Linux computing environment.

Downloads are about 3 megabytes, and are available as follows:

Linux version: http://www.amsat.org/amsat/ftp/software/Linux/ppplus-0.90.tar.gz

DOS/Windows version: http://www.amsat.org/amsat/ftp/software/PC/tracking/pplus090.zip

Portable PREDICT Plus was created by John A. Magliacane, KD2BD, and is released under the GNU General Public License. Additional information is available at: http://www.qsl.net/kd2bd/predict.html

[ANS thanks John, KD2BD for the above information]

Predict hemsida

Klla:

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