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Ham Satellite news

Aktuellt schema för AO-51

Fljande schema gller numera fr Echo under resten av september och hela oktober:
—-
Update 27 Sept — Schedule and Info

Echo Schedule for October listed below.

FM Repeat and 9k6 BBS Open — 27 Sept thru 28 Sept

FM repeat mode OPEN
Uplink 145.920 FM with 67 hz tone
Downlink 435.300 FM

FM 9k6 BBS mode OPEN for user activity, uploading of messages and small to
moderate filesize pictures is OK
FM 9k6 BBS mode OPEN
Uplink 145.860 FM 9k6 digital, PBP
Downlink 435.150 FM 9k6 digital, PBP

Experimenters Wednesday for 29 September

PSK31 Test (Round 2)

Uplink: 28.140 USB PSK31 ONLY
Downlink: 435.300 FM, 1 watt output

October 2004 AO-51 (Amsat Echo) Schedule
Updated 27 Sep 2004

Sep 30
FM Repeater, V/U, High Power Mode ON
9k6 Digital, V/U, PBP BBS OFF, TXA OFF

Oct 6 Experimenters Wednesday
38k4 Digital Downlink, V/U, PBP BBS OPEN for Users
FM Repeater OFF, TXB OFF

Oct 7
FM Repeater, V/U, ON
9k6 Digital, V/U, PBP BBS, OPEN for Users

Oct 13 Experimenters Wednesday
No Mode Change Scheduled, Continue current Mode

Oct 14
FM Repeater, V/U, ON
9k6 Digital, V/U, PBP BBS, OPEN for Users

Oct 20 Experimenters Wednesday
FM Repeater, L/U, ON, Output Power TBD
9k6 Digital, V/U, PBP BBS OFF, TXA OFF

Oct 21
FM Repeater, L/S, ON
9k6 Digital, V/U, PBP BBS OFF, TXA OFF

Oct 27 Experimenters Wednesday
TBD, Check back later for Planned Mode

Klla: AMSAT-NA

Categories
Ham Satellite news

38k4-tester på AO-51

Nu p onsdag 22/9 krs 38k4-tester p AO-51 enligt nedanstende:

Experimenters Wednesday for 22 September

Start: 22 Sep at 0145 utc
End: 23 Sep at 0245 utc

38k4 BBS mode. We will open the BBS up for user testing with the 38k4 downlink. The uplink will be at 9k6.

Uplink: 145.860 FM, 9k6 Digital, Pacsat Broadcast Protocol (PBP)
Downlink: 435.150 FM, 38k4 Digital, PBP, 1 watt output

Klla: AMSAT-NA

Categories
Ham Satellite news

AO-40 baninfo

Peter Guelzow, DB2OS, reports that Victor Kudielka, OE1VKW did an analysis some weeks ago and was the first to discover some odd changes in the Mean Motion of AO-40.

It appears that the eccentricity may have changed, but it is also influenced by other effects and can not be used alone to evaluate possible changes in AO-40 s orbit. Viktor has some expanded diagrams of mean motion and eccentricity, as well as for the heights of peri- and apogee and their velocities on his home page:
http://cacofonix.nt.tuwien.ac.at/~oe1vkw/ao40/2004.html

Viktor noted, I am unable to judge which points are just imprecise measurements and what are the influences of data smoothing or other manipulations. The only big enough effect is the change in mean motion Peter continues, If you look carefully on the data, you will see that the orbit change already happened *before* the sudden battery event. We can only speculate, that it is the battery. It could be indeed also some remaining fuel? Peter added. The thrust phase is also much longer than the battery event, not only a few hours or days. Perhaps,could be smoothing/manipulation of the NORAD data too. There is room for a lot of speculation.

Peter concluded, Assuming the S/C mass to be 400kg, than this change is due to an impulse of 40 kg m/s or equal to 5 minutes of hot Arcjet firing.I have no idea if the battery is capable to do this. Indeed, if it is shortened it will get glowing hot and vent everything.

[ANS thanks Peter, DB2OS for the above information]

Klla: ANS

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Ham Satellite news

AO-51 Echo update

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

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Ham Satellite news

Senaste schema för Echo AO-51

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

Categories
Ham Satellite news

AO-51 Operation Notes

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