AMSAT-OSCAR 40 (Phase-3D) 2001/5
bearbeitet von Frank Sperber, DL6DBN/AA9KJ
AMSAT-DL Journal

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AO-40 Update

ALON/ALAT waren am 10. Juni 300/-15, das Magnetorquing Richtung 270/0 geht weiter.

G6LVB beschreibt den Umbau eines 60 cm Offest-Spiegels für den S-Band- Downlink unter www.g6lvb.com/60cm.htm . Der Artikel ist allerdings in Englisch.

Nach einem Programmieraufruf von RUDAK-Kommandostation Jim White gibt es nun drei verschiedene Programme zur Konvertierung von RUDAK-WOD unter www.amsat.org/amsat/ftpdelta.html zum Download. RudakTLM für Windows, WOD2CSV unter DOS und eine Java- Version. Die Daten müssen nach der Umwandlung noch mit einer Tabellenkalkulation zur Anzeige gebracht werden. Eine Beispieldatei kann hier heruntergeladen werden: www.coloradosatellite.com/P3D/RUDAKIntro.html .

ALON/ALAT 300/-15 (June 10th) still moving to 270/0

G6LVB describes how to use an offset-dish for S-downlink, see www.g6lvb.com/60cm.htm .

Three programs to convert RUDAK-Whole-Orbit-Data are available at www.amsat.org/amsat/ftpdelta.html .
They are named RudakTLM (Win), WOD2CSV (DOS) and a program for Java
A sample file of RUDAK WOD is available at www.coloradosatellite.com/P3D/RUDAKIntro.html .

DL6DBN , 11.06.2001

S2-Linkberechnung

 Gene Marcus, W3PM/GM4YRE, hat eine Tabellenkalkulation erstellt, mit der die Leistung der eigenen S2-Downlinkausrüstung berechnet werden kann. Außerdem wird angezeigt, welche QSO-Signale vom S2-Transpondersender damit erwartet werden können. Durch Spielen mit den Werten für Rauschzahl, Verstärkung und Kabeldämpfung der einzelnen Stufen lässt sich schnell nachweisen, wie durch geringe Rauschzahlen und hohe Verstärkung an der Antenne die Signale verbessert werden können. Unten sind die Ergebnisse einer S-Band Station mit gutem Vorverstärker, Konverter und einem 60-cm- Spiegel zu sehen, mit der während der ersten Transponderphase gute Ergebnisse erzielt wurden.

Gene Marcus, W3PM/GM4YRE, provided a spread sheet to calculate the performance of your S2-downlink equipment and what signals you can expect from the S2- transponder of AO-40. Play with noise floors, gain, cable losses and squint and learn how signals can be improved by low-noise - high-gain stages close to the antenna. See below the results of a typical S-equipment with good preamp, downconverter and 60 cm dish, which performed quite o.k. during the 1st transponder-period.

Download: http://home.hiwaay.net/~mmarcus/download/ao40_s2.xls

Lageänderung noch im Gange - Attitude change still in progress

DL6DBN , 04.06.2001

2001-05-30: X-pndrs OFF - ALON/ALAT=345/-26

A  HI, THIS IS AMSAT OSCAR-40       2001-05-30  04:22:36  #01B8
+--------------------------------------------------------------+
| ALON/ALAT=345/-26 moving to 270/0 TRANSPONDERS OFF |
+--------------------------------------------------------------+
M QST AMSAT OSCAR-40 ***UPDATE*** 2001-05-29
ALON/ALAT=345/-26. Middle beacon on continuously.
Transponders off during reorientation.
Magnetorquing in preparation for ArcJet tests (270/0).
The AO-40 team would like your telemetry files!
Please "zip" compress your daily telemety files and e-mail to:

Minimal Squint: >30 degs !

DL6DBN , 30.05.2001

AO-40 Update

  Aktueller Transponderfahrplan und Fluglage

Um dem sich schnell verschlechternden Sonnenwinkel zu begegnen und um die Lageänderung nach 270/0 vorzubereiten, haben wir ALAT auf -17° verringert. ALON ist derzeit bei 0° (Bakeninfo am 28. Mai).

Der Verlauf der Lageänderung wurde kurz zuvor mit YACE-Bildern ermittelt (Orbit 259, Download ab 24.5. 6 UT).

Wir werden ALAT auf -25° bringen bevor ALON der Sonne anpassen. Als Ergebnis macht es augenblicklich keinen Sinn, X-TX, K-TX oder C-RX weiter zu testen, da der minimale Squint bei über 20° liegt und keine brauchbaren Signale erwartet werden können. Außerdem hat das RUDAK-Team um mehr Zeit für RUDAK-Arbeiten gebeten.

Daher wurde der Fahrplan verändert, um die K-, X-, C-Test zu beenden und RUDAK mehr ununterbrochene Zeit bei relativ guten Squintwinkeln zu geben. Der Fahrplan für den S2-Downlink ist nun so:

MA Mode
------------------------------
240-039 beacon only
040-099 RUDAK
100-179 L1/U passband On
180-239 RUDAK

Die S2-Mittelbake ist immer an.

Die Messageblöcke werden jeweils auf den neuesten Stand gebracht.

73s Peter , DB2OS
für das gesamte AO-40-Team

  New schedule - attitude change in progress

In order to escape the rapidly approaching sun and get ready for our move to 270/0, we have lowered ALAT to approximately -17 degs. ALON is currently estimated at 0 degs (beacon info May 28th).

These values were tweaked with YACE images shortly (Orbit 259, download started at about 0600 UTC on 5/24).

We will continue to lower ALAT to about -25 degs, before beginning to move ALON past the sun.

The result of all this is that there is no reason to continue the X-Tx, K-Tx, or C-Rx testing at the moment as >20 deg. minimum squint is not enough for useful signals. In addition, the RUDAK team has asked for more time for RUDAK.

Accordingly, the schedule will be modified to stop the K-Tx, X-Tx, C-Rx testing and give RUDAK more uninterrupted time with a relatively good squint angle.

The schedule for S2 downlink will be as follows:

MA Mode
------------------------------
240-039 beacon only
040-099 RUDAK
100-179 L1/U passband On
180-239 RUDAK

The S2 MiddleBeacon (MB) is continuously On.

Message blocks will be updated to reflect these new and slightly reduced transponder times.

73s Peter DB2OS for the AO-40 team

AMSAT-DL , 28.05.2001

AO-40 Mini-Glossar

ALON/ALAT wurde am 17.5. mit 4/1 vermessen, allerdings beginnen Fluglageänderungen für den Arcjet-Test.

Im neuesten AMSAT-DL Journal gibt es ein Mini-Glossar , das aktuelle Begriffe um Fluglage und Squint erläutert.

DL6DBN , 22.05.2001

New Transponder Schedule

 The transponder schedule was modified:

Since orbit 255 the K-TX (24 GHz) and X-TX (12 GHz, solid state PA) transmitters are now ON between MA 122 and MA 134. The frequency for the Middle Beacon (and also the internal "Engineering Beacon") for K-band is 24048.035 MHz. So far, no reports have been yet received, although the output indicator for K is nominal and everything looks good.

Here is a graph showing K-TX-telemetry while testing:

RUDAK-Status-Report by J. White, WD0E

 Over the past few days as AO-40 has been re-oriented through an attitude where the high gain antennas were more or less earth pointing some further testing has been done. The hardware modulators and demodulators have been tested on RUDAK-B and found to be working. Initial software testing has been done. Remaining testing has been done on the RUDAK-A processor. The following software has been loaded and run on A: The standard housekeeping task, the CEDEX experiment control task, the GPS task, the SCOPE task, the CAN driver, the DSP control task, and the file system. Initial CEDEX data has been collected and passed to the CEDEX experiment principal investigator for review. The GPS A and B receivers have been turned on and bytes exchanged with them. Files are being automatically created by the CEDEX and GPS tasks in the file system. Several files have been uploaded and downloaded. Adjustment of the modulator outputs has been calibrated against received signal strength and the MB. The DSPs have been turned on and off and their power consumption noted. The SCOPE camera B (wide angle) has been turned on but as yet no communications with it has been attempted. Examination of log files automatically created by the file system have shown now evidence of errors in the file system memory. Some initial whole orbit data has been collected and reviewed. These data were of the temperature sensors accessed via the CAN nodes around the satellite. Equipment modifications and upgrades have been undertaken at the WD0E command station.A great deal more needs to be tested and checked out. The processes is just starting.

Receiving AO40's S-Band transponder using a low gain antenna

 This morning, around MA 170, an attempt was made by Danny Orban, ON4AOD constructor of AO-40's S1-TX-PA, to find out what the minimum antenna gain would be to receive the middle beacon on the S2 Transponder. The antenna used is a single element, linearly polarised, microstrip antenna. The gain peaks just above 7 dB.

With this antenna, the middle beacon is just above the noise floor and produces a stable signal with no fading. No attempt was made to decode telemetry but it is expected that this will not work. The receive converter used has a Noise Figure of 2 dB.