December 2008 - AMSAT-BB - mailman.amsat.org

Re: Spacecraft Magnetic Attitude
by Clint Bradford 10 Dec '08

10 Dec '08

> www.aprs.org/attitudes.html Fascinating data! Clint Bradford P.S. - The very first phrase of the text, "Magentic Stabilization," had me looking for my scientific dictionary, Bob! (grin)

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Spacecraft Magnetic Attitude
by Robert Bruninga 10 Dec '08

10 Dec '08

To see a plot on the sky of the orientation of a magnetic stabilized satellite (PCSAT, ECHO, etc) see this page: www.aprs.org/attitudes.html This might be useful for those folks with hand-held antennas. I prepared it several years ago, but stumbled across it today while looking for the location of the Earth's magnetic pole. I found an interesting plot that shows the Earth's magnetic "dip pole" moving very fast these days, almost 5 degrees in 10 years! But unless you ever travel the arctic, I guess your boy scout compass will be good for the rest of your life anyway... Bob, Wb4APR

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soundcard is ok with ISS 9k6 packet
by nader omer 10 Dec '08

10 Dec '08

HI all I succeded to work ISS packet mode at 9k6 using AWGPE and UISS softwares and a soundcard for more info see my webpage link http://www.st2nh.com/internationalspacestation-iss Also see my experment with AO-51 9k6 telemetry and GO-32 9k6 telemetry by softwares and a soundcard http://www.st2nh.com/satellites 73,Nader,st2nh www.st2nh.com

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Re: AO-51 Uplink Frequency Change
by Clint Bradford 10 Dec '08

10 Dec '08

Should we consider this a permanent change - or a temporary one? Clint Bradford -------------------------------------- Clint Bradford, K6LCS / KAF3359 909-241-7666 - cell

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PCSAT little joy
by Robert Bruninga 10 Dec '08

10 Dec '08

PCSAT not useable. No joy today. Like yesterday, on the first ascending pass, we got a successful logon and restore commands, but they did not hold to the next rev. Again, I almost got in on the second pass, but a QRM packet took the energy I was hoping for. Third pass to the NW was too high in latitude so she was already dead. Will try again tomorrow. The only time we can get in is on an ascending pass, with some solar sun on the south panel, and this only occurs on an ascending pass, in the local morning in the Northern Hemisphere, in the winter, between the latitudes of about 30 to 40 deg and only when the orbit's ground track is in line with the terminator. Because PCSAT is magnetically stabilized, the angles work out just right only for a few minutes a day a few days per winter. Below that latitude there is not enough sun on the bottom panel (faces down in the southern hemisphere). Near that latitude there is some southern sun on this panel, but above that latitude, the best solar panel is pointing to space. Bob, WB4APR

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ESEO -The European Student Earth Orbiter - development gets underway
by Graham Shirville 10 Dec '08

10 Dec '08

Hi all, The ESA Education website now has this interesting page concerning the ESEO satellite mission: http://www.esa.int/SPECIALS/Education/SEMYQ2STGOF_0.html Slightly greater technical information is also available on the AMSAT-UK website here: http://www.uk.amsat.org/content/view/677/68/ We are not able to be more precise at this time as detailed discussions about the communications sub-system have still to take place - hopefully we will have some firm decisions within a few weeks so that design, development and manufacture of the hardware can commence quickly. We promise to keep information about this project flowing as much as we can. best 73 from the AMSAT-UK team! Graham G3VZV

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Re: AO-51
by Alan Sieg WB5RMG 10 Dec '08

10 Dec '08

KO4MA sez: > Notice the Doppler curve is different between the three on the right. As I see it, the one in the center of those three ( (435.881) indicated as almost exactly in position to translate via AO-51 to the 145.92 downlink..) is already more like ~2 min past TCA (at the base line). I would expect anything coming out of FO-29's transponder to show the same dopppler rate as the other signals, say the beacon at 435.795 ... Unless it was going thru yet another satellite first ..!.. Or possibly not going thru FO-29 at all, but heard direct from a 2nd bird. SO-50 was just ahead of AO-29 on that pass. Hummm... Even tho the AO-51 uplink has already been changed, I may try and grab a waterfall tonite centered on 435.850 ... Just to see if there are two different doppler rates again. Very Interesting . . . /;^) -- <- Licensed in 1976, WB5RMG = Alan Sieg * AMSAT#20554 -> <- http://www.somenet.net * http://wb5rmg.somenet.net -> <- http://www.linkedin.com/in/alansieg * My 'Day Job' ->

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SINAD Vs. Noise Figure Testing
by Stan W1LE 10 Dec '08

10 Dec '08

Hello The Net: Upon the suggestion of Domenico, I8CVS, I conducted some tests to compare SINAD to Noise figure testing. Noise figure testing was performed using a HP8970B with 346 noise source on a ARR preamplifier, one of their switched units, model SP144VDG. Performance was optimized at 144 MHz. for a noise figure of 0.9 dB and gain of 25 dB. The preamp was added before the IC-910H, which was set to 144.000 MHz in a SSB (USB) mode. SINAD , SIgnal + Noise + Audio Distortion testing allows a complete receiver to be tested from the RF input port, thru the IF's and demodulation to audio. For SSB mode testing I injected a low level RF carrier, (~ -120 dBm), no modulation, into the preamplifer with RX. I tuned the RX frequency to 1000 Hz less than was actually injected. example: for a RF of 144.000 MHz, I tuned the RX, in a SSB (USB) mode, to 143.999 MHz. SINAD instruments use a 1000 Hz tone for further processing. Connecting the audio output to a SINAD meter, in my case a Helper Instruments, Inc. model Sinadder Linear 5, I was able to get a SINAD reading from the meter. While monitoring the SINAD meter, I tweaked the preamplifier tuning and could not improve the original SINAD measurement. Conclusion: If the noise figure is optimized, the SINAD measurement will also be optimized. An additional test was performed, adding a fixed 10 dB BNC attenuator after the preamplifier and before the RX. The SINAD measurement did not change. This indicated that at least 10 dB of excess gain was present and can be eliminated. It is always best to minimize system gains to maximize the ability to handle strong signals and to reduce higher order intermodulation distortion. Minimize system interstage gains until the system SINAD sensitivity or the noise figure is slightly degraded. In this example, if I was able to reduce 10 dB of excess gain, this would result in lowering the 3rd order intermodulation distortion by 30 dB . !!! I hope this helps folks to consider SINAD testing of their system, to verify performance. Stan, W1LE FN41sr Cape Cod

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ISS 9600 changed to 145.825MHz
by Mineo Wakita 10 Dec '08

10 Dec '08

ISS 9600 digipeat changed to 145.825MHz from 145.800MHz. JE9PEL, Mineo Wakita

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info
by w3vvp 10 Dec '08

10 Dec '08

I'm looking for a 903 transverter w/144 if. Dem is only place I have found one SSB does not have one. Does any one have one for sale or know of any place that sells them. I hope this is not to far out of line for the BB. Any info greatly appreciated. George

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