[amsat-bb] AMSAT-BB Digest, Vol 13, Issue 168

Todd W Deckard twdeckard at earthlink.net
Sat May 19 12:03:59 UTC 2018


mailing list bounced my pedantic response due to attached image size ...

here’s a link to a parallel thread that has the image of ISS altitude over time.

http://forums.qrz.com/index.php?threads/need-help-with-ascending-node.549308http://forums.qrz.com/index.php?threads/need-help-with-ascending-node.549308//



Sent from my iPhone

> On May 19, 2018, at 6:43 AM, Todd W Deckard <twdeckard at earthlink.net> wrote:
> 
> As an aside, the ISS makes an adjustment approximately once a month.   They operate at a higher altitude now that the shuttle is no longer used for resupply.    Here is a plot from heavens-above.
> 
> <image1.png>
> 
> 
> I have observed that if you are using an Arduino or another processor with single precision math, the computed results age very quickly for any LEO and practically I must update every few days.
> 
> if you are using a more respectable math engine and are only concerned about the orbital elements; the error in the satellite position is approximately a kilometer at the epoch of the TLE.   Then the simplified perturbation model (SPG4) used by the common software we use loses about 1-2km a day.
> 
> all of this is a bit pedantic if you are hand pointing an antenna in the noble tradition ...
> 
> best
> Todd
> Sent from my iPhone
> 
>> On May 18, 2018, at 9:51 PM, amsat-bb-request at amsat.org wrote:
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>>  1. Re: when are TLE's too old to use? (Gregory Beat)
>>  2. Re: Recording TX & RX from one or two radios? (Mark D. Johns)
>>  3. Re: when are TLE's too old to use? (skristof at etczone.com)
>>  4. FUNcube-1 mode change (Jim Heck)
>>  5. Falconsat With Wisp and Kenwood TS-200  Internal TNC
>>     (Vincenzo Mone)
>>  6. Falconsat With Wisp and Kenwood TS-200  Internal TNC
>>     (Vincenzo Mone)
>>  7. Falconsat With Wisp and Kenwood TS-200  Internal TNC
>>     (Vincenzo Mone)
>>  8. Re: Recording TX & RX from one or two radios?
>>     (skristof at etczone.com)
>>  9. Re: Recording TX & RX from one or two radios? (Ken M)
>> 10. Re: Recording TX & RX from one or two radios? (John Brier)
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