[amsat-bb] when are TLE's too old to use?

[Todd W Deckard]

It’s my experience with my arduino based tracker that the TLEs age rapidly and must be refreshed on game day.   

I attributed this to the single precision math although it could be due to some more fundamental misunderstanding on my part.

Now that there are no more shuttle re-supply flights even ISS reboosts are fairly infrequent.

I am using the most excellent  qrpTracker library (Bruce Robertson VE9QRP) which is in turn derived from PLAN13 (James Miller G3RUH). 

https://youtu.be/VG5L5oP2uNk

https://github.com/twdeckard/AE-35/blob/master/sketch_ae-35/sketch_ae-35.ino

Best
Todd


Sent from my iPhone

> On May 12, 2018, at 6:21 PM, Alfredos (fredy) Damkalis <fredy at fredy.gr> wrote:
> 
> Recently it was posted in libre.space community discourse[1] by cgbsat
> an interesting analysis about TLE of a couple of satellites and what
> delays you should expect in observation starting time when you use TLE
> 0-10 days old.
> 
> Delays vary depending on satellite, difference could be from some
> seconds to some minutes (in ISS case).
> 
> I'm very interested if there are similar analyses.
> 
> 73,
> fredy
> 
> [1] https://community.libre.space/t/tle-updates-and-scheduling/1987/4
> 
>> On 05/12/2018 08:02 PM, Ron VE8RT wrote:
>> I understand that there won't be a good answer for how old can TLE's be
>> before they're of no use.  If you were going to be offline for an
>> extended period, roughly, for a LEO, how long would you go before
>> they're worthless?
>> 
>>   Ron VE8RT
>> 
>