[amsat-bb] Re: Decoding Keps
tomdoyle1948 at gmail.com
Wed Sep 19 18:14:02 PDT 2012
Check this out.
73 W9KE Tom Doyle
On Wed, Sep 19, 2012 at 7:19 PM, David A. Rush <david at rushtone.com> wrote:
> I've been working on some code to decode the two-line Keplerian data like
> the ARRL sends out weekly (with a thank-you to AMSAT-NA).
> A couple of the values are in a somewhat cryptic format, the "BSTAR" and
> "second derivative of the mean motion". The strings tend to be either a
> space or a + sign, five digits, usually a minus sign (but seen at least once
> as a plus sign) and finally another digit, such as:
> What I have found about this format is that it is "decimal assumed", and
> examples suggest that +89689-4 = 0.89689 * 10 ^-4 or 0.000089689, if I
> converted that correctly.
> I'm guessing that the first character is the sign (+ or -) of the number,
> where a space is assumed positive. I've only seen one example of the 7th
> character being a plus (and all the digits were zero), so I assume that + or
> - are valid values for the exponent. I guess the format is fundamentally
> limited to an exponent between +9 and -9.
> Am I interpreting it correctly? Any other insight?
> David, ky7dr
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Sent from my computer.
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