OK, I think I finally get it..(slow, but learning).

The UFCORS site does not let me directly get a .02n file with my 02o files anymore...You have to get the generic file for ephemeris and rename yourself...

I understand the reasoning....Less storage space on CORS servers, since ephemeris data is generic in nature and doesn't need to be downloaded with each raw file...I just wish I had figured it out earlier....b

I am sure there is a reason for it, but why does the processing software require an ephemeris for each receiver/day? It would seem that one ephemeris should cover an entire session.

Curious
Shawn

Could it be that Solutions requires an "E" file with each receiver because of the way the software handles the vectors one at a time?

Solutions requires an E-file for each B-file because:

1. That's the way they come from the receiver.

2. Different receivers may not have all of the same SV's in the ephemeris (only the ones they tracked), so Solutions combines all of the E-files.

I hope to see this handled in a more flexible manner in future s/w, particularly now that CORS and precie ephemerides are so frequently used.

Brian

You said, "Different receivers may not have all of the same SV's in the ephemeris (only the ones they tracked), so Solutions combines all of the E-files".
Sorry, I didn't mean to "Frame" you (just kidding Jim), but that statement worries me. Are you saying that the "e" file downloaded from a Locus unit doesn't have a complete ephemeris for all sv's... that it may only have ephemeris for those sv's tracked during the session? If this is the case, my method of using CORS sites (O.R.G.I.)will be severly hampered, especially if the Broadcast Ephemeris will not be available on UFCORS site. I think what I noticed in the last few weeks was the broadcast eph was available as soon as the CORS site data was put online as I was able to download it. A wait of a couple of days and the broadcast seemed to be superceded by the r.o. or precise.

Anyway, you're saying that the "E" file from a Locus unit may not satisfy the needs for processing data for other sites (not directly relative to the Locus unit)during the same session?

Thanks for your help as always.

J.D.

Modified By J.D. Billings on 2/14/2002 at 3:35 PM

J.D.,

Yes. If a CORS site is tracking SV's your Locus is not, they can't be used in a solution anyway (no common time, no solution). Other sites will have their ephemeris, but it doesn't matter.

Regards,
Brian

Brain,

That's understandable concerning the sv's not tracked by the Locus unit wouldn't be used in the solution anyway, if you don't consider the possibility of including CORS to CORS vectors "outside" the window of the Locus unit. I suppose when processing TM's data in a session, his nav file does the trick there. And, if necessary I guess I could copy the "E" file generated from his nav file to use with the CORS sites in that general area.

Am I properly phrasing the questions? Sometimes I fail to ask the right questions.

J.D.

is the broadcast file downloaded from a CORS site the complete constellation or only the SV's that that particular site tracks and uses ??

I probably should know this but how many different SV's track thru any site in a 24 hr. period ?? All of them ??

JD,

Cors records 1,2,3,4,5,6,7,8,9
JD records 3,5,7,9,10,11,12,13,14

only common SVs are used. Therefor I think you are right about needing to use TM's nav file when processing his data unless the downloadable broadcast file has everything.

Jimbo

PS: Looping to VINTON AND CIVIC today.
k-index 3 to 2 to 1 to 3

An ephemeris (precise or otherwise) should contain the data on 'all' the SV's...
Otherwise, it would be very unusable and not worth downloading...
I downloaded the daily broadcast to process Jimbo and Post and it seemed to work fine...

As far as processing...Yes, only common SV's are used, but the ephemeris is what the software uses to know this...

TM

Just about ready with Jimbo and Post...Jimbo has the best chance...Post had a bad night...
Paulk E and Paulk W are very good so far since they had ample SV's and mucho time...

Just some information...Each SV based on it's orbit tracks around the globe twice per day...
If you see it at 6:00am then you'll see it at 6:00pm....

The SV's orbit on a 12 hour schedule...twice per day for all the users...Give a long enough occupation, then the same SV will show up in twice in the computations...

TM

You said:

"An ephemeris (precise or otherwise) should contain the data on 'all' the SV's..."

Why? If you have no code or carrier measurements for given SV's, why should you have ephemeris data for them? Granted, this may well be a legacy from the days when SRAM (receiver memory way back when) was expensive, but that's the way it is. Regarding precise ephemerides, I agree that they should cover a 24-hour period.

Regards,
Brian

I may be in a fog, but what ephemeris is used for mission planning, and would an incomplete ephem give you incomplete mission planning. Seems like I've had this happen.

- jlw

Each SV sends the 'complete' ephemeris (or broadcast if you prefer, for all the SV's..Wouldn't work any other way...
I download one eph and can mission plan anywhere in the world...

Maybe the precise package under the UFCORS is different..I'll have to look into this, but when downloading 6-7 Cors files , then they all have the same IGS Rapid ephemeris included..

Am I wrong Brian?

TM

MP uses an "almanac", which differs from an ephemeris in that it contains rough orbital parameters for ALL sv's. The almanac doesn't contain sufficient info for post=processing (not the full broadcast ephemeris), just enough info for planning.

The MS (Mission Planning) uses the almanac (which is a truncated version of the subframe 5 message contained in the GPS message...It only contains the Keplarian movements, so it's a very basic flight plan...(but for all the SV's) and takes some 12.5 minutes to download (all receivers download this , even if they can't send to a computer), but they need it to look for the SV's...

Still looking into the eph files (trying to examime the data), but an eph file should contain all the data on all the SV's, not just one particular satellite...I might be wrong on this Brian, so help me if I am...Always willing to learn .....


TM Still learning after all these years..