Promark2 problem
Posted By Jon Charlton on 11/6/2001 at 5:54 AM

Has anyone else encountered this particular problem....I have just received a pair of Promark 2's for evaluation. I have been logging data and processing it, and I set up a test run logging data over last Saturday night into the early hours of Sunday morning. When I downloaded the data I was suprised to find it thought the data was logged next week...ie from late Saturday 10th to early Sunday 11th. Unless the receivers can predict the future, I found this rather odd!

I guess what has happened is that as the logging session spans the change of GPS week, the week number of the END of the session has been taken rather than that of the BEGINNING. It is an unusual problem, and not one which most people are likely to encounter, but I thought I'd warn people to watch out for it.


Jon...Why is this a problem?
Posted By Trimble Man on 11/6/2001 at 7:33 AM

Don't both files have the same header/footer? They processed okay didn't they? (also they store in GPS time and not local time which has always caused some new users to get confused, especially when running programs to predict PDOP's for the day)...
TM


Re: Promark2 problem
Posted By Jon Charlton on 11/6/2001 at 9:03 AM

Trimble man...

No..they don't process OK. (I'm not a new GPS user btw, just new to the Promark).

It's a problem for two reasons
1) The file won't process as the processing software (Solutions 2.5) thinks the file dates are one week out (GPS week 1139 instead of 1138 in this case). It cannot overlap with a data set obeserved (as was the case) from a different GPS receiver.

2) It's just plain wrong. I don't want to have data labelled as one week different from it's actual date of observation.

I admit this is a bit of an esoteric error, but it's worrying none the less.

Jon.


Re: Promark2 problem
Posted By Richard Phelan on 11/6/2001 at 11:30 AM

Hi:

This is a known issue with the Promark II when any data is collected near UTC midnight each Saturday night.
This ephemeris issue only happens with Promark II data that is collected near that time.

For now, a workaround is to replace the Broadcast Ephemeris from the Promark II with one from another source -- CORS or another type of Ashtech GPS receiver. I've e-mailed the steps to you for getting a CORS replacement ephemeris. These steps are also located at

ftp://ftp.ashtech.com/software/Ashtech%20Solutions/promarkIIephemeris/


Regards,

Richard

Thales Navigation Tech
Support




Re: Will they receive
Posted By James Webb on 11/6/2001 at 12:19 PM

next weeks stock market ticker from the satellite ??


;-}

Jimbo


Richard
Posted By J.D. Billings on 11/6/2001 at 1:16 PM

I am glad to know of this problem. I do have occassion to do gps obs at midnight UTC myself, and here lately Saturdays are not much different than the 5 Mondays preceeding (i.e. Monday #1 Monday), Monday #2 (Tuesday), Monday #3 (Wednesday), etc.

Are there any other strange phenom's like this that PM2 users should be aware of?

Just curious.

J.D.



Jon, Didn't mean to infer you were new..
Posted By Trimble Man on 11/6/2001 at 6:04 PM

Sometimes it's good to put a 'little' more information in a post..Lot's of lurkers that are new (or thinking about getting into GPS)..
I agree that this is a problem, but sounds like they are working on it.

TM