Hi:

    The Promark II will erroneously label the GPS data one week too far in the future when the
data is collected near the Week Rollover at midnight UTC on Saturday of each week.  This problem only
happens with data that is collected near this time. The Ephemeris file is causing the problem.


WORKAROUND 1:


	If there is a good Promark II ephemeris file (e-file) from that SAME day and SAME approximate time 

period that is being decoded properly, do the following:


(1) Make a backup of this good e-file using Windows Explorer. Keep the same e-file name.

(2) Remame this good e-file to MATCH the name of the bad e-file that is being decoded incorrectly

(3) Copy this renamed e-file into the same directory where the bad e-file is located. You will
have to overwrite the bad e-file. This is OK. 


   WORKAROUND 2: If no good Promark II ephemeris file is available:

Replace the Broadcast Ephemeris from the Promark II with one from another source -- CORS or another type of Ashtech GPS receiver.  Here are the steps for getting a replacement ephemeris from a CORS site:


Here are the steps for getting a replacement Broadcast Ephemeris from the CORS site.


(1) Set your browser to www.ngs.noaa.gov


(2) Click on the CORS link


(3) Click on the User Friendly CORS link.


(4) Choose the correct Julian day to match your field data times. Precise Ephemeris is not needed.


(5) Choose about one hour's worth of data during the times that the Promark II data was collected.
 

(6) Download the data and unzip it.


(7) Start up the Solutions 2.50 RINEX converter


(8) Convert the RINEX files that you just downloaded into Ashtech B and E files.


(9) Rename the E-file that you just created in (8) to be the SAME NAME as the Promark II E-file that is 
causing the difficulties.


EXAMPLE: If your Promark E-file is called E1234a01.300 you will have to rename the CORS-derived E-file to
the SAME name.


(10) Copy this renamed E-file in to the directory where the Promark II data is located. You will have
to ovwerwrite the existing E-file.