Subject: duplicated DORIS/JASON data
From: Pascal Willis <[email-masked]>
To: [email-masked]
Cc: Alfred Piuzzi <[email-masked]>, Carey Noll <[email-masked]>, Vincent Patrick <[email-masked]>, Martine Feissel <[email-masked]>, Sabine HOURY <[email-masked]>, "John C. Ries" <[email-masked]>, Nikita Zelensky <[email-masked]>, Bruce J Haines <[email-masked]>
Date: Mon, 28 Apr 2003 11:15:55 -0700

Hello Jean-Paul,

I understand you point and your reasons are valid most of the 
time,specially for ENVISAT/DORIS data.

However, there are still some other problems, like

for cycle ja1data040.001.Z

data are effectively duplicated :

  JASON13935KIUB 03 40 6351869821112  70000003-5543068196 947268 58 
300    -671  43085181  1196
  JASON13935KIUB 03 40 6351869821112  70000003-5543068196 947268 58 
300    -671  43085181  1196

the channel is 1 (cut -c 90-90) for both measurements

There are 87 measurements like that on that specific day (03FEB09)

Best regards
Pascal

>Hello Pascal,
>
>In your mail you talk about duplicated data. However, this is not 
>the case: one
>measurement has been performed on channel 1, the other one on 
>channel 2. Most of
>the time, when tracking the same beacon, both channels give the same 
>result, and
>we indicate this by using 3 as channel indicator in the file. 
>However, there are
>times when the two channels do not give the same result. Often this can be
>linked to the fact that one of them at least is in error, and we have many
>filters to remove those data.
>
>But there are also cases when we cannot discriminate between the 
>measurements of
>the two channels. In this case they both end up on the delivery file. This is
>normal, as both measurements are valid in our sense.
>
>The fact that you see it more on ENVISAT is certainly related to the screening
>procedure which is not as extensive for this type of receiver. The filters on
>simultaneous but different measurements were introduced after the 
>"problem" was
>discovered on Jason, and they might not work as well on ENVISAT which is a
>receiver of a different technology. We will look into this.
>
>Jean-Paul

-- 
Pascal Willis
Jet Propulsion Laboratory, MS 238-646     Ph : 1-818-393-4748
4800 Oak Grove Drive                      FAX: 1-818-393-4965
Pasadena CA 91109                         Em : [email-masked]