| Author |
Message |
Prashant B
Guest
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 Posted:
Mon Dec 05, 2005 5:08 pm Post subject:
Negative Phase : RINEX Files |
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I am looking for an explanation for the negative phase measurements
that are observed in the RINEX files. Normally the phase measurement is
the count of the number of cycles(+ the fractional part), and this in
turn is used to calculate the distance once the ambiguities are fixed.
As i am invloved in developing a post processing software, should i
treat the negative phase measurements in the same way as i use the +ve
ones?
Thanks in advance
Regards
Prashant |
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Guest
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| Posted:
Tue Dec 06, 2005 5:08 pm Post subject:
Re: Negative Phase : RINEX Files |
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Prashant B wrote:
| Quote: | I am looking for an explanation for the negative phase measurements
that are observed in the RINEX files. Normally the phase measurement is
the count of the number of cycles(+ the fractional part), and this in
turn is used to calculate the distance once the ambiguities are fixed.
As i am invloved in developing a post processing software, should i
treat the negative phase measurements in the same way as i use the +ve
ones?
Thanks in advance
Regards
Prashant
|
A large receiver clock bias will cause negative pseudoranges, but all
the ranges from the receiver would be negative (or small). The code to
carrier phase ambiguity can be anything so it could also cause negative
carrier pseudorange measurements. (The receivers I work with
initialize the ambiguity to the code measurement at the beginning of
the track so I've never acutally seen this)
Tom |
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Guest
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| Posted:
Fri Dec 09, 2005 5:08 pm Post subject:
Re: Negative Phase : RINEX Files |
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Prashant B wrote:
| Quote: | I am looking for an explanation for the negative phase measurements
that are observed in the RINEX files. Normally the phase measurement is
the count of the number of cycles(+ the fractional part), and this in
turn is used to calculate the distance once the ambiguities are fixed.
As i am invloved in developing a post processing software, should i
treat the negative phase measurements in the same way as i use the +ve
ones?
|
The easiest way to understand this is to examine a RINEX file
downloaded from SOPAC. If you compare the carrier phase values from
second to second for each satellite, you will see that for some
satellites the values increase every second, and for others the values
decrease from second to second. You should be able to determine which
is which by looking at the change in pseudorange values. Satellites
that are getting closer will show are positive increase in carrier
phase, and satellites which are moving away will decrease from second
to second.
Wether this causes the overall carrier phase value to be negative
depends on how the receiver initialises the carrier phase value. A
common method is to start the carrier phase track off at zero when the
receiver is turned on, and this will lead to negative carrier phase
values for the satellites that are moving away from the receiver.
Peter. |
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Prashant B
Guest
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| Posted:
Mon Dec 12, 2005 5:08 pm Post subject:
Re: Negative Phase : RINEX Files |
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Thanks for the replies, Tom and Peter. That really helped me in
understanding the concept and getting my basics clear. Yes I was having
a vague idea about the tracking of the cycles by the receiver, but now
I have made my self clear. |
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