Clock constraint seems not necessary in Scenario 'PPP'

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Hi,
scenario ppp provided in TUG ftp sets clock parameters as follow:

This constraint seems not necessary for transmitter clocks because they are known value provided by sp3 file, which will further be reduced from observation equation and do not cause rank-deficiency. Thus I'd like to confirm wether it's more feasible to set this constrain to '0'?
Hope someone to help and thanks in advance!
Yongzhao Fan

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Note that I've tried PPP in constrain and unconstrain mode, no rank-deficiency occurs, but the position results differ in microm level.

This proves that constraint did affect the results, but seems not necessary.

[tmayerguerr]

Hi,

The constraints are only applied if all conditions are met

• The respective parameters must estimated
• The respective transmitters and/or receivers must be selected
• The sigma must be > 0

As in your case only transmitters are selected without transmitter clock error estimation , the constraint is not applied here.

regards
Torsten