Sign Convention for Plotting Velocity and Phase

[hariiirs]

I am confused with the sign convention of velocity and phase retrieved from StaMPS processing using ascending and descending passes. What should be the sign conventions for the following situations-

Ascending Data

1. If reference image predates the secondary image- what is the meaning of positive and negative velocities and phase
2. If reference image postdates the secondary image-what is the meaning of positive and negative velocities and phase
3. If reference image is in the middle of all the secondary images - what is the meaning of positive and negative velocities and phase

Descending Data

1. If reference image predates the secondary image- what is the meaning of positive and negative velocities and phase
2. If reference image postdates the secondary image-what is the meaning of positive and negative velocities and phase
3. If reference image is in the middle of all the secondary images - what is the meaning of positive and negative velocities and phase

Please help me if you know it. I am using StaMPS-master (Version 4.1b).

Thanks in advance
Hari Shankar

[ranneylxr]

Hi Hari,
Do you know the answers? I am also confused with the sign convention of velocity and phase retrieved from StaMPS processing.
Thank you very much!
sincerely,
Xiaoran.

[constantinevi6]

Hello,
Following the code in ps_output.m, here is the summary:
No matter what As or Des orbit, velocities with positive value mean uplift / close to the satellite, negative mean subsidence / away from the satellite.

And phase (using ps_plot('u-dm') in MATLAB) with positive value means subsidence / away from the satellite compare to the reference date.
Negative means uplift / close to the satellite compare to the reference date.

note that the output .xy file from ps_output.m will convert phase to accumulated displacement in mm, in this file:
positive value means uplift / close to the satellite compare to the reference date,
negative means subsidence / away from the satellite compare to the reference date.

If I have any mis understand, please let me know, thank you.

[hariiirs]

Yeah The explanation regarding sign convention is correct provided reference images is predated with the secondary images. Regards Hari Shankar

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