search

GenericMappingTools / gmt

The Generic Mapping Tools
https://www.generic-mapping-tools.org
Other
853 stars 357 forks source link

mgd77sniffer. Meaning of DC. #8139

Closed Esteban82 closed 10 months ago

Esteban82 commented 11 months ago

In mgd7sniffer I read 3 times the word "DC". I suspect that means something like a constant value but I am not very sure. I would like to know exactly what it means so I can make a PR to clarify it in the docs.

Apply scale factor and DC adjustment to specified data field.

Grid comparison activates several additional error checks. (1) Re-weighted Least Squares Regression of ship versus grid data determines slope and DC shift, which when differing from expected 1 and 0, respectively, may indicate incorrectly scaled ship data, including incorrect units or instrument drift as well as erroneous gravity tie-in

Information pertaining to an entire cruise, such as NCEI and survey institution identification codes, cruise examination time, two-way travel time corrector information, data precision warnings, as well as systematic scales, DC shifts and correlation coefficients from global grid comparisons are reported as E77 header information.

PaulWessel commented 11 months ago

DC shift is very much direct-current offsets...in other words a constant. Here are the better terms:

Apply scale factor and offset ...

...determines slope and interest ...

...systematic scales, constant offsets, and correlation...

Esteban82 commented 11 months ago

Ok, great. I will make a PR.