SonTek ADP - Profile Data Conversion: GADPAMP; SNR; STD

SonTek
ADP Software Manual Version 6.42 (November 1, 2000)
17
3.3. Profile Data Conversion: GADPAMP / SNR / STD
These five programs extract different portions of the ADP profile data from the binary files:
signal strength (as the log of the return signal amplitude), signal to noise ratio (SNR), current
speed and direction, standard deviation, and velocity. Each program operates using under the
same command protocol.
GADP___ <ADP file>
GADP___ <ADP file> <output file>
GADP___ <ADP file> <output file> <first profile> <last profile>
File names must be given without extension. The programs assume that the ADP data file has
extension .ADP. If no output file name is specified, the programs use the same name as the
binary data file. Specifying the first and last profile permits the user to extract a subset of the
data. If they are not specified, the programs extract all profiles in the file.
Each program generates several multiple ASCII tabular data files. The output files generated by
each program are listed below.
• GADPAMP creates files with extension ".A1", ".A2", and ".A3" corresponding to signal
strength for beams 1, 2, and 3, respectively.
• GADPSNR creates files with extension ".SN1", ".SN2", and ".SN3" corresponding to SNR
for beams 1, 2, and 3, respectively.
• GADPSTD creates files with extensions ".SD1", ".SD2", and ".SD3" corresponding to the
standard deviation of velocity components based upon the coordinate system selected
(Beams 1, 2, and 3 / Vx, Vy, and Vz / VEast, VNorth, and VUp).
These programs generate tabular data files with one line per profile. The first value in each line is
the profile number within the data file. This is followed by the measurement at each depth cell in
the profile, starting with cell 1 (closest to the transducer). The range from the instrument to the
center of each cell is given in the ASCII file generated by GADPCTL. This range can also be
calculated by the following formula.
Range = Blanking_Distance + (Cell_Number*Cell_Size)
The units for each of these programs are shown in the table below.
Profile Data Units
Program Units
GADPAMP counts (see explanation below)
GADPSNR decibels (dB) (see explanation below)
GADPSTD cm/s
GADPVEL cm/s (degrees clockwise from Y-axis (XYZ coordinates)) or
(degrees from magnetic north (ENU coordinates)) for direction
For signal strength data, GADPAMP uses internal ADP units called counts; one count equals
0.43 dB. GADPSNR extracts the signal to noise ratio of the ADP. This is the signal strength
minus the system noise level, converted to dB. SNR (Signal-to-noise ratio) data determines
maximum profiling range (see ADP Principles of Operation).