How to decode 16-bit signed binary file in IEEE754 standard

Question

I have a file format called .ogpr (openGPR, a dead format used for Ground Radar data), I'm trying to read this file and convert it into a matrix using Matlab(R).

In the first part of file there is a JSON Header where are explained the characteristics of data acquisition (number of traces, position etc), and on the second part there are two different data blocks. First block contains the 'real' GPR data and I know that they are formatted as:

1. Multibyte binary data are little-endian
2. Floating point binary data follow the IEEE 754 standard
3. Integer data follow the two’s complement encoding

I know also the total number of bytes and also the relative number of bytes for each single 'slice' (we have 512 samples * 10 channel * 3971 slices [x2 byte per sample]). Furthermore: 'A Data Block of type Radar Volume stores a 3D array of radar Samples At the moment, each sample value is stored in a 16-bit signed integer. Each Sample value is in volts in the range [-20, 20].'

Second block contains geolocation infos.

I'd like to read and convert the Data Block from that codification but it ain't clear especially how many bytes break the data and how to convert them from that codification to number.

I tried to use this part of code:

bin_data = ogpr_data(48:(length(ogpr_data)-1),1);
writematrix(bin_data, 'bin_data.txt');
fileID = fopen('bin_data.txt', 'r', 'ieee-le');
format = 'uint16';
Data = fread(fileID, Inf, format);fclose(fileID)

Answer 1

Looks like your posted code is mixing text files and binary files. The writematrix( ) routine writes values as comma delimited text. Then you turn around and try to use fopen( ) and fread( ) to read this as a binary file in IEEE Little Endian format. These are two totally different things. You need to pick one format and use it consistently, either human readable comma delimited text files, or machine readable binary IEEE format files.