Cumming 《合成孔径雷达成像 算法与实现》光盘读取数据程序

function read_ceos_raw ( output_file_pre, start_line_blk, blk ) % % ------------------------------------------------------------------------- % This function reads the CEOS format RSAT-1 RAW data from the CD % This function is called by extract_data.m % ------------------------------------------------------------------------- % output_file_pre : output file prefix ( path + prefix + block number) % start_line_blk : extract data starting from row number 'start_line_blk' % blk : the block number % % input_path : Input file path % length_replica : Length (I & Q) of replica (for Fine Beam -> 2880 bytes) % tot_Nrg_cells : Total number of columns available in the dataset % Nrg_lines_blk : Number of samples in azimuth % first_rg_cell : Extract data starting from column number 'first_rg_cell' % Nrg_cells : Number of samples in ranged % UseMATfiles : Do you want to write MAT files for the data rather than % binary files for all the data and parameters? % ------------------------------------------------------------------------- % date created : May 05, 2004 by Kaan Ersahin & Millie Sikdar % date modified : Nov 30, 2004 by Kaan Ersahin % Modified: Dec 17 by Ian Cumming % - Added UseMATfiles option % ------------------------------------------------------------------------- % 'RSI - D4' refers to the document RSI-GS-026, Rev 3.0 - May 8, 2000 % that describes the detailed format of the RADARSAT-1 raw data CDs. tic num_aux = 50; % RSI - D4 Pg.32 num_header = 192; % RSI - D4 Pg.32 file_header_length = 16252; % RSI - D4 Pg.103 load CD_run_params % Specify input data file path and open to read file_in = strcat( input_path, CD_data_file_name ); fid = fopen( file_in, 'r' ); % Create output file names and open to write if MAT files not used if ~UseMATfiles file_replica = '_replica.dat'; % one replica per 8-line file_data_header = '_data_header.dat'; % header of each line file_aux = '_aux.dat'; % auxiliary data from each line file_data = '_data.dat'; % radar signal data file_file_header = '_file_header.dat'; % header of file 'dat_01.001' file_replica = strcat(output_file_pre, file_replica); file_data_header = strcat(output_file_pre, file_data_header); file_aux = strcat(output_file_pre, file_aux); file_data = strcat(output_file_pre, file_data); file_file_header = strcat(output_file_pre, file_file_header); fod1 = fopen( file_replica , 'w' ); fod2 = fopen( file_data_header, 'w' ); fod3 = fopen( file_aux , 'w' ); fod4 = fopen( file_data , 'w' ); fod5 = fopen( file_file_header, 'w' ); % Read file header file_header = fread( fid, [file_header_length,1], 'uint8' ); % Write file header in a binary file as unsigned integers fwrite( fod5, file_header, 'uint8'); fclose( fod5 ); end % of if ~UseMATfiles % some useful calculations num_pixel_data = 2*tot_Nrg_cells; % 18576 h = num_header; % 192 ha = num_header + num_aux; % 242 hpa = num_header + num_aux + num_pixel_data; % 18818 % Define 'rep_block' as the 8-line block of data including one replica % 'start_rep' and 'end_rep' locates the replica in the 'rep_block' % 'start_col' and 'end_col' locates the area of interest in the columns rep_block_length = length_replica + 8*hpa ; start_rep = (first_replica-1)*hpa + num_header + num_aux + 1; end_rep = start_rep + length_replica - 1 ; start_col = ha + 2*(first_rg_cell - 1) + 1 ; end_col = start_col + 2*Nrg_cells - 1; % The number of bytes to skip from the beginning of the file (Nbytes_skip) Nrep_blks_row1 = ceil(start_line_blk/8) - 1; Nbytes_blocks = Nrep_blks_row1 * rep_block_length; Nbytes_skip = file_header_length + Nbytes_blocks; fseek( fid, Nbytes_skip , 'bof' ); % go to start of the 1st data block data = int8( zeros(Nrg_lines_blk, 2*Nrg_cells) ); % Allocate data array N_8line_blocks = ceil(Nrg_lines_blk/8); fprintf('\nReading %1.0f small 8-line blocks from range line %5.0f\n',... N_8line_blocks, start_line_blk ) for kb = 1 : N_8line_blocks % Read and decode 8 lines at a time % read one 8-line block of radar data and replica temp = uint8( fread( fid, [rep_block_length,1], 'uint8' ) ); % separate the replica and 8 lines of [header, aux and data] replica = temp(start_rep : end_rep)'; temp = [ temp(1 : start_rep-1)' temp(end_rep+1 : rep_block_length)' ]; temp = reshape(temp, hpa, 8)'; % Shape array as 8 rows by all columns % Extract the desired set of range cells data(1+8*(kb-1):8*kb, :) = temp( : , start_col : end_col ); if ~UseMATfiles % Write replica, header, aux and data in a binary file header (:,1:8) = temp( : , 1 : h )'; aux (:,1:8) = temp( : , h+1 : ha )'; count1 = fwrite( fod1, replica, 'ubit4' ); % 4-bit replica count2 = fwrite( fod2, header , 'uint8' ); % 8-bit header count3 = fwrite( fod3, aux , 'uint8' ); % 8-bit aux data count4 = fwrite( fod4, data(1+8*(kb-1):8*kb, :)' , 'ubit4' ); end % of if UseMATfiles end fclose(fid); % Close input file if ~UseMATfiles % Close output files fclose(fod1); fclose(fod2); fclose(fod3); fclose(fod4); fprintf('This block written to binary file:\n%s\n', file_data ) end %-------------------------------------------------------------------------- % Decode the data, save as MAT file , if UseMATfiles == 1 %-------------------------------------------------------------------------- if UseMATfiles == 1 disp 'Decode data by subtracting 16 from upper register' vv = version; vers = str2num(vv(1)); % Find MATLAB version seven = int8( 7 ); if vers == 7 one = int8( 1 ); two = int8( 2 ); sixteen = int8( 16 ); data = two*(data - sixteen*int8(data > seven)) + one; else data = int8( 2*(double(data) - 16*double(data > seven) ) + 1 ); end % Separate the I and Q channels and form a complex array data = complex( data(:, 1:2:2*Nrg_cells), data(:, 2:2:2*Nrg_cells) ); if SaveV6 eval(['save -v6 ' output_path 'CDdata' num2str(blk) ' data']) disp 'Save int8 data in MAT file in V6 format' else eval(['save ' output_path 'CDdata' num2str(blk) ' data']) fprintf('Save int8 data in file: CDdata%1.0f.mat\n', blk) end % somedata = data(1,1:4) % Check a few data samples end % of if UseMATfiles toc