function [t,v] = loadwfm(filename);

% This function loads the binary data from a Tektronix ".WFM"
% file.  The Tektronix TDS series oscilloscopes use a binary
% datafile to store oscilloscope waveforms.  The file format
% is documented in the accompanying file, 'tdsffmt.doc', which
% was obtained from the tektronix website.
% 
% USAGE
%
% [t,v] = loadwfm(filename);
%
% INPUT
%
% filename - name of Tektronix WFM file
%
% OUTPUT
%
% t - evenly spaced vector of times (s)
% v - corresponding vector of measured voltages (V)

FID = fopen(filename,'r','ieee-be');

c = fread(FID,1,'uchar'); 
if (c == 'L')
  fread(FID,6,'uchar');
else
  fread(FID,7,'uchar');
end
ndigits = fread(FID,1,'uchar'); ndigits = char(ndigits) - '0';
bytecount = fread(FID,ndigits,'uchar');
magicnum = fread(FID,1,'int32');
wfmlength = fread(FID,1,'int32');
vertPos = fread(FID,1,'double');
horzPos = fread(FID,1,'double');
vertZoom = fread(FID,1,'double');
horzZoom = fread(FID,1,'double');
acqMode = fread(FID,1,'int16');
minMaxFormat = fread(FID,1,'int16');
duration = fread(FID,1,'double');
vertCpl = fread(FID,1,'int16');
horzUnit = fread(FID,1,'int16');
horzScalePerPoint = fread(FID,1,'double');
vertUnit = fread(FID,1,'int16');
vertOffset = fread(FID,1,'double');
vertPos = fread(FID,1,'double');
vertGain = fread(FID,1,'double');
recordLength = fread(FID,1,'int32');
trigPos = fread(FID,1,'int16');
wfmHeaderVersion = fread(FID,1,'int16');
sampleDensity = fread(FID,1,'int16');
burstSegmentLength = fread(FID,1,'int16');
sourceWfm = fread(FID,1,'int16');
videoTrigLineNumber = fread(FID,1,'int16');
field = fread(FID,1,'int16');
frameSize = fread(FID,1,'int16');
lineWidth = fread(FID,1,'double');
standard = fread(FID,1,'int16');
tsHeader = fread(FID,6,'int16');
preamble = fread(FID,16,'int16');
curvedata = fread(FID,recordLength,'int16');
postamble = fread(FID,16,'int16');
checksum = fread(FID,1,'int16');

fclose(FID);

t = ((0:recordLength-1)' - recordLength*trigPos/100.0)*horzScalePerPoint;
v = curvedata*vertGain/25.0/256.0 + vertOffset - (vertPos*vertGain);