function b = read_hdradv ( fn, gb );
% READ_HDRADV - Read ASCII .hdr file, assign readable names
% b = read_hdradv( fn, [gb]);
%
% Input:
%   fn - path for ASCII .hdr file
%   gb - optional subset of burst numbers to extract (default is all)

% Chris Sherwood, USGS
% Last revised Sept 20, 2001

a = load( fn );
[nr,nc]=size(a);

fprintf(1,'Found %d columns and %d bursts\n',nc,nr);
if(exist('gb')~=1),gb=1:nr';, end
fgb = gb(1); lgb=gb(end);
nburst = (lgb-fgb)+1;     % total number of bursts
fprintf(1,'Using %d bursts (bursts %d - %d).\n',nburst,fgb,lgb);

b.b_num  = a(fgb:lgb,1);  % burst number
b.jt = julian( a(fgb:lgb,2:7) ); %start time for each burst
if(0),
% skip these...return julian date only
yr   = a(fgb:lgb,2);  % year           ( time is for start of
                    %                  averaging interal)
mo   = a(fgb:lgb,3);  % month
da   = a(fgb:lgb,4);  % day
hr   = a(fgb:lgb,5);  % hour 
mn   = a(fgb:lgb,6);  % minute
sc   = a(fgb:lgb,7);  % second
end

b.sr   = a(fgb:lgb,8);  % sampling rate (Hz) 
b.spb  = a(fgb:lgb,9);   %samples per burst

b.data = a(fgb:lgb,10);   % recorder data byte
b.c    = a(fgb:lgb,11);  % sound velocity (m/s)
b.probe_ht = a(fgb:lgb,12);  %distance from probe tip to boundary (cm)
b.sv_ht = a(fgb:lgb,13);  %distance from sampling volume to boundary (cm)
b.batt=a(fgb:lgb,14); % mean battery voltage (V)
b.x_mn = a(fgb:lgb,15); % beam 1/x/east mean velocity (cm/s)
b.y_mn = a(fgb:lgb,16); % bean 2/y/north mean velocity (cm/s)
b.z_mn = a(fgb:lgb,17); % beam 3/z/up mean velocity (cm/s)
b.amp1_mn = a(fgb:lgb,18);  %mean signal strength, receiver 1, counts
b.amp2_mn = a(fgb:lgb,19);  %mean signal strength, receiver 2, counts
b.amp3_mn = a(fgb:lgb,20);  %mean signal strength, receiver 3, counts
b.co1_mn = a(fgb:lgb,21);  %mean correlation, receiver 1, per cent
b.co2_mn = a(fgb:lgb,22);  %mean correlation, receiver 2, per cent
b.co3_mn = a(fgb:lgb,23);  %mean correlation, receiver 3, per cent
b.hdg_mn  = a(fgb:lgb,24); % mean heading (degrees magnetic)
b.pitch_mn= a(fgb:lgb,25); % rotation about Y axis
b.roll_mn = a(fgb:lgb,26); % rotation about X axis
b.t_mn    = a(fgb:lgb,27); % temperature, deg C
b.p_mn    = a(fgb:lgb,28); % pressure, dBars
b.ext_press_mn = a(fgb:lgb,29); % external pressure (dBars)
b.ext_analog1_mn = a(fgb:lgb,30);  % external analog channel 1 (counts)
b.ext_analog2_mn = a(fgb:lgb,31);  % external analog channel 2 (counts)
b.x_sd = a(fgb:lgb,32); % beam 1/x/east std. deviation (cm/s)
b.y_sd = a(fgb:lgb,33); % beam 2/y/north std. dev. (cm/s)
b.z_sd = a(fgb:lgb,34); % beam 3/z/up std. dev. (cm/s)
b.amp1_sd = a(fgb:lgb,35);  %std dev signal strength, receiver 1, counts
b.amp2_sd = a(fgb:lgb,36);  %std dev signal strength, receiver 2, counts
b.amp3_sd = a(fgb:lgb,37);  %std dev signal strength, receiver 3, counts
b.co1_sd = a(fgb:lgb,38);  %std dev correlation, receiver 1, per cent
b.co2_sd = a(fgb:lgb,39);  %std dev correlation, receiver 2, per cent
b.co3_sd = a(fgb:lgb,40);  %std dev correlation, receiver 3, per cent
b.hdg_sd  = a(fgb:lgb,41); % sd mean heading (degrees magnetic)
b.pitch_sd= a(fgb:lgb,42); % sd pitch
b.roll_sd = a(fgb:lgb,43); % sd roll
b.t_sd    = a(fgb:lgb,44); % sd temperature, deg C
b.p_sd    = a(fgb:lgb,45); % sd pressure, dBars
b.ext_press_sd = a(fgb:lgb,46);
b.ext_analog1_sd=a(fgb:lgb,47);
b.ext_analog2_sd=a(fgb:lgb,48);