function [d,p]=fixcompass(d,p)

% 

% fix compass issues

%

% p.fix_compass=1  apply offset only

% p.fix_compass=2  fix up looking compass to down looking compass + offset

% p.fix_compass=3  fix down looking compass to up looking compass + offset

%

% p.hdg_offset will apply a fixed rotation to the compass. In most cases you

%        will want to set the compass that you trust to 0 and rotate the other one

%        by the difference in direction between the two beam 3 headings as mounted 

%        on the frame

%        : [downoffset  upoffset]

%

% once you done this rotup2down gets disabled since I assume you know what the offset was

%

% M. Visbeck LDEO 2004

%

disp('FIXCOMPASS adjust compass')

% use tilt sensors to figure out allingment between instruments

diary off

  hoff2=fminsearch('checktilt',0,[],[d.rol(2,:);d.pit(2,:);d.rol(1,:);d.pit(1,:)]);

diary on

disp([' mean instrument alignment based on tilt is ',num2str(hoff2),' deg'])

[lb,lt]=size(d.ru);

if p.fix_compass==2

 p=setdefv(p,'hdg_offset',[0 hoff2]);

elseif p.fix_compass==3

 p=setdefv(p,'hdg_offset',[-hoff2 0]);

else

 p=setdefv(p,'hdg_offset',[0 0]);

end

p=setdefv(p,'hdg_offset_used',[0 0]);

rot=p.hdg_offset;

rotv(1,:)=ones(1,lt)*rot(1);

disp([' offset down looking compass by : ',num2str(rot(1))]) 

p.hdg_offset_used(1)=p.hdg_offset_used(1)+rot(1);

if p.fix_compass==3

  disp(' use up looking compass on down looking ADCP')

  rotv(1,:)=d.hdg(1,:)-d.hdg(2,:)+rot(1);

  p.rotup2down=0;

end

if length(d.izu)>0

  rotv(2,:)=ones(1,lt)*rot(2);

  disp([' offset up looking compass by : ',num2str(rot(2))]) 

  p.hdg_offset_used(2)=p.hdg_offset_used(2)+rot(2);

  if p.fix_compass==2

   disp(' use down looking compass on up looking ADCP')

   rotv(2,:)=d.hdg(2,:)-d.hdg(1,:)+rot(2);

   p.rotup2down=0;

  end

end

rotm=meshgrid(rotv(1,:),d.izd);

[d.ru(d.izd,:),d.rv(d.izd,:)]=uvrot(d.ru(d.izd,:),d.rv(d.izd,:),rotm);

if length(rotv(1,:))==size(d.bvel,1)

 [d.bvel(:,1),d.bvel(:,2)]=uvrot(d.bvel(:,1),d.bvel(:,2),rotv(1,:)');

else

 [d.bvel(1,:),d.bvel(2,:)]=uvrot(d.bvel(1,:),d.bvel(2,:),rotv(1,:));

end

if length(d.izu)>0

 rotm=meshgrid(rotv(2,:),d.izu);

 [d.ru(d.izu,:),d.rv(d.izu,:)]=uvrot(d.ru(d.izu,:),d.rv(d.izu,:),rotm);

end