function plotp1p1
t=caltomjd([2004,1,1]):caltomjd([2004,12,31]);
s={}; for n=1:31, s={s{:},sprintf('GPS%02d',n)}; end
bias=readdcb(t(1),(t-t(1))*86400,s,'e:\gps\ion\%Y%m');
tt=(t-t(1))*24;
gut('newfigg','','',[600,400]);
ggt('newaxes','',[0.08,0.08,0.86,0.86],'taxis',t(1),'xlim',[tt(1),tt(end)]);
plot(tt,bias,'-'); plot(tt,bias,'.');
ylabel('P1-P2 Bias (m)'); title('P1-P2 Bias Values')
