Heterodyne mapping is done by offset pointing the telescope. Especially for larger maps, OTF mapping is more efficient for larger maps because a common reference position is used for all the cells in each row.
uip> for i 1 to 3
uip> rao /map (i-2)*15
uip> for j 1 to 3
uip> deco /map (j-2)*15
uip> oo_scan N /designated_off
uip> next
uip> next
OFF ON
uip> rao /map -15
uip> deco /map -15
uip> oo_scan N /designated_off
uip> deco /map 0
uip> oo_scan N /designated_off
uip> deco /map +15
uip> oo_scan N /designated_off