GB650778A - Improvements in or relating to radio navigation aiding devices - Google Patents

Abstract

650,778. Radio direction-finding. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. June 18, 1947, No. 16144. [Class 40 (vii)] In a navigation aiding device employing a direction-finder to enable a craft to home on to a radio beacon, a straight course is maintained in the presence of a drift force by a compass unit, any displacement of which from the current course setting is caused to operate through a telemeter system and reorient the direction-finder directional aerial so that the navigator in reheading the craft to realign the aerial with the beacon corrects for drift and maintains a straight course. As shown, a three-wire telemeter system comprising resistance elements L8 and P7 is associated with the loop L of a direction finder unit C providing " homing" " facilities and a repeater P18 of a master compass. One pair of contacts L6, L7 are positioned by the loop and a second pair carried by rotatable slip rings P10, P11 are positioned by the compass repeater. After correctly heading the craft at the beacon, the contacts P8, P9 are first aligned with tapping point P6 so as to balance the telemeter system and then a clutch P17 operated to engage the compass repeater P18 with the slip rings. Thereafter any change in the compass setting reacts in a displacement of contacts P8, P9 and causes a potential to appear on leads W4, W5. This potential is applied to unit C through a periodic make-andbreak switch D, and at the next make actuates a motor L3, L4, L5 to cause the loop, together with contacts L6, L7 to be rotated until balance of the telemeter system is re-established. For the purposes of steering an indicator P is provided, the coils P1, P2, P3 being connected via switch SW1 in the lower position to the " homing " output of unit C. The craft is headed to maintain the needle at 0 degrees on a fixed bearing scale P14. Normal radiocompass facilities are also provided by unit C and are obtained by placing switch SW1 in the upper position. Hence, the loop is automatically maintained aligned on a beacon with the bearing repeated to the indicator P, the pointer indicating relative bearing on scale P14 and true bearing on a rotatable scale P15 controlled from a compass repeater P16. Specification 550,619 is referred to.