BSH (Germany) type approved for AIS, ECDIS, Radar and Heading Repeater interfacing, the NT990HDI (Heading Data Interface) will convert virtually any Synchro or Step by Step heading input signal to heading data transmitted on 1 (NT990HDI/1) or 2 (NT990HDI/2) isolated NMEA 0183 output channels. The output channels may be independently set for IEC 61162/1 (4800 baud) or IEC 61162/2 (38400 baud).

A speed log giving 200 or 400 ppNm may also be connected to the NT990HDI to provide NMEA 0183 speed information to proprietary systems.

All inputs to the NT990HDI are Opto-Isolated to eliminate common mode and loading problems.

The NMEA 0183 output sentences may be set for heading only ($HEHDT), heading and Rate Of Turn ($HEROT), heading and speed ($VDVHW) or heading, rate of turn and speed.

Heading information is permanently displayed on a 4-digit LED display with variable intensity for night viewing whilst built in alarm functions triggered by internal monitors warn of heading input or NMEA output failure.