4.1 Functionality4.1.1 The THD receives a heading signal and
generates a suitable output signal for other devices.
4.1.2 Any sensor part may be included in the device.
4.1.3 Any correcting devices or parameters
should be protected against inadvertent operation.
4.2 Presentation of information4.2.1 All displays with the exception of
the sensor, and all outputs of heading should indicate true heading.
4.2.2 Manually settable values used for electronic
correction should be indicatable by adequate means.
4.3 Accuracy4.3.1 The THD should be tested for accuracy
with the sensing part connected. If the sensing part is so designed that it is
included in the transmitting part, the equipment should be tested together with all
parts.
4.3.2 The THD should meet at least
the following accuracy at the output of the device under sea conditions as specified
in resolution A.424(XI) or A.821(19) as applicable:
.1 Transmission and
resolution errors. The transmission error including the resolution error should be
less than ±0.2º;
.2 Static errors. The
static error should be less than ±1.0º;
.3
Dynamic errors.* The dynamic error amplitude should be less than ±1.5º. The dynamic
error frequency should be less than 0.033Hz equivalent to a period not shorter than
30s if the amplitude of the dynamic error exceeds ±0.5º; and
.4 Follow-up errors: The follow-up error for different rates of
turn should be:
.4.1 less than ±0.5º at rates up to
10º/s; and
.4.2 less than ±1.5º between a
rate of 10º/s and 20º/s.
4.4 InterfacingAt least one output should be in accordance with
the relevant international marine interface standard.**
* If the sensing part is a magnetic one it should meet resolution A.382(X) and
should be tested separately in accordance with the relevant standard.
** Publication IEC 61162.