Page 88 - Electronic Navigation Cyber Book

Bridge Audio. Recorded from one or more microphones placed so that
conversations at or near the conning stations, radar displays, chart tables
and other work stations may be adequately recorded. The microphones

should also capture, when practical, the input and output of intercom,
public address systems and audible alarms on the bridge.
Communications Audio. VHF communications relating to ship operations,

including transmitted and received audio signals. This must be
independent of the bridge audio.

Radar/AIS Data (Post-Display Selection). Electronic signal information
from one of the ship’s radars, which records all the information actually
presented on the master display of that radar at the time of recording.
This includes range rings or markers, bearing markers, electronic plotting
symbols, radar maps, any parts of the electronic chart or map that were
selected, the voyage plan, navigational data, navigational alarms and the

radar status data that were visible on the display. The recording method
must be such that it will present a faithful replica of the entire radar display
on playback. The S-

VDR specification provides an allowance for limitations of bandwidth
compression techniques that are essential to the working of the S-VDR.
The S-VDR standard also states that if there is no commercial off-the-
shelf interface available to obtain radar data the S-VDR may be permitted
to substitute AIS data in its place. If radar data is recorded, AIS
information may be recorded additionally as a beneficial secondary

source of information. The VDR performance standard requires the
following additional data items to be recorded. The S-VDR is not required
to record these data sets if they are not available in a digital serial data
output format (IEC 61162), but they must be recorded when the data is
available in accordance with international digital interface standards
using approved sentence formats. When existing sensors and systems

are upgraded to provide NMEA serial data output, they must be
interfaced with the S-VDR to comply with the annual recertification.
Depth. Depth beneath the keel, up to a resolution of 0.1 meter, including

the depth scale currently being used.

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