3.1 The combined GPS/GLONASS receiver equipment should:
.1.1 be capable of receiving and processing the Standard Positioning
Service (SPS) signals of the GPS as modified by Selective Availability (SA) and
range code signals in GLONASS and provide position information in latitude and
longitude World Geodetic System (WGS) 84 co-ordinates in degrees, minutes and
thousandths of minutes. Means may be provided to transform the computed position
into data compatible with the datum of the navigational chart in use. Where this
facility exists, the display and any data output should indicate that the
co-ordinate conversation is being performed and should identify the co-ordinate
system in which the position is expressed;
.1.2 operate on the L1 frequency signal and C/A code in GPS and L1
frequency signal and range code in GLONASS;
.1.3 be provided with at least one output from which position information
can be supplied to other equipment. The output of position information should be in
accordance with the relevant international standard;*
.1.4 have static accuracy such that the position of the
antenna is determined to within 35 m (95%) in non-differential mode and 10 m (95%)
in differential mode with horizontal dilution of precision (HDOP) < 4 or position
dilution of precision (PDOP) < 6;
.1.5
have dynamic accuracy such that the position of the ship is determined to within 35
m (95%) in non-differential mode and 10 m (95%) in differential mode with HDOP <
4 or PDOP < 6 under the conditions of sea states and ship's motion likely to be
experienced in ships ; **
.1.6 be capable
of selecting automatically the appropriate satellite transmitted signals for
determination of the ship's position with the required accuracy and update rate;
.1.7 be capable of acquiring satellite
signals with input signals having carrier levels in the range of -130 dBm to -120
dBm. Once the satellite signals have been acquired the equipment should continue to
operate satisfactorily with satellite signals having carrier levels down to -133
dBm;
.1.8 be capable of acquiring
position to the required accuracy, within 30 min, when there is no valid almanac
data;
.1.9 be capable of acquiring
position to the required accuracy, within 5 min, when there is valid almanac data;
.1.10 be capable of re-acquiring
position to the required accuracy, within 5 min, when all GPS and GLONASS signals
are interrupted for a period of at least 24 h, but there is no loss of power;
.1.11 be capable of re-acquiring position
to the required accuracy, within 2 min, when subjected to a power interruption of 60
s;
.1.12 be capable of re-acquiring an
individual satellite signal and utilizing it in the position solution within 10 s
after being blocked for 30 s;
.1.13
generate and output a new position solution at least once every 1 s;
.1.14 have a minimum resolution of
position, i.e. latitude and longitude of 0.001 min; and
.1.15 have the facilities to process DGPS and DGLONASS data
fed to it, in accordance with Recommendation ITU-R M.823 and the appropriate RTCM
standard.
*IEC 1162 Publication **Resolution A.694(17); IEC 721-3-6, IEC 945
and IEC 1108-3 Publications