1 INTRODUCTION
1.1 The Global Navigation Satellite System (GLONASS) is a space-based
positioning, velocity, and time system that has three major segments: Space, Control
and User. The GLONASS Space Segment, will normally be composed of 24 satellites
placed in three orbital planes with eight satellites in each plane. The satellites
operate in circular 19,100 km orbits at an inclination angle of 64.8° and with an 11
h and 15 min period. The spacing of satellites in orbit will be arranged so that a
minimum of four satellites will be in view to users world-wide, with a position
dilution of precision (PDOP) of <6. Satellites of the system transmit signals on
"L" band frequencies. Each satellite has separate lettered frequencies L1 (1602,
5625-1615.5 MHz).
1.2 Each L1 frequency carries a code standard accuracy (C), which is
used in shipborne GLONASS receiver equipment. A navigation data message is
superimposed on this code.
1.3 Receiver equipment for the GLONASS intended for navigational
purposes on ships with maximum speeds not exceeding 70 knots should, in addition to
the general requirements contained in resolution A.694(17)footnote, comply with the following minimum performance
requirements.
1.4 These standards cover the basic requirements of position-fixing for navigation
purposes only and does not cover other computational facilities which may be in the
equipment.
2 GLONASS RECEIVER EQUIPMENT
2.1 The words "GLONASS receiver equipment" as used in these performance
standards include all the components and units necessary for the system to properly
perform its intended functions. The equipment should include the following minimum
facilities:
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.1 antenna capable of receiving GLONASS signals;
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.2 GLONASS receiver and processor;
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.3 means of accessing the computed latitude/longitude
position;
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.4 data control and interface; and
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.5 position display and, if required, other forms of output.
2.2 The antenna design should be suitable for fitting at a position on
the ship which ensures a clear view of the satellite constellation.
3 PERFORMANCE STANDARDS FOR GLONASS RECEIVER EQUIPMENT
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The GLONASS receiver equipment should:
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.1 be capable of receiving and processing the Standard
Positioning Service (SPS) signals of the GLONASS system and provide position
information in latitude and longitude PZ-90 co-ordinates in degrees, minutes
and thousandths of minutes and time of solution referenced to UTC (SU).
Means should be provided to transform the computed position based upon PZ-90
into WGS-84 or into data compatible with the datum of the navigational chart
in use. Where this facility exists, the display should indicate that the
co-ordinate conversion is being performed and should identify the
co-ordinate system in which the position is expressed;
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.2 operate on the Standard Positioning Service (on lettered L1
frequencies and C code);
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.3 be provided with at least one output from which position
information can be supplied to other equipment. The output of position
information based upon PZ-90 or WGS-84, should be in accordance with
international standards;footnote
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.4 have static accuracy such that the position of the antenna is
determined to within 45 m (95%) with horizontal dilution of position (HDOP)
= 4 (PDOP = 6);
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.5 have dynamic accuracy such that the position of the antenna
is determined to within 45 m (95%) with horizontal dilution of position
(HDOP) = 4 (PDOP = 6) under the conditions of sea states and ship’s motion
likely to be experienced in ships;footnote
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.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;
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.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 signal having carrier levels down to -
133 dBm;
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.8 be capable of acquiring position to the required accuracy,
within 30 min, when there is no valid almanac data;
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.9 be capable of acquiring position to the required accuracy,
within 5 min, when there is valid almanac data;
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.10 be capable of re-acquiring position to the required accuracy,
within 5 min, when the GLONASS signals are interrupted for a period of at
least 24 h, but there is no loss of power;
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.11 be capable of re-acquiring position to the required accuracy,
within 2 min, when subjected to a power interruption of 60 s;
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.12 generate and output to a display and digital interfacefootnote a new position solution at least once every 1
s;footnote
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.13 have a minimum resolution of position, i.e. latitude and
longitude of 0.001 minutes;
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.14 generate and output to the digital interfacefootnote course over the ground (COG), speed over the
ground (SOG) and universal time co-ordinated (UTC). Such outputs should have
a validity mark aligned with that on the position output. The accuracy
requirement for COG and SOG should not be inferior to the relevant
Performance Standards for Headingfootnote and SDME;footnote
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.15 have the facilities to receive and process differential
GLONASS (DGLONASS) data fed to it in accordance with the standards of
Recommendation ITU-R M.823. When a GLONASS receiver is equipped with a
differential receiver, performance standards for static and dynamic
accuracies (paragraphs 3.4 and 3.5 above) should be 10 m (95%);footnote and
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.16 be capable of operating satisfactorily in typical
interference conditions.
4 PROTECTION
Precautions should be taken to ensure that no permanent damage can
result from an accidental short circuit or grounding of the antenna or any of its
input or output connections or any of the GLONASS receiver equipment inputs or
outputs for a duration of 5 min.
5 FAILURE WARNINGS AND STATUS INDICATIONS
5.1 The equipment should provide an indication if the position
calculated is likely to be outside of the requirements of these performance
standards.
5.2 The GLONASS receiver equipment should provide as a minimum:
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.1 an indication within 5 s if either:
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.1.1 the specified HDOP has been exceeded; or
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.1.2 a new position has not been calculated for more than 1
s.footnote
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Under such conditions the last known position and the time of
the last valid fix, with explicit indication of this state, so that no
ambiguity can exist, should be output until normal operation is resumed;
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.2 a warning of loss of position;
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.3 differential GLONASS status indication of:
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.3.1 the receipt of DGLONASS signals; and
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.3.2 whether DGLONASS corrections are being applied to the
indicated ship's position;
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.4 DGLONASS integrity status and alarm; and
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.5 DGLONASS text message display.