272
14 Pseudo-Ranging Radio Navigation Systems
if the receiver has special built-in technology to eliminate impulse interference. The
range reaches 500 km.
The logic of the operation is to provide increased accuracy by using a reference
GNSS receiver (base station), located at a point with known coordinates by comparing
the coordinates of a known location with what is received. Then satellite corrections
are calculated and transmitted in real time on the frequencies assigned by the UMAS
to nearby users.
Traditionally, the differential subsystem includes:
Unified Measurement Acquisition Stations, which control the quality of relayed
signals by means of a geodetic reference station. UMAS are designed with redundant
configuration, which guarantees its reliability and autonomy in case of failures and
disturbance.
A processor that calculates differential corrections and generates data for transmission to the user. The generated correction files can contain data from the receiving
station and frequency and time standards.
Equipment for transmission of differential corrections (transmission is most often
carried out “directly” from the UMAS).
Receiving equipment of users, providing reception and accounting of differential
corrections (as a rule, combined with ship’s GNSS equipment).
The UMAS includes the following components:
• two reference stations [main and backup sets (OS)] for determining differential
corrections and generating corrective information;
• computer for remote control and operational monitoring of the UMAS state;
• two integrity monitors (main and backup sets of integral control station (ICSt);
• access control equipment;
• differential amendments transmitter;
• communication system (Ethernet, RDSI, GSM or Inmarsat) and uninterruptible
power supply;
• checkpoint (CP).
The main task of the control point (CP) is to monitor the operation (maintenance)
of Unified Measurement Acquisition Stations, communication lines (RDSI, GSM or
Inmarsat) between them and the CP and a special data transmission channel (GIC—
GPS integrity channel). As well as ensuring the integrity of observations of satellite
radio navigation systems, the formation of integrity data for transmission to users.
Through a combination of satellite positioning systems, electronic cartography,
communications systems and open information systems architecture, the maritime
electronics industry has developed a navigation device called the Universal Automatic Identification System (UAIS) or simply Automatic Identification System
(AIS).
An automatic identification system is mandatory for ships over 300 tons,
including passenger ships, regardless of tonnage.
AIS stations exchange data with each other on two VHF channels. All AIS stations
separate transmissions by time. AIS stations use internal GNSS receivers as a source
of synchronization and uniform time.
14 Pseudo-Ranging Radio Navigation Systems
if the receiver has special built-in technology to eliminate impulse interference. The
range reaches 500 km.
The logic of the operation is to provide increased accuracy by using a reference
GNSS receiver (base station), located at a point with known coordinates by comparing
the coordinates of a known location with what is received. Then satellite corrections
are calculated and transmitted in real time on the frequencies assigned by the UMAS
to nearby users.
Traditionally, the differential subsystem includes:
Unified Measurement Acquisition Stations, which control the quality of relayed
signals by means of a geodetic reference station. UMAS are designed with redundant
configuration, which guarantees its reliability and autonomy in case of failures and
disturbance.
A processor that calculates differential corrections and generates data for transmission to the user. The generated correction files can contain data from the receiving
station and frequency and time standards.
Equipment for transmission of differential corrections (transmission is most often
carried out “directly” from the UMAS).
Receiving equipment of users, providing reception and accounting of differential
corrections (as a rule, combined with ship’s GNSS equipment).
The UMAS includes the following components:
• two reference stations [main and backup sets (OS)] for determining differential
corrections and generating corrective information;
• computer for remote control and operational monitoring of the UMAS state;
• two integrity monitors (main and backup sets of integral control station (ICSt);
• access control equipment;
• differential amendments transmitter;
• communication system (Ethernet, RDSI, GSM or Inmarsat) and uninterruptible
power supply;
• checkpoint (CP).
The main task of the control point (CP) is to monitor the operation (maintenance)
of Unified Measurement Acquisition Stations, communication lines (RDSI, GSM or
Inmarsat) between them and the CP and a special data transmission channel (GIC—
GPS integrity channel). As well as ensuring the integrity of observations of satellite
radio navigation systems, the formation of integrity data for transmission to users.
Through a combination of satellite positioning systems, electronic cartography,
communications systems and open information systems architecture, the maritime
electronics industry has developed a navigation device called the Universal Automatic Identification System (UAIS) or simply Automatic Identification System
(AIS).
An automatic identification system is mandatory for ships over 300 tons,
including passenger ships, regardless of tonnage.
AIS stations exchange data with each other on two VHF channels. All AIS stations
separate transmissions by time. AIS stations use internal GNSS receivers as a source
of synchronization and uniform time.