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Main ❯ Navigation & tracking systems ❯ Zima2/Zima USBL: Compatibility information sheet for positioning and heading systems
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Zima2/Zima USBL Compatibility requirements for GNSS |
Compatibility requirements for heading and position determination systems
1. General information
The Zima2 USBL system, like Zima, can convert the coordinates of the responder-beacons from the local polar coordinate system to the geographic one in real time.
For this purpose, the specialized software needs data on the geographic position of the Zima2-B antenna (or Zima-B, in the case of the Zima system) and on its orientation relative to the cardinal directions.
The host software for the Zima2 and Zima systems is not mutually compatible; for details, refer to the user’s manual for the specific system.
Two options are possible:
- The data on the geographic position and orientation of the antenna are generated using a GNSS compass. This option is the most preferable
- The data on the geographic position of the antenna are generated by a GNSS receiver, and the data on its orientation relative to the cardinal directions are generated using a magnetic compass
2. Protocol requirements
The specialized software can connect two additional sources of navigation data via a serial connection. The devices are connected physically either using physical serial ports (COM, if the PC is equipped with them) or using the ports of interface converters RS-232/422/485 <-> USB.
The specialized software supports the NMEA 0183 protocol, and in particular, the following sentence types:
- HDG - Orientation data relative to the cardinal directions (magnetic compass)
- HDT - Orientation data relative to the cardinal directions (GNSS compass)
- RMC - Geographic position data (GNSS receiver)
For correct operation, either the pair of sentences RMC + HDT (provided by a GNSS compass) or RMC + HDG (GNSS receiver and magnetic compass) is required.
If the specialized software receives both types of angular orientation sentences (HDG and HDT), the software will use only the data from the HDT sentences.
3. Accuracy and update rate requirements
The accuracy of the GNSS receiver must be no worse than 2.5 m (2DRMS), and the update rate of the geographic position data must be at least 1 update per second.
Recommended accuracy of the orientation readings relative to the cardinal directions: 1° (DRMS), at an update rate of 5 Hz.
Navigation data sources with lower accuracy may be used, but keep in mind that the error, especially in determining the angular orientation, is ultimately carried over to the calculated position of the responder-beacons: the errors in determining the angle of arrival of the signal of the responder-beacon and in determining the antenna orientation relative to the cardinal directions using a magnetic or GNSS compass are summed.