Today there are a few existing challenges in ocean resource development in the field of navigation and positioning, such as:
- There is no alternative to hydroacoustic;
- A word “navigation” implies “connection + time measurement”;
- Low speed of wave propagation in the environment (~1500 mps):
- Significant delays;
- Route complexity and difficulties in subscriber synchronisation;
- Excessively lengthy system reaction to it’s change;
- A narrow available band of frequencies.
There are three types of navigation systems using long baseline (LBL), short baseline (SBL) and ultrashort baseline (USBL). The description of each and every one of them, their comparison and a brief introduction to our developments are listed below.
Long Baseline Navigation System. The length of the navigation base exceeds the trajectory of the positionable object.
|
What gets measured |
Merits |
| Propagation time (synchronised watch or a request-response method) | The accuracy is higher when compared to other types |
| Difference in time of arrival of signals | There is a possibility to provide an unlimited amount of passive receivers with coordinates |
| The option of having both bottom and above-water base with geolocation and GNSS synchronisation |
Our long baseline underwater acoustic navigation system RedWAVE was developed to provide navigational data (absolute geographical coordinates and depth) for various underwater objects in a submerged state: remotely operated underwater vehicles (ROV), manned submersibles, autonomous underwater vehicles (AUV), as well as divers (in case of using instruments in a version for divers).
Short Baseline Navigation. The length of a navigation base corresponds with the trajectory of the positionable object (base elements often kinematically related).
|
What gets measured |
Merits |
| Propagation time (synchronised watch or a request-response method) | Ease of use |
| Difference in time of arrival of signals | Easy to install on a vessel |
| The accuracy is higher than an USBL | |
| Allows to simultaneously provide an unlimited number of passive receivers with coordinates |
We have currently developed and offer our Customers Engineering Support, that includes full assistance and support of underwater works using a specialised short baseline underwater navigation complex that allows to determine position and orientation of our Customer’s equipment. The service includes provision of specialised navigation equipment along with the work of our engineers maintaining and operating the equipment.
Ultra Short Baseline Navigation. The length of the navigation base is significantly less than the trajectory of the positionable object.
|
What gets measures |
Merits |
| Propagation time (synchronised watch or a request-response method) | Ease of use |
| Horizontal angle of signal arrival and Rx-Tx depth difference | Small equipment kit |
| Horizontal and vertical angles of signal arrival | Price |
Our invention – Zima Navigation System is an Ultra Short Baseline Navigation System (USBL) with the principle of operation based on the use of a phased array antenna for determining the horizontal angle of arrival of a signal and determining the distance to the beacon by the “request-response” method.
Types of Navigation Systems: where and whichever one to apply?
| Long Baseline | Short Baseline | Ultra Short Baseline |
| If positioning is required | Positioning in technical basins | If speed and easy deployment is required |
| If there is a need for maximum accuracy with a peg to geography | When there is an option of fixing base elements and identifying their relative position | If there is a need for closing in on a target checking with it progressively |
| If simultaneous positioning of an unlimited or a significant number of objects with a similar to GNSS coordinate on each of the objects is required | If it is difficult or impossible to install a Long Baseline, and a USBL yields insufficient results in terms of required accuracy | If a coordinate is required on a tracking station (the location of a direction-finding aerial) |
| If it is possible to equip a vessel with Baseline elements | If only a relative position is required |
If you still have questions after reading this article, please leave them in the comments below.