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A short class with Sarah and her students. The other ways are under More.
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Today, we will start discussing shore-based methods for position fixing. Can anyone tell me what they think this might involve?
Does it involve using landmarks on the shore?
Exactly! These methods use fixed points on land to help determine the location of a vessel. One common method is using range and bearings. Can someone tell me how range and bearings work?
Isn't range the distance from the shoreline? And bearings would be the angles from those landmarks?
Correct! We use the combination of both to pinpoint a vessel's position. Remember the acronym RB for Range and Bearings. Any questions about that?
What if there are no visible landmarks?
Great question! That's where intersecting lines of sight and horizontal sextant angles come in. They help surveyors establish position even without visible landmarks. Let's recap: we learned that shoreline methods can utilize fixed land points to determine a ship's location using RB, intersecting lines of sight, and sextant angles.
Moving on, let's discuss radio and satellite methods. Who here has heard of DGPS?
I've heard it gives better accuracy than regular GPS!
That's right! DGPS uses fixed ground-based stations to correct GPS signals. This offers significantly improved accuracy. Can anyone explain how RTK-GPS differs?
RTK-GPS uses the phase of the signal for even higher accuracy, right?
Exactly! RTK-GPS can provide centimeter-level accuracy, making it ideal for detailed surveys. Remember the phrase 'Real Time, Kinematic Precision' to recall these key features. Any further questions?
What about total stations? How do they fit into this?
Excellent point! Total stations with prisms on boats are used for close surveys to measure distances and angles precisely. To summarize, we discussed how DGPS and RTK-GPS enhance position fixing accuracy, and how total stations can be utilized in nearshore environments.
Utilizing fixed land points for determining vessel positions.
Advanced systems enhancing the accuracy of GPS signals.
Uses reference stations for improving GPS accuracy.
Provides high precision positioning through signal phase measurements.
Fixing positions with ranges and sights, ensures our vessels navigate right.
Imagine a captain using landmarks to chart a course at twilight, willing to sail safely home guided by stable, sound measures.
Remember R D S for Range, Bearings, and DGPS when fixing positions.
SBR: Shore-based methods, Bearings, and Radio methods for position fixing.
Term
What is DGPS?
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Term
Define RTK-GPS.
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The distance from a known point on land to a vessel or survey equipment.
The angle between a reference direction and a line to an object or location.
An enhancement to GPS that provides improved location accuracy using ground-based reference stations.
A GPS technique that uses signal phase measurements to provide highly accurate location data in real-time.
An optical/electronic instrument used to measure distances and angles for surveying.
Position fixing techniques are essential methods used in hydrographic surveying to determine the precise locations of sounding points.
This section discusses various techniques for fixing positions in hydrographic surveys, including shore-based methods like range and bearings, and advanced radio and satellite methods such as Differential GPS (DGPS) and Real-Time Kinematic GPS (RTK-GPS). Accurate position fixing is critical for creating precise maps of underwater features.
Position fixing techniques are vital in hydrographic surveying for ensuring the accuracy of data collected. Accurate positioning allows for reliable mapping of underwater features essential for navigation and construction. The main categories of position fixing techniques include:
By utilizing these position fixing techniques, hydrographic surveyors can achieve a high level of accuracy, ensuring the integrity of nautical charts and supporting safer maritime navigation.