Detailed Explanation

EDM operates based on the principle of measuring distance by calculating the time it takes for a signal (commonly a laser or radio wave) to travel to a target and back. The device sends out a specific frequency of light or radio waves, which hits the target and reflects back to the device. By multiplying the time taken by the speed at which the signal travels, the device can calculate the precise distance to the target. This method provides accurate distance measurements necessary for surveying and understanding land features.

Detailed Explanation

1. Infrared EDM uses infrared light which is less affected by environmental conditions but has a limited range. 2. Laser EDM uses focused laser beams for high precision over long distances but can be disrupted by rain or fog. 3. Microwave EDM utilizes radio waves which can penetrate through obstacles like trees better than light-based methods. The choice of EDM type depends on the specific survey requirements and environmental conditions.

Detailed Explanation

1. The theodolite measures angles in the horizontal and vertical planes. 2. The EDM measures distance to the target. 3. The microprocessor processes and calculates data from both measurements. 4. The display/interface allows the user to input data and read measurements. 5. Data storage saves the calculations and settings for later use, facilitating efficient survey data management.

Detailed Explanation

A Total Station allows surveyors to measure horizontal angles to determine directions and vertical angles to calculate elevation changes. Combined with distance measurements, these angles can be used to create precise maps and models of the land. This data is essential for various applications like construction, where accurate site plans are critical.

Detailed Explanation

1. Ellipsoid simplifies the Earth's varied shape into a smooth, mathematical form useful for calculations. 2. Geoid accounts for gravitational variances; it is more complex than the ellipsoid and reflects actual sea levels. 3. Mean sea level serves as the baseline for measuring elevations and is influenced by tides and atmospheric pressure.

Detailed Explanation

GNSS provides unparalleled accuracy for navigation and positioning across the globe, making it useful for many applications. However, GNSS can be affected by environmental factors such as weather, tall buildings (urban canyons), and situations where satellite signals are obstructed. This dependency poses challenges in infrastructure and areas without line-of-sight to satellites.

Detailed Explanation

L1 is the first frequency used (1.57542 GHz) primarily for civilian applications. L2 (1.2276 GHz) is used mainly for military purposes but is also available for high-precision users. L5 (1.17645 GHz) provides enhanced accuracy and safety features for critical systems such as aviation.

Detailed Explanation

Initialization is crucial because it allows GNSS equipment to accurately determine its position by comparing the measurements from a stationary base station to establish corrections. The base station broadcasts this information to other GNSS receivers to enhance their accuracy significantly using differential correction methods.

Detailed Explanation

1. Ephemeris refers to the satellite's precise orbit information. 2. Epoch is a specific time instance for data collection. 3. Dual-frequency receivers can receive signals from multiple frequency bands for better accuracy. 4. PRN is a unique identifier for each satellite signal. 5. Selective Availability was a practice to intentionally degrade civilian GPS accuracy. 6. Carrier Phase relates to signal measurement for high accuracy positioning.

Detailed Explanation

In static GNSS surveying, the receiver remains at a single location for an extended period to gather data, which enhances precision due to the averaging of satellite signals. Kinematic GNSS surveying involves moving the receiver, which continuously collects data in real-time, useful for applications like vehicle navigation.

Detailed Explanation

GDOP (Geometric Dilution of Precision) assesses overall satellite positioning quality. PDOP (Position Dilution of Precision) measures positional accuracy, while HDOP (Horizontal Dilution of Precision) and VDOP (Vertical Dilution of Precision) assess horizontal and vertical positioning accuracy respectively. Lower values indicate better accuracy.

Detailed Explanation

Receiver clock errors arise from inaccuracies in the local device's timekeeping compared to satellite clocks. Orbital errors stem from satellite position discrepancies, and environmental factors like buildings or trees can cause multi-path errors as signals reflect off surfaces before reaching the receiver. Atmospheric conditions also introduce delays in signal transmission.

Detailed Explanation

By using a network of stationary base stations at known locations, differential correction identifies and relays adjustment information to mobile units. This greatly enhances positional accuracy by correcting signal errors resulting from atmospheric interference or signal obstructions.

Detailed Explanation

SBAS works by receiving GNSS signals and transmitting correction messages to improve accuracy and reliability. By supplementing information on atmospheric conditions and satellite positioning, it provides users with more precise navigation options.