Fundamentals of Surveying (FS) Practice Exam

Which advantage is associated with dual-frequency receivers compared to single-frequency receivers?

1. lower PDOP values

2. ability to track a greater number of satellites

3. fewer errors due to atmospheric effect

4. fewer ephemeris errors

The correct answer is: fewer errors due to atmospheric effect

Dual-frequency receivers offer significant advantages primarily in terms of signal processing, particularly when it comes to mitigating errors caused by the atmosphere. The core benefit of using dual-frequency technology is that it can utilize both L1 and L2 frequencies, which allows for more accurate correction of ionospheric delay. Ionospheric delay occurs because signals from satellites travel through the ionosphere, which can slow them down and vary based on the day's conditions. By simultaneously receiving signals at two different frequencies, the receiver can calculate the delay experienced by each frequency and thus remove the ionospheric error more effectively. This results in improved positioning accuracy compared to single-frequency receivers, which cannot make such corrections and are more susceptible to atmospheric interference. While lower PDOP values, the ability to track a greater number of satellites, and fewer ephemeris errors could suggest advantages, they are not inherent benefits of dual-frequency technology. The focus on dual frequencies primarily addresses the atmospheric errors, making this option the most relevant advantage associated with dual-frequency receivers.