Question T3A10
From subelement T3 - T3A
What effect does multi-path propagation have on data transmissions?
Why is this correct?
Multipath propagation causes signals to arrive via different paths with varying delays, causing them to interfere with each other at the receiver. This interference corrupts the digital data stream, leading to increased error rates. Options A and B incorrectly suggest simple rate adjustments solve the problem, while option C is wrong because FM modulation doesn't eliminate multipath interference effects on digital data.
Memory tip
Digital signals require precise timing and amplitude relationships. When multipath creates overlapping signals with different arrival times, it destroys these critical relationships. Look for 'interference' or 'corruption' concepts when multipath affects digital modes.
Learn more
Digital modes depend on precise signal characteristics for accurate data recovery. When multipath propagation creates multiple signal copies arriving at different times, these overlapping signals interfere destructively with the intended data stream. This is why digital emission standards often include error detection and correction protocols. Understanding this principle helps explain why packet radio and other digital modes perform better with strong, stable signals and why some digital protocols are designed to be more resilient to multipath environments.
Think about it
Why do you think multipath propagation affects digital transmissions more severely than voice communications, and what design features might make some digital modes more resistant to these effects?