In determining the direction to an emitter, what does the RSDS compare?

In the context of the RSDS (Radio Signal Directional System), the correct choice focuses on how the strength of the signal is integral to determining the direction to an emitter. The directional capabilities of the RSDS rely significantly on measuring the strength of signals received from multiple angles. By analyzing variations in signal strength, it can be determined which direction the emitter is located, as stronger signals typically indicate proximity and directionality of the source.

This method leverages the principle that signals attenuate over distance and obstacles, resulting in a measurable difference in the received signal strength from various directions. Therefore, the RSDS utilizes this comparative strength to triangulate or pinpoint the location of the emitter effectively.

The other options do not directly provide the necessary comparison for determining directionality. For instance, while speed, time of arrival, and frequency might play roles in different communications or radar systems, in this specific context of RSDS, signal strength is the pivotal factor that enables accurate directional determination.