Unauthorized Signal Detection And Information Loss Vulnerability Assessment Checklist

1. Is the signal energy mechanical or electromagnetic? Sound energy is mechanical and radio frequency/microwave and optical/laser transmissions are electromagnetic.

2. What is the signal carrier frequency and bandwidth? The bandwidth of speech ranges from 20 Hz to 20 KHz but radio frequency transmitter frequencies can vary tremendously depending on the device. The power of the radiated signal is an important factor in estimating vulnerability to unauthorized signal detection that potentially leads to information loss.

3. What are the intervening materials between the signal source and the receive location? Recognize that signals often take multiple indirect routes in arriving at a destination. Understanding the effect of materials as a function of signal frequency will enhance the accuracy of estimates of the vulnerability component of risk.

4. What is the distance to the nearest point where there is no control over the physical access to internal space? This is the maximum distance of signal security (or conversely the minimum distance of vulnerability) since an adversary could be physically present at that location and not much can be done about it. If signal sources are point sources with energy propagating equally in all directions, the intensity of information-carrying signals scales as the inverse-square with distance (i.e., 1/r2 where r represents distance) in open environments.

5. What is the power of the dominant noise or interfering source in the frequency range of concern? If the transmitted signal power is below the power of the dominant source of noise at the minimum distance of vulnerability at that signal frequency and bandwidth then there is zero vulnerability to information loss from that signal at that distance (and beyond). It is important to evaluate the noise power across the entire signal bandwidth.