Electromagnetic Interference from Wind Turbines - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 570

Figure 9-18. Thresholds of perception of simulated TVI by a HAWT on channels 7 and
50, for two types of receivers. [data from Sengupta and Senior 1978, 1979a].
Figure 9-19 shows the long- and short-term tolerances of test subjects to backward-zone
TVI with Receiver A, again with signals on Channels 7 and 50. Simulation tests like these
indicate that there is no single value of the modulation perception index that is applicable
to all signal levels in both the backward and forward interference zones of a HAWT.
However, the long-term tolerance index of the dominant backward-zone interference is
almost constant at 0.15. Therefore, this is the value recommended for the boundary of the
entire region about a HAWT, within which unacceptable video distortion may occur.
Figure 9-19. Tolerance levels for simulated TVI in the backward zone of a HAWT. A
long-term modulation tolerance of 0.15 is indicated. [Sengupta and Senior 1978, 1979a]