An active noise cancellation system has a speaker which is utilized to generate sound to cancel engine noise, as is known. In many embodiments, reference memory corresponding to the data memory is used to determine whether to refresh the data memory. The change in appearance of the temperature-indicating element indicates to the operator of the device a temperature condition at the working end of the device. The second pole has at least one detent proximate a connecting end sized to releasably engage with a plunger on the plunger assembly. The ATSC signal detector comprises a matched filter that matches to at least a modulated version of an ATSC field sync signal for detecting the presence of an incumbent ATSC broadcast signal. A set of graphics contexts is provided having fixed associations with the applications.