Technical Content Alert!!! The rule changes discussed below are highly technical. If you’re OK with stuff like “attenuation [must be] greater than the attenuation at 1 kHz by at least: 60 log10(f/3) decibels, where ‘f’ is the audio frequency in kHz”, you should have no problem. Others should proceed with caution.
A couple of years ago we reported on a number of changes made by the FCC to its rules governing Travelers' Information Stations (TIS), the first changes to the TIS rules since TIS were established in 1977. Now those changes have been tweaked, although not as much as some might have liked.
As noted above, the tweaks are highly technical, so much so that we won’t go into detail here. (There's a reason we chose law school rather than a career in engineering.) TIS cognoscenti should take a close look at the FCC’s decision for the real nitty-gritty. To summarize:
The filtering requirement for TIS has been changed from 3 kHz to 5 kHz. The expectation is that this should improve the quality of TIS signals to match commercial AM station signals – but TIS operators who might prefer, for whatever reason, to continue to use 3 kHz filters may do so. (The Commission declined to eliminate the filtering requirement entirely.)
The roll-off curve relative to signal attenuation has been adjusted in light of the changed filtering requirement.Continue Reading...