Travelers Information Stations occupy a rarified broadcasting niche that many are completely unaware of. Limited range, programming and choice of frequencies don’t help them and the sound quality is … blech!
The TIS were purposefully hamstrung with a low-quality signal from their beginning in 1977. But the FCC seems to have taken pity upon them with a recent R&O (15-37) and freed them, a little bit, to improve their audio quality. The previous 3 kHz low-pass filter limitation has been lifted and can now be replaced with a more open-ended 5 kHz low-pass filter.
According to Bill Baker at TIS equipment provider Information Station Specialists, it’s the first modification of the original 1977 TIS service specs. Baker notes that the FCC says that this upgrade will allow the TIS to sound more like standard AM stations.
Information Station Specialists is offering its clients a swap out of the stock 3 k filter for a new 5 k filter, which now can be part of the transmitter circuitry or standalone, ahead of the audio input. Baked into the FCC ruling is the waiving of transmitter recertification requirement after the modification.
IIS has also announced that its new TR6000 transmitter systems will come with the upgrade, called by them “TIS-HQ.”