How narrowbanding will affect your scanner listening:
Narrowbanding, required by Jan 2013, will reduce transmission widths to 12.5 KHz efficiency technology (about 11 KHz total deviation above and below the center frequency) as opposed to the 25 KHz efficiency technology currently allowed. Once an agency is narrowbanded, a transmission’s “volume level” or modulation will sound too low on a receiver that is still set to listen to that frequency as a standard FM channel because half of what the scanner wants to hear is no longer there. On older scanners, like the first generation trunk trackers, there is nothing you can do about that, as there is no narrowband setting. But newer scanners will have a narrowband setting called NFM mode. By switching that frequency to NFM you will “perk up” the volume of that frequency to the range you are used to.
A frequency being monitored in NFM mode that receives a standard FM transmission might sound odd to you. It might sound clipped or lack full vocal range since it is not receiving the complete modulation of that signal. Something else to be aware of is the wideband setting on scanners or WFM mode. WFM should not be confused with the current standard (FM). WFM is an even wider flavor of FM used only by broadcasters. A FM transmission being received in WFM will sound quieter. And a NFM transmission being received in WFM mode will sound extra, extra quiet.
It is possible that not all agencies operating on a specific frequency that you monitor will narrowband at the same time. If that is the case, your listening may become a bit of a roller coaster for the rest of the year but hopefully more like the Whizzer than the Eagle. But some transmitters that you are used to hearing at a certain powerhouse volume are going to lose their punch. A smaller bandwidth coupled in some cases with less ERP (effective radiated power) will result in some dispatch centers simply no longer sounding as clear to you. Hopefully those agencies will still have good coverage within the area they are responsible for.
One benefit to the changeover is that conforming to the new standard has motivated some dispatch centers to add a repeater. In those cases, if you are close enough hear the repeater; you’ll also be able to hear the rig traffic. Some repeaters will pop up on the channels you are already listening to, while other newly allocated repeater pairs will go live.
Joining the Chicago Area Radio Monitoring Association is a great way to find out about new developments in the world of Chicagoland fire radio. Joining is as simple as signing up for their free Yahoo Group. There is a link to that and to their frequency database (called profiles) on the CARMA website at www.carmachicago.com An excellent list of the current face of Chicagoland fire radio is available at http://plaws.net/scan/IL/chi-fire.html
Happy monitoring!
Dave
Live Fire/Emergency Radio Stereo Mix
Chicago & 36 neighboring counties
