Rod, The new narrowbanding initiative simply changes the emission designator from 16K0F3E for a conventional analog system to 11K0F3E. The first four characters in the emission designator provide information about the necessary bandwidth of the signal. The 16K0 means 16 kHz, and is the sum of twice the highest modulating frequency (3 kHz) and twice the peak deviation (5 kHz). Thus, (2 x 3) + (2 x 5) = 16 kHz, expressed as 16K0.
The new narrowband channels have the same maximum modulating frequency of 3 kHz, but now are limited in deviation to one-half of the previous limit or 2.5 kHz. Thus, (2 x 3) + (2 x 2.5) = 11 kHz, expressed as 11K0. In the new narrowband scheme, voice, tone, and data deviations are half of their previous values. PL (CTCSS) tones must now be set for 250 Hz deviation, vice 500 Hz, in order that the voice plus tone deviation remain within the 2.5 kHz limit. This also means that paging tones must also be reduced in amplitude. However, I have tested a few pagers and found that the majority of them are sensitive enough to decode the tones even when the amplitude is reduced. Before changing out all of your pagers, run some bench tests to see if they can reliably decode the paging tones when the tones are reduced in deviation to stay within the 2.5 kHz limit of 11K0F3E emissions. If the RF frequency remains the same, you may not have to do anything to your pagers. When you buy new pagers, get the narrowband models, but for now you may be okay. Test every one of your existing pagers before making a decision to replace them. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, February 17, 2008 9:09 AM To: [email protected] Subject: [Repeater-Builder] Wide Band / Narrow Band Our local fire, police and ambulance departments are going to Narrow Band per the FCC. I was told by one fire department that their pagers will only work one narrow band. Now this guy must be talking about the tones for the pagers? But to me wide or narrow the tones are the same. Right? Going narrow just means that they are taking up less of the band width for their frequency? He also said that scanners will not be able to listen to them unless the scanner is set up for narrow band. His wife gave me her nice Uniden BC-895XLT scanner because her husband told her the same thing. Some one who is in the know would like to fill us in on the topic. All EMS departments will be narrow band by April, in our area; from what he said. Rod
