453.537 MHz

Joseph11 · #1 (**permalink**) 02-04-2005, 06:59 AM

I was searching the 453.xxx MHz range today and found police or public works operating on 453.537 MHz. I looked on the Internet, RR, and the FCC database and found no information about this frequency. All transmissions begin with DTMF tones. Does anyone know what this is? I am in the Beachwood/Toms River, NJ area.

EDIT: I just heard someone play a 8 or 9 tone song on 453.537 MHz, it sounds familiar, but I can't remember what it is.

DJ88 · #2 (**permalink**) 02-04-2005, 07:19 AM

The frequency is actually 453.5375. The last number doesn't register on the older scanners, but you still receive it. Per the FCC Database, it is licensed to:

Montville Twp. Board of Fire Commissioners
Freehold Twp. Dept. of Public Wotks
N.J. Department of Corrections, Cumberland County
Raritan Twp. Fire
Union County

You are probably getting Freehold Twp. Public Works.

Joseph11 · #3 (**permalink**) 02-04-2005, 07:28 AM

Oh, Thanks.

kb2vxa · #4 (**permalink**) 04-30-2005, 01:38 PM

Hi DJ88 and all,

"The frequency is actually 453.5375. The last number doesn't register on the older scanners, but you still receive it."

Yes and no, let me explain for the benefit of the newbies. The frequency is the closest the PLL can manage but in any case the last digit would be 5 except for the display error. 5kHz increments is the best the PLL can divide the frequency of the master injection oscillator. In this case "center frequency" would be .535 but for the IF offset. Confusing? Not really, since the IF won't track between VHF and UHF if the signal were centered it's offset a bit and the passband is wide enough to accept it. The IF signal is shifted in the passband one way for VHF Lo and Hi, then shifted the opposite way for UHF because the on air frequencies are allocated likewise.

For what it's worth most passbands are 14kHz wide which doesn't afford very good adjacent channel rejection so if bleed over is a problem just program 5kHz up or down to get away from the other signal.

DJ88 · #5 (**permalink**) 04-30-2005, 05:12 PM

That was probably a very good explanation, however I have no idea what you were talking about as I, and some others who visit these boards, are not as highly versed in radio technology as you are. What little I do know is plenty enough for me to enjoy the hobby. I program the frequencies and listen, whether or not they have a 5 at the end.