Frequency Question, Having Trouble Figuring It Out...

[btritch]

My local Fire Department have always used 154.145 as an output repeater channel and 151.370 as an input repeater channel, To my knowledge this is the ONLY channel they use for dispatch and operations, it's the only channel I know of that they use...However, Strangly and oddly enough, Last night I picked them up on a new frequency while searching, A house fire was toned out, it came across output frequency of 148.595 (which I didn't think was even the same band range), Is it that this could be to frequency that sets off their pagers? Or maybe they've aquired a new channel? Strange thing though, When the tone came over, I heard it loud and clear on the above new channel, But my PSR 500 here at home records all of the traffic on that channel and it never recorded the tone, It picked up when they acknowledged that they were en route, it didn't even pick up the voice part on the 154.145 but it did on the 148.595 one...can anyone explain this new phenomenon on why this happened? Could it have been this is their private channel that is not realeased to the public, I know they have one along with other FD's and PD's in the county..Can anyone shed any light on this, Does anyone know what could or what might have been or happened? 'preciate any help anyone can give or advice also..

Thanks!

 

[zz0468]

The 148 MHz range above the ham band is allocated to Federal and military use. It's likely that you're hearing either an intermod, or an image.

 

[af5rn]

The 148 MHz range above the ham band is allocated to Federal and military use. It's likely that you're hearing either an intermod, or an image.

Agreed. There is some obscure off chance that some federal agency is simulcasting your local fire for interoperability, but I seriously doubt it. Ninety-nine point nine percent chance it's an image.

 

[SAR923]

Hmmm...5.550 Mhz down from the normal frequency. What scanner were you using? I'll bet the second IF is somewhere around the frequency difference and you were picking up an image.

 

[btritch]

Older model, RS 2025, Not crazy about it but it picks up what I need in town anyway..

An image, That far down the band, If I were in front of the PD where it was dispatched or in front of the FD where it was recived I might see but I wasn't, I was about 4 miles from either...It was hard to believe they were that low down but I guess all things are possible. Guess I should start monitoring it all the time and see what I get huh?

 

[af5rn]

Yeah, most images I have received were coming from nowhere near my immediate location. As I recall, I used to receive 403mhz government band comms on images up in the 482mhz range.

 

[btritch]

Ok, I'm going to assume that's that is what it was, Until I find out otherwise, LOL, As long as I'm hearing their traffic on the old usual frequency I'm not going to make any assumptions but if they stop using the old one then I'll wonder, Thanks everyone for the help, It had me puzzled, I had heard of images before but I'd never gave that a thought being that far away on the spectrum...Thanks again everyone, I appreciate it a lot!

 

[af5rn]

Yeah, don't confuse images with simple bleedover. Images can and do occur far, far away from the actual frequency, and are quite clear, sounding like they are on-frequency. Bleedover is a more local phenomenon, occurring very close to the actual frequency.