Fire Dispatches in 148 Range

[TinEar]

Probably due to some weird propagation, around 2 p.m., I'm hearing fire dispatches on both 148.15 and 148.1375. Both are CAP freqs. One of them is using a warbling tone before dispatching. Caught a box 18-7 but don't think this is anything local. I guess these could be government installation fire departments from somewhere because of the freq range but the CAP freqs are supposed to be reserved nationwide. Nothing I can add up results in a harmonic of a VHF freq in the normal fire department freq range that would wind up at 148. Strange stuff.

Edit: It lasted about 15-20 minutes and then I heard nothing else.

 

[Llwellyn]

Someone could have been rebroadcasting fire dispatches onto the CAP frequencies as part of a drill; we would often crossband repeat (if anyone had the equipment to do so) important comms from other agencies onto our allocated frequency and onto the business frequency some of the members owned so that members with radios that didn't receive out of the HAM bands could still hear. It's hard to find a radio that's CAP/MARS enabled now that doesn't also pick up all of 138-174 but it used to be pretty common for 2m HT's to only do 144-150. We'd also put the ground-ground frequency of the airport onto a 2m FM channel when we were doing airport events so you didn't have to have a separate AM receiver.

 

[TinEar]

Llwellyn, I guess that could explain it. As mentioned, it faded away a short time after I made the post so no telling where the origination point was even if it was a CAP rebroadcast of a local freq. I was hoping to get more of it to try to pin down the location. No such luck. Thanks.

Alan

 

[marylandterpan]

Llwellyn, I guess that could explain it. As mentioned, it faded away a short time after I made the post so no telling where the origination point was even if it was a CAP rebroadcast of a local freq. I was hoping to get more of it to try to pin down the location. No such luck. Thanks.

Alan

What kinda equipment do you have to pin point a radio freq direction or where its comming from ?

 

[TinEar]

What kinda equipment do you have to pin point a radio freq direction or where its comming from ?

It's not done with equipment - at least not equipment like direction finders - that we amateurs can't begin to afford. We pinpoint the location by listening to the message itself - street names perhaps or a Morse callsign that's given to identify the station. Then, using the database at this site, we either look up the callsign to see who it belongs to or do a search using the frequency and possibly PL/DPL tone to see if we can find a match. Sometimes you recognize a location given in the message that helps with the identity.

 

[marylandterpan]

10-4 .. .. ..

 

[ka3jjz]

Actually Tin hams have been doing that for years, with very low power transmitters and directional arrays - it's called foxhunting, and in Europe and other places, there's even a world championship for it. Handheld beams on 2 are a bit big (but manageable - see the Arrow dual band antennas for Satcom), but on 440 they get much smaller. Hams even build homebrew gear (including attenuators and antennas) for just this purpose. However, for stuff like you heard, it would be a little tough because of its transitory nature. If it was a constant thing, 3 or 4 folks in the same general area, each with a beam, could get a rough idea of where the transmitter is located (the more radials are searched the more accurate it can become. Yep, we're talking about triangulation). Without going into too much more detail, this is one method used when someone is fooling around on repeaters that shouldn't be there....'nuff said. 73s Mike

 

[Dank]

Probably due to some weird propagation, around 2 p.m., I'm hearing fire dispatches on both 148.15 and 148.1375. Both are CAP freqs.
Edit: It lasted about 15-20 minutes and then I heard nothing else.

Alan,
For what its worth I too, heard some very weak comms on 148.15 lastnight about 6pm or so. They were too weak to make out but ossib;e more of what your caught.
Dan

 

[trimmerj]

Doesn't the Naval Acadamy have a fire channel in 147 - 150mhz range ?

 

[hill]

Yes, the Naval Academy has a fire dispatch in that range and it is 148.425 Mhz.

Hope this helps,
Larry

 

[TinEar]

Yup...148.425 for fire and 149.0 for police at the Academy. But the signals I heard were from out of the area - at least the dispatches weren't similar to anything local I've heard in the past.

Dan, sounds like maybe you got a piece of what I was hearing on 148.15.