Signal Blocking

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bwhite

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Just curious, is there a way, perhaps using my handheld scanner, that I can tell if there is a signal blocker in a local, large county-owned building?
It seems that the staff's walkie talkies work but cell phones, pagers, and the fire department's radios do not. Step out the door 2 feet and you have bars.
Cell signals are not 4 bars in the area but they work, the big church across the street has decent indoor connectivity. Yes, I know cell phones are famous for the "stand on one leg facing west north west when the moon is full" to get a signal in some areas.
 

SonicN

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Just curious, is there a way, perhaps using my handheld scanner, that I can tell if there is a signal blocker in a local, large county-owned building?
It seems that the staff's walkie talkies work but cell phones, pagers, and the fire department's radios do not. Step out the door 2 feet and you have bars.
Cell signals are not 4 bars in the area but they work, the big church across the street has decent indoor connectivity. Yes, I know cell phones are famous for the "stand on one leg facing west north west when the moon is full" to get a signal in some areas.
If it is a big, solid concret-building, the radiosignals can be blocked without any signal blocker, and there might be a posibility that staff's walkies got a repeater set up somewhere in the building.
 

bwhite

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If it is a big, solid concret-building, the radiosignals can be blocked without any signal blocker, and there might be a posibility that staff's walkies got a repeater set up somewhere in the building.
Yeah, I agree but it is just erie how you quickly go into "radio silence". It annoyed me at first but when our fire radios were useless in there then I got concerned.
 

kandrey89

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Its also possible that depending on the type of building and its purpose or primary occupants, that the building was EMI shielded. Hence no radio signals in or out, and correct on the repeaters, you'd definitely need repeaters if the building is pretty tall, as the walkie talkies will have a limited vertical distance too.
 

bwhite

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It is actually a new high school about 2 to two and a half stories, fairly high up. My guess is that the construction is just too much to penetrate. I thought perhaps I could close-call or signal-stalk something.
 

FLRAILMAN

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High school, well that probably explains it. The school system probably has a signal blocking system in place to defeat the brats from texting each other from two desk away & the interference to the fire department radios is probably collateral damage. Don't school kids pass notes anymore?

HowStuffWorks "How Cell Phone Jammers Work"

FLRAILMAN
 

poltergeisty

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Just curious, is there a way, perhaps using my handheld scanner, that I can tell if there is a signal blocker in a local, large county-owned building?
It seems that the staff's walkie talkies work but cell phones, pagers, and the fire department's radios do not. Step out the door 2 feet and you have bars.
Cell signals are not 4 bars in the area but they work, the big church across the street has decent indoor connectivity. Yes, I know cell phones are famous for the "stand on one leg facing west north west when the moon is full" to get a signal in some areas.
Keep in mind you are talking about three separate pieces of hardware here all using different frequency ranges. So if there were some kind of signal blocker in place it must be a triple bander! :lol: Of course your pager may be using 900-1100 MHz and your radio could be 800 MHz.

A while back I though that perhaps someone had bought a cell phone jammer near me because for some reason I could not for the life of me acquire a WIFI connection with my laptop. The signal bars were all there but the damn thing just wouldn't grab a DHCP. Pissed me off too because I knew there could not be a driver issue or anything. So reluctantly I reinstalled everything cursing ^&*^%$ and checking the router's channel, SSID, etc, to no avail. Then thinking of possible sources of RF interference it dawned on me, "MY DAMN WIRELESS CCD !" Unplugged the fan that had the wireless camera and what do you know, a freaking WIFI connection! So you can't be too sure where interference lies . It could be a wireless camera... :lol:

Can't help but think how many people will wonder now if there's a wireless camera that could be interrupting their WIFI connnection's :lol:
 
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bwhite

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Yeah, the pager is 900, the cell and fire freqs are in the 800s.
Everyone supposes that there is a blocker but you are correct, if it is a blocker it must be a tri-band.
The school admin swears up & down that there is no blocker and I 98% believe them, I just wanted to sniff around. I'll check out the "How Stuff Works" link.
 

mdulrich

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Since your concern is FD communications, the chief should send a letter outlining the communications problems and asking if there is any kind of blocking technology in use. The chief should outline the concerns for firefighter safety and the difficulty that would be experienced should an incident happen inside their building. If the response comes back negative, then there needs to be a cooperative effort to solve the communications problem. By putting it in writing they should fully understand the implications of keeping anything hidden and if they have nothing in place they should welcome getting the problem solved.

Also, you didn't mention if repeaters are in use, is trunking used, etc. If repeaters or trunking is in use, do you still have the communication problems when operating in direct mode?

Mike
 

bwhite

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Since your concern is FD communications, the chief should send a letter outlining the communications problems and asking if there is any kind of blocking technology in use. The chief should outline the concerns for firefighter safety and the difficulty that would be experienced should an incident happen inside their building. If the response comes back negative, then there needs to be a cooperative effort to solve the communications problem. By putting it in writing they should fully understand the implications of keeping anything hidden and if they have nothing in place they should welcome getting the problem solved.

Also, you didn't mention if repeaters are in use, is trunking used, etc. If repeaters or trunking is in use, do you still have the communication problems when operating in direct mode?

Mike
I don't think talk-around (direct) was attempted. I agree that the chief's should ask questions and maybe they have.
 

bwhite

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No one mentioned that if there is a blocker, it would be a violation of federal law.
Didn't mention it but I know there is a big stink at SuperMax, Baltimore's prison. The Gov wants a cell blocker there and he's getting resistance for exactly this reason. So I guess the inmates can continue to call in "hits" on people that put them there. Sigh.
 
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