• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

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Whistler TRX-2 vs. Uniden SDS-100: Which Receives Better in P25 Multi-Cast Environment?

What's Your Favorite Brand Of Police Scanner?

  • Whistler/Gre/Radio Shack

    Votes: 6 16.7%
  • Uniden Bearcat

    Votes: 27 75.0%
  • Some Other Brand

    Votes: 3 8.3%

  • Total voters
    36

SteveSimpkin

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Apr 13, 2009
Messages
641
Location
Lancaster, CA
#21
I'm sure the TV's have something built in to emanate a special RF signal otherwise that van would be picking up a lot of other RF that wasn't TV's.
I think it is more likely that they have specialized receiving equipment that is looking only for the signals given off by the TV set as a side effect of the receiver design (local oscillator, HV flyback transformer, etc) while filtering out any other signals that may be present in the surrounding environment.
 

kruser

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Nov 25, 2007
Messages
2,969
Location
St. Louis County, MO
#22
I think it is more likely that they have specialized receiving equipment that is looking only for the signals given off by the TV set as a side effect of the receiver design (local oscillator, HV flyback transformer, etc) while filtering out any other signals that may be present in the surrounding environment.
This was always my understanding how they did it.
 

kruser

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St. Louis County, MO
#24
There was a lot of it going on years ago but could probably not be done on modern digital tv sets.
I would suspect the same but after reading the Wiki link that SteveSimpkin included, I'm no longer sure they are not still doing this as it does have mention of more modern LCD sets still being able to be detected. It sounds pretty far fetched to me though.
TV detector van - Wikipedia
 

KevinC

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Jan 7, 2001
Messages
4,444
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Somewhere other than home :(
#25
I would suspect the same but after reading the Wiki link that SteveSimpkin included, I'm no longer sure they are not still doing this as it does have mention of more modern LCD sets still being able to be detected. It sounds pretty far fetched to me though.
TV detector van - Wikipedia
We're getting off-topic here, but a story I read from the 60's stated that almost all cases of people being caught without a license was due to a nosy/jealous neighbor or the government going around and just hearing TV's via an open window.
 
Joined
May 5, 2012
Messages
99
Location
Parma, Ohio
#26
I don't think the squelch level comes into play or have any effect with P25 digital reception.
Well on my TRX-1 if I have the squelch turned on full I don't hear any voice at all on my local P-25 system.
If I set it at about 9 o'clock I get voice back.

So in my case it does have an effect.
 
Joined
Feb 14, 2005
Messages
29
Location
Minnesota, USA
#27
Well on my TRX-1 if I have the squelch turned on full I don't hear any voice at all on my local P-25 system.
If I set it at about 9 o'clock I get voice back.

So in my case it does have an effect.
I run the squelch as low as possible on my TRX-2, but I do need to have it up enough to enable scanning of NOAA Weather Radio when traveling on a Storm Chase. :)
 

Ubbe

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Joined
Sep 8, 2006
Messages
3,015
Location
Stockholm, Sweden
#28
Both Uniden and Whistler uses the squelch to detect if it is a carrier on the frequency and only then stops scan and starts to try to decode a digital signal. If the squelch are set to 0 it will think it is a carrier on each frequency and will spend time trying to get some data and scan rate will be ridicuosly slow. If the squelch are adjusted too high it will just skip over weak channels and not stop on them. If you turn the squelch up on a Uniden BCD536 and then down again it will open squelch on the 1 setting on an empty channel and then close again at 2, which is an excellent squelch handling. Whistlers TRX2 on the other hand will open squelch at 4 when turning it down and not close again until the 8 setting. It is a big differense in signal level between the two settings, the hysteres is too high, which makes it difficult to use a TRX2 without missing some of the action that the Uniden scanner manage to monitor.

/Ubbe
 

VK3RX

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Feb 24, 2013
Messages
191
Location
Australia
#29
I would suspect the same but after reading the Wiki link that SteveSimpkin included, I'm no longer sure they are not still doing this as it does have mention of more modern LCD sets still being able to be detected. It sounds pretty far fetched to me though.
Certainly still possible, and being done.

Some of the radiation would come from the set itself, and some can be radiated by the feed system and antenna.

It is why military radios and other gizmo's they use have high suppression of such radiation, to prevent detection by the opposition :)
 
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