800Mhz police trunk phone conversation?

800Mhz police trunk phone conversation?

Post by Cbake7 » Mon, 03 Aug 1998 04:00:00

I am continually picking up phone calls in the 800 range. These are non
cellular from police officers in their car calling land line phones. I can here
the party they are calling crystal clear, but the officers reception drops off
after a few seconds. What kind of phones are they using? Are they operating on
a drop freq that is above or below the freq I'm on? I am tired of only hearing
one side of the conversation...the other side is so faint that it isn't
discernable......
Chris Baker
94 RMX 250
88 Z50R (The Beast)
 
 
 

800Mhz police trunk phone conversation?

Post by Ryan Faricy KC0DS » Mon, 03 Aug 1998 04:00:00


Many newer police communications systems have an autopatch that sometimes
switches channels every now and then. It is very much like an amateur radio
patch -- uses only a radio and the repeater -- to make telephone calls.

I am not sure why the other side is faint, though.
--
73 de Ryan Faricy KC0DSZ
Twin Cities Repeater Club - 147.21+
SkyWarn ID# 2212-98
RySoft Corporation

http://home.att.net/~jtonsa/

Why not tell Bill Gates where HE can go today?!


Quote:>I am continually picking up phone calls in the 800 range. These are non
>cellular from police officers in their car calling land line phones. I can
here
>the party they are calling crystal clear, but the officers reception drops
off
>after a few seconds. What kind of phones are they using? Are they operating
on
>a drop freq that is above or below the freq I'm on? I am tired of only
hearing
>one side of the conversation...the other side is so faint that it isn't
>discernable......
>Chris Baker
>94 RMX 250
>88 Z50R (The Beast)

 
 
 

800Mhz police trunk phone conversation?

Post by Cbake7 » Mon, 03 Aug 1998 04:00:00

Unlike the trunked tramissions, this one with stay on the scanner for the
entire conversation, it just bugs me as to why I can only hera one side of the
conversation?????
Chris Baker
94 RMX 250
88 Z50R (The Beast)
 
 
 

800Mhz police trunk phone conversation?

Post by Ryan Faricy KC0DS » Mon, 03 Aug 1998 04:00:00

Are you sure they aren't cellular, then? You could be picking up an image
from a 900 MHz cordless phone.

Cellular calls will have a high-pitched tone in the background (called SAT,
supervisory audio tone, I believe), around 6000 Hz.

Not many other types of normal autopatches or cordless phones will have this
"SAT".
--
73 de Ryan Faricy KC0DSZ
Twin Cities Repeater Club - 147.21+
SkyWarn ID# 2212-98
RySoft Corporation

http://home.att.net/~jtonsa/

Why not tell Bill Gates where HE can go today?!


Quote:>Unlike the trunked tramissions, this one with stay on the scanner for the
>entire conversation, it just bugs me as to why I can only hera one side of
the
>conversation?????
>Chris Baker
>94 RMX 250
>88 Z50R (The Beast)

 
 
 

800Mhz police trunk phone conversation?

Post by Jac » Mon, 03 Aug 1998 04:00:00


Quote:>Unlike the trunked tramissions, this one with stay on the scanner for the
>entire conversation, it just bugs me as to why I can only hera one side of the
>conversation?????

On the trunked system I monitor a phonepatch will stay on the same
frequency for the entire conversation, but I can hear both party's
crystal clear. Are these calls on a freq assigned to your local pd?

-

26.1972800/-080.1707083  
Fort Lauderdale, FL
http://broward.home.ml.org

 
 
 

800Mhz police trunk phone conversation?

Post by Cbake7 » Tue, 04 Aug 1998 04:00:00

Yes it is a freq assigned to my local PD. I have an RS Pro60 and have
programmed all the freqs listed in Beyond Police Call plus freqs that I've
picked up from limit scans and info from others. I can always here the phone
rining and the person (or machine) that answers. Then I can here the officer
for approximately 10 seconds and he fades away. The remainder of the
conversation, no matter how long, is always the called party. If I turn the
volume wide open I can barely here the officer, meantime, the called party is
always crystal clear, next door type reception...what gives???

Quote:>Unlike the trunked tramissions, this one will stay on the scanner for the
>>entire conversation, it just bugs me as to why I can only hear one side of
>the conversation?????

>On the trunked system I monitor a phonepatch will stay on the same
>frequency for the entire conversation, but I can hear both party's
>crystal clear. Are these calls on a freq assigned to your local pd?

>-

>26.1972800/-080.1707083  
>Fort Lauderdale, FL
>http://broward.home.ml.org

Chris Baker
94 RMX 250
88 Z50R (The Beast)
 
 
 

800Mhz police trunk phone conversation?

Post by Gregory Kn » Tue, 04 Aug 1998 04:00:00



>>Unlike the trunked tramissions, this one with stay on the scanner for the
>>entire conversation, it just bugs me as to why I can only hera one side of the
>>conversation?????

>On the trunked system I monitor a phonepatch will stay on the same
>frequency for the entire conversation, but I can hear both party's
>crystal clear. Are these calls on a freq assigned to your local pd?

Some systems attain a degree of privacy by not re-transmitting the
input side of the conversation. There is no requirement to transmit
that side of the conversation since it is only intended for the person
on the landline end of the connection (usually). Conceptually they
could do this by simply breaking the audio connection between the
repeater receiver and transmitter whenever the receiver squelch is
open. In practice they probably use a hybrid which is why you can
sometimes hear a little bit of the mobile side of the conversation.

Greg Knox