Not receiving all calls

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W5TWX

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I called the police for a shots fired in my neighborhood this morning. I didn't hear the call go out on my scanner, but 6 PD units showed up to search the neighborhood.
I didn't hear any talk between the units and I know they had to be talking to each other because they all covered severak blocks around me.

I have a Uniden 396T and I have all the "System Frequencies" entered in my radio and I have all the "Talk Groups" entered as well. After a few minutes I switch over to search mode from scan mode. Still no talk. The system I'm monitoring is the ROUND ROCK PD part of the Williamson County portion in this large system. The link is: http://www.radioreference.com/apps/db/?sid=2

I'm wondering if they were using the "simplex or imput" freqs of this system. I'm very confused about this incident. They had to be communicating some how, but I couldn't hear a thing. Not even in search mode on this system.

Please advise or comment.

Thanks
 

HAFD_CADET

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I recently had the same problem. I'm thinking dispatch probably sent the call out through the computer. I know some police departments use Nextel group connect aside from their digital radios too for some reason.
 

W5TWX

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They have encryption available to them in this system, but they wern't using it either. I know that they do have Nextels, but it seems to me that it would be easier for them to use their radio system since there was 6 units involved. Don't you think?
 

HAFD_CADET

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They have encryption available to them in this system, but they wern't using it either. I know that they do have Nextels, but it seems to me that it would be easier for them to use their radio system since there was 6 units involved. Don't you think?

They use Nextel group connect. It's the same as Nextel 2 way but you can link 25 people into the conversation. They could have been using that.
 

rescue161

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A lot of systems use simplex channel that you won't be able to hear while you're in trunked mode, even if you go to "search" mode. You'd have to know what simplex frequencies they are using and put them in a seperate bank/system/group and scan them conventionally.
 

rescue161

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Next time, place your scanner into close-call mode and listen. If they are close enough and if they are using the simplex frequencies, you'll snag them out of the air. You could try these pulled from the link you posted:

Code:
Simplex Frequencies in use by system users:

I-Call-Central	866.01250	repeater only
I-Call 1D NE	866.51250	repeater on I-Call NE, simplex on I-Call 1D
I-Call 2D SE	867.01250	repeater on I-Call SE, simplex on I-Call 2D
I-Call 3D SW	867.51250	repeater on I-Call SW, simplex on I-Call 3D
I-Call 4D NW	868.01250	repeater on I-Call NW, simplex on I-Call 4D
Critical 1D	867.37500	simplex 
Critical 2D	867.45000	simplex 
AFD DIR 16	866.97500       simplex
If the above frequencies don't bring you any luck, you could try 45 MHz below the normal frequencies on the tower that your scanner is trunk-tracking on, i.e., if you were monitoring site 104 Honeycomb IR using 867.26250, 867.72500, 868.17500 and 868.77500, try using 822.2625, 822.7250, 823.1750 and 823.7750. They could also be using the inputs from other towers that are farther away as to not interfere with the other tower.

Could be any combination of this and what others have posted as well.
 

W5TWX

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Scott - I completely forgot about CLOSE CALL. Thanks for reminding me of that. Next time there is a call in the neighborhood i'll try that. I have those simplex freqs now programed in too. I'll also try the 45MHz shift that you suggested.

Thanks everyone for sharing all the ideas.
 

W5TWX

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On those simplex freqs you mentioned above, would I program them into a MOT P25 system or a conventional system?
 

rescue161

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On those simplex freqs you mentioned above, would I program them into a MOT P25 system or a conventional system?
Conventional only. It sucks to have to make a whole new system, but that's the way it has to be done. Just leave the system on all the time. You may be surprized at what you hear.
 

rescue161

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Same as the simplex. They should all be in a conventional system. I would only use the 45 MHz offset frequencies as a last resort as anytime any user on the system is close to you, you're gonna get traffic and it'll just get confusing.
 

GSXR1181

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They use Nextel group connect. It's the same as Nextel 2 way but you can link 25 people into the conversation. They could have been using that.
This is why you didn't hear the call. A lot of area's, including mine have something similar to this. Can't remember the name of the program, but all dispatchers have to do is enter the information into there CAD, and it is sent to a 800Mhz modem inside there car. It comes up similar to a work order, the officer clicks it, and makes the call. After he is finished, he links back up, and sends the info back to the CAD server.

Most of the state officers here have them in there car. Usually the ones that don't have the modem's are the rookies. You can identify the car's that have them cause they will have two antenna's usually around 8" mounted next to each other that look identical. One is a TX, and the other is a RX.
 
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