DPS Austin on Digital

[Russell]

Yesterday afternoon DPS Austin went digital on A2 w/repeater on. I haven't heard any traffic on any other channels and 155.46 is dead.

Russell

 

[VintageJon]

Interesting you should post this. As I said in my post early this week the 155.460 MHz was
going great guns. Today It's all noise and I'm getting a bunch of noise on an EDACS DPS freq I have programmed. (Will try to determine freq next time it happens...)

What's the freq?
What's the modulation type?

More info please as I enjoy hearing them. (Long family history with DPS here in Austin.)

Best,
Jon
THANKS,

 

[Russell]

A2 is 155.4675 in APCO P25 digital (IMBE) with a 118 NAC on a conventional (non-trunked) repeater. This almost completes the transition of DPS to P25 in most of Texas. The notable exception is Region V (from Mineral Wells to Lubbock, Amarillo, etc.) seems to still be analog. We try to keep the DB as up to date as possible (I've updated it with the Austin changes).

I programmed the digital channel plan and the old analog channel plan into my scanner so when they shift I still catch them. I don't track DPS geographically (in the scanner) as I am constantly back and forth between Dallas and Austin and then do the family thing out to Sherman/Paris/Tyler and even Lubbock occasionally.

Of course we still hear DPS on any county system including those with trunked systems. Those are a little hard to keep up with, but if you listen to unit numbers on these systems you can tell which ones are DPS as opposed to SOs or local PDs. I'm really interested in their use of the 700mhz tower at the Capitol. That seems to be pretty short range tower and I haven't been able to peg them there, yet.

I enjoy hearing them, too. I've been monitoring DPS since the late 70's.

Russell

http://www.radioreference.com/apps/db/?aid=71

 

[mam1081]

I'll bet they are working on Mineral Wells next - the dispatcher and mobiles were both heard on 155.46 on Friday 4/11/08 (repeater mode - seems to be common when they are about to switch).

 

[nd5y]

I don't know if it has anything to do with the digital switch but they have been doing that several times here the past few weeks and also having radio problems and doing other strange things.

Last month they put up two new dishes at the top of the tower at the MWL office and removed the old one which was about 1/2 way up. I guess they replaced the 900 MHz microwave link between MWL and Whitt. I don't know if that has anything to do with switching to P25 or maybe the new MDTs.

They have been running the Whitt tower in repeater mode sometimes, simulcasting on 155.370 sometimes, simulcasting from MWL and Whitt both on 155.460 making it so you can't hear either one, and sometimes talking into Whitt on 154.680 from the MW office.

The Whitt tower also as a bad noise problem. When the mobiles are talking when they have the repeater on they have a crackling noise like something is loose on the tower or some electrical arcing, even on near full-quieting signals. I heard the same thing on the forest service repeater on that tower. I don't know what noise like that does to a P25 digital signal but I bet they won't be able to hear S#!T if they don't fix it.

 

[Russell]

I'll bet they are working on Mineral Wells next - the dispatcher and mobiles were both heard on 155.46 on Friday 4/11/08 (repeater mode - seems to be common when they are about to switch).

This does seem to be the MO. Austin went to repeater on 155.46 then switched to P25 shortly thereafter. I heard the dispatcher announce that the radio shop was taking the old base down. Shortly after that they were up on 155.4675 (A2) in digital w/repeater on. I suspect they will drop the repeater mode after some time.

Russell

 

[VintageJon]

Russell,
Thanks for the reply.
I've set the 155.46750 to FM and I'm hearing both sides operating the goofy Pro-96 on the 800MHz 1/4 wave ground-plane here on top the hill.

Folks seem to be switching to "Channel 2" there this evening. As I have the whole DB programmed I let it run on the DPS and see if I can find Channel 2...
Any clue on 2, anyone?

Best,
Jon

 

[Russell]

Channel 2 is probably a simplex channel on the base/repeater output only. They are most likely on 155.4675 direct.

Russell

 

[TXEMT]

just curious as to why they would turn the repeater off, when San Antonio switched they had the repeater on and it sounded good most areas...just seems like it would be better for the troopers to hear each other...never have understood why they like the duplex stuff. Guess major cities would need more that one tower to cover the entire area.

 

[rattlerbb01]

just curious as to why they would turn the repeater off, when San Antonio switched they had the repeater on and it sounded good most areas...just seems like it would be better for the troopers to hear each other...never have understood why they like the duplex stuff. Guess major cities would need more that one tower to cover the entire area.

Historically speaking, when you are in half-duplex mode, you, the dispatcher, are only having to listen to 154.680 or 154.695 from your local tower, therefore only hearing closeby units that can be heard from the tower you operate. However, since most of the state was only using two base station frequencies, 155.445 and 155.460, if you were to turn the repeater on, the dispatcher would be forced to listen to the output, and would most likely experience much intrusion from neighboring stations. For instance, Tyler has been getting blown out of the water by Bryan's Repeater on A1 as of late. IMHO, the thing for DPS to do would be to do away with the channel plan and license other frequency pairs to reduce interference. The radios they have can hold 256 channels..............

 

[W5TWX]

How do I program the 396T to receive the new DPS digital system? I'm confused...

What is 118NAC?

 

[nd5y]

You only enter the frequencies with no tone and no tone search.
Your NAC question was answered twice in your other two posts.

 

[W5TWX]

I did a multi- post because I needed an answer fast. I have someone waiting for an answer.

 

[Russell]

How do I program the 396T to receive the new DPS digital system? I'm confused...

What is 118NAC?

To elaborate on Tom's reply, the Unidens don't decode NAC so just program them as Tom stated, Freq only, FM mode, no tone, an no tone search. (I do not have a 396, but tone search on the Pro96 ignores digital channels and will not break squelch).

NAC is to digital as PL is to analog. On the old analog plan channels 10 through 17 used the same frequency but different PLs, if your radio did not decode PL then you only programmed the frequency. On the new digital channel plan channels 10A to 19A are still the same freq but use different NACs.

The 396 does not decode NAC, but the new GREs (PSR500/600) do. I'm a channel plan guy, I program each freq and NAC combination so I can tell the channels apart, just like I used to program each analog freq and PL combination so I could tell the channels apart.

Russell