SCPD Data

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Renegade631

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Anyone know what this means?

"10-55 Switch to data band"

Also, do the computers in the cars send/receive data over the same system as voice? And if so is it possible to intercept that data?
 

bezking

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Nowadays there is no way to decode he information send via MDTs. Even if there was a way, it is illegal.
 

studgeman

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It is possible to send voice and data over the same system, depending on the system. While I am not familiar with Suffolk Co. I can give you an example out of Oneida Co. Several village and town PDs run data over 800MHz EDACS with their primary voice over VHF-High. They also have voive talkgroups on the EDACS system, but utilize the same 800MHz radio. Renselaer County, runs EDACS data and could theoritically do the same thing, in a limited fashion.
 

FrankRaffa

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Our MDT system runs on the DOITT trunk. Chiefs and certain special units can switch their radios from data to voice.
 

OTA-K

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Anyone know what this means?

"10-55 Switch to data band"
Data band used to be channel 9 on the SCPD VHF Freqs. (Or ch. 4 on the really old radios)

With the advent of the MDC's, there is no more data band. If your MDC is down or can't run data for some reason, your primary dispatcher will run it for you. If it's a busy night, units sometimes switch to Command Band to run it.

Back in the day, if you told your disptacher "207 10-55", he knew you were going down to Ch-9 (Data band) to run something / someone, and if he needed to call you, you were there.
Other times if u asked your primary dispatcher to run some data, and he was too busy, he would say either '10-55' or 'switch to data', in which case you would switch to Ch-9.

But again, data band is gone.
 

SCANdal

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631,

Data Band was 155.790R (146.2) for the town and village police departments that still use VHF high band (OTA-K reports above that apparently that repeater is off line and the function shifted to Command Band, 155.685R, 146.2) and talkgroup 62448 on the County 800 MHz trunked system.

SCANdal
 
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OTA-K

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631,

...(OTA-K reports above that apparently that repeater is off line and the function shifted to Command Band, 155.685R, 146.2) and talkgroup 62448 on the County 800 MHz trunked system.

SCANdal
Scandal..

Sorry, actually, what I meant to say is there is no longer any dedicated 'DATA' channel or freq... I don't know if the VHF Freq is active or not, but all data is now run on MDC, Primary dispatch or Command band..
By implementing the MDC program, the dept. was able to get rid of the data band..
 

Rudy3145

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I believe the only old SCPD Vhf channels that are still up & running are 155.685 Command Band and 154.845 2nd Pct. They used to also have the 6th Pct and Data Band up, but those are no longer.

The Command band is still up for interop (MTA PD, Town and Village PD's on Vhf, Fed Govt agencies also have access) The Vhf is patched with the 800 system.

The 2nd Pct suffers reception & tx problems with the 800 system, so they kept the old Vhf channel up and the sector cars still have Vhf radios in them along with an 800 radio.

Every SCPD Pct now had a tower w/a microwave dish and 1 antenna. Does anyone know what these are being used for? Is it the MDT system?
 

CloroxCowboy

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The SCPD mobile data system uses Motorola's RD-LAP at 19.2 kbps. It operates over conventional channels in the 482-488 band. While the radio signals for RD-LAP are generally not encrypted (DES, DES-XL, etc.) there are no known decoders for the RD-LAP protocol outside of a Motorola radio modem. The 800 trunked system is not used to support mobile data terminals.

On analog Motorola systems, whether conventional or trunked, mobile data terminals can be supported, but the channel must be exclusive for data. On their digital systems, whether conventional or trunked, voice and data can share the same channel.

The microwave antenna at each precinct is used to provide regular network connectivity (desktop computers, telephones, etc.); the other radio antenna is for a desktop radio in the station house.
 

gatekeep

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Check SCPD's FCC license WQEZ320. Those are the 480mhz frequencies, that *should* be used for the MDT system. Not that it matters, nothing to listen to but data transmissions...
 

Renegade631

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This looks interesting in combination with what I have heard here,

http://www.geocities.com/SiliconValley/Lab/1067/MDTFAQ.HTM

What is MDTW1234?
MDTW1234 is a software package which, with the right hardware, will allow someone to monitor Motorola's Mobile Data Terminals (MDTs) which use the MDC-4800 protocol.
None of the information broadcasted is encrypted, so in theory it is legal to monitor. However, I am not a lawyer, so you should study the laws regarding this matter before attempting anything.
http://www.geocities.com/SiliconValley/Lab/1067/MDT.HTM

June 16/98: I have received numerous requests for a 19.2k RD-LAP version of MDTW1234. Unfortunately, this protocol is not used in our area, making development work extremely difficult. One of the MDTW1234 users informed me that a Motorola tech said that RD-LAP is the same as MDC-4800, with the exception of baud rate. With this in mind, Bonzo has written MDTW192.EXE version 1.0 Beta. It is currently UNTESTED; if the MDT users in your area use 19.2k RD-LAP, try it out and let us know if it works via email. If everything checks out, 19.2k will become a command-line switch in MDTW1234.

June 23/98: The test results are in; it appears that 19.2k RD-LAP is NOT just a faster MDC-4800. One tester pointed out that MX-COM manufactures an RD-LAP-compatible modem chip called the MX-929B. For more info, download the data bulletin (viewing requires Adobe Acroreader, a free download). MX-COM also manufactures numerous other interesting modules.
 

Renegade631

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I gotta say, I have been trying to read about decoding radio data in general, and it looks like some SERIOUS effort has been put into preventing anyone from getting anything useful even on the older systems no longer in use...

Everything is dead links and old sites that say things like "You need a VERY VERY Fast computer like a Pentium II"
 

OTA-K

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anyone remember "a 45 and a 45a.negative stolen or unreported". they used to drive me BONKERS ! .
I hear what you're saying..But not sure I understand.. Rephrase the question...
But I do remember 1 dispatcher for 2 pcts on the mids, Data on channel 9, and radios with channels A-D, though.. :)

Enlighten me....
 

radioman2001

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I noticed that the info was almost 10 years old also. There was a big effort by the FBI to prosecute some poor electronics tech for devising a hardware method to decode the MDC-4800 signals in 1999. There really hasn't been much talk of it lately, I wonder if thats why most of the info is 10 years old
 

KA1RBI

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The SCPD mobile data system uses Motorola's RD-LAP at 19.2 kbps. It operates over conventional channels in the 482-488 band. While the radio signals for RD-LAP are generally not encrypted (DES, DES-XL, etc.) there are no known decoders for the RD-LAP protocol outside of a Motorola radio modem ...
Someone has released a decoder for RD-LAP - see

http://radiorausch.googlepages.com/home

I've been able to pick up some RD-LAP stuff here, guessing it's from around Syracuse, but not 100% sure. The signals frame up OK, and are positively RD-LAP, but the content that's displayed is gibberish - possibly encrypted. Haven't kept detailed logs but if I recall correctly there's RD-LAP at both 9.600 and 19.200. All of this is 4L-FSK.

On another front, I'm happy to report progress in decoding P25 signals. I expect they'll be releasing an IMBE voice decoder RSN as well, but at present there's a P25 signal decoder plus a plugin for Wireshark (a very fancy free software protocol analyzer)

At the moment the site <http://www.sedition.org.au> seems to be having problems. I've published a month-old copy of the code at

http://www.lightlink.com/mhp/op25-trunk.tar.gz (file size is 766K - I'll leave it up for 2-3 days)

The op25 project and the radiorausch stuff is based on GNU Radio, which is somewhat oriented toward folks who have the USRP radios. These are the boxes which eat several MHz of spectrum all at one time. I have found that it's possible to get all this cool software working using a scanner with a standard discriminator tap connected to the PC's sound card. The subject is probably well outside the scope of the NY Radio listening forum by now !!

73
 
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