Open Sky

Want to know how something works? Harness the power of the Brainiacs!

Open Sky

Postby Chris from Milwaukee » Fri Mar 26, 2010 10:15 pm

Greetings to the Braintrust.

I am an avid scanner listener. My scanner lives right next to my bed and I listen to it almost every night. Recently, the Milwaukee Police Department stopped broadcasting on the good old UHF frequencies and started transmitting on this Open Sky thing. From what I have been been able to dig up on this system it is a rather flawed communications system that Harris just bought from MA/COM. It has lots of issues... They have been trying to implement this system since 2005. It fails to work inside of buildings, the consoles have serious issues and will be antiquated by 2012 and will need to be replaced, and worst of all the general scanning public as well as other law enforcement agencies cannot monitor the transmisssions. The MPD has spent over $17.5 million on this worthless thing and now they need to "borrow" another million to "try and get it to work properly". And for the record, after 2012, Harris will no longer support the system.

My questions are: Isn't all digital broadcasting similar? They calim that the Open Sky system is a propriatary digital system. Since digital to me is 1-0 kind of deal, can someone expalin this propriatary concept to me?

And, since the Uniden can connect to the internet (though so far I have refused to do so since it was getting everything I wanted to listen to), does anyone know of a site where I could possibly download some software that would make the Uniden Open Sky capable? (I know, a longshot)

The Uniden website currently does not offer any upgrades for the Open Sky format. The unit is a Uniden BCD996T Trunk Tracking scanner.
BCD996XT.jpg
BCD996XT.jpg (39.23 KiB) Viewed 1893 times


And finally, there is lots of chatter on the scanner boards that the FCC has mandated public service bands to go narrowband. Some people are saying that this is the case while others are saying that it's a recommondation rather than a mandate. I have been surfing the FCC website but have been unable to find anything just yet (it's a pretty big site). Anyone here have any insight into this or could post a link as to where I should be reading?

It's a shame to drop over 5 bills on radio and not be able to listen to your favorite stations. :x
Chris from Milwaukee
Feeding Broadcast Engineers Worldwide
(And transmitter salesmen too!)
User avatar
Chris from Milwaukee
 
Posts: 628
Joined: Fri Nov 16, 2007 12:40 pm
Location: Milwaukee, WI
Has thanked: 0 time
Been thanked: 0 time

Re: Open Sky

Postby w9wi » Sat Mar 27, 2010 6:47 am

Chris from Milwaukee wrote:I am an avid scanner listener. My scanner lives right next to my bed and I listen to it almost every night. Recently, the Milwaukee Police Department stopped broadcasting on the good old UHF frequencies and started transmitting on this Open Sky thing. From what I have been been able to dig up on this system it is a rather flawed communications system that Harris just bought from MA/COM. It has lots of issues... They have been trying to implement this system since 2005. It fails to work inside of buildings, the consoles have serious issues and will be antiquated by 2012 and will need to be replaced, and worst of all the general scanning public as well as other law enforcement agencies cannot monitor the transmisssions. The MPD has spent over $17.5 million on this worthless thing and now they need to "borrow" another million to "try and get it to work properly". And for the record, after 2012, Harris will no longer support the system.


I don't think it's the same system, but digital public-service radio came VERY close to suffering an embarrassing failure on Election Night 2000.

Nashville's digital system crashed that night. Had the election been decided that night, (President|Senator) Al Gore would have been in Nashville delivering his (victory|concession) speech during the failure.

My questions are: Isn't all digital broadcasting similar? They calim that the Open Sky system is a propriatary digital system. Since digital to me is 1-0 kind of deal, can someone expalin this propriatary concept to me?


From what I've been reading, the problems with digital LMR (Land Mobile Radio) communications are largely software glitches, not problems with the transmission of RF. Though it does seem in some cases, not enough base stations are being specified, and coverage is suffering.

What's proprietary is the protocol used to convert the information to be transmitted into a stream of ones & zeros. Even in the original digital transmission mode (Morse Code!) there was a code, a mapping between letters of the alphabet and a series of open and closed circuits. I don't know if Mr. Morse copyrighted his code -- if he did, the copyright expired long ago! -- but he certainly could have. And then, if someone else wanted to transmit text messages over an electrical circuit, they would have had to develop their own code.

So it is with LMR. You might not be able to patent the idea of using a sequence of ones & zeros to transmit a voice message*, but you can patent your method of converting that message to a digital stream.

There does exist an open standard, (APCO-25, IIRC) for which scanners exist. I'm of the impression it isn't all that popular, though there is some use of it around here.

And finally, there is lots of chatter on the scanner boards that the FCC has mandated public service bands to go narrowband. Some people are saying that this is the case while others are saying that it's a recommondation rather than a mandate. I have been surfing the FCC website but have been unable to find anything just yet (it's a pretty big site). Anyone here have any insight into this or could post a link as to where I should be reading?


http://www.apcointl.com/frequency/documents/NarrowbandOrder.html which contains links to the official FCC documents. This does seem to be mandated.

* though today, I wouldn't bet against it...
--
Doug Smith W9WI
Pleasant View, TN EM66
w9wi
 
Posts: 704
Joined: Tue Feb 05, 2008 11:40 am
Location: Pleasant View, Tennessee
Has thanked: 2 times
Been thanked: 6 times

Re: Open Sky

Postby NECRAT » Sat Mar 27, 2010 7:53 pm

APCO25 digital is by far the most common use of digital scanner transmission. It's an open standard and there are several models which can decode it without a problem.

Digital APCO25 can be easily encrypted as well. There are two types of APCO25 trunked systems. 3600 baud and 9600 baud. Rhode Island is implementing a statewide system and several towns have decided to go to 100% encrypted. The plan is to have the whole state encrypted when moved to this system.

Open Sky is propietary and operates on a system similar to cell phone technology, and even if the standard was availble to manufacturers, it would be nearly impossible to monitor because of the way it operates. Open sky suffers from major problems with building penetration (i've heard the system uses very low power, due to the digital modulation scheme). New York State was going to switch the whole state over to this system but after testing it in a few Western Counties, as well as two up in the Adirondacks, the system failed every test the state of New York required them to pass to impliment the system. The system failed, the state has backed out of the system.

The propiatary difference, is how channel data is sent out, how the radio system controls each transmitter, how the system ids other users. There are a lot of things which seperate one from the other, including how the actual digital system is modulated and encoded.

Another type of digital system used is EDACS Pro-Voice. This system is also propietary and not detectable with any consumer grade equipment.

Motorola used to have a older propietary system but they have switched to APCO25. The city of Cleveland uses this.

When you look at digital transmission schemes, even in Broadcasting, there are different types. For instance, DTV uses a digital standard known as 8VSB, however HD radio uses COFDM.

As far as your Uniden 996 scanner model is concerned, it can ONLY do APCO25, and is not upgradable to any other standard. Chris, make sure you have the latest software on that scanner, so it can pick up trunking systems which have "rebanded".

Also the narrow band change is a FCC mandate, and everyone needs to be on it, I believe by the end of the year.
http://www.necrat.us

"To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be."
User avatar
NECRAT
Moderator Team Leader
 
Posts: 2615
Joined: Sat Nov 17, 2007 9:13 pm
Location: Quincy, MA
Has thanked: 33 times
Been thanked: 26 times

Re: Open Sky

Postby K9EZ » Tue Mar 30, 2010 6:25 pm

NECRAT wrote: Rhode Island is implementing a statewide system and several towns have decided to go to 100% encrypted. The plan is to have the whole state encrypted when moved to this system.


So they have one antenna up for the coverage then? 8)
Kent Winrich
Owner, Consultant, Floor Sweeper and Official Thread Hijacker
Broadcast and Technology Blog http://sceotech.com/blog/
Raleigh, NC
User avatar
K9EZ
Site Admin
 
Posts: 2986
Joined: Wed Nov 14, 2007 3:16 pm
Location: Raleigh, NC
Has thanked: 1 time
Been thanked: 2 times

Re: Open Sky

Postby NECRAT » Tue Mar 30, 2010 8:51 pm

For the VHF system, yes, they did. (A couple of voting receive sites and one transmit site)

However the 800 system seems to cover a whole 3 miles from the tower, so they have multiple sites up.
(And all ready the system is way over taxed, several reports of users with busy tones, etc on it...)

great job Rhode Island... really... good job. I mean it. (Sorry to blow up your sarcasim meter with that one Kent).
http://www.necrat.us

"To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be."
User avatar
NECRAT
Moderator Team Leader
 
Posts: 2615
Joined: Sat Nov 17, 2007 9:13 pm
Location: Quincy, MA
Has thanked: 33 times
Been thanked: 26 times

Re: Open Sky

Postby boiseengineer(old) » Tue Mar 30, 2010 9:46 pm

About 10 years ago the city & county tried to go to an 800 MHz Motorola system. After 5 years the only users were the trash trucks and city buses. Now they've moved on to a Motorola 700 MHz APCO25 system. City PD & Sheriff are on it. Fire & EMS are resisting. Test have proved 700 MHz doesn't seem to work for fire scenes. So, they're trying to cobble their Fire/EMS VHF into the 700 MHz system. They have both systems at the fire houses and that echo between the VHF & 700 MHz drives them nuts.

Recently they realigned their talk groups. All of the media can no longer hear City or County PD dispatch even though some of it's not supposed to be encrypted. Fire/EMS are still heard ok. Get a headache trying to figure out that Uniden. Can’t afford the Motorola radio!
boiseengineer(old)
 

Re: Open Sky

Postby K9EZ » Wed Mar 31, 2010 1:52 pm

NECRAT wrote:For the VHF system, yes, they did. (A couple of voting receive sites and one transmit site)

However the 800 system seems to cover a whole 3 miles from the tower, so they have multiple sites up.
(And all ready the system is way over taxed, several reports of users with busy tones, etc on it...)

great job Rhode Island... really... good job. I mean it. (Sorry to blow up your sarcasim meter with that one Kent).


No worries, only an engineer could come up with a real answer.

How could it be busy???? There are what... 5 people that live there (except during the Newport Jazz Festival and when the Kennedys hit town?)

<sarcasm meter FIXED>
Kent Winrich
Owner, Consultant, Floor Sweeper and Official Thread Hijacker
Broadcast and Technology Blog http://sceotech.com/blog/
Raleigh, NC
User avatar
K9EZ
Site Admin
 
Posts: 2986
Joined: Wed Nov 14, 2007 3:16 pm
Location: Raleigh, NC
Has thanked: 1 time
Been thanked: 2 times

Re: Open Sky

Postby VXO » Sun Apr 04, 2010 2:24 pm

I love the horrible steps some have taken to monitor ProVoice systems...

Trunking scanner with IF tap -> Signal gen + Mixer -> GE/Ericsson/M/A-Com/Harris/Joe's Stone Crab ProVoice capable radio programmed to receive everything on one preset channel.

Ow. My brain.

So... Milwaukee actually got OpenSky to work? Great... it'll last about four years before (insert name of company) decides to EoL it... hardcore. The smart money's on the interoperable TDMA standard, DMR (mototrbo and similar). Didn't the whole New York State OpenSky system just about ruin M/A-COM? They didn't get it working up to standard in time, and the state used their option to cash out what they spent on the whole Charlie Foxtrot.
A K T I V - S C H A U M
VXO
 
Posts: 46
Joined: Thu Nov 15, 2007 2:18 pm
Location: Miami, FL
Has thanked: 0 time
Been thanked: 0 time

Re: Open Sky

Postby NECRAT » Mon Apr 05, 2010 1:54 pm

VXO wrote:the whole New York State OpenSky system just about ruin M/A-COM? They didn't get it working up to standard in time, and the state used their option to cash out what they spent on the whole Charlie Foxtrot.


From my post above

New York State was going to switch the whole state over to this system but after testing it in a few Western Counties, as well as two up in the Adirondacks, the system failed every test the state of New York required them to pass to impliment the system. The system failed, the state has backed out of the system.
http://www.necrat.us

"To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be."
User avatar
NECRAT
Moderator Team Leader
 
Posts: 2615
Joined: Sat Nov 17, 2007 9:13 pm
Location: Quincy, MA
Has thanked: 33 times
Been thanked: 26 times


Return to Ask the Engineers

Who is online

Users browsing this forum: No registered users and 1 guest

cron