EDACS Systems

[jpm]

For those having a problem with the wide vs narrow EDACS could one help to distinguish the two.Clearly the book states Narrow, wide and scat. the database shows standard. According to the database a EDACS wide is standard. Thanks in advance.

 

[rick521]

For those having a problem with the wide vs narrow EDACS could one help to distinguish the two.Clearly the book states Narrow, wide and scat. the database shows standard. According to the database a EDACS wide is standard. Thanks in advance.

Enhanced Digital Access Communications System (EDACS) is available in VHF, UHF, 800 and 900 frequency bands and wideband (25 kHz) and narrowband (12.5 kHz) configurations,

Hope this helps.

 

[fmon]

At the top of the page, click on RRWiki then Trunking. EDACS has a lot of info available. Your question is addressed in 2. Flavors.

Edit: My apologies, the "Flavors" data has yet to be edited into the links.

 

[loumaag]

I think jpm was trying to post a hint for others, not asking for help. The problem is that he didn't state what he was attempting. Let me give it a try.

The book he refers to is probably any Uniden Owner's Manual because Uniden choose those terms. Yes, Wide = Standard, Narrow = Narrow, and SCAT is a single channel trunking support system.

None of those are associated with spectrum uses, they deal with the data bandwidth of the EDACS control channel. Standard (Wide) = 9600 baud and Narrow = 4800 baud. To be frank, I am unsure of what SCAT uses, but assume it is the same everywhere.

Both Standard (Wide) and Narrow control channels can be used on SNFM (or as Uniden calls them NFM) frequency bandwidths (11K) or NFM (or as Uniden calls them FM) frequency bandwidths (20K). The most common type of EDACS CC is the Standard (hence the name). All current trunk tracking scanners can track those. I am unaware of any GRE built scanner that can track EDACS Narrow.

Is this where you were heading jpm?

 

[pro92b]

All the 800 MHz EDACS systems I've ever received have been wide (9600 bps control channel). At 900 MHz they should all be narrow (4800 bps control channel) with one exception, the LCRA system. My understanding is that LCRA uses 9600 bps control channels but with NFM voice channels.

Two SCAT systems are receivable here, one at 800 MHz and one on the VHF HI band. Both are 9600 bps wide.

I'm not certain what type is usually employed in the UHF band (450-512).

 

[jpm]

This post was for the ones having problems with the EDACS systems they are attempting to program. Thanks for the clarrification Lou that this wasn't my issue but to help others understand this EDACS programming issue.

 

[loumaag]

This post was for the ones having problems with the EDACS systems they are attempting to program. Thanks for the clarrification Lou that this wasn't my issue but to help others understand this EDACS programming issue.

That's what I figured.

All the 800 MHz EDACS systems I've ever received have been wide (9600 bps control channel). At 900 MHz they should all be narrow (4800 bps control channel) with one exception, the LCRA system. My understanding is that LCRA uses 9600 bps control channels but with NFM voice channels.

Two SCAT systems are receivable here, one at 800 MHz and one on the VHF HI band. Both are 9600 bps wide.

I'm not certain what type is usually employed in the UHF band (450-512).

Are you trying to equate the 11MHz bandwidth to not being able to handle the 9000 baud bandwidth? The two things have nothing to do with each other. The 9600 bps signal works quite well in the narrow FM bandwidth allocation, which you can see the LCRA sites prove quite well. They are all narrow bandwidth, including the control channels.

 

[Voyager]

All the 800 MHz EDACS systems I've ever received have been wide (9600 bps control channel). At 900 MHz they should all be narrow (4800 bps control channel) with one exception, the LCRA system.

That's what I always thought, too, but several people apparently have EDACS Wide systems on 900 MHz.

I thought all 900 MHz was supposed to be narrow. (thought - past tense)

Joe M.

 

[pro92b]

Are you trying to equate the 11MHz bandwidth to not being able to handle the 9000 baud bandwidth? The two things have nothing to do with each other. The 9600 bps signal works quite well in the narrow FM bandwidth allocation, which you can see the LCRA sites prove quite well. They are all narrow bandwidth, including the control channels.

That's 11 kHz bandwidth, and yes my contention is that 11 kHz is inadequate for 9600 bps control channels. 9600 bps yields a maximum modulation frequency of 4800 Hz which corresponds to an extended series of alternating 1's and 0's . Carson's rule is that 2 x (deviation + max mod freq) = bandwidth. If deviation is 2.5 kHz the bandwidth is 14.6 kHz, clearly exceeding the 11 kHz allocation. If 9600 bps control channels were good at narrow bandwidths, there would not be a 4800 bps control channel available. BTW, if you set a Uniden trunktracker to EDACS narrow, it looks for a 4800 bps control channel. Conversely if you program a trunktracker to EDACS wide it sets the channels to FM because the wider bandwidth is needed for best control channel decoding.

My understanding is that LCRA does use a 9600 bps control channel BUT they use low deviation on the voice channels (Uniden's NFM). This is quite unusual for 900 MHz. Maybe LCRA has been around for a long time and that's why it is a strange hybrid system. I don't believe new systems deployed at 900 MHz would be set up this way due to adjacent channel interference issues.