[FedCom] Acadia National Park Maine Using P25

Fri Aug 12 11:03:05 EDT 2005

Hi everyone,
The major reason given for agencies to migrate to P-25 digital format
is for interoperability. 

The most common argument against migrating is that most agencies can
already interop via conventional (analog) voice radio, like they have
been doing for the past 50+ years.

Yes, this is true.   But there is a bit more to the story....

But given the fact that different agencies communicate over different
frequency bands, tying two different bands together for a emergency
link has always been a bit of a headache due to balancing (analog)
audio levels between one user and another.  

Plus, to further confuse the mix is the different flavors of trunking
protocols.

APCO-16 Trunking Standard:  
Motorola Type-1, Type-2 formats.  
GE's EDACS format. 
EF Johnson's LTR format.

And even within P-25 trunking; Phase-1 (2 point @ 3600 baud) vs.
Phase-2 (QPSK @ 9600 baud) data rates.  (Moto started at Phase-1,
whereas M/A-Com totally skipped the interim Phase-1 and went directly
to the final 9600 baud Phase-2 P-25 format.)

The benefit gained by moving everyone to a common voice format, with
its common data rate allows easier patching of one
brand/format/protocol to another in an emergency.  All the parts fit!

A secondary benefit gained is the ability to remote the digital format
audio from one location to another via Internet Protocol (IP) packets. 
This can be done via the Internet, or by an agency's internal (secure)
intranet system.  You are seeing more and more of this daily.  The
biggest user I am aware of is the US Forest Service.  By IP'ing their
repeaters, from their National Wildfire Command Center in Boise
(Idaho), they link their command/support/technical staff in Boise to
any wildfire crew anywhere in the Lower 48 states, Alaska and Hawaii
via a IP or satcom link to a repeater or base station on-scene.  The
benefit is enormous.

As technology evolves, things change.  

- Folks grumbled when marine radio moved from AM to SSB in 1977.  
- Now people gripe when they are required to move from SSB to Inmarsat!

- Ditto for wideband (5 kHz deviation) migrating to narrowband (2.5 kHz
deviation).    
- Some of the people were upset when the ORIGINAL "wideband" (15 kHz
deviation) was forced to move to the ORIGINAL "narrowband" (5 kHz
deviation) in the 1960's.

- Digital audio format vs. traditionally analog audio format.

The simple fact is people resist change.  The Homeland Security money
is the "carrot" to entice agencies/local governments to new P25 format
equipment.  Kinda like seeding a field.  It will in time bear fruit.

> AND.....thank you once again...George "Dubya"...for your
> intense insight....aaaarrrrgggg....

Fred:
I must respectfully disagree with you on the above statement.  APCO's
efforts towards a P-25 standard has been around long before the current
administration came into office, and was started in the
early/mid-1990's. 

The unfortunate events of 09-11-2001 were simply a wake-up call to
agencies to FINALLY get systems and equipment in place to
intercommunicate.  To finally stop the 'turf wars' between agencies and
department.  DHS provided the money to get things started.

I can speak from experience.  I used to manage a public safety trunking
system (> 3,000 radios) for a city.  I had twenty-six conventional
patches to allow my fire/ems/pd folks to communicate with all of our
surrounding 'bedroom' communities in a mutual aid situation. 
Frequencies ranged from 30 MHz up to 465 MHz, with different deviations
(wide vs. narrow) and 26 different analog audio levels to keep properly
aligned.  Heck, I had two 30-88 MHz patches to the military on
PRC-77's!  A major pain in the butt.  If it was digital it would have
been a whole lot easier to maintain.  

BTW: I still work in two-way radio as a Master Technician.

Mark, KB4CVN

> Message: 2
> Date: Thu, 11 Aug 2005 14:10:46 EDT
> From: PalladinMe at aol.com
> Subject: Re: [FedCom] Acadia National Park Maine Using P25
> To: fedcom at mailman.qth.net
>
> This truly amazes me...
> I guess some Homeland Security money became available..
> for whatever use, that deemed Acadia National Park a security
> risk...as  well 
> as allocate funds for encryption...I sure hope Smokey "da" Bear has a
> P25  
> scanner....
> AND.....thank you once again...George "Dubya"...for your
> intense insight....aaaarrrrgggg....
> Regards to the group..
> Fred KB1JDL
> Northford, CT
> 
> 

____________________________________________________
Start your day with Yahoo! - make it your home page 
http://www.yahoo.com/r/hs 