You Guys crack me up
This
M/A-com OpenSky TDMA 800 MHz 25 kHz RF Channel Spacing Digital Trunking Radio Network with
AMBE Encryption
is nothing more than a
modified /\/\
iDEN Digital Radio Network that was sold to
NEXTEL 10 to 12 years ago!
And your jumping up and down about the digital noise the
NEXTEL system produces and rebanding the 800 MHz Frequencies. I wonder how
M/A-com's OpenSky Network System will sound to adjacent
Narrow Band RF Channels? Maybe just as noisey!
There are some differences that I can see. First and foremost being the use of the 25 kHz RF Channels, as M/A-com with their infinite wisdom are only dividing the RF Channel into to independent 12.5 kHz signal bandwidths carrying transports, one to carry
Data and second to carry
Voice Traffic not being Frequency Efficient the way I view this digital technology system but it's a trade-off feature..
I've read and reread the M/A-com OpenSky Web Page:
http://www.opensky.com/about.asp
And I can
not find a single item in their document that states anything about
Telephone Inconnect Calls to the outside world. I suppose that option has gone away as if
Public Safety Personnel do
not ever need it anymore.
What I do like is the feature of
Analog to
Digital migration if you are already are using a 800 MHz Trunking Network. Purchase all of the new Infrastructure Equipment first and then the Digital Subscribers units as the funds become available. I would need to believe that this M/A-com system is using Linear FM Technology to be compatible with older Analog FM (Class C) Trunking RF Signals.
/\/\'s
iDEN Digital RF Signaling uses Linear AM (Class B) with a 16 Bit QAM Signaling within the 25 kHz RF Channel and is
not backwards compatible with the older Analog FM Technology. The "Over-The-Air" transport is /\/\ VSELP between the
Enhanced
Base
Transceiver
Stations (
EBTS) and the
Subscribers units. Depending on how the
Dispatch or
Direct Connect Voice Traffic was assigned to RF Channels, it uses only 2
TS and if the RF Channel was handling the
Telephone Interconnect Calls, there were 3
TS assigned. The RF Channels could be set up as
6:1 or
4:1 depending on what
NEXTEL wanted. All of the
Base
Site
Controllers (
BSC were routed through
T1 DACCs and then out to the individual
EBTS Cell Tower Sites. NEXTELs equipment is already set up to accept Cipher but the RF TDMA is fairly secure in itself because of the
Time
Division
Multiple
Access and coupled with the Time Slots.
M/A-com's
AMBE Encryption is a low level format compaired to DVP, DES or AES-256 but when used with TDMA and TS, it's probably adequate for Secure Technology. I believe that the Amateur Radio Community is using the AMBE for
ICOMs D*Star and
AOR Digital SSB Formats. M/A-com's web page does
not provide the "Over-The-Air' signaling transport and
AMBE is
not compatible with
IMBE.
QUOTING: PhasedlockedLunatic:
M/A-Com does offer P25 products (M7100 mobiles, P7100 and P5100 portables, MASTR III base/repeater). It's not that M/A-Com isn't P25 compliant, it's that your agency purchased their OpenSky system which is not P25.
It's all about the choice.
Tony: The info I received was from a former fireman from New Salem. I usually just listen to other talkon these matters, then decide for my self. I now under stand he was off by a few bucks in his conversation.