Subject: [NEXTEL-1] RE: What is the difference between P25 and cellpone format?

From: [email-masked]
Date: Mon, 21 Jul 2003 17:28:30 -0400

Original Message --------
   From: John Powell <[email-masked]>
Subject: RE: What is the difference between P25 and cellpone format?

The "voice compression chip" has no significance to the bandwidth being employed.
It simply gives a digital representation of the incoming voice stream, with the
output being a particular number of kilobits per second.  Most of the "full rate"
vocoders (IMBE/AMBE, VSELP, Thompson used by TETRA, etc) have about the same
output rate.  We chose the IMBE vocoder over all of the others in the early 90s
because the quality of the reproduced signal far surpassed all of the competition
at that time.  Another important characteristic was performance in a noise
environment.  IMBE performs well with sinusoidal background noise such as a siren,
but passes compression type noise such as a gunshot - both very important
considerations in our field.  That selection was made after extensive testing
involving both DoD and a private testing lab.  >From personal experience in all of
those tests, there is no comparison in voice quality for IMBE vs VSELP.  I'd guess
that is why Motorola no longer uses VSELP, even though it is their technology.

The cost of the IMBE intellectual property is not "very expensive" - few know what
it actually is because of the nondisclosure agreement required during the
negotiations with the P25 Steering Committee.  I am a member of the SC and know
what those numbers are...  lets say they are not insignificant, but also not
anywhere close to being the primary reason the radios are so expensive as compared
to cell phones.  The reasons for expensive equipment are the quality of the
equipment, and most importantly, the quantity produced: tens of millions vs tens
of thousands!

John Powell
P25 Steering Committee

P.S.  At the time this vocoder was selected, the idea of spectrum auctions at the
Congress and FCC was still years away.

At 08:18 AM 7/21/2003 -0600, Byron Schmidt wrote:

> Leonard and group,
>
>   I think your observations are valid.  You need to know that one of the reasons
> that the P25 radios are more expensive that other digital solutions is the
> choice of the voice compression chip that gives us the narrowband capabilities
> the FCC wants.  The IMBE/AMBE coder is a very expensive license to the
> manufacturers.  It s choice by P25 folks as the standard locks out other
> possibilities.  VSELP and other digital coding techniques cannot be used because
> of their incompatibility.  They would have been cheaper, but did not meet the
> required bandwidth specs again driven by the FCC.  Remember the FCC sells
> spectrum space, so the more space they can save the more money to be made.  I
> think that is wrong, but that is just my opinion.  One other thing.  The more
> stuff we add to the P25 system, the more convoluted it becomes.  I am a member
> of the K.I.S.S. organization.  Simple is better sometimes.  But the question is
> how do you convince the P25 powers that be of that?  The manufacturers will make
> whatever the standard is currently.  They will make money at it in any case.
> Later.
>
>
>
> Byron L. Schmidt, DAFC, GS-11
>
> Deputy State Director
>
> CAP-USAF Liaison Office. Idaho
>
> 208-345-8263 (Voice)
>
> 208-333-8247 (FAX)
>
> [email-masked]

------------------------ Yahoo! Groups Sponsor ---------------------~-->
Get a FREE REFINANCE QUOTE - click here!
http://us.click.yahoo.com/nHYuCC/ca0FAA/ySSFAA/61FxlB/TM
---------------------------------------------------------------------~->

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

---

From: Rick Parrish <[email-masked]>
Date: Mon, 21 Jul 2003 16:57:15 -0500

[email-masked] wrote:

>The cost of the IMBE intellectual property is not "very expensive" - few know what it actually is because of the nondisclosure agreement required during the negotiations with the P25 Steering Committee.  
>
IMBE is obsolete. *gasp*

There are newer, more advanced speech compression vocoders
(supporting variable bit rates and offering higher fidelity) available
that incur ZERO licensing costs. Even DVSI has dropped their own
IMBE in favor of AMBE.

As for the NDA, I'm a little weary of any government organization or
association that allows any of its deals - particularly something so 
crucial
to the implementation of Project 25 - to be conducted in a cloaked,
secretive manner.

>I am a member of the SC and know what those numbers are...  lets say they are not insignificant, but also not anywhere close to being the primary reason the radios are so expensive as compared to cell phones.  The reasons for expensive equipment are the quality of the equipment, and most importantly, the quantity produced: tens of millions vs tens of thousands!
>  
>
Chips are chips - and the requirements met by the chipsets found in
most cell phones are pretty darn close to what you'd expect in a trunked
two-way radio. The manufacturer that can leverage the production volumes
of cellular technology will have a better product at a lower cost.

-rick

------------------------ Yahoo! Groups Sponsor ---------------------~-->
Free shipping on all inkjet cartridge & refill kit orders to US & Canada. Low prices up to 80% off. We have your brand: HP, Epson, Lexmark & more.
http://www.c1tracking.com/l.asp?cid=5510
http://us.click.yahoo.com/GHXcIA/n.WGAA/ySSFAA/61FxlB/TM
---------------------------------------------------------------------~->

---

From: [email-masked]
Date: Mon, 21 Jul 2003 18:40:31 -0400

> that incur ZERO licensing costs. Even DVSI has dropped their own

True- Even  iDEN's new vocoder offers more advantages than DVS I's old P-25 vocoder. One day P-25 will realize that Cellular is the leader and they are just followers.
P-25 should look closely at the advancements in cellular technology and incorporate
their research and development in P-25. Where is the 4 Slot P-25 spec? By the time we see it cellular carriers will be running OFMD. Even the wideband data guys have a new spec for Public Safety. Slow P-25 production = Slower P-25 Adoption.

> to the implementation of Project 25 - to be conducted in a cloaked,

Yea- that's why we need insiders who are willing to talk with under the condition of anonymity.

> two-way radio.

Yep, Yep- economy of scale-

> The manufacturer that can leverage the production volumes

------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for Your HP, Epson, Canon or Lexmark
Printer at Myinks.com. Free s/h on orders $50 or more to the US & Canada.
http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/sOykFB/k9VGAA/ySSFAA/61FxlB/TM
---------------------------------------------------------------------~->