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OT: RE: [aprssig] D-710 at FCC test site

Dave Baxter dave at emv.co.uk
Tue Aug 7 08:15:59 UTC 2007


Does this imply that in the US, many celular phones still use analog FM
for the audio?

I thought (wrongly it would seem?) that 99.9% of the developed world had
long since changed over to GSM (digital) for mobile phones, I know both
my GSM phones work OK in the US, I've used them there several times
(East, West and North) the only proviso as far as I know, is that they
must be what we call "Tri Band" units.   All you hear on a "scanner" are
buzz's and burps from them...

However I do now know that much of the third world is still slowley
building an 900MHz analogue infrastructure, some charities here still
accept old but working analog cellphones for refirbishment and export to
such teretories.  That I only found out after slinging several old but
otherwise fully working units into the local tip a few years back.

As for "multiplayer PCB construction"...  Is that how they manage to
make it a dual band radio?  :-)

As to the read protection of the FLASH firmware:  If you poke about the
more dimly lit areas of the web (content filters fully functional!) you
can find several sites where there are explicit details as to how to
reset the "security" features of many popular FLASH progarmmable MCU's,
without affecting the code you can then read out, it's not simple, but
it seems it can be done with a good degree of reliability.   Should
anyone have the time and money to invest...   Seems to be a popular hack
for many cable/satelite TV viewing cards, that are just MCU's in a wafer
thin package.


Dave G0WBX.

> "This letter attests to the fact that Kenwood scanner 
> receiver models TM-V71A / TM-D710A meets the requirements of 
> the FCC Rules, 15.121(a). Compliance is achieved through the 
> following method(s):
> (1). The Microprocessor employed has internal flash memory, 
> however the programming information cannot be read out from 
> the Microprocessor, therefore it has same means of protection 
> as a masked Microprocessor .
> (2). The Microprocessor is not to accept programming, 
> selection, scanning or direct entry of Cellular band frequencies.
> (3). Filtering precludes reception of mixer images or 
> harmonics of Cellular band frequencies.
> (4). Subminiature SMD assembly and inaccessible multiplayer 
> PCB construction all but precludes attempts at circuit 
> hardware modifications.
> ___________________________________
> Tamaki Shimamura
> Communication Equipment Division
> Kenwood Corporation "
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