Calypso/Iota/Rita chip recommendations

Michael Spacefalcon msokolov at ivan.Harhan.ORG
Wed Aug 14 21:01:16 UTC 2013


Peter Stuge <peter at stuge.se> wrote:

> It would be neat if you choose a filter part with a footprint that
> can also accomodate a balun more easily than in the Compal phones,

Actually my hope is to build a quad-band phone (unlike the dual- or
tri-band ones we have so far) by copying this reference design from
TI:

ftp://ftp.ifctf.org/pub/GSM/Calypso/Leonardo_plus_quadband_schem.pdf

[The above PDF came from one of the Chinese sites; the /pub/GSM
 directory of my FTP site above is my own sort of mini-Wikileaks for
 all things dealing with the Calypso and related things - I encourage
 everyone to check out the collection of goodies which I've accumulated
 so far, and which only keeps growing. :-)]

As you can see on that schematic, instead of using separate antenna
switch and Rx SAW filter parts, the Leonardo reference boards used
integrated RF front-end modules - in the case of the quad-band
Leonardo Plus, it's a quad-band RF FEM that works perfectly with the
Rita.

The specific part on that Leonardo+ board seems to be Epcos M034F.  A
quick search for that part hasn't shown up any availability, but then
it was only a very quick search, and even if that specific part isn't
available, I reason that there must be functional equivalents from
other manufacturers.

> so that a phone could be assembled "either way".

You mean a filterless sniffer version?  I have to admit that sniffing
and other GSM hacking aren't really my areas of interest - instead all
I want is a 100% "normal" cellphone, but with just one difference:
running software/firmware whose full source is physically available
(be it legal or otherwise) for the exercise of the Four Freedoms
defined by the FSF, as a moral requirement.

SF




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