[ale] OT cellular protocol versions

[Alex Carver]

On 2015-01-22 16:29, Phil Turmel wrote:
> On 01/22/2015 06:32 PM, Alex Carver wrote:
>> Sounds like a Sidekick.
>>
>> What network is he on?  That affects the communication channel.  Not
>> everything is LTE just yet, lots of things are still using various
>> modulations and channel types (2G GSM, 3G EDGE, CMDA, 4G LTE or WiMax).
>>
>> It might be his phone, it might not be. Tower sharing can cause
>> interference and vegetation can cause other issues.  If the phone gets
>> dropped a lot then the tiny SAW filters used in some phones can be
>> damaged causing poor reception.
> 
> OMG!  Industry is using SAW filters?  (I'm presuming that's "Surface
> Acoustic Wave").  My college department head was an early researcher on
> these, and I played (briefly) with them as a sophomore EE.  Talk about a
> blast from the past.
> 
> I just looked:  he's still on the faculty.
> 
> http://ece.umaine.edu/faculty/john-vetelino/
> 
> Phil

Yep, you presume correctly.  They've been using SAWs for a long while
now.  Even my Kenwood TH-D7A handheld uses four of them.  In phones that
use them, they're way up at the front end to perform band preselect
before the DSP does the RF-to-baseband demodulation.  Makes the DSP's
job easier.

Nearly everything that needs a narrowband receiver (GPS, phones, etc.)
almost always gets at least one SAW way up at the antenna.  There used
to be devices that used SAWs in the IF sections but IF has been
disappearing in favor of the direct demodulation so the SAWs moved up to
the RF-preselect job.