US triband vs EU triband

[Dieter Spaar]

Hello Joerg,

Joerg Reisenweber wrote:
> I just confirmed basic functionality of 850/1800/1900 devices (US Freerunner) 
> for 900MHz networks. RF sensitivity is poor, but sufficient for areas with 
> good coverage.
> For Germany a US device (850/1800/1900) worked flawlessly with German operator 
> T-Kom (in urban area), and rather poor with Vodafone. Both are 900MHz 
> networks.
>
> Please notice I didn't yet check for the actual band used, so *if* T-Kom *and* 
> Vodafone both had 1800MHz BTS here in the tested area, then this report might 
> be moot. Anyway the result meets expected behaviour and 1800MHz BTS are not 
> known for either operator.
>   

So this is what I suspected but could not be answered by anyone till now.
According to my investigation the only difference between the two
variants should be a different filter in the reception path, in one case a
bandpass filters GSM850, in the other it is GSM900. Transmitter path
should be the same. As a result the phones should work in all four bands,
however with about 30 dB less signal strength in the not supported band.
A different issue is calibration, its not sure if the transmitter path 
for all
four bands is calibrated properly.

Best regards,
  Dieter