Re: [Openbts-discuss] OpenBTS-Project

[David A. B. <dbu...@jc...>]

Fabian -

We used something similar at Burning Man.  The problem, though, is  
that once you start tx-ing and real power in the downlink band, it  
will bleed like crazy into the uplink band.  You need, at a bare  
minimum, something on the order of 100 dB of isolation between  
downlink and uplink if you want to operate over any significant range  
and to really get the full range of the protocol I think you need  
more like 160 dB.  Even if the USRP output were very clean (which it  
is not), you will have an isolation problem.  You will need a good  
duplexer to get to isolation you need, or at least a good pair of  
uplink/downlink filters.  Otherwise your range will be limited to  
just 10-20 meters, regardless of your transmitted power levels.

-- David


On Nov 20, 2008, at 1:59 AM, Fabian Uehlin wrote:

> Hello David,
>
> we ordered the USRP and 2x RFX1800. Unfortunately the items are out  
> of stock and so we will get it in ca. 4 weeks.
> We got a temporary licence (GSM1800) and we are allowed to transmit  
> 1W ERP. The daughterboards has an100+mW output, so we think about
> buying an extra module like this http://www.macom.com/DataSheets/ 
> PA1132.pdf
> Do you have any experience?
>
> Thanks & Regards -Fabian Uehlin-
>
> Am 31.10.2008 um 00:05 schrieb Fabian Uehlin:


David A. Burgess
Kestrel Signal Processing, Inc.