Re: [Discuss-gnuradio] RFX400 Tuning & WBX Comparison

[Matt Ettus]

On 06/09/2010 12:12 AM, Andrew Gilbett wrote:
> Hi,
>
> When I ask my RFX400 to tune a frequency for example 438.600MHz I get
> the following output.
>
> A: Flex 400 Tx MIMO B
>         r.baseband_frequency = 442000000.0
>         r.dxc_frequency = -3400000.0
>         r.residual_frequency = -0.381469726562
>         r.inverted = False
>
> This means that the synthesiser tunes to 442MHz and in the FPGA the
> base band signal is frequency translated to -3.4MHz? Thus the output
> is on frequency at 438.600MHz.
> Have I spelled that out correctly? I am just trying to get a picture
> of how the system works to tune all the frequencies that I may throw
> at it.

Yes, that is correct.

> Also questions about the WBX:
> How come the RFX400 is now depreciated in favour of the WBX but the
> rest of the RFX series are not and seem to be covered by the WBX
> frequency range?

The WBX is better than the RFX400 in every specification, and so we have 
discontinued the RFX400.  Nobody was buying them anymore after the WBX 
came out.

While the RFX900 and RFX1800 frequency ranges are also covered by the 
WBX, and the WBX specs are in _most_ cases slightly better, we still 
sell the RFX900 and RFX1800 because:

- The RFX900 and RFX1800 have as much as 6dB higher power output
- OpenBTS only works with the RFX-series for now.


> The connector J101 pictured on the WBX on the image available on the
> ettus website; is that so that a SMA connector can be directly
> attached to the receiver? Thus eliminating problems relating to cross
> talk in the little rf switches on the grand-daughter board.

Yes, you can directly connect the antenna to J101 and bypass the 
daughterboard.  This also bypasses the first LNA.  However, there are no 
problems relating to cross talk.

Matt