Re: [Discuss-gnuradio] WBX Dual Receiver

[Marcus D. Leech]

On 02/23/2016 11:22 PM, Justyn wrote:
> Hello,
>
> I'm experimenting with the MIMO capabilities of the N210s with WBX 
> daughter cards and seeing how far I can get before I need the MIMO 
> breakout cable or GPSDO.
>
> One of the first things I'd like to see is if both receivers on the 
> WBX daughter card can run at the same time (TX/RX and RX2).
>
> Unfortunately, if I add two USRP source blocks with the same IP to my 
> flow graph and try it out, I get D's on the output.
>
> According to 
> http://files.ettus.com/manual/page_general.html#general_ounotes, it 
> seems that I'm getting "discontinuous packets" and are subsequently 
> dropping data (which I can confirm).  I assume it's because I'm 
> receiving data packets with the same source address, and probably 
> duplicated sequence numbers which GNU Radio thinks are discontinuous.
>
> Is there a way around this? Is this a bug?  It seems if I have the 
> bandwidth and physical hardware, I should be able to leverage those 
> capabilities, no?
>
> This USRP and my workstation are connected through a switch, but if I 
> add a separate identical N210 with WBX to the switch, I get both sets 
> of data, so it's not a bandwidth issue.
>
> --
> Justyn
There is only a single receive chain on a WBX card--there are, granted, 
two ANTENNA PORTS that may be selected that the receive chain
  attaches to, but there really is only one receive chain on a WBX card.

The fact that you have two distinct UHD/USRP objects trying to 
communicate with the same physical USRP is going to create a fair amount
  of confusion in the lower layers which will result in unpredictable 
behaviour.