Re: [Discuss-gnuradio] Some USRP2 Questions

[Matt Ettus]

> 13) With Basic TX board, USRP1 can generate maximum of 44 MHz frequency,
> What USRP2 is capable of ?
>   

44 MHz is the highest frequency in the first nyquist zone on the USRP1.  
Much higher frequencies can be used in the higher zones.

The USRP2 takes 100 MS/s rates and interpolates up to 400 MS/s.  Direct 
frequencies up to ~170 MHz should be usable.

> 14) What is USRP2 overrun message?
>   

Currently overruns are shown on the UART port, not on the host.  They 
are shown with a "O".  The reality is that you should never see them.  
If the host computer can't keep up you will see "S" messages in the 
terminal on the host, standing for "sequence number error".

> 15) What is USRP2 underrun message?
>   

Underruns are shown on the UART port as "U".

> 16) What are the most important (hot) trunk USRP2 code that we need to check
> to understand USRP2 architecture, configuration and operation?
>   

In the FPGA code, the tx_control.v and rx_control.v show inband 
signalling, dsp_core_rx and dsp_core_tx show the DSP, and u2_core.v is 
the top level.  In the firware, start with txrx.c.

> 17) How much USRP2 FPGA resources does the currently FPGA firmware needs?  
>   

37 out of 40 block RAMs, 16 or 18 of the 40 multipliers, and about 35 to 
40% of the logic area.


Matt