Re: Confusion about 'ports'

[Marcus D. Leech]

On 2022-03-16 18:17, Chad Spooner wrote:

Marcus:

That did it! Thanks much.

I was definitely confused about being able to use both TX/RX and RX2 on subdev B to receive two signals. When I was doing that, I was thinking 'B:0' was sufficient--same device. But switching the antenna back to A, RX2 (as in the original two-block configuration) and using 'A:0 B:0' worked, so then I switched back and tried 'B:0 B:0' but that doesn't work.

Now I also understand (a little bit better anyway) the documentation

https://files.ettus.com/manual/page_configuration.html

I appreciate your patience and skill Marcus,

C

    A card like WBX or UBX has a *SINGLE* receive chain, and *THAT
    CHAIN* can be switched to either "look" at RX2 or the TX/RX port. 
    In half-duplex configurations, it's
      common to have a single antenna that is dynamically either
    connected to the receiver (RX) or transmitter (TX), but there are
    also configurations where the receiver
      (RX) needs to be completely isolated (on a different physical
    antenna port) from the transmitter (TX).
    
    Sub-device specs are of the general form:
    
    <which-side>:<name>
    
    For X310, that's "A" and "B" for "which-side", and the
    "<name>" component depends on the daughtercard that is
    installed there.

On 3/16/22 2:42 PM, Marcus D. Leech wrote:

On 2022-03-16 17:31, Chad Spooner wrote:

Marcus:

Yes, I did miss that reply! Very sorry about that. Let me try to answer your questions:

First, I did try to use a single Source block with two channels on the advice of a colleague. I've been unable to get that to work either. (More on that below, after I answer your questions.)

The x310 has WBX (A) and UBX (B) daughtercards.

The x310's UBX RX2 input is coming from the TX/RX output of an N210 with a WBX daughtercard. The N210 is generating a DSSS signal and transmitting it on TX/RX.

The x310's WBX RX2 input is coming from a passive antenna (Ettus WA5JVB Log Periodic 850 MHz to 6500 MHz).

The x310's UBX TX/RX transmits the sum of the UBX RX2 and WBX RX2 signals.

A third SDR (x300) receives the x310's UBX TX/RX signal and that is the USRP I fetch data from using uhd_rx_cfile.

********

You need to specify a subdev spec of:

A:0 B:0

Right now, you just have B:0, so it's trying to produce two channels from a single sub-device ,and, obviously, failing.

-- 
Chad M. Spooner, PhD
NorthWest Research Associates
301 Webster Street
Monterey, CA 93940
cmspooner@nwra.com
831 582 4904
cyclostationary.blog