ADC to DDC mux value, measure SNR/SNIR

GNU Radio
1

Hi,

I am trying to do beamforming using 2 RFX 2400 boards. I am facing an
issue with setting the mux value (to set ADC connection to DDC and/or
DUC connection to DAC) on transmitter and receiver side. On the
transmitter side I am using the value 0xba98 and I think this works. On
the receiver side I have used values like: 0xf3f2f1f0 (which didn’t
work), 0xf0f0f1f0, 0x00001100 and a few other values (which also didn’t
work). I have used the link the following link in uderstanding how to
set mux: http://www.nd.edu/~jnl/sdr/docs/tutorials/4.html#tth_sEc2.3
http://www.nd.edu/~jnl/sdr/docs/tutorials/4.html#tth_sEc2.3 Can
anyone help me understand how to set the mux value and what value
should I use on transmit and receive side if 2 daughter boards are used
to form a transceiver?

(0, 1) or (1,1) value for (side, subdev) is giving an error saying that
this tuple is out of range. value (0,0) and (1,0) only has to be set on
both transmit and receive side. My understanding was subdev=0 would
physically map to one of the antennas on the daughterboard and subdev=1
maps to the other antenna. My understanding is surely wrong and I am
missing something, can anyone pls help me understand this?

Is there anyway to measure the Signal to Noise ratio or SNIR value?

Really appreciate any help

Thanks
Meenaktchi

2

On Thu, Mar 29, 2007 at 01:10:58PM -0700, Candy Yiu wrote:

Hi,

I am trying to do beamforming using 2 RFX 2400 boards. I am facing an
issue with setting the mux value (to set ADC connection to DDC and/or
DUC connection to DAC) on transmitter and receiver side. On the
transmitter side I am using the value 0xba98 and I think this works. On
the receiver side I have used values like: 0xf3f2f1f0 (which didn’t
work), 0xf0f0f1f0, 0x00001100 and a few other values (which also didn’t
work).

The RFX-2400 does uses quadrature downconversion.
To access two boards simultaneosly you want the to set the mux value
to 0x32103210. The top 16-bits are don’t care, as long as the Q
fields are not 0xf.

/*!

  • \brief Set input mux configuration.
  • This determines which ADC (or constant zero) is connected to
  • each DDC input. There are 4 DDCs. Each has two inputs.
  • 

    • 

  • Mux value:
    • 

  • 

  • 3 2 1
    • 

  • 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
    • 

  • ±------±------±------±------±------±------±------±------+
    • 

  • | Q3 | I3 | Q2 | I2 | Q1 | I1 | Q0 | I0 |
    • 

  • ±------±------±------±------±------±------±------±------+
    • 

  • 

  • Each 4-bit I field is either 0,1,2,3
    • 

  • Each 4-bit Q field is either 0,1,2,3 or 0xf (input is const zero)
    • 

  • All Q’s must be 0xf or none of them may be 0xf
    • 

  • 

    • 



*/

bool set_mux (int mux);


You’ll also need to set_nchannels to 2.




(0, 1) or (1,1) value for (side, subdev) is giving an error saying that

this tuple is out of range. value (0,0) and (1,0) only has to be set on

both transmit and receive side. My understanding was subdev=0 would

physically map to one of the antennas on the daughterboard and subdev=1

maps to the other antenna. My understanding is surely wrong and I am

missing something, can anyone pls help me understand this?




If you’re using both daughterboards simultaneously, then the rx subdev

stuff isn’t going to help you out. You need to specify the mux value

by hand.


gnuradio-examples/python/multi-antenna/multi_file.py is similar to

what you are trying to do, though it handles 4 channels using two

Basic Rx daughterboards. The mux setting is different in that case

since it’s presenting four real signals to 4 DDCs, not 2 quadrature

signals to 2 DDCs as in the case with the RFX-* boards.


N.B., you’ll want to use the standard fpga image (which includes

half-band filters), not the “std_4rx_0tx.rbf” file used in the

4-channel examples.


Eric