[USRP-users] R: subdev vs. channels

Crozzoli Maurizio maurizio.crozzoli at telecomitalia.it
Tue Jul 14 08:40:13 EDT 2015


Thank you Michael!

With reference to the logs below I need further clarifications.

If we try to get data from more than two channels we get an error.

I am a bit surprised because I would have expected to get 4 RX chains:

-          one for RX Frontend: A | Name: FE-RX2 | Antennas: TX/RX

-          one for RX Frontend: A | Name: FE-RX2 | Antennas: RX2

-          one for RX Frontend: B | Name: FE-RX1 | Antennas: TX/RX

-          one for RX Frontend: B | Name: FE-RX1 | Antennas: RX2

Could someone please comment on that?

TIA!

BR,
Maurizio.



From ‘./rx_multi_samples --args="master_clock_rate=30000000" --secs=1 --nsamps=90000000 --rate=15000000 --channels="2"’

---------------------- Start log --------------------------------------
linux; GNU C++ version 4.9.1; Boost_105500; UHD_003.007.003-0-unknown


Creating the usrp device with: master_clock_rate=30000000...
-- Operating over USB 3.
-- Initialize CODEC control...
-- Initialize Radio control...
-- Performing register loopback test... pass
-- Performing register loopback test... pass
-- Performing CODEC loopback test... pass
-- Performing CODEC loopback test... pass
-- Asking for clock rate 30.000000 MHz
-- Actually got clock rate 30.000000 MHz
-- Performing timer loopback test... pass
-- Performing timer loopback test... pass
Using Device: Single USRP:
  Device: B-Series Device
  Mboard 0: B210
  RX Channel: 0
    RX DSP: 0
    RX Dboard: A
    RX Subdev: FE-RX2
  RX Channel: 1
    RX DSP: 1
    RX Dboard: A
    RX Subdev: FE-RX1
  TX Channel: 0
    TX DSP: 0
    TX Dboard: A
    TX Subdev: FE-TX2
  TX Channel: 1
    TX DSP: 1
    TX Dboard: A
    TX Subdev: FE-TX1

Setting RX Rate: 15.000000 Msps...
Actual RX Rate: 15.000000 Msps...

Setting device timestamp to 0...

---------------------- Stop log --------------------------------------


From ‘uhd_usrp_probe’:

---------------------- Start log --------------------------------------
linux; GNU C++ version 4.9.1; Boost_105500; UHD_003.007.003-0-unknown

-- Operating over USB 3.
-- Initialize CODEC control...
-- Initialize Radio control...
-- Performing register loopback test... pass
-- Performing register loopback test... pass
-- Performing CODEC loopback test... pass
-- Performing CODEC loopback test... pass
-- Asking for clock rate 32.000000 MHz
-- Actually got clock rate 32.000000 MHz
-- Performing timer loopback test... pass
-- Performing timer loopback test... pass
  _____________________________________________________
/
|       Device: B-Series Device
|     _____________________________________________________
|    /
|   |       Mboard: B210
|   |   revision: 4
|   |   product: 2
|   |   serial: 30875E1
|   |   FW Version: 4.0
|   |   FPGA Version: 3.0
|   |
|   |   Time sources: none, internal, external, gpsdo
|   |   Clock sources: internal, external, gpsdo
|   |   Sensors: ref_locked
|   |     _____________________________________________________
|   |    /
|   |   |       RX DSP: 0
|   |   |   Freq range: -16.000 to 16.000 Mhz
|   |     _____________________________________________________
|   |    /
|   |   |       RX DSP: 1
|   |   |   Freq range: -16.000 to 16.000 Mhz
|   |     _____________________________________________________
|   |    /
|   |   |       RX Dboard: A
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Frontend: A
|   |   |   |   Name: FE-RX2
|   |   |   |   Antennas: TX/RX, RX2
|   |   |   |   Sensors:
|   |   |   |   Freq range: 50.000 to 6000.000 Mhz
|   |   |   |   Gain range PGA: 0.0 to 73.0 step 1.0 dB
|   |   |   |   Connection Type: IQ
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Frontend: B
|   |   |   |   Name: FE-RX1
|   |   |   |   Antennas: TX/RX, RX2
|   |   |   |   Sensors:
|   |   |   |   Freq range: 50.000 to 6000.000 Mhz
|   |   |   |   Gain range PGA: 0.0 to 73.0 step 1.0 dB
|   |   |   |   Connection Type: IQ
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Codec: A
|   |   |   |   Name: B210 RX dual ADC
|   |   |   |   Gain Elements: None
|   |     _____________________________________________________
|   |    /
|   |   |       TX DSP: 0
|   |   |   Freq range: -16.000 to 16.000 Mhz
|   |     _____________________________________________________
|   |    /
|   |   |       TX DSP: 1
|   |   |   Freq range: -16.000 to 16.000 Mhz
|   |     _____________________________________________________
|   |    /
|   |   |       TX Dboard: A
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Frontend: A
|   |   |   |   Name: FE-TX2
|   |   |   |   Antennas: TX/RX
|   |   |   |   Sensors:
|   |   |   |   Freq range: 50.000 to 6000.000 Mhz
|   |   |   |   Gain range PGA: 0.0 to 89.8 step 0.2 dB
|   |   |   |   Connection Type: IQ
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Frontend: B
|   |   |   |   Name: FE-TX1
|   |   |   |   Antennas: TX/RX
|   |   |   |   Sensors:
|   |   |   |   Freq range: 50.000 to 6000.000 Mhz
|   |   |   |   Gain range PGA: 0.0 to 89.8 step 0.2 dB
|   |   |   |   Connection Type: IQ
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Codec: A
|   |   |   |   Name: B210 TX dual DAC
|   |   |   |   Gain Elements: None

---------------------- Stop log --------------------------------------


Da: Michael West [mailto:michael.west at ettus.com]
Inviato: lunedì 13 luglio 2015 22:27
A: Crozzoli Maurizio
Cc: USRP-users at lists.ettus.com
Oggetto: Re: [USRP-users] subdev vs. channels

Hi Maurizio,
The subdevice specification is not necessary to supply in most cases.  It allows users to more specifically map the RF front ends to channels.  By default, the front ends are enumerated where channel 0 is the first front end on the first device and channel N is the last front end on the last device.  The order of the device adresses during the multi_usrp object creation defines the order of enumeration of the devices.

For your use case, you do not need to provide a subdev spec.  You only need to provide the correct ordering for the device addresses and indicate the channel(s) you intend to use.

Regards,
Michael
P.S.  The documentation for all products can be found at http://files.ettus.com/manual/

On Mon, Jul 13, 2015 at 1:14 AM, Crozzoli Maurizio via USRP-users <usrp-users at lists.ettus.com<mailto:usrp-users at lists.ettus.com>> wrote:
With reference to the sample code “rx_multi_samples.cpp” provided in the Ettus code site, could someone please explain (or give some reference to some documentation) the difference between the “subdev” specification and the “channels”?

With reference to the boards B220 and E310 (we already have the first one, we are just buying the second one), we would like to be able to select more than one RX chain (from 2 to 4) but it is not clear if that situation is to be handled by “subdevices” and/or “channels”. Looking at the code it seems that all the “trick” is done by managing the “channels” and the “subdevices” is almost useless… For sure I am wrong, that is why I am asking for help here…

TIA!

BR,
Maurizio.

PS Why just a few week ago http://code.ettus.com/ could be freely accessed and now it requires username/password? And how to get them?
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