[USRP-users] data anomaly N200's and MIMO

Dan Sego bubbadoradar at gmail.com
Sun Dec 21 12:48:59 EST 2014


Hello to the list.

I have two N200r4 units connected via MIMO, both with WBX. Each is
connected to an identical antenna using identical, but not intentionally
phase matched, coax. The master unit has an internal GPSDO.

After tuning, LO lock, GPS lock, and MIMO lock are confirmed I start
continuous sampling, retaining ~10k samples (rate=12.5 MSPS, fc32) at
intervals of 0.04 sec (approximately 25 Hz burst sample rate). I retain 28
packets of 363 samples, dumping the remainder in the inter-burst interval
into the bit bucket.

At each burst start, and only for the first packet, the signal magnitudes
(sampling HDTV at 575 MHz, with timed command tuning of the LOs to 575 MHz
so the channel allocation is centered at 0 Hz in the baseband) are as
expected. For the second burst, and all subsequent bursts of the
inter-burst interval, the slave samples/measurements are attenuated by ~28
dB. One example is pictured below.

Configuration is a Thinkpad and Windows 7 with Win32; Microsoft Visual C++
version 10.0; Boost_105400; UHD_003.008.000-release. I've attached the
console run output.

Any suggestions or has anyone experienced similar?

cheers, Dan Sego
​
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20141221/d15864a7/attachment-0002.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: N200 data anomaly.jpg
Type: image/jpeg
Size: 58179 bytes
Desc: not available
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20141221/d15864a7/attachment.jpg>
-------------- next part --------------
Win32; Microsoft Visual C++ version 10.0; Boost_105400; UHD_003.008.000-release

-- Opening a USRP2/N-Series device...
-- Current recv frame size: 1472 bytes
-- Current send frame size: 1472 bytes
-- Creating WSA UDP transport for 192.168.10.3:49156
-- Creating WSA UDP transport for 192.168.10.3:49158
-- Creating WSA UDP transport for 192.168.10.3:49157
-- Creating WSA UDP transport for 192.168.10.3:49159
-- Detecting internal GPSDO.... Found an internal GPSDO
-- Creating WSA UDP transport for 192.168.10.2:49156
-- Creating WSA UDP transport for 192.168.10.2:49158
-- Creating WSA UDP transport for 192.168.10.2:49157
-- Creating WSA UDP transport for 192.168.10.2:49159
-- Setting references to the internal GPSDO
-- Initializing time to the internal GPSDO
Using Devices: Multi USRP:
  Device: USRP2 / N-Series Device
  Mboard 0: N200r4
  Mboard 1: N200r4
  RX Channel: 0
    RX DSP: 0
    RX Dboard: A
    RX Subdev: WBXv3 RX+GDB
  RX Channel: 1
    RX DSP: 0
    RX Dboard: A
    RX Subdev: WBXv3 RX+GDB
  TX Channel: 0
    TX DSP: 0
    TX Dboard: A
    TX Subdev: WBXv3 TX+GDB
  TX Channel: 1
    TX DSP: 0
    TX Dboard: A
    TX Subdev: WBXv3 TX+GDB

Actual RX Rate Master: 12.500000 Msps...

Actual RX Rate Slave: 12.500000 Msps...

Actual Gain Master: 10.000000 dB...

Actual Gain Slave: 10.000000 dB...

GPS lock status: locked
GPS epoch time: 1419183071 seconds
-- Successfully tuned to 575.000000 MHz
-- 
-- Successfully tuned to 575.000000 MHz
-- 
Checking LO Lock Master LO: locked...
Checking LO Lock Slave LO: locked...
Checking MIMO Lock MIMO: locked...

sample time first packet2.3000003

full seconds2.3000003


sample time first packet2.34068534

full seconds2.34068534


Done!



More information about the USRP-users mailing list