LFTX Rev 2.2 Compatibility Issue with USRP2

GNU Radio
1

Hi,

We have a USRP2 with a LFTX Rev 2.2 daughterboard. When I run a GRC
program,
I try to look at the signal with a spectrum analyzer and the signal is
not
there. There is no error at all, everything seems to be up and running.
The
system is recognizing the USRP2, daughterboard and I have also played
around
with the subdev’s but everything is correct.

To make sure there is nothing wrong with the LFTX, I pulled it out from
the
USRP2 and installed it on a USRP N210. In the N210 I re-run the same
exact
GRC program and finally see the signal at the spectrum analyzer. To
confirm
that the USRP2 transmit side is working, I’ve installed a RFX1800 and
re-run
the same GRC program and this also works perfect.

Here is the specs of my config.:
Linux: Ubuntu 10.04LTS
kernel release: 2.6.32-41
GNU Radio Companion 3.6.0
UHD_003.004.002

Has anyone had this issue before?

Thanks!!

View this message in context:
http://old.nabble.com/LFTX-Rev-2.2-Compatibility-Issue-with-USRP2-tp34044804p34044804.html
Sent from the GnuRadio mailing list archive at Nabble.com.

2

GRC program and finally see the signal at the spectrum analyzer. To confirm

Thanks!!
With your LFTX plugged in to the USRP2, please send the output of

uhd_usrp_probe --args “addr=192.168.10.2” (or whatever the address
of your USRP2 is)

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

3

Marcus,

This is the output:

linux; GNU C++ version 4.4.3; Boost_104000; UHD_003.004.002-0-g7f44d838

– Opening a USRP2/N-Series device…
– Current recv frame size: 1472 bytes
– Current send frame size: 1472 bytes

UHD Warning:
Unable to set the thread priority. Performance may be negatively
affected.
Please see the general application notes in the manual for
instructions.
EnvironmentError: OSError: error in pthread_setschedparam

/
| Device: USRP2 / N-Series Device
| _____________________________________________________
| /
| | Mboard: USRP2-REV4
| | hardware: 1024
| | mac-addr: 00:50:c2:85:36:70
| | ip-addr: 192.168.10.2
| | gpsdo: none
| | serial: 1648
| |
| | Time sources: none, external, external, mimo
| | Clock sources: internal, external, mimo
| | Sensors: mimo_locked, ref_locked
| | _____________________________________________________
| | /
| | | RX DSP: 0
| | | Freq range: -50.000 to 50.000 Mhz
| | _____________________________________________________
| | /
| | | RX DSP: 1
| | | Freq range: -50.000 to 50.000 Mhz
| | _____________________________________________________
| | /
| | | RX Dboard: A
| | | _____________________________________________________
| | | /
| | | | RX Subdev: 0
| | | | Name: Unknown (0xffff) - 0
| | | | Antennas:
| | | | Sensors:
| | | | Freq range: 0.000 to 0.000 Mhz
| | | | Gain Elements: None
| | | | Connection Type: IQ
| | | | Uses LO offset: No
| | | _____________________________________________________
| | | /
| | | | RX Codec: A
| | | | Name: ltc2284
| | | | Gain Elements: None
| | _____________________________________________________
| | /
| | | TX DSP: 0
| | | Freq range: -250.000 to 250.000 Mhz
| | _____________________________________________________
| | /
| | | TX Dboard: A
| | | ID: LF TX (0x000e)
| | | _____________________________________________________
| | | /
| | | | TX Subdev: AB
| | | | Name: LF TX (0x000e) - AB
| | | | Antennas:
| | | | Sensors:
| | | | Freq range: -32.000 to 32.000 Mhz
| | | | Gain Elements: None
| | | | Connection Type: IQ
| | | | Uses LO offset: No
| | | _____________________________________________________
| | | /
| | | | TX Subdev: BA
| | | | Name: LF TX (0x000e) - BA
| | | | Antennas:
| | | | Sensors:
| | | | Freq range: -32.000 to 32.000 Mhz
| | | | Gain Elements: None
| | | | Connection Type: QI
| | | | Uses LO offset: No
| | | _____________________________________________________
| | | /
| | | | TX Subdev: A
| | | | Name: LF TX (0x000e) - A
| | | | Antennas:
| | | | Sensors:
| | | | Freq range: -32.000 to 32.000 Mhz
| | | | Gain Elements: None
| | | | Connection Type: I
| | | | Uses LO offset: No
| | | _____________________________________________________
| | | /
| | | | TX Subdev: B
| | | | Name: LF TX (0x000e) - B
| | | | Antennas:
| | | | Sensors:
| | | | Freq range: -32.000 to 32.000 Mhz
| | | | Gain Elements: None
| | | | Connection Type: Q
| | | | Uses LO offset: No
| | | _____________________________________________________
| | | /
| | | | TX Codec: A
| | | | Name: ad9777
| | | | Gain Elements: None

–
View this message in context:
http://old.nabble.com/LFTX-Rev-2.2-Compatibility-Issue-with-USRP2-tp34044804p34048534.html
Sent from the GnuRadio mailing list archive at Nabble.com.

4

When I first noticed such behavior, I had both the N210 and USRP2
running in
the same computer connected through a switch.

addressing:
PC eth0 ip = 192.168.10.1
USRP2 with addr = 192.168.10.2
N210 with addr = 192.168.10.3

But the LFTX plugged in the USRP2 did not work.

I then decided to just have the USRP2 connected directly to the pc, but
still didn’t work at all. And like I said, I used the USRP2 with the
RFX1800
and work just fine, even the LFRX works with plugged in the USRP2.

–
View this message in context:
http://old.nabble.com/LFTX-Rev-2.2-Compatibility-Issue-with-USRP2-tp34044804p34051871.html
Sent from the GnuRadio mailing list archive at Nabble.com.

5

Hi Josh,

Definitely both daughterboards has different frequency ranges, I just
wanted
to test the TX channel of the USRP2 to make sure is working.

That is the way I’m testing the LFTX, I have a spectrum analyzer
connected
to the RX ports.

This is the flowgraph:
SignaSource —> UHD:USRPSink

I have tested the USRP2 with previous UHD and also with the legacy
gnuradio
version, but did not work either. LFTX pins are OK, and it works in the
N210, so probably something with the USRP2 motherboard.

Thanks for suggestions,

Juan

Josh B.-3 wrote:

not
GRC program and finally see the signal at the spectrum analyzer. To
I suggest putting a known signal into the usrp sink and put a scope on

–
View this message in context:
http://old.nabble.com/LFTX-Rev-2.2-Compatibility-Issue-with-USRP2-tp34044804p34054371.html
Sent from the GnuRadio mailing list archive at Nabble.com.

6

On 06/20/2012 05:08 PM, juancolon wrote:

USRP2 and installed it on a USRP N210. In the N210 I re-run the same exact
GRC program and finally see the signal at the spectrum analyzer. To confirm
that the USRP2 transmit side is working, I’ve installed a RFX1800 and re-run
the same GRC program and this also works perfect.

LFTX and RFX1800 have very different frequency ranges. Perhaps you are
not looking in the right frequency range for your signal? LFTX is just a
direct line from the DAC, so +/- 30 or so MHz centered about DC.

I suggest putting a known signal into the usrp sink and put a scope on
the output of the LFTX. If RFX is working, the DAC output should
definitely be there.

-josh