What is MIMO B?

Hi all,

I’ve implemented an application script to cover both ISM bands 433 MHz
and
2.4GHz. For that purpose I connect a Flex 2400 (RXA/TXA) and a Flex 400
(RXB/TXB) on a USRP Rev 3 motherboard. Everything goes well. But if I
connect
a USRP rev 4.1 or 4.2 with the same d’board configuration to the
USB-Bus, the
python script prints out:

Using RX d’board B: Flex 400 Rx MIMO B
Using TX d’board B: Flex 400 Tx MIMO B

The script runs normal but no packet is received and no packet is send
(no
packet is arriving at another receiver (No Gnuradio receiver).
If the USRP rev 3 is used the print out is:

Using RX d’board B: Flex 400 Rx MIMO B
Using TX d’board B: Flex 400 Tx MIMO B

and packets are received and sent. The print output is obtained by
‘print
“Using TX d’board %s” % (self.subdev.side_and_name(),)’. Where comes
this
MIMO B difference comes from? Is this the reason why the application
runs
with one board and not with the other? How can I solve the problem?

Ah, before I forget it. Perhapes this could help you to give me an
answer. If
I run usrp_fft.py from the examples, I get a ‘Failed to tune to initial
frequency’ in the status bar of the application window. If I try to
introduce
a frequency, the shell outputs:


File “/usr/local/lib/python2.4/site-packages/gnuradio/usrp.py”, line
184, in
tune
return tune(self, chan, subdev, target_freq)
File “/usr/local/lib/python2.4/site-packages/gnuradio/usrp.py”, line
122, in
tune
ok, baseband_freq = subdev.set_freq(target_freq)
File “/usr/local/lib/python2.4/site-packages/gnuradio/db_flexrf.py”,
line
174, in set_freq
R, control, N, actual_freq = self._compute_regs(freq)
File “/usr/local/lib/python2.4/site-packages/gnuradio/db_flexrf.py”,
line
392, in _compute_regs
assert self.B_DIV >= self.A_DIV
AssertionError

Please, help me… I am very grateful for every kind of help
Thank you guys!

Luis Simoes

On Mon, Dec 11, 2006 at 03:50:59PM +0100, Luis Simoes wrote:

with one board and not with the other? How can I solve the problem?
Matt can provide the details. The difference depends on how the
daughterboard gets its master clock. The rev4 usrp runs a clock
to the daughterboard that the earlier versions didn’t. That in
combination with how the daughterboard is configured (jumper
positions) gives the difference.

As to why it works on one but not the other I’m not sure.

Ah, before I forget it. Perhapes this could help you to give me an answer. If
I run usrp_fft.py from the examples, I get a ‘Failed to tune to initial
frequency’ in the status bar of the application window. If I try to introduce
a frequency, the shell outputs:

That means that the frequency you provided on the command line is out
of the range that the daughterboard can tune.

File “/usr/local/lib/python2.4/site-packages/gnuradio/db_flexrf.py”, line
392, in _compute_regs
assert self.B_DIV >= self.A_DIV
AssertionError

Please create a ticket in trac for this.
login: guest
password: gnuradio

This should be caught in a higher layer, and give a better error
message.
The problem is the same: you are asking the daughterboard to tune to a
frequency outside of its range.

Which daughterboard are you using and what is the value that you are
passing to the -f command line option?

Please, help me… I am very grateful for every kind of help
Thank you guys!

You’re welcome!

Eric

Thank you, Eric

Which daughterboard are you using and what is the value that you are
passing to the -f command line option?

I am using the Flex400 daughterboard on TXB/RXB and I run ./usrp_fft.py
-d16
-R B -f 433000000. With the rev3 usrp there is no problem but rev4 usrp
gives
the AssertationError. It is not possible to tune to the desired
frequency
while ./usrp_fft.py is running. The response is always ‘Failed’ and
values
for DDC and Analog BB are 0.

Please, help me… I am very grateful for every kind of help
Thank you guys!

You’re welcome!

Eric

Luis Simoes

On Mon, Dec 11, 2006 at 05:59:09PM +0100, Luis Simoes wrote:

for DDC and Analog BB are 0.
OK.

FYI, you can also use -f 433M

Eric