Recieve with two antenas individually and simultaneously

GNU Radio
1

Hi,

I have the following connections in my grc file.

usrp source(900M)–>gmsk mod–>packet decoder–>file sink1
usrp source(928M)–>gmsk mod–>packet decoder–>file sink2

I am trying to receive the packets at two different frequencies.I can
definitely see some data in the file sinks i used.But,the problem is
each
file sink shows a certain number of packets only.For example,if
usrp@900M
receives packets 22,23,24,usrp@928M receives packets 25,27.As you can
see
that 26th packet is missing and might have been dropped.Each antenna is
separating the continuous flow of packets and no duplicity of packets is
formed.Can someone explain why is this happening?!And what can i do to
get
rid of this and receive all the packets individually on each
antenna(like
usrp@900 receives 21,22,23,24 and usrp@928M also received 21,22,23,24).

If i am unclear with the question,please do let me know.

Thanks,
Manjusha.

2

receives packets 22,23,24,usrp@928M receives packets 25,27.As you can see

When asking this type of questions, it’s best to actually attach your
flow-graph, or a pointer to a pastebin of your flow-graph, and give
DETAILS
of your hardware setup. What type of USRP? How many and what type
of daughtercards, etc…

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

3

Okay…

Here are the additional details…

I am using USRP1,RFX900,750Mhz to 1050mhz transceiver daughter board.
Also,kindly find the attached grc file i am using.

Please let me know if more details are required…

Thanks! final_msg_rx.grc
http://gnuradio.4.n7.nabble.com/file/n41495/final_msg_rx.grc

4

using Volk machine: ssse3_64
– Opening a USRP1 device…
– Using FPGA clock rate of 64.000000MHz…
Traceback (most recent call last):
File “/home/gnuradio/grc/Project/relays/top_block.py”, line 126, in

tb = top_block()
File “/home/gnuradio/grc/Project/relays/top_block.py”, line 62, in
init
self.uhd_usrp_source_0.set_center_freq(900e6, 1)
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/uhd/uhd_swig.py”,
line 1879, in set_center_freq
return _uhd_swig.uhd_usrp_source_sptr_set_center_freq(self, *args)
RuntimeError: vector::_M_range_check

Done

we just tried using single USRP source but we got the error which is
shown
above,Is it possible to use a single usrp and single daughter-board at
different frequencies and receive the signal. final_msg_rx.grc
http://gnuradio.4.n7.nabble.com/file/n41518/final_msg_rx.grc
for your reference the GRC file is attached

Thanks

5

http://gnuradio.4.n7.nabble.com/file/n41495/final_msg_rx.grc
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So, to clarify, you have a SINGLE USRP1, a SINGLE RFX900?

You flow-graph uses two independant UHD sources, which won’t work. You
need a single UHD source, configured for two output channels,
and use the dual-DDC mode to extract your two frequencies (which, by
the way, are far enough apart that this will barely work).

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

6

File “/usr/local/lib/python2.7/dist-packages/gnuradio/uhd/uhd_swig.py”,

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Here’s an example of something that should work – It uses a USRP2/N210
device addressing, but you should be able to change this for a USRP1.

7

–
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http://gnuradio.4.n7.nabble.com/recieve-with-two-antenas-individually-and-simultaneously-tp41492p41521.html
Sent from the GnuRadio mailing list archive at Nabble.com.

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Does it give you errors, or just not hte output you expect?

How about you attach an FFT to both sides, and see if they are what you
expect?

I mean, at this point, we’re debugging your flow-graph for you

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

8

It does not give me any error but there is no output at all. We have
attached
FFT as shown in the GRC file 51.png
http://gnuradio.4.n7.nabble.com/file/n41523/51.png Here attached the
screen shot of the FFT plot

9

I tried doing that…I gives me no output when i use Mb0 sub device
specification.here is the file after changes are made. final_msg_rx.grc
http://gnuradio.4.n7.nabble.com/file/n41521/final_msg_rx.grc

Thanks!

10

We will be happy if someone tells us where we are actually going wrong.

Thanks!