Help with rx_sample_to_file.cpp program and modulation scheme change in UHD

Hi

I am pretty new to UHD. I was looking for some example programs which
can send and receive a text file, and I came across two programs in
the website
(http://code.ettus.com/redmine/ettus/projects/uhd/repository/revisions/master/show/host/examples)
named rx_samples_to_file.cpp and tx_samples_to_file.cpp.

I ran these programs in USRP1. and gave the following arguements:
1)./tx --rate 500000 --freq 10000000 --file rr.txt[this is the name
of the file i transferred]
2)./rx --rate 500000 --freq 10000000 --file r1.txt[this is the name of
the file where i store the received text]

When I tried to transmit and receive some sample text files, the
sender transmitted it correctly, but the receiver is not receiving
anything. When I opened the received file, I found that the file was
more than 10MB and there were some gibberish text in the file. The
programs specify in the help options that they transmit and receive
binary samples, so I don’t know if I am working with the correct
programs or if I am giving the correct arguments while running them.

I also need to change the modulation schemes for different channel
environments. Actually, I am working on adaptive modulation schemes in
my experiments. However, I don’t find an option to change the
modulation schemes in UHD. (I saw those options in python based
non-uhd codes, e.g. benchmar_Rx and benchmark_Tx). Are there any
programs like that in UHD codes that allow change of modulation
schemes?

Your feedback will be very appreciated.

Thanks,


Regards

Shantharam Balasubramanian
MS in Electrical and Computer Engineering
Rutgers University
Ph:732-543-6863
Email:[email protected]

On 09/20/2011 10:25 AM, shantharam balasubramanian wrote:

of the file i transferred]
2)./rx --rate 500000 --freq 10000000 --file r1.txt[this is the name of
the file where i store the received text]

Those files are supposed to contain baseband samples.

When I tried to transmit and receive some sample text files, the
sender transmitted it correctly, but the receiver is not receiving
anything. When I opened the received file, I found that the file was
more than 10MB and there were some gibberish text in the file. The
programs specify in the help options that they transmit and receive
binary samples, so I don’t know if I am working with the correct
programs or if I am giving the correct arguments while running them.

You have scared me.

I also need to change the modulation schemes for different channel
environments. Actually, I am working on adaptive modulation schemes in
my experiments. However, I don’t find an option to change the
modulation schemes in UHD. (I saw those options in python based
non-uhd codes, e.g. benchmar_Rx and benchmark_Tx). Are there any
programs like that in UHD codes that allow change of modulation
schemes?

Gnuradio implements many modulation schemes. UHD provides an interface
to send/recv baseband samples. You should use gnuradio w/ UHD to
implement a receiver and transmitter chain.

I highly recommend installing gr-uhd component and getting familiar w/
gnuradio-companion:
http://code.ettus.com/redmine/ettus/projects/uhd/wiki#Gnuradio-UHD

-Josh

On 20/09/2011 1:45 PM, Josh B. wrote:

implement a receiver and transmitter chain.

I highly recommend installing gr-uhd component and getting familiar w/
gnuradio-companion:
http://code.ettus.com/redmine/ettus/projects/uhd/wiki#Gnuradio-UHD

-Josh

Also, a good book on digital signal processing might be helpful.

Hi Josh,

Thanks for the email. I went through the website you mentioned and I
found
there were benchmark_tx.py and benchmark_rx.py files in the gr-digital
folder.

We imaged the nodes using gnuradio-uhd-working.ndz. Using this image, we
see
the following folders when we log in to the nodes:

gnuradio-uhd

Inside this folder, I see:

gnuradio uhd

If I select uhd, I see the folders that are available in the website (
http://code.ettus.com/redmine/ettus/projects/uhd/repository):

firmware fpga host images

On the other hand, I was expecting to see the gr-digital folder after
selecting the gnuradio folder because the gr-digital folder is inside
the
gnuradio folder in the link (
https://github.com/trondeau/gnuradio/tree/digital/gr-digital/examples).
Unfortunately, I don’t see the gr-digital folder there.

Can you tell me what image I should burn on the SD cards in order to see
this folder and the files that I can see on the website?

Thanks,

Shantharam

Dear Josh,

Thanks for the reply. I have some questions regarding installing grc.
The questions are probably too naive since we are still at the
beginning level of using gnuradio.

We work in WINLAB, Rutgers University. It has a 400 grid testbed and 2
sandboxes that are compatible with GNUradio. There are SD cards
inserted in the nodes. We just load gnuradio images before starting
any experiment (using commands like: omf-5.2 load all
gnuradio-uhd-3.1.2-usrp1.ndz). Now, when you ask us to install gr-uhd,
do you mean that we should install it in the SD cards? Because
gnuradio is not installed in our computers. We just load the image in
the SD cards (inserted in the nodes), ssh to the nodes and then run
the example programs.

Your feedback will be very appreciated.

Thanks,

Shantharam

On Tue, Sep 20, 2011 at 1:45 PM, Josh B. [email protected] wrote:

sender transmitted it correctly, but the receiver is not receiving
environments. Actually, I am working on adaptive modulation schemes in


Regards

Shantharam Balasubramanian
MS in Electrical and Computer Engineering
Rutgers University
Ph:732-543-6863
Email:[email protected]

Hi Josh,

Inside this folder, I see:
gnuradio folder in the link (
https://github.com/trondeau/gnuradio/tree/digital/gr-digital/examples).
Unfortunately, I don’t see the gr-digital folder there.*

Can you tell me what image I should burn on the SD cards in order to see
this folder and the files that I can see on the website?

Thanks,

Shantharam


Regards

Shantharam Balasubramanian
MS in Electrical and Computer Engineering
Rutgers University
Ph:732-543-6863
Email:[email protected]

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