Hi all:
Have you ever using the
gnuradio/gr-digital/examples/ofdm/rx_ofdm.grc?And I change the
rx_ofdm.py as follows:
self.connect((self.digital_ofdm_chanest_vcvc_0, 1),
blocks.file_sink(gr.sizeof_gr_complex * fft_len,
‘channel-estimate.dat’))
And i use the matlab:
csi=read_complex_binary(‘channel-estimate.dat’);plot(1:64,real(csi(1:64,1)),‘rs-’)
The result is attached.But I think the result is wrong.Have
someone do the similar thing like me?Can we discuss this?
Environement: 2 USRP N210 and SBX
Thank you.
Best regards,
xd
On 07/13/2014 01:06 PM, xianda wrote:
Hi all:
Have you ever using the
gnuradio/gr-digital/examples/ofdm/rx_ofdm.grc?And I change the
rx_ofdm.py as follows:
self.connect((self.digital_ofdm_chanest_vcvc_0, 1),
blocks.file_sink(gr.sizeof_gr_complex * fft_len, ‘channel-estimate.dat’))
And i use the matlab:
Please read the fine manual:
GNU Radio Manual and C++ API Reference: gr::digital::ofdm_chanest_vcvc Class Reference.
The channel estimate is on a tag.
M
On 07/15/2014 09:39 AM, xianda wrote:
Hi Martin:
Thank you for your kindly reply.
Another question I want to ask.
When I use the rx_ofdm,I add a UHD:USRP
Source.(Environment: USRP N210)I know when the block Schmidl &Cox OFDM
synch. detect the signal,the port “detect” will output 1.And I test it.I
use the rx_ofdm when I don’t use the tx_ofdm.It means that no signal
exist.But I find 1 in the port “detect”.Why?When no signal exist,it
should output 0.Why I see 1 from it?
…bad luck? It’s not impossible to generate false alarms. What did you
feed the block?
Martin
Hi Martin:
Thank you very much.But I test again and again,the
rx_detect don’t exist 1.And some little value approach 0 exists.But in
the header stream chain some values exist.I think when 1 don’t exist
there shouldn’t have value in the header stream chain.Why?
Best regards,
xd
Oh,I guess that because i receive signal which at the frequency of
2.45e9.It is like the wifi.May be I receive the wifi signal?Am i right?
Thank you.
Hi Martin:
Thank you for your kindly reply.
Another question I want to ask.
When I use the rx_ofdm,I add a UHD:USRP
Source.(Environment: USRP N210)I know when the block Schmidl &Cox OFDM
synch. detect the signal,the port “detect” will output 1.And I test it.I
use the rx_ofdm when I don’t use the tx_ofdm.It means that no signal
exist.But I find 1 in the port “detect”.Why?When no signal exist,it
should output 0.Why I see 1 from it?
Thank you so much.
Best regards,
xd
At 2014-07-14 04:37:37, “Martin B.” [email protected] wrote:
On 07/13/2014 01:06 PM, xianda wrote: >> Hi all: >> Have you ever using
the >> gnuradio/gr-digital/examples/ofdm/rx_ofdm.grc?And I change the >>
rx_ofdm.py as follows: >>
self.connect((self.digital_ofdm_chanest_vcvc_0, 1), >>
blocks.file_sink(gr.sizeof_gr_complex * fft_len,
‘channel-estimate.dat’)) >> And i use the matlab: > >Please read the
fine manual:
GNU Radio Manual and C++ API Reference: gr::digital::ofdm_chanest_vcvc Class Reference.The channel estimate is on a tag. > >M >
_______________________________________________ >Discuss-gnuradio
mailing list >[email protected]
https://lists.gnu.org/mailman/listinfo/discuss-gnuradi
Hi Marcus:
Thank you.Sorry for that.
I wrongly use the read_complex_binary to analyse the
detect at the second time.As I said(But I test again and again,the
rx_detect don’t exist 1.And some little value approach 0 exists.).If I
use the read_char_binary to analyse the detect.There is 1 under every
test.I said the truth.It isn’t stochastic problems maybe.And I attached
my modified rx_ofdm.grc.You can run it when no tx signal exist.And you
will see r_detect.dat will exist 1.(In matlab,use the
read_char_binary.m).And a1.dat and a.dat isn’t null.(In matlab,use the
read_complex_binary.m).You can test it.Thank you.
Maybe I am wrong,please correct me.Thank you.
Best regards,
xd
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Hi Xianda,
how should we possibly tell? You expect us to be able to guess what is
going wrong with your measurement, in an environment that is unknown
to us, using a receiving antenna, modified flowgraph and tx signal
that you did not really define.
As Martin said, if a detector outputs a 1, it might be a false alarm,
also known as bad luck.
With stochastic problems, you always have to make a trade off between
false alarm rate and type II errors. This is called receiver operating
characteristic. With most detectors, you can adjust their parameters
to accommodate your false alarm rate/detection rate needs.
Greetings,
Marcus
On 15.07.2014 12:56, xianda wrote:
“detect”.Why?When no signal exist,it should output 0.Why I see
blocks.file_sink(gr.sizeof_gr_complex * fft_len,
‘channel-estimate.dat’)) >> And i use the matlab: > >Please
read the fine manual:
GNU Radio Manual and C++ API Reference: gr::digital::ofdm_chanest_vcvc Class Reference.
The channel estimate is on a tag. > >M >
_______________________________________________ Discuss-gnuradio
mailing list [email protected]
Discuss-gnuradio Info Page
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
iQEcBAEBAgAGBQJTxSMPAAoJEBQ6EdjyzlHtRwEH+gPol6VhuE5BBqyq5GUD7H9P
GhTufylcZhwuK5XLbZg1l5ZrcqrcJu8+CZRFmWuK2vIml4JhzVPre5gPSbYeRdFs
e+aZ+mT3TN62oXXurvq+YM6mnBdewR2bi8h/DtkC77OkB5SvL6j6rREWSg73flCB
/sh2hgHuQkJ8d2sh8ut0L1NF6rlbB3l+unwEgjGeLnDyH3fdFjfUDPlh7OiX318w
GmfPasCiSMMmcSqXCIaXcHaaVF/cdip7Yd8LQACMKJvZBT9AvGh5i725z3Drytdl
20B69ymrWD93bEdBjN7WAyAAvDJVbE6nWv1gXuUYfkbnGHwIaGomXfU8PQrPY14=
=qRmz
-----END PGP SIGNATURE-----
XD,
I’m having real trouble understanding what you’re doing.
Try this: generate white noise and put it into the detector. Do you see
any 1s? I would guess no.
M