Crespi Floriana wrote:
Hi,
I have a problem with OFDM system.
I transmit OFDM signal at 2.4 GHz, but I receive half of the total packets.
Moreover, only half of the packets received are correct.
CRC controller is perfect but i want a ber estimate, so I change the
payload (binary file) and I receive check bit by bit.
The result of my alteration test is similar than CRC test.
I have a lot of frequency offset, therefore I change manually the frequency
receiver.
I use revision 6845 and RFX 2400.
Example with crc:
The final packet I receive:
ok: False pktno 4602 n_rcvd 1300 n_right 83
Why can't i get all the packets?
Could you help me??
I'm testing OFDM system without USRP and none of the packets are lost.
Thanks a lot.
Crespi,
I'm not sure what state the OFDM code was in at that revision. That is
likely a result of the timing issue I discussed in a previous email to
the list.
The latest revision of the trunk has a much better implementation that
works well over the air and perfectly in the loopback simulation. There
is 1 minor problem left that I hope to get to over the weekend for the
over the air operation. Remember, though, that we don't do any channel
coding, so any wrong bit will cause a packet error. If you run the code
currently over the air, BPSK is almost perfect while QPSK and QAMs will
miss many packets due to only a few bit errors.
In general, the OFDM code is development work so it's likely to be
buggy. We are working on it, but I can only spend a bit of my time with
it currently. I would be very happy to see other people getting into the
code and figuring out ways to make it better.
Thanks,
Tom
_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
