Re: [Discuss-gnuradio] OFDM Transmitter and Receiver - poor synchronization with USRP1

[Martin Braun]

On 20.05.2015 20:19, Michal Vaclík wrote:
> Hi, I am sorry for the delayed response.
> 
> I checked the centering of the OFDM signal and it looks pretty good.
> Even looking at the signal's spectrum using SDR# on other computer was
> very nice - book-grade example of nicely shaped OFDM spectrum. Today I
> upgraded from GNU Radio v 3.7.6.1 to 3.7.7.1 and reception
> (syncrhonization and detection) has improved dramatically. Even at
> relatively low sample rate (1M, anything lower simply doesn't
> synchronizie). Unfortunately the received packets still weren't enough
> for any kind of real world transmission. 
> 
> Was OFDM improved in some kind of way in v3.7.7.1 (I don't see anything
> related to OFDM in changelog)? I simply launched the same flowgraph on
> newer version and it works much better.

Hm, not that I recall... but good for you :)

I forget, were you using the example codes with default settings? If so,
does doubling the sampling rate *without* changing the total bandwidth
(i.e. doubling the FFT size) help with sync at lower bandwidths?

M