Re: [Discuss-gnuradio] CSI in gr-ieee80211

[Paul Fuxjaeger]

On 28.03.14 19:40, Surligas Manos wrote:
> Which device did you used for receiving samples? I have noticed a same
> phenomenon with my device, caused by a coarse implementation of a high
> pass filter.

The filter in the Maxim2829 in the XCVR2450 that we used can be
configured to 0, 100Hz and 30kHz and the default is 100Hz I believe? If
you didn't change anything there this cannot explain your problem. Any
filter than goes above 150kHz would be a problem for the centerish
carriers in 802.11 OFDM (~300kHz carrier spacing).

what happens if you TX a sinusoid and stepwise tune the RX to slightly
off frequencies (take note of the *actual* RX LO frequency when doing
the sweep - the difference to that one and the TX sinusoid matters).
Does the RX power also start to decrease as soon as you set the TX-RX
offset smaller than 150kHz?

-paul

PS: as Sebastian said, the outer subcarriers being lower can be
explained by odd decimation factors like 5 - which causes the
digital-downconversion filter chain to change to a single CIC stage I
believe.