zo
Sent a my mobile...Dqe
----- Reply message -----
From: "Ian Buckley" <i...@ionconcepts.com>
To: "Dan CaJacob" <dan.caja...@gmail.com>
Cc: "discuss-gnuradio@gnu.org" <discuss-gnuradio@gnu.org>
Subject: [Discuss-gnuradio] rrc_filter in generic_mod_demod
Date: Wed, Jun 12, 2013 07:52
Dan, Any chance you can attach those pictures in a different way and resend, I
couldn't find a way to view them and I'm curious to see them.-Ian
On Jun 11, 2013, at 10:12 PM, Dan CaJacob <dan.caja...@gmail.com> wrote:There
are two parameters that will affect your TX power: digital amplitude and RF
gain. The digital amplitude sets the amplitude of your signal going into the
DAC. UHD expects a signal between 0 and 1.0, but to keep your output nice and
linear, keep your signal amplitude belw 0.2. Conversely, 0.02 seems pretty
low. RF gain is applied in the aughtercard once your signal has been up
converted. My practice is to keep the signal amplitude at 0.2 max amplitude,
then adjust RF gain to control power. You'll end up getting less than the max
rated power output (e.g. 20 dBm for WBX, but you'll have a clean RF signal.
I very recently characterized a WBX across the full range of amplitude and gain
settings. Here's the result. Note that the non linearity belw a gain of about
-10 dB is due to the signal power being belw the bottom range of the power
sensor.
And here's a plot for just the 0.2 amplitude curve.
On Tuesday, June 11, 2013, yeran wrote:
Dear all,
I am doing channel estimation in gnu radio narrow-band. I'm collecting data at
the receiver side after the time_recov block. It has been through the
gr.firdes.root_raised_cosine in the time_recov. But the plot I get is as the
figures in the attachment. It looks like the fluctuation of the channel
amplitude has some pattern, it looks like signal pulse shaping in there. But
doesn't the gr.firdes.root_raised_cosine works as the rrc matched filter, and
already take off the pulse shaping?
Also, when I do experiment, I found out something strange. According to my
understanding, the --tx-amplitude on the transmitter benchmark sets the
transmission power. So the bigger the amplitude is, the better performance it
should be, since the SNR will be bigger. But in actual experiment, it is
totally the opposite way! The amplitude of 0.02, or even 0.002 works better
than the default 0.25. Has anyone come across the same problems?
Highly appreciate if anyone can give me some suggestions on this! Thanks in
advance!!
Ada
<rrc.png>
--
Very Respectfully,
Dan CaJacob
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