On 2021-08-18 11:02 p.m., ?? WANG Cui wrote:
Hi Marcus,
Thanks for the explanation, so I have to prepare the I/Q samples in my
program.
Furthermore, can I understand the send() function will
multiplex/transform the I/Q samples to final REAL baseband waveform
samples. Then the USRP hardware simply multiply amplitude of each REAL
sample to the carrier frequency and transmit?
WANG Cui
You might usefully spend some time here:
https://kb.ettus.com/Knowledge_Base
Also the "tx_samples_from_file" example applicaton shows you how samples
are delivered to the send() function. Most applications use floating-point
I/Q samples on the host side, and the UHD driver converts them to
16-bit values over the wire.
*From:*Marcus D. Leech <[email protected]>
*Sent:* Thursday, August 19, 2021 10:43 AM
*To:* [email protected]
*Subject:* [USRP-users] Re: How to prepare I/Q sample for tx_streamer
On 2021-08-18 10:31 p.m., ?? WANG Cui wrote:
Hi,
Maybe I am asking a newbie question.
When use tx_streamer::send() function to send signal, the required
format is I/Q samples (say otw_format = sc16). I understand should
provide I/Q samples buffer in arguments.
I am wondering for the I/Q samples, should I provide binary values
buffer (e.g. I: 1, -1, 1..., Q: -1, 1, -1...), then the USRP
firmware will modulate the binary values to specific Cos/Sin waves?
Or I should do the Cos/Sin modulation in my program (e.g. I: 0,
-.001, 0.002..., Q: -1, 0.999, -0.998...) before pass the buffer
send() function?
I searched the documents, but can’t find answer, thanks in advance
for explanation,
WANG Cui
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The whole point of an SDR is that it doesn't have any pre-defined
notion of what modulation techniques are used, etc. That's entirely
up to you.
You're sending a complex-baseband representation of *waveforms*. The
UHD library is NOT a DSP library. It is a device-interface library.
If you need something higher-level, there's Gnu Radio
(http://www.gnuradio.org) or even MATLAB. But SDR radios in general
don't have any
built-in modulation. They want sampled baseband waveforms.
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