Hello all, This message is a reply to a previous thread which I started. The contents of which can be found below.
https://www.mail-archive.com/usrp-users@lists.ettus.com/msg09327.html My question now concerns what data is actually stored in the final I and Q components that are sent to the host. The question and the answer are presented below. Q1 The daughter-board is set so that one channel retrieves the I component and the other channel the Q. I retrieved this information with the uhd_usrp_probe command. In the output under RX0 its says connection type = Q and on RX1 connection type = I. What command do I have to use to change connection type of RX0 from Q to I, so that I could have two channels measuring the real component. A1 That isn't possible. Signals are presented to the host as complex samples. The TVRX2 *analog hardware* uses a so-called "low-IF" architecture, and the N210 has a single 2-channel complex ADC. Each of those two channels is *hard wired* to go to one of the ADC channels, and the DDC algorithms in the FPGA convert that to a complex base-band signal that is then filtered, downsampled, and sent to the host computer. >From this answer, am I to understand that both of the signals coming from antenna 1 and 2 respectively are first mixed with a signal provided by the local oscillator (LO) so that they are separately converted to baseband. After which the information of the baseband originating from antenna 1 is stored in the Real part of the complex number and the signal coming from antenna 2 to imaginary part. And only then then filtering and down sampling occurs. What I want to know is that are the downsampled and filtered baseband signals from antenna 1 and 2 preserved in the IQ components respectively. Furthermore, as I and Q usually mean in-phase and quadrature component, is the signal coming from antenna 2 mixed with a LO-signal that has been shifted by 90 degrees in phase compared to the LO-signal that is mixed with channel 1. Thank you again PS. I'm sorry, but I could not reply directly to the thread as I did not receive a response email to my in-box. If someone can instruct me how to accomplish the reply procedure with gmail, or provide a link with the relevant information I would be more than happy to use the list as it is intended to be used.
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