Hello all, I'm trying to take a step back from my previous postings and try a simple approach to try and understand working with over the air communications with the USRPs. Let me know if it would be better to post this in the USRPs-Users list.
I'm trying to have a simple TX and simple RX side so I can eliminate and unnecessary complications. The TX side has the following flowgraph: Vector Source(preamble+data)->DPSK Mod(DBPSK,2samples/symbol)-> Multiply Const(.707) -> UHD:USRP SINK(2.448GHz center freq, 10dB default gain) RX Side: UHD:USRP Source(2.448GHz center freq, 10dB gain default) -> DPSK DEMOD(DBPSK, 2 samples/ symbol, rest default values) - > file sink I'm checking the progress of the communication by looking at a constellation plot that is connected directly to the USRP SOURCE block on the receiver side. I'm getting a very elliptical shape, more spread out in the horizontal direction but not by much. I'm also looking at the bits from the receiver side in matlab and my preamble is not showing up. These were the same problems I had when trying to use a correlated system for OTA communications. I feel like I'm missing something really simple. Does anyone know of a simple TX, RX grc setup that I can use to test my USRPs? Again, I really appreciate the help you guys give. Logan Washbourne Electrical Engineering Graduate Student (Electromagnetics)
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