Re: [Discuss-gnuradio] Pay You $$$ to Mentor Me - Tx OFDM 64 QAM and Rx Measure Error Vector Magnitude

[Marcus Müller]

HI IFly88,

I don't fully understand your requirements – on one hand, you just say "I just want OFDM with 15 kHz subcarrier spacing and QAM/QPSK inside", on the other hand you mention LTE: an arbitrary OFDM signal with the right subcarrier spacing and constellation mapping does not constitute a validly measurable LTE signal. Your LTE receiver needs a lot of specific structure in the frames to be able to synchronize, and equalize, to an LTE transmission.

So, what exactly are you using to measure EVM? What is the higher level goal of this? Your transmit hardware will always also play a part in the signal quality you receive, so it's usually better to first sit down and contemplate what you want to measure, then design a system.

Best regards,
Marcus

On 09/23/2017 10:30 PM, Ifly88 wrote:

Name your price to give me pointers and help me kick start this project.  I want to emulate a 64qam, 16qam, and qpsk LTEs signal to test for signal impairments.  Basically take 15khz sub carriers over channel bandwidths of 1.4mhz to 20 mhz and modulate them with 64qam, 16qam, and qpsk.  I want to use another receiver to Rx the signal and calculate error vector magnitude for each of those three modulations.  I'll be using HackRF One radios or will use BladeRF if necessary.

I'be been spinning my wheels for a few days trying to get this to work on GRC and need some guidance.

Please help.

ifly88 at protonmail dot com

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