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Altera_Forum
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19 years ago

NCO Megacore Phase Adjust

Hello I am using the Altera Megacore NCO Compiler and need to dinamically adjust the phase of the generated sine wave. The core has an input called phase_mod_i[] which is used for this purpos...
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Altera_Forum
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13 years ago

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Hi, i'm a student university and i made a QPSK modulator with Altera Stratix II and i don't understand how set NCO for an phase modulation and how define the constallation mapper....

thx for support

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The steps for qpsk are:

get your data bits(0,1) as pairs

map pairs to two separate I,Q streams (as +1/-1)

shape the pulses but I assume this step is too much for Uni student so ignore it

multiply each of I,Q streams by cos/sin in a complex multiplier(mixer)

The output of multiplier will be the modulated qpsk (centerd on your chosen nco frequency)

The +1/-1 will simply invert or leave the phase of your cos/sin (0 or 180 degrees)