16 qam vhdl code

[tal]

hi
i'm doing a project and i need a vhdl code for 16 qam modulation.

thanks

 

[Nicolas Matringe]

tal a écrit:

hi
i'm doing a project and i need a vhdl code for 16 qam modulation.

Shouldn't be too hard to do, that's just two identical AM modulators fed
with quadrature carriers...
2 hours work at worst. Come on, you can do it can't you?

 

[tal]

tal a écrit:

Shouldn't be too hard to do, that's just two identical AM modulators fed
with quadrature carriers...
2 hours work at worst. Come on, you can do it can't you?

hi
i did the vhdl code for the maping but i dont known how to convert the
i an q bits to sine wave.

Anyone could help?
thanks.

 

[Guenter]

hi
i did the vhdl code for the maping but i dont known how to convert the
i an q bits to sine wave.

Anyone could help?
thanks.

Andraka consulting has a paper about modulation/demodulation techniques
with FPGA, maybe that helps.

http://www.andraka.com/papers.htm

Guenter

 

[Ray Andraka]

I did have a QAM64 example in a prior incarnation of that presentation. That one doesn't have it in there.
Basically, you need to pass the I and Q bits through a nyquist filter (this is just an FIR filter with a usually
root raised cosine response). You'll need to upsample as you filter, which is equivalent to stuffing zeros between
each IQ sample and then low pass filtering. It is more efficiently done as a polyphase interpolating filter, which
lets the filter work at the IQ rate rather than the upsampled rate. The filtered IQ is your complex baseband.
You'll mix that with a complex exponential (sine and cosine) to get your IF or broadcast carrier. If you can set
the sample rate of the IQ to be 4x the carrier (or IF) then the mixer's local oscillator is 1,j,-1,-j, which can be
accomplished with a pair of adder/subtractors.

hi
i did the vhdl code for the maping but i dont known how to convert the
i an q bits to sine wave.

Anyone could help?
thanks.

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email (e-mail address removed)
http://www.andraka.com

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