Radio Transmission

[Special K]

Hi! I've been doing some simulations of PSK and QAM modulation, but I have several doubts.

First of all, whitch should be the value for the carrier frequency ( is there a  range of values that i can use to generate diferent results?) I mean, whitch are the frequencies communly used for PSK and QAM??

Another question.... is there a threshold fot the SNR (Signal to noie ratio) Eb/No using this modulations shcemes??? If there is, whitch is its value?? I m transmmiting in a AWGN channel.  

[GovBob]

The answer for your first question is kind of hard. PSK and different M-aries of QAM are used throughout the RF band. Cell phones, WIFI, WIMAX. The new P25 standard for Land Mobile Radio uses a type of QPSK called C4FM in the 138-174 MHz band and 400MHz band. TETRA uses Pi/4 DQPSK and yet others are using 16QAM.

Your second question depends on the M-aries of your QAM. I did a quick WIKI search and there are some calculations you can perform for theoritical limits. http://en.wikipedia.org/wiki/Eb/N0

There are also some great resources located http://decibel.ni.com/content/groups/rf-developers-network

The Baseband Developers Kit is fun.

Hope this helps