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Technology Stocks : The New Qualcomm - a S&P500 company -- Ignore unavailable to you. Want to Upgrade?

To: lkj who wrote (6929)	2/25/2000 10:01:00 PM
From: engineer	Read Replies (1) \| Respond to of 13582

Yes it does use QPSK at the basic modulator interface. then it oversamples by 16x on the symbols internally and then does a whole boatload of digital modulation on top of that. HDR uses basically the same thing for RF modulation, but does a whole different way for digital modulation. One thing that you have to think about for HDR is that it uses all 64 Walsh channels at the same time, so you get a basic 64x data rate right from the start. It then uses a different Viterbi Decoder for a higher data rate ( I think it is rate 7/8). It also raises the symbol integrator level to only do 8 times over sampled and allows for a higher Eb/No level. when you do this, you get the basic 14.4 rate multiplied by 62 and then multiplied by 2 and then multiplied by 1.4 again for the Viterbi rate differnce (Rate 2/3 versus rate 7/8). this gets the data rate for a single channel around 2.5 Mbps.