Qpsk > 16qam

[NoKnowledge]

Yesterday my upstream was on QPSK and today it's on 16QAM, whats the difference please?

[Web-Junkie]

Apart from QPSK = Quadrature Phase Shift Keying and QAM = Quadrature Amplitude Modulation, don't know :(

Better wait for one of the eggheads to tell you :)

[Creative]

Yesterday my upstream was on QPSK and today it's on 16QAM, whats the difference please?

The main difference is that 16QAM allows more data to be sent at the same time. QPSK sends two bits of info per symbol, QAM16 sends 4bits.
It requires a better signal to noise ratio than QPSK, but in the supposedly closed and noise free cable enviroment this is easily achievable.