Digital waveform comparison

Family	Spectral efficiency	Envelope / PAPR	Synchronization burden	Relative FPGA cost	Typical use
QPSK	2 bits/symbol	Constant symbol envelope; shaped waveform has moderate peaks	Carrier, phase, timing and quadrant resolution	Low–medium	Robust general-purpose links
16-QAM	4 bits/symbol	Non-constant; sensitive to back-off and linearity	QPSK requirements plus tighter gain/phase accuracy	Medium	Higher-throughput linear links and OFDM payloads
OFDM	Many parallel carriers	High PAPR; clipping/back-off must be managed	Packet timing, CFO, pilots and channel estimation	High: FFT, buffers, pilots, equalizer	Frequency-selective broadband channels
GFSK	1 bit/symbol in this lab	Constant envelope, approximately 0 dB PAPR	Symbol timing; discriminator can avoid carrier phase recovery	Low	Low-power telemetry and nonlinear transmitters
CSS	SF bits per long chirp symbol	Constant envelope	Preamble, dechirp/FFT, CFO and sample-rate tracking	Medium–high: chirp source, FFT and peak detector	Long-range/low-rate links
DSSS	Data rate reduced by spreading factor	BPSK-like constant envelope	PN-code acquisition and tracking	Medium: LFSR and high-rate correlator	Interference resistance and code-domain links

These are implementation-level comparisons for the course models, not claims of standards interoperability.