Spectral Efficiency Simulation for various Modulation Schemes

Spectral Efficiency Lab

Determine if your channel bandwidth supports your chosen modulation scheme.

Bit Rate ($R_b$) in kbps

Modulation Scheme BPSK / ASK (Binary) QPSK / 4-QAM (M=4) 8-PSK (M=8) 16-QAM (M=16) 64-QAM (M=64)

Use Nyquist Min. BW ($B = R_s$)

Default: Null-to-Null BW ($B = 2R_s$)

Current Efficiency (η): 0.5 b/s/Hz

Required Bandwidth for this setup:

20.00 kHz

Signal Processing Knowledge Check

Which modulation technique is most susceptible to power-line noise and fading?

Efficiency vs. Resilience

Higher spectral efficiency (like 64-QAM) allows you to pack more data into the same bandwidth, but it requires a much cleaner signal (High SNR) to avoid errors.

The BW Trade-off

For BPSK, the Null-to-Null bandwidth is $2R_b$. If you use pulse-shaping (like Raised Cosine), you can approach the Nyquist limit of $1R_b$.

Why BPSK Wins

Even though BPSK has low spectral efficiency (0.5 to 1.0), its 3dB advantage over BFSK makes it the standard for Deep Space Telemetry.

M-ary Logic

In QPSK ($M=4$), each symbol carries 2 bits. This doubles the efficiency compared to BPSK without increasing the bandwidth.

Ready for the BER vs SNR analysis?

Visualize how noise power affects these efficiency levels.

Launch Simulator