| 1 | function baseband(rolloff, M, numSymbs) |
| 2 | %% Set defaults for inputs |
| 3 | if nargin < 3 |
| 4 | numSymbs = 1000; |
| 5 | end |
| 6 | if nargin < 2 |
| 7 | M = 2; |
| 8 | end |
| 9 | if nargin < 1 |
| 10 | rolloff = 0.5; |
| 11 | end |
| 12 | |
| 13 | %% https://www.mathworks.com/help/comm/examples/passband-modulation-with-adjacent-channel-interference.html |
| 14 | Rsym = 1e6; % symbol rate (sym/sec) |
| 15 | |
| 16 | span = 6; % filter span |
| 17 | sps = 4; % samples per symbol |
| 18 | |
| 19 | fs = Rsym * sps; % sampling freq (Hz) |
| 20 | |
| 21 | t = (0 : 1 / fs : numSymbs / Rsym + (1.5 * span * sps - 1) / fs)'; |
| 22 | |
| 23 | EbN0_db = 0:0.2:10; |
| 24 | EbN0 = 10 .^ (EbN0_db ./ 10); |
| 25 | Es = 1; |
| 26 | Eb = Es / log2(M); |
| 27 | N0 = Eb ./ EbN0; |
| 28 | |
| 29 | EsN0 = EbN0 .* log2(M); |
| 30 | EsN0_db = 10 .* log10(EsN0); |
| 31 | |
| 32 | plotlen = length(EbN0); |
| 33 | ber = zeros(1, plotlen); |
| 34 | |
| 35 | data = randi([0 M - 1], numSymbs, 1); |
| 36 | modData = pskmod(data, M, 0, 'gray'); |
| 37 | |
| 38 | xBaseband = txFilter(modData, rolloff, span, sps); |
| 39 | |
| 40 | for i = 1:plotlen |
| 41 | snr = EbN0_db(i) + 10 * log10(log2(M)) - 10 * log10(sps); |
| 42 | noiseEnergy = 10 ^ (-snr / 10); |
| 43 | |
| 44 | yBaseband = awgn(xBaseband, snr, 'measured'); |
| 45 | |
| 46 | rBaseband = rxFilter(yBaseband, rolloff, span, sps); |
| 47 | |
| 48 | rSampled = rBaseband(sps*span/2+1:sps:(numSymbs+span/2)*sps); |
| 49 | demodData = pskdemod(rSampled, M, 0, 'gray'); |
| 50 | [bitErrors, ber(i)] = biterr(data, demodData); |
| 51 | end |
| 52 | |
| 53 | figure(1); |
| 54 | clf; |
| 55 | |
| 56 | %% Plot simulated results |
| 57 | semilogy(EbN0_db, ber, 'r', 'LineWidth', 2); |
| 58 | hold on; |
| 59 | |
| 60 | theoreticalPSK(EbN0_db, M, 'b', 'LineWidth', 1); |
| 61 | legend('Simulated', 'Discrete'); |
| 62 | |
| 63 | title(strcat(num2str(M), '-PSK with Gray code')); |
| 64 | grid on; |
| 65 | xlabel('$E_b/N_0$ (dB)'); |
| 66 | ylabel('BER'); |
| 67 | |
| 68 | formatFigure; |
| 69 | end |