From b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b Mon Sep 17 00:00:00 2001
From: priyanka
Date: Wed, 24 Jun 2015 15:03:17 +0530
Subject: initial commit / add all books

---
 3161/CH8/EX8.1/Ex8_1.sce | 36 ++++++++++++++++++++++++++++++++++++
 3161/CH8/EX8.2/Ex8_2.sce | 37 +++++++++++++++++++++++++++++++++++++
 3161/CH8/EX8.3/Ex8_3.sce | 24 ++++++++++++++++++++++++
 3161/CH8/EX8.4/Ex8_4.sce | 33 +++++++++++++++++++++++++++++++++
 4 files changed, 130 insertions(+)
 create mode 100644 3161/CH8/EX8.1/Ex8_1.sce
 create mode 100644 3161/CH8/EX8.2/Ex8_2.sce
 create mode 100644 3161/CH8/EX8.3/Ex8_3.sce
 create mode 100644 3161/CH8/EX8.4/Ex8_4.sce

(limited to '3161/CH8')

diff --git a/3161/CH8/EX8.1/Ex8_1.sce b/3161/CH8/EX8.1/Ex8_1.sce
new file mode 100644
index 000000000..05b7ce0fc
--- /dev/null
+++ b/3161/CH8/EX8.1/Ex8_1.sce
@@ -0,0 +1,36 @@
+clc;
+//page 436
+//problem 8.1
+
+//Given frequency range fc= 1MHz to fc = 1.0005Mhz
+//Single side message bandwidth is fM
+fM= (1.0005 - 1)*10^6;
+disp('Message bandwidth is '+string(fM)+' Hz');
+//The textbook contains a calculation error here. The calculated fM in the textbook is 500kHz instead of 5kHz, following which all the solutions are erroneous  
+
+//Given input signal strength Si= 1mW
+//Let output signal strength be So
+//So=Si/4
+Si= 10^(-3);
+So= Si/4;
+disp('Signal output strength is '+string(So)+' dB');
+
+//Given Power Spectral Density n = 10^-9 W/Hz
+//Let output noise strength be No
+n= 10^-9;
+No= (n*fM)/4;
+disp('Output Noise Strength is '+string(No)+' dB');
+
+//Let SNR at filter output be SNR
+SNR= So / No;
+disp('Output SNR is '+string(SNR)+' dB');
+
+//By reduction of message signal Bandwidth the Output Noise strength changes
+//Let the new output noise strength, bandwidth and SNR be be No_new, fM_new and SNR_new respectively
+fM_new = 75/100*fM;
+No_new = n*fM_new/4;
+SNR_new = So / No_new;
+
+disp('Changed SNR is '+string(SNR_new)+' dB');
+
+
diff --git a/3161/CH8/EX8.2/Ex8_2.sce b/3161/CH8/EX8.2/Ex8_2.sce
new file mode 100644
index 000000000..b9feabfd0
--- /dev/null
+++ b/3161/CH8/EX8.2/Ex8_2.sce
@@ -0,0 +1,37 @@
+clc;
+//page 436
+//problem 8.2
+
+//Given frequency range fc - fm = 0.995MHz to fc + fm = 1.005Mhz
+//Double side message bandwidth is fM
+fM= (1.005 - 0.995)*10^6 / 2;
+disp('Message bandwidth is '+string(fM)+' Hz');
+//The textbook contains a calculation error here.
+//The calculated fM in the textbook is 500kHz instead of 5kHz,
+//Following which all the solutions obtained here are erroneous.
+
+//Given input signal strength Si= 1mW
+//Let output signal strength be So
+//So=Si/2
+Si= 10^(-3);
+So= Si/2;
+disp('Signal output strength is '+string(So)+' dB');
+
+//Given Power Spectral Density n = 10^-9 W/Hz
+//Let output noise strength be No
+n= 10^-9;
+No= (n*fM)/2;
+disp('Output Noise Strength is '+string(No)+' dB');
+
+//Let SNR at filter output be SNR
+SNR= So / No;
+disp('Output SNR of the DSB-SC wave is '+string(SNR)+' dB');
+
+//By reduction of message signal Bandwidth the Output Noise strength changes
+//Let the new output noise strength, bandwidth and SNR be be No_new, fM_new and SNR_new respectively
+fM_new = 75/100*fM;
+No_new = n*fM_new/4;
+SNR_new = So / No_new;
+disp('Changed SNR is '+string(SNR_new)+' dB');
+
+
diff --git a/3161/CH8/EX8.3/Ex8_3.sce b/3161/CH8/EX8.3/Ex8_3.sce
new file mode 100644
index 000000000..042dfa9ce
--- /dev/null
+++ b/3161/CH8/EX8.3/Ex8_3.sce
@@ -0,0 +1,24 @@
+clc;
+//page 446
+//problem 8.3
+
+//Given bandwidth of signal is fM = 4kHZ
+fM = 4*10^3;
+//Given power spectral density of white noise n = 2*10^-9 W/Hz
+n = 2*10^-9;
+//Also given that minimum output SNR is 40dB
+//Signal undergoes a loss of 30dB
+
+//For SSB:
+// Required minimum output SNR = Si_min_SSB / (n*fM) = 40 dB = 10^4
+Si_min_SSB = (10^4)*n*fM;
+// Required minimum signal strength at transmitter output Si_tran = Si_min * 30 dB
+Si_tran_SSB = Si_min_SSB * 10^3;
+disp('Required minimum SSB signal strength at transmitter output is'+string(Si_tran_SSB)+' W');
+
+//For DSB-SC:
+// Required minimum output SNR = (Si_min_DSB/3) / (n*fM) = 40 dB = 10^4
+Si_min_DSB = 3*(10^4)*n*fM;
+// Required minimum signal strength at transmitter output Si_tran = Si_min * 30 dB
+Si_tran_DSB = Si_min_DSB * 10^3;
+disp('Required minimum DSB signal strength at transmitter output is'+string(Si_tran_DSB)+' W');
diff --git a/3161/CH8/EX8.4/Ex8_4.sce b/3161/CH8/EX8.4/Ex8_4.sce
new file mode 100644
index 000000000..7bf00c03b
--- /dev/null
+++ b/3161/CH8/EX8.4/Ex8_4.sce
@@ -0,0 +1,33 @@
+clc;
+//page 447
+//problem 8.4
+
+//Given bandwidth of signal is fM = 60 kHZ
+fM = 60*10^3;
+
+//Given power spectral density of white noise n = 2*10^-6 W/Hz
+n = 2*10^-6;
+
+//Given time average of square of mssg signal P = 0.1W
+P = 0.1;
+
+//Noise power at input baseband range NM
+NM = n * fM;
+
+//Threshold occurs at carrier power Pc = 2.9 * NM
+Pc_Threshold = 2.9 * NM;
+
+//For carrier power Pc = 10W, output SNR
+Pc = 10;
+SNRo = Pc * P / NM ;
+disp('Output SNR is '+string(SNRo)+' dB');
+
+//Carrier power is reduced by 100 times making the new power Pc_new
+Pc_new = Pc / 100;
+
+//In the given solutions the NM value is 1.2W instead of 0.12W
+//The corect answer is 0.0925926 instead of 0.000926
+SNR_new = (4/3) * P * (Pc_new/NM)^2;
+disp('Output SNR when carrier power is reduced is '+string(SNR_new)+' dB');
+
+
-- 
cgit