2013 - DSP LOG

Migrated to Amazon EC2 instance (from shared hosting)

Being not too happy with the speed of the shared hosting, decided to move the blog to an Amazon Elastic Compute Cloud (Amazon EC2) instance. Given this is a baby step, picked up a micro instance running an Ubuntu server and installed Apache web server, MySQL, PHP . After doing a bit of tweaking with this new instance, imported the SQL database and other files from the shared hosting and pointed the A name record to the new IP address. This switch happened over this weekend.

One particular issue which I faced was frequent crashing of MySQL due to memory limitations. Followed few online instructions to improve the situation and the current configuration seems to be holding up (but this is a cause of worry – need to figure the right solution).

Anyhow, hope you like the decreased page load time! 🙂

Some helpful links from the web:

a) How to install WordPress on Amazone EC2

b) Move WordPress site from shared hosting to Amazon EC2

c) DIY: Enable CGI on your Apache server

d) Import MySQL Dumpfile, SQL Datafile Into My Database

e) Making WordPress Stable on EC2-Micro

f) how to enable mod_rewrite in apache2.2 (debian/ubuntu)

GATE-2012 ECE Q28 (electromagnetics)

Question 28 on electromagnetics from GATE (Graduate Aptitude Test in Engineering) 2012 Electronics and Communication Engineering paper.

Q28. A transmission line with a characteristic impedance of 100 ${\Omega}$ is used to match a 50 ${\Omega}$ section to a 200 ${\Omega}$ section. If the matching is to be done both at 429MHz and 1GHz, the length of the transmission line can be approximately

(A) 82.5cm

(B) 1.05m

(C) 1.58m

(D) 1.75m

Image Rejection Ratio (IMRR) with transmit IQ gain/phase imbalance

The post on IQ imbalance in transmitter, briefly discussed the effect of amplitude and phase imbalance and also showed that IQ imbalance results in spectrum at the image frequency. In this article, we will quantify the power of the image with respect to the desired tone (also known as IMage Rejection Ratio IMRR) for different values of gain and phase imbalance.

GATE-2012 ECE Q15 (communication)

Question 15 on communication from GATE (Graduate Aptitude Test in Engineering) 2012 Electronics and Communication Engineering paper.

Q15. A source alphabet consists of N symbols with the probability of the first two symbols being the same. A source encoder increases the probability of the first symbol by a small amount ${\epsilon}$ and decreases that of the second by ${\epsilon}$ . After encoding, the entropy of the source

(A) increases

(B) remains the same

(C) increases only if N=2

(D) decreases

GATE-2012 ECE Q7 (digital)

Question 7 on digital from GATE (Graduate Aptitude Test in Engineering) 2012 Electronics and Communication Engineering paper.

Q7. The output Y of a 2-bit comparator is logic 1 whenever the 2 bit input A is greater than 2 bit input B. The number of combinations for which output is logic 1 is

(A) 4

(B) 6

(C) 8

(D) 10

GATE-2012 ECE Q13 (circuits)

Question 13 on analog electronics from GATE (Graduate Aptitude Test in Engineering) 2012 Electronics and Communication Engineering paper.

Year: 2013

Migrated to Amazon EC2 instance (from shared hosting)

GATE-2012 ECE Q28 (electromagnetics)

Q28. A transmission line with a characteristic impedance of 100 ${\Omega}$ is used to match a 50 ${\Omega}$ section to a 200 ${\Omega}$ section. If the matching is to be done both at 429MHz and 1GHz, the length of the transmission line can be approximately

(A) 82.5cm

(B) 1.05m

(C) 1.58m

(D) 1.75m

Image Rejection Ratio (IMRR) with transmit IQ gain/phase imbalance

GATE-2012 ECE Q15 (communication)

Q15. A source alphabet consists of N symbols with the probability of the first two symbols being the same. A source encoder increases the probability of the first symbol by a small amount ${\epsilon}$ and decreases that of the second by ${\epsilon}$ . After encoding, the entropy of the source

(A) increases

(B) remains the same

(C) increases only if N=2

(D) decreases

GATE-2012 ECE Q7 (digital)

Q7. The output Y of a 2-bit comparator is logic 1 whenever the 2 bit input A is greater than 2 bit input B. The number of combinations for which output is logic 1 is

(A) 4

(B) 6

(C) 8

(D) 10

GATE-2012 ECE Q13 (circuits)

Q13. The diodes and the capacitors in the circuit shown are ideal. The voltage ${V(t)}$ across the diode ${D1}$ is

(A) ${\cos(\omega t)-1}$

(B) ${\sin(\omega t)}$

(C) ${1-\cos(\omega t)}$

(D) ${1-\sin(\omega t)}$

Q28. A transmission line with a characteristic impedance of 100 is used to match a 50 section to a 200 section. If the matching is to be done both at 429MHz and 1GHz, the length of the transmission line can be approximately

(A) 82.5cm

(B) 1.05m

(C) 1.58m

(D) 1.75m

Q15. A source alphabet consists of N symbols with the probability of the first two symbols being the same. A source encoder increases the probability of the first symbol by a small amount and decreases that of the second by . After encoding, the entropy of the source

(A) increases

(B) remains the same

(C) increases only if N=2

(D) decreases

Q7. The output Y of a 2-bit comparator is logic 1 whenever the 2 bit input A is greater than 2 bit input B. The number of combinations for which output is logic 1 is

(A) 4

(B) 6

(C) 8

(D) 10

Q13. The diodes and the capacitors in the circuit shown are ideal. The voltage across the diode is

(A)

(B)

(C)

(D)

Q28. A transmission line with a characteristic impedance of 100 ${\Omega}$ is used to match a 50 ${\Omega}$ section to a 200 ${\Omega}$ section. If the matching is to be done both at 429MHz and 1GHz, the length of the transmission line can be approximately

Q15. A source alphabet consists of N symbols with the probability of the first two symbols being the same. A source encoder increases the probability of the first symbol by a small amount ${\epsilon}$ and decreases that of the second by ${\epsilon}$ . After encoding, the entropy of the source

Q13. The diodes and the capacitors in the circuit shown are ideal. The voltage ${V(t)}$ across the diode ${D1}$ is

(A) ${\cos(\omega t)-1}$

(B) ${\sin(\omega t)}$

(C) ${1-\cos(\omega t)}$

(D) ${1-\sin(\omega t)}$