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Krishna Sankar Madhavan Pillai
Krishna Sankar M is a Signal Processing Engineer at an Indian firm based out of Bangalore, India. His typical activities on a working day involve identifying and modeling digital signal processing algorithms for wireless receivers.
dspLog
The blog started some in February 2007 on the free Blogger platform and was hosted at http://dsplog.blogspot.com with the following objective:
Explain and discuss the basic text book concepts in digital signal processing and digital communication using simple Octave scripts.
Seeing consistent increase in traffic over the 6-7 months from inception, it was decided to move to an independent platform hosted at www.dsplog.com.
Target audience
(a) Students taking courses in digital signal processing/digital communication and requiring help to understand some of the concepts.
(b) Practicing engineers who are fresh to the domain of digital signal processing and requiring help.
(c) Ofcourse, the experienced engineers can share tips and tricks associated with the digital signal processing trade. 
Probable contents
(a) Understanding basic concepts pertaining to FIR/IIR filtering
(b) Sample rate conversion
(c) Bit and Symbol error probabilities for typical digital communicatio
(d) Orthogonal Frequency Division Multiplexing
(e) more…
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Related posts
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{ 12 comments… read them below or add one }
I have been asked to write a 1/4 soft input viterbi decoder in VHDL or Verilog (I use VHDL as I’m more familiar with it). I have a decent knowledge of Convolutional Codes and Viterbi Decoding and I have access to a 1/2 Viterbi decoder (which I didn’t create). My question is..is a 1/4 decoder much more complicated to design or is there anyway I can use the existing 1/2 decoder?
@Bob: Well, its not complex. However, you need to re-construct the trellis based on the current state-next state, input-output transition matrix for rate 1/4 code.
Hello,
While I was putting the code, I downloaded from
http://www.dsplog.com/db-install/wp-content/uploads/2009/08/script_ber_bpsk_convolutional_code_viterbi_decode.c
in the codeblocks or in Visual Studio, it gives me error.
In codeblocks, it gives error at line number 42 and 138
error: undefined reference to `_exp10′|
Could you please tell me how to resolve this.
@Ajay: I also had the same problem when I tried to compile with gcc. I worked around it by using -lm option when compiling.
Maybe, the following URI might provide you more info:
http://ubuntuforums.org/archive/index.php/t-1071822.html
Good luck.
Mr. Kri Index to Various dashnan, I want to know , While assigning Subcarrier
Index to each data, You have used -26 to +26 neglecting 0. may know how this process is done. WHY Such change in subcarrier index is followed
@Selvi: 0th subcarrier is not used by controlling the assignment of symbols to subcarriers. In general, modulating the DC subcarrier is not preferred as the DC impairments in RF etc will corrupt the information.
Do u have MATLAB code for transfering data between two computers using parallel port?
@smruthi: Sorry, I do not have. However, you might want to check the following links:
(a) MATLAB TCP/IP – code example by Steven Kolak
http://www.mathworks.com/matlabcentral/fileexchange/11802
(b) TCP/IP Communication for Real-Time and Embedded Systems By Sam Mirsky
http://www.mathworks.com/company/newsletters/digest/2008/july/tcpip.html
(c) Instrument Control Toolbox 2.9
http://www.mathworks.com/products/instrument/
Dudes, I salute you for this. One wonderful blog.
Hi Krishna,
Yesterday I sent a mail to your address and also posted a question on forum asking about plotting eye diagram. On one of the thread I found this and had few doubts.
When you say you are plotting 2 bits I see that high and low of that bit are at center of plot. So is it plotted as half of previous bit-current bit-half of next bit
?
Just found this website. What a wonderful gold-mine! Krishna, very nicely done!
–Pascal
hi dude,
i am stuck with coding in matlab of simulation environment for mobile communication system (mose) for power control in mobile radio system.
please help me