Archive for March, 2009

NI PXI

Posted in Key Posts, Rant on March 30th, 2009 by James – Be the first to comment

A shinny new NI PXI system *drool* Some links for reference: http://digital.ni.com/public.nsf/allkb/3003B0E10C3C71E286256CAD0070FCAA http://zone.ni.com/devzone/cda/tut/p/id/4731 http://zone.ni.com/devzone/cda/tut/p/id/3592 http://digital.ni.com/public.nsf/websearch/C074C33F4DE3FA5186256D3D007788DA?OpenDocument

Update, status of the project

Posted in Project Related on March 28th, 2009 by James – Be the first to comment

Just got myself a cozy corner in a lab (which has secure digital doors). Set up the shinny new computer on friday, and we will be moving the VSA in on monday.. Can’t wait to start doing stuff!

Power Spectrum

Posted in Project Related on March 20th, 2009 by James – Be the first to comment

Power spectrum is very useful in seeing what a channel are in use. Due to the volume of notes on the Power Spectrum it will not be replicated here.

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Windowing Functions

Posted in Project Related on March 20th, 2009 by James – Be the first to comment

Another important concept linked to DFT/FFT is the use of windowing functions.

First of all, we see that DFT/FFT uses a finite number of samples, and what happens is we are just cutting off samples after a certain number, and feed that into the FFT. When we look at it, this is the same as multiplying the samples with a rectangular window that is 1 inside N, and 0 elsewhere.

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DFT and FFT

Posted in Project Related on March 20th, 2009 by James – Be the first to comment

DFT and FFT stand for Discrete Fourier Transform and Fast Fourier Transform respectively.

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Gibb’s Phenomenon

Posted in Project Related on March 20th, 2009 by James – Be the first to comment

Gibb’s Phenomenon is also know as ringing artifact. It’s where a sampled signal shows small oscillations on the edges when they are reconstructed, wikipedia shows some very good examples

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Current Implementations of Cognitive Radios

Posted in Key Posts, Project Related on March 12th, 2009 by James – 1 Comment

This entry focuses on a few implementations of CR published in various top journals and conferences.

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Radio Spectrum

Posted in Project Related on March 12th, 2009 by James – Be the first to comment

The radio spectrum is divided into the following:

Frequency Designation
Frequency Range
Ultra Low Frequncy (ULF) < 3Hz
Extremely Low Frequency (ELF) 3Hz – 3kHz
Very Low Frequency (VLF) 3kHz – 30kHz
Low Frequency (LF) 30kHz – 300kHz
Medium Frequency (MF) 300kHz – 3MHz
High Frequency (HF) 3MHz – 30MHz
Very High Frequency (VHF) 30MHz – 300MHz
Ultra High Frequency (UHF) 300MHz – 3GHz
Super High Frequency (SHF) 3GHz – 30GHz
Extremely High Frequency (EHF) 30GHz – 300GHz
Submilimeter 300Ghz – 3THz

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IEEE Std 1900.1, Definition and Concepts for Dynamic Spectrum Access

Posted in Key Posts, Project Related on March 12th, 2009 by James – Be the first to comment

No reseach is complete without the use of some fancy weird terminology! To this end, the IEEE Standard Definition and Concepts for Dynamic Spectrum Access (IEEE Std 1900.1) is a gold mine haha, all kinds of terminologies people have come up with. This post will highlight a few that are funny, or useful to this project. This is just a water down, near laymen terms version of the standard, for personal quick reference only

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Goodie, a 802.22 Standard has come out, sort of

Posted in Project Related on March 11th, 2009 by James – Be the first to comment

Carrying on from the last post, seems there is a 802.22 standard that seems to be out (as the document below sugests), but its not listed in the IEEE standards library anywhere, maybe its very very new and just printed

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