Well from long I have had longing to experiment with radios and during my engg. days, all I wanted to build is a simple rf tx and rx using minimal components, which sends data via ASK and or Morse code(by changing pulse width) and if required signal processing/control using micro-controller. I will be posting an article in the coming week about my ideas and we will also see the minimal requirements of a receiver(from what I learnt from the book Science of Radio).
Finally , after scrounging for some time off my work and following the technique to overcome procrastination/fear as in the film "We're the Millers" , I shelled of Rs.1700 from my account to buy RTL-SDR from ebay.in. Well nothing much to tell about this device as I myself haven't gone through the hardware in detail.But to get it setup was quite easy on windows by following the instructions(of download) on Nooelec website. The package called "Zadig" will configure/install the necessary drivers and using the software SDR# you will be able to tune to FM,AM or scan and tune across the spectrum.
Frankly, currently I don't know the spectrum that well.What all frequency ranges to look around for HAM radio,air traffic control ,TV reception, AM and other bands etc.. and how to go about decode or making information out of them.Need to dig up information about it.
Also the software SDR# threw up different kinds of filter names ,filter order ,digital noise cancellation and gain and sampling settings, seeing all this I got startled.How I miss taking up a DSP course in college !!
Although I had started up with DSP course from EPFL , it was quite fragmented due to unablitiy to find time and I wasn't able to follow it up thoroughly.But just today I found up a very nice resource which can help kick start with DSP.Here is the link:
http://www.bores.com/courses/intro/
I did a quick browse through it in about 2 hours(till FIR filters) and I am now at least familiar with basic know how or the flow of how about going designing FIR filter.Few of the filter names(like Blackman, Hanning) actually correspond to type of window functions which are applied to FIR filters.Also many of the concepts related to finite-time signals, quantization,aliasing, sampling and signal reconstruction got revisited and in-fact I want to experiment with it to get thorough with the concepts.(infact many of the things which are explained were my fundamental doubts during Circuits(Signals) and Systems course during my BE course)
Also now I know what to stress more when going through the EPFL DSP course.
So all this will help me through gainning more insights of how DSP is done post which I think I can contribute more to my company focus of designing high-end products of DSP signal processing namely data convertors and DSP processors.
Also it is helping me to realize what I exactly want to do as I previously defined.
Next post will contain my idea of the TX-RX unit
1/ Decide upon TX and RX architecture
(a) TX will be a micro-controller and antenna
(b) RX will be diode detector/super regenerative architecture(from one transistor FM receiver) plus micro-controller doing signal processing cum protocol implementation to combat interference.
2/ Verifying via simulation
3/Designing board
4/Experimenting/Evaluation
For "Tank Circuit - diode based detector" , I have a circuit from one of the Hindi Electronics Magazine and Mike's articles(talking electronics guy)
For "Super -regenerative architecture" - I have few articles from net (sommerset single transistor FM radio) and a few paperss from IEEE which I had read in col.
Also I have a few articles from 2012 Elektor which also deals with SDR RX and TX implementation.
I have previously worked with ASK based 433 MHZ tx and rx modules but I don't want to use them.
Well, wait for the next article, it will be fun :)
The RF/DSP series start now :)
Continuing EPFL DSP course from 10-11 pm and 8-9 am everyday from now on.