IDEAS

This is an introduction to PWM generation with Raspberry pi using Python. We all love blinking LEDs. Setting the GPIO pins  high or low to lit or off LED seems so simple. But creating a dim/glow LED requires a little bit info about PWM generation.Simply PWM is all about varying the percentage of duty cycle of a square wave. Duty cycle means the diff between ON time and OFF time in one cycle of a wave. Duty cycle refers to the actual work done time in a single cycle, which is the ON time. We can say a DC signal is '100% ON time wave or has 100% duty-cycle. Paradox : DC signal has 0% OFF time, so we can't call it a wave ... :) Okey... lets start.. Raspberry has particular numbers of GPIO pins which could be used for this experiment. And we would use python to code with...So let us first write the program and discuss the logic... Assuming you are working through SSH to conect to your Pi. And no GUI is available...Login to R pi.. and assuming home folder as working d...

Hi all... This is about using the poor man's SDR dongle ( RTL2832U ) with GNU Radio to receive Commercial FM stations ( Wideband FM stations)... Installation of GNU Radio was a breeze in Ubuntu 12.04 using the build script by Marcus Leech.. thank to him... My core 2 duo machine took 2 hours to build the whole thing... :) Being a total noob in the complex base-band world, i decided to try something for getting familiarized with GNU Radio.. Opened gnuradio-companion.. Tried out some examples. Most of them were based on USRP  SDR Transceiver. But the source block listed the support of RT2832U to be used as a source.. thanks to osmocom . So now i decided to create a WFM receiver in GNU Radio with IQ signals collecting from poor man's receiver. Hooked the SDR dongle.. checked with some similar implementations over internet.. Created a LPF, WFM receive block, GUI Waterfall Sink block, Audio Sink block. Spend a considerable amount of time in understanding all parameters ...

Hi all...        I was totally excited after receiving the RTL-SDR dongle, the poor man's Software Defined Radio Receiver. I hooked it up to see the beautiful spectrum of signals in SDR# software.   And it worked like awesome. The blue waterfall is just awesome.... I wanted to test the device as fast as i could...But since i live in a villlage with no Commercial FM coverage, it semed to difficult to get hold to any strong RF signals.. Still i could get some random energies in 945-960 Mhz GSM band...pretty noisy... digital data.. so not much to be heard to... After some random browsing, i came across a beautiful project to make the Rasp Pi transmit in Wide Band FM mode. The project name is PiFm . It is a nice simple example of SDR transmitter. So without any hardware for FM modulation, a 300 lines C code modulates the DPLL output of Pi's ARM Processor with respect to the digital music data from a wave file. "Kudos to the guys who did it..". The output com...