From RevSpace
Revision as of 19:11, 17 April 2019 by Cmpxchg (talk | contribs) (3. Quick 'theory' of signal processing)
Jump to navigation Jump to search
Event Foundations Friday: Software Defined Radio workshop
Name Foundations Friday: Software Defined Radio workshop

Duration 2019-06-28 20:00 - 2019-06-28 23:00

* Location: Overgoo 1, Leidschendam
* Open from: 20:00

1 Prerequisites:

Please bring your own RTL-SDR hardware (very cheap, $20-$40 or less) or other SDR hardware (USRP or other GNURadio supported SDR). There might be a few available @ revspace coin-op machine by the time the workshop starts.

2. Quick introduction

Quick introduction into GNURadio companion user interface and concepts and keyboard shortcuts (have it preinstalled and git client to download the samplecode)

3. Quick theory of signal processing

This could take about one to or 1.5 hours Interactive session

3.1 Real signals

Real sinewaves

 In the timedomain
 Displayed using time sink / oscillioscope
 Displayed uisng frequency sink / FFT / spectrogram

Multiplying real-sinewaves, in the time domain

Displayed using time sink / oscillioscope
Displayed uisng frequency sink / FFT / spectrogram
Usage of the word 'mixing' in radioterms (multiplication or usage of other non-linearities)

3.2 Complex signals

Quadrature or complex (IQ) sinewave signal sources

Displaying IQ signals in timedomain ('constellation' diagram)
Displaying IQ signals in frequency domain (using FFT or frequency sinks)

Multiplying quadrature (IQ) sinewaves and spectrogram

Effect of quadrature multiplication (phases of are added) 
Usage of complex multiplication in signal processing

3.3 Filtering complex signals

Filtering IQ signals using FIR filters with complex taps. FIR or Finite Impulse Response filters. IIR filters will be skipped.

3.4 Calculating FIR filter coefficients or parameters

Filtering coefficients/taps, impulse response of filter

(very quick) calculating FIR filter coefficients/taps using gr-filter 

Performance limitations, tradeoffs between

 computational complexity of filter (number of multiplies per processed sample)
 steepness of cut-off frequency
 flatness of passband of filter (integrity of signal that still should pass through the filter)
 depth and ripple of stopband of filter (flatness of suppression of unwanted signal)

Using inverse FFT/inverse DFT and windowing functions to determine filter coefficients/taps

4. Radio receivers and/or detectors

- Build a simple mono FM receiver using blocks with built-in feedback networks - Build a RDS FM receiver and connect it with your RTL-SDR or other gnuradio-support SDR/radiodata input device

5. Bonus

Build with welle.io a SDR-based DAB+ receiver from source. For this a QTQuick 5.x installation might be required.


(Nick)Name Has (some) SDR Reciever
cmpxchg Yes
minicom Yes