Difference between revisions of "Event:SoftwareDefinedRadioSDRFMDABontvangerworkshop"
(→3. Quick 'theory' of signal processing) 

Line 8:  Line 8:  
InfoOpen=20:00  InfoOpen=20:00  
}}  }}  
+  
+  Goal of the workshop:  
+   To receive a simple wireless microphone signal from the presenter, using your own laptop  
+  + softwaredefined radio receiver  
+   To understand a few basic concept of radio, signal processing, and softwarebased radio signalprocessing  
+  in particular.  
== 1 Prerequisites: ==  == 1 Prerequisites: ==  
−  Please bring your own RTLSDR hardware (very cheap, $20$40 or less)  +  Please bring your own radioreceiver: 
−  +   A RTLSDR hardware (very cheap, $20$40 or less)  
+   A funcube dongle  
+   Other SDR hardware (USRP or other GNURadio supported SDR)  
+   A laptop with GnuRadio and Gnuradiocompanion installed (version 3.7.5 ... 3.7.11 is ok)  
There might be a few available @ revspace coinop machine by the time the workshop starts.  There might be a few available @ revspace coinop machine by the time the workshop starts.  
+   Optional: a gqrx installation or other softwaredefined radio/waterfall receiver with WBFM support  
== 2. Quick introduction ==  == 2. Quick introduction ==  
−  Quick introduction into GNURadio companion 3.7.  +  Quick introduction into GNURadio companion 3.7.x user interface and concepts and keyboard shortcuts 
(have it preinstalled and git client to download the samplecode)  (have it preinstalled and git client to download the samplecode)  
−  == 3.  +  == 3. Theory of signal processing == 
−  This  +  This takes about half an hour, it is an interactive session so 
−  +  that we can adapt the speed a bit depending on prior knowledge  
+  of the participants. Questions in between are very welcome,  
+  we will be with a small group.  
−  ==  +  == 4. Practice of signal processing == 
+  
+  The examples will be provided via git and just need to be started,  
+  so the focus is understanding the signal flow, making modifications  
+  predict what will happen, and then test the result in practice.  
+  This takes about another half hour  
+  
+  == 4.1 Real signals ==  
Real sinewaves  Real sinewaves  
In the timedomain  In the timedomain  
Line 32:  Line 51:  
Usage of the word 'mixing' in radioterms (multiplication or usage of other nonlinearities)  Usage of the word 'mixing' in radioterms (multiplication or usage of other nonlinearities)  
−  +  == 4.2 Complex signals ==  
−  ==  
Quadrature or complex (IQ) sinewave signal sources  Quadrature or complex (IQ) sinewave signal sources  
Displaying IQ signals in timedomain ('constellation' diagram)  Displaying IQ signals in timedomain ('constellation' diagram)  
Line 41:  Line 59:  
Usage of complex multiplication in signal processing  Usage of complex multiplication in signal processing  
−  ==  +  == 4.3 Filtering complex signals == 
−  Filtering IQ signals using FIR filters with complex taps. FIR or Finite Impulse Response filters. IIR filters will be skipped.  +  Filtering IQ signals using FIR filters with complex taps. FIR or Finite Impulse Response filters. IIR filters will be skipped. Hilbert transform filters might be skipped too (generating complex analytical signals from real ones). 
−  ==  +  == 4.4 Calculating FIR filter coefficients or parameters == 
Filtering coefficients/taps, impulse response of filter  Filtering coefficients/taps, impulse response of filter  
−  +  Calculating FIR filter coefficients/taps using grfilter  
Performance limitations, tradeoffs between  Performance limitations, tradeoffs between  
−  +  Computational complexity of filter (number of multiply/add operations per processed sample)  
−  +  Steepness of cutoff 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  +  (Using inverse FFT/inverse DFT and windowing functions to determine filter coefficients/taps will be skipped) 
+  
+  == 5. Radio receivers and/or detectors ==  
+   Build a simple mono FM receiver using blocks using builtin feedback networks  
−  +  The transmitter in question is an ordinary wireless presentation microphone for stageusage.  
−  +  It will generate a mono, wideband FM signal in the 473494 MHz band.  
−    +  The transmitter will also feature a tonecode of 35 kHz that will be inaudible to the public and normal 
+  receivers. The tone is used to detect nearby presence of the transmitter, and estimate the  
+  signal level.  
−  +  The goal is to  
−  +   find the frequency  
+   demodulate the FM signal using basic gnuradio blocks  
=== Attendees ===  === Attendees === 
Revision as of 20:10, 5 June 2019
Event Foundations Friday: Software Defined Radio workshop  

Name  Foundations Friday: Software Defined Radio workshop

Duration  20190628 20:00  20190628 23:00 
Information 

Goal of the workshop:  To receive a simple wireless microphone signal from the presenter, using your own laptop
+ softwaredefined radio receiver
 To understand a few basic concept of radio, signal processing, and softwarebased radio signalprocessing
in particular.
Contents
1 Prerequisites:
Please bring your own radioreceiver:  A RTLSDR hardware (very cheap, $20$40 or less)  A funcube dongle  Other SDR hardware (USRP or other GNURadio supported SDR)  A laptop with GnuRadio and Gnuradiocompanion installed (version 3.7.5 ... 3.7.11 is ok) There might be a few available @ revspace coinop machine by the time the workshop starts.  Optional: a gqrx installation or other softwaredefined radio/waterfall receiver with WBFM support
2. Quick introduction
Quick introduction into GNURadio companion 3.7.x user interface and concepts and keyboard shortcuts (have it preinstalled and git client to download the samplecode)
3. Theory of signal processing
This takes about half an hour, it is an interactive session so that we can adapt the speed a bit depending on prior knowledge of the participants. Questions in between are very welcome, we will be with a small group.
4. Practice of signal processing
The examples will be provided via git and just need to be started, so the focus is understanding the signal flow, making modifications predict what will happen, and then test the result in practice. This takes about another half hour
4.1 Real signals
Real sinewaves
In the timedomain Displayed using time sink / oscillioscope Displayed uisng frequency sink / FFT / spectrogram
Multiplying realsinewaves, 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 nonlinearities)
4.2 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
4.3 Filtering complex signals
Filtering IQ signals using FIR filters with complex taps. FIR or Finite Impulse Response filters. IIR filters will be skipped. Hilbert transform filters might be skipped too (generating complex analytical signals from real ones).
4.4 Calculating FIR filter coefficients or parameters
Filtering coefficients/taps, impulse response of filter
Calculating FIR filter coefficients/taps using grfilter
Performance limitations, tradeoffs between
Computational complexity of filter (number of multiply/add operations per processed sample) Steepness of cutoff 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 will be skipped)
5. Radio receivers and/or detectors
 Build a simple mono FM receiver using blocks using builtin feedback networks
The transmitter in question is an ordinary wireless presentation microphone for stageusage. It will generate a mono, wideband FM signal in the 473494 MHz band. The transmitter will also feature a tonecode of 35 kHz that will be inaudible to the public and normal receivers. The tone is used to detect nearby presence of the transmitter, and estimate the signal level.
The goal is to  find the frequency  demodulate the FM signal using basic gnuradio blocks
Attendees
(Nick)Name  Has (some) SDR Reciever 
cmpxchg  Yes 
minicom  Yes 