Below are my notes from watching the videos.

• Episode 51 Part 1: Intro to GNU Radio (Part One) from the 2012 DCC, Tom Rondeau, KB3UKZ.
  • GNU Radio was started in 2001.
  • GNU Radio is a development platform to develop applications.
  • GNU Radio is designed to be real-time. The computer hardware will determine how fast of real-time it can process.
  • GNU Radio is programming with processing blocks.
  • The scheduler is the core of GNU Radio.
  • The scheduler operates on block flow diagram.
  • Processing blocks are connected together and define how radio data flows and is processed.
  • GNU Radio flow graph moves data from source blocks , to signal processing blocks, then to sink blocks.
  • A flow graph is run by the scheduler.
  • The scheduler moves blocks of data from one block to another block.
  • A flow graph cannot have feedback from one block to another block.
  • A signal processing block can have feedback inside the block.
  • Rate changing blocks input rate/output rate, 1:1, 1:N, N:1 or M:N.
  • Layers: GR Companion graphical programming/user interface at top, next layer Python, the bottom layer is C++.
  • File sinks can be use used for debugging the data flow diagram.
  • GNU Radio program options
  • QT GUI is new interface, WX GUI is the old interface.
  • Double click on a block to bring up the block properties.
  • Color of the data flow indicates the data type.
  • To create block data flow connections, click on the block data output port and then click on the block data input port.
  • Red indicates errors.
  • GNU Radio default sampling reate is 32 KS/s.
  • CPU thread per block operation means faster parallel operation based on how many threads can be operated in parallel on your computer hardware.

• Episode 51 Part 2: Intro to GNU Radio (Part Two) from the 2012 DCC, Tom Rondeau, KB3UKZ.
  • Great graphical demo of convolution filtering a signal.
  • Nyquist sampling rate is 2X the information bandwidth.
  • Sampling change is key to SDR operation.
  • Decimation is downsampling.
  • Interpolation is upsampling.
  • Always filter when changing sample rate.
  • Filter before downsampling.
  • Filter after upsampling.
  • Need to check 2012 Google Summer of Code
  • GNU Radio Filter Design Tool greates a CSV file.
  • gr_filter_design
  • Filter windowing
  • Recommend using Blackman-harris
  • Worst is Hamming window (Default)
  • Build memu.
  • Generate icon creates the Python code file.
  • QT slider bar example (QT GUI Range).
  • Options, ID: top_block, top_block.py file.
  • Should change the the name top_block.
  • Change Generate Options to QT GUI.
  • Block properties short cuts
  • Ctrl-c: copy text
  • Ctrl-v: past text
  • Ctrl-x: copy and cut text
  • Block properties variables
  • Constants, variables and Python expressions are allowed.
  • Red stop sign icon stops the GRC program.
  • Zeros in the bottom window indicates dropped data when the program is running.
  • In RPi terminal enter python to start the python interperter.
  • To quit enter quit().
  • Filter transition period.
  • Small transition creates a large number of taps. More processing time and power is needed.
  • Large transition creates a small number of taps. Less processing time and power is needed.
  • GNU Radio uses single precision numbers for floats (one number) and complete (two numbers).
  • Use the magnifying glass to search for a block blocks.
  • For example, search on WX will show all the WX Widgets and WX Instrumentation blocks.
  • GUI Grid Position
  • Row starts at 0, column starts at 0, row span, column span
  • Throttle block limits the data rate flow (this is poor clock accuracy).
  • Do not use the Throttle block with real hardware.
  • Use the Throttle block for simulations without hardware.

• Episode 51 Part 3: Intro to GNU Radio (Part Three) from the 2012 DCC, Tom Rondeau, KB3UKZ.
  • WX GUI Waterfall Sink FFT Rate default is 15 times per second
  • File New or Ctrl-n to start from scratch.
  • Options block, change the ID name so that you do not ower write other files.
  • Options block, Generate Options: WX tends to have problems with open GL, use QT.
  • Save file as same name as top block .grc.
  • Block data types need to match, tend to work with complex data, for example I/Q data.
  • Data type color are shown in Help, Types.
  • Red data flow arrows indicate data type mismatch.
  • Click on block, use the up/down arrows to change the block data type.
  • Block properties colors
  • Orange is number
  • Purple is string
  • Dark blue is variable name
  • Use FIR filters. IIR filters
  • Single pole IIR.
  • FFT filter
  • Convolution is time is equal to multiplication is frequency.
  • Greater than 20 taps the FFT filter is faster than FIR filter.
  • FIR and FFT filter can downsample (decimation) in their processing block.
  • FFT complex in/complex out.

• Episode 51 Part 4: Intro to GNU Radio (Part FOUR) from the 2012 DCC, Tom Rondeau, KB3UKZ.
  • Hilbert filters DC to positive frequencies. Removing the negative frequencies.
  • Hilbert filters real signal/complex signal (analytic waveform).
  • Most SDR designs are based on complex data (I/Q).
  • SDR hardware.
  • 2004 USRP (~$1+). UHD blocks)
  • FunCUBE Dongle (~$100) (see 2011 DCC www.ARVN.tv).
  • DVTV RTL Dongle (~20) osmocom group.
  • RDS decode.
  • Digital demo Narrow Band FM Receiver block NBFM Receiver Wide Band FM Receiver block WBFM Receiver Disable blocks to prevent block to compile.