Hackfest1403

Hackfest March 2014 in Karlsruhe

Post-WSR 2014: 13th to 15th of March 2014 at CEL in Karlsruhe

Attendees

• Philip Balister
• Martin Braun
• Moritz Fischer
• Attila Kinali
• Sebastian Koslowski
• Jan Krämer
• Sylvain Munaut
• Marcus Müller
• Tom Rondeau
• Balint Seeber
• Dimitri Stolnikov

Projects

GNU Radio Buffer Architecture

Primarily Tom Rondeau

• Buffers need to be more flexibility for accelerators
• Modifying buffers is potentially hazardous and not trivial
• first step: get in-place buffers to work

• if that works, other buffers should be manageable, too
  
• for sync blocks without history, that should be doable
  
• for concatenated blocks, the most upstream one needs to know the read pointer position of every single downstream buffers
  
• missed something in setting up the buffer readers for all upstream blocks
  

' fixed afterwards for proof-of-concept

• interweaved backpressure might lead to inefficiencies
  
• forking flowgraphs may need special treatment

QT instrumentation

Tom Rondeau

• number sink completes the QT toolkit (now equal to WX)
• nicely configurable, sensible defaults, QT style sheets usable
• discussion: switch default gen. option to QT (prob. will do)
• discussion: hide "wrong" gui toolkit for gen. option (problem being that the error message is non-intuitive)
• Tabs in block properties to reduce complexity

GSoC

• Discussion of already available Proposals
• testing of VNA feasibility (Sylvain Munaut)

• does work theoretically
  
• requires patching UHD, pull req. on github
  
• data consistent
  
• annoying: B210 does not support timed commands, gives no information on time of tuning

• not encouraging people to generate last minute proposals

GRC

Sebastian Koslowski

• improved fault handling

• When block is missing, in the past all connections were undone, the block would just be invisible
  
• new: red box, disabled, invalid; gives name of missing block as key
  
• all parameter types now string
  
• after generation of missing block, everything will fall into place

• external tool button -> filter design tool

• external filter tool setting file, but taps just get exported, no external file dependencies of the .grc file

• tabs

• new xml element <param><tab></tab></param>, as defined in <param_tab_order>
  
• core affinity, buffer sizes, etc always in Advanced tab
  
• If no tabs specified, defaults to General tab (means we don't have to change old XML files)
  
• Documentation tab for easier viewing of docs

PFB channelizer

Sylvain Munaut

• benchmarking
• trying to improve speed
• doing a tree of PFBs can sometimes be better than one large PFB
  • channels > 512 can be broken into multiple stages of channelizers
  • cache or other memory constraints may explain why this helps
• deinterleaving inside the PFB block instead of using a stream_to_streams block didn't work out

QT GUI in external applications

Sylvian Munaut

• Support for QTGUI sinks in C++ FGs
• fixing some swig-related bugs

gr-mac

Balint Seeber

• based on John Malsbury's work
• revolves around Simple MAC block
• OFDM as well as GMSK as Radio interface work
• TUN/TAP and socket to socket
• implemented ARP cache equivalent (802.3 Tracker)

• broadcast for unknown MAC addresses

• demonstration is awesome
• test application: send an image progressively
• ARQ actually working
• Demo'd by bridging Sylvain over a GR link and routed through Balint's laptop to connect with IRC

GPS receiver in GR

Attila Kinali

• self-built GRC flow graph unfeasible large
• Literature complicated to the uninitiated
• GNSS-SDR exists

• highly complex
  
• highly modular
  
• framework for receiver generation

• you feed in receiver parameters
  
• builds flow graph on runtime
  
• great flexibility, but complicated to understand if you're new to this

• GNSS seems to be using only one core, not realtime
  
• Tom needs to revisit GNSS-SDR, refresh friendship with them
  

' Corgan already working with GNSS and continuing the relationship

FAQ

• Discussion on the new FAQ
• make a meta-FAQ entry point

• 4 target audiences

• Students
  
• Commercial interested
  
• Software Hackers
  
• Hams

Some updates to docs and Doxygen

Martin Braun

• Better looking
• Search box available
• Older versions of Doxygen will generate warnings but still complete