The Amp Hour

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Natural Sciences
**The Amp Hour**

The Amp Hour is a weekly conversation about electronics and the people who design them.

Latest Episodes:

An Interview with Derek Kozel Feb 26, 2018

Show notes

Welcome, Derek Kozel of Ettus Research (a National Instruments company) and the GNUradio project!

Derek recently moved to Cardiff, Wales (UK). His new house will soon be outfitted with many antennas.
At university he was part of the ham radio club (W3VC), which got him into the whole industry.
Repeaters
Chris suggested a Baofeng as an HT (which was met with disgust). Derek uses a Yaesu VX-6
After college Derek went to work at SpaceX on sensor networks.
Derek now works at Ettus Research. We had the founder Matt Ettus on the show in episode 101.
Just a sampling of SDR applications
- Radar for space debris (?)
- Ultrasound
- MRI machine on the desktop
Hard parts of SDR
- Software
- Filters
- Antennas
Antenna Theory by Balanas
RTL-SDR / SDR Sharp (now Airspy)
Derek and Chris were hanging out at FOSDEM
Though CERN obviously has a very intricate front end, the LHC only outputs roughly 40Gb/s. This is the equivalent of one SDR.
Open BTS - an open source implementation of a cell phone tower
Range networks
The main view of GNU Radio Companion (GRS) is the flow graph
Web SDR applications
Former guest Mike Ossmann did a bunch of SDR tutorials.
Digital vs analog modes
On-off keying is like what garage door openers do in infrared
Frequency Shift Keying (FSK) is bouncing between frequencies. Common ones are 1200 Hz, 2200 Hz (usually shifted up to different carrier frequencies)
APRS network
(Forward) error correction
Digital video broadcast is already possible and happens in some cases in the amateur world. Better examples are the recent SpaceX launch and their perfect feeds back to earth.
Ettus USRP1
GNU radio adoption is rising in both the for profit and non profit space.
Derek is now an officer for the GNU radio project and his boss Martin Braun is the community leader.
This is where Chris got the idea for a Manufacturing group for KiCad. Interested? Sign up for the mailing list here.
Club Mate (blech). But if you really like it there may be an open source version on the way.
Framework where you can drop your code into the FPGA (because it's open source). Check that out, as well as the schematics for much of the hardware at files.ettus.com
Osmocom
Conference for GNUradio - Sept 17-21 in Henderson (LasVegas). You can see the schedule from last year.
The EISCat project is doing "Radar for the clouds" (among other things). Read more about them here, here and here.
GNUzilla
Beam steering/forming is used broadly in that project (but is a base physical idea). Watch a demo of it here. This is an implementation of MIMO.
Vector library of optomized kernels (VOLK)
GPUs, custom ASIC, FPGAs
Receiving satellites
- Open Satellite project
- AIS - airplane tracking 1.09 GHz
Decoding LoRa (GR LoRa...and...GR LoRa). This was done by Matt Knight of Bastille, his talk was mentioned a few times from CCC.
Reducing the learning curve
Where to learn more about GNUradio
- Main site
- Wiki / Tutorials
- Discuss Mailing List
- Slack channel
- IRC
Find Derek online
- On twitter! @derekkozel
- IRC
- Email
Talks
- HDDG
- Links to other talks/slides

Just Terrestrial and Space Things Feb 19, 2018

Show notes

Yes, it’s true. Dave and Chris talk about IoT in earnest, mostly because Chris brought it up.

See below (or use this link) to take our yearly-ish survey for a chance to win a 1000x from Keysight. Also win more during the Keysight Wave event (formerly Scope Month)
Dave and David are testing the lifetime of a range switch using a jig.
Using the HY3131 datasheet you could in theory write your own firmware for the 121GW. An EEVblog community member started reverse engineering the firmware.
FOSDEM
Tjeerd in the background making a face at Chris showing hardware :-D
KiCad 5 Announcements
Chris is looking to talk to people doing KiCad manufacturing. Sign up to get notified about future discussions here.
Richard Ginus (past guest) helped design the TWTG / TTN gateway. He did a better job of explaining it than Chris does here. There is an EU version (868 MHz) and a US/Aus version (915 MHz). Dave was looking at this lower cost one.
Jereon on the show talking about the ESP32.
LoRa stuff by Andreas Spiess, including super cheap gateways. You can get them here as well (but watch the video for caveats about them).
SigFox is a similar offering but with a reversed model to TTN (charge for access to the towers)
MickMake does great videos with weekly roundups of new boards, including lots of connected products.
Particle announced their new mesh products! Each board has an nRF52, which uses OpenThread to create the mesh (AFAIK).
Don't use Iota for IoT (apparently)
Ben Heck is moving on! But you can try out for his job
Circuit boards...in spaaaaace!

An Interview with John Saunders Feb 11, 2018

Show notes

Welcome John Saunders of Saunders Machine Works and NYCCNC!

Chris met John when he was doing a tour of mHub
John was an early member of NYC Resistor
Former guest Robert Feranec runs Fedevel academy
Training on site (prices as stated in podcast, obviously subject to change)
- 2 day introduction $300
- 3 day hands-on $1175
- 2 day advanced
They cover things like
- CAD (using Fusion360)
- CAM (using Fusion360)
- Workholding
Wednesday widgets is a regular segment on NYCCNC
Guerrilla guide to machining
Pocket NC
Daishin Seiki helmet video
David2 mcad solidworks video comparison
Clickspring
OnShape
Injection molding
Morgan press
Lego brick drafts
eMachineShop
Project Dreamcatcher by Autodesk
Online tools for getting mechanical things made (by machining)
- xometry
- protolabs
- plethora
John says a good starter project is: a vice handle
NYCCNC has an Excel file feeds and speeds
Former guest Claire (nee Clifford) Wolf started the OpenSCAD
Scraping - precision surfaces
They do electronics as well! This is a vibe bowl screw feeder controlled by an Arduino.
John does a podcast along with John Grimsmo, called The Business of Machining
Other mechanical podcasts
- Making It
- Making Chips
Other YouTube channels that John follows for machining (aside from Clickspring, linked above)
- Ox Tool with Tom Lipton
- Robin Renzetti
Want to try out Fusion360? Check out John's getting started page.
Want to meet up with John when he's in Australia? He'll be doing a Sydney meetup Tues March 13th
Not announced at the time of recording, but John will be doing an "open house" at mHub in Chicago on September 9th. This will be the night before IMTS, also in Chicago.

It was great having John on to tell us about machining and mechanical concerns. While we normally focus on electronics on this show, it's increasingly important to have a broad view of the product development cycle and the various processes required to get something created for the market. We think NYCCNC helps beginners get a footing in the field. Be sure to subscribe!

An Interview with Jason Kridner and Robert Nelson Feb 04, 2018

Show notes

Welcome Jason Kridner (@Jadon) and Robert Nelson of the Beagleboard.org board!

Jason was one of our first guests on TAH, episode 59!
The original Beagleboard ran angstrom and Maimo (sp?)
Users of the Nokia N900 helped to port to the processor platform.
Debootstrap
Golden delicious - open moko
Beagle x15
Device tree
AM35xx
uBoot
Where (and how) to start building your own images: on an x15 because it's fast
Yocto project
Pocket Beagle. Chris complained about the headers for the pocketbeagle.
The new SIP is from Octavo.
Tom Bewley from UCSD teaches a course using the BeagleBone blue. It runs Ardupilot and other robot/drone software out of the box
Ken Shirriff's episode
A memory management unit is usually the delimitation between embedded and full blown linux
PRUs - programmable realtime unit
BeagleLogic - Sigrok
3.8 is the most used kernel
gist for coding pru
e-ale.org
Cloud9 ide
NodeRed - NodeJS
Config pin tool
Internet Connection Sharing (ICS)
Weekly images for continuous integration
GCC test suite
The AM3358 is ARMv7, A8
Embedded.fm specter meltdown
Thumb2 allows 16 bit and 32 bit but broke a lot of stuff.
Best image to start with: stretch stable - 4.9
Etcher.io
where to get support
- Beagleboard group - google groups
- IRC channel - beagle

Debugger vs Printeffer Jan 29, 2018

Show notes

Dave is back from vacation! Chris is leaving soon!

We have had a range of great guests in the past few weeks (reverse chronologically)
While Dave was gone he had a bunch of awesome guest videos!
Dave unintentionally helped sponsor Chris's meetup with a BM235 multimeter The cost of doing business is real...but benefits others!
There have been 121GW meter issues, though the first batch has shipped. They didn't think to make David the courier.
Chris reminds that "manufacturing isn't glamorous"
At first Chris thought Dave might be dealing with the worldwide capacitor shortage. Former guest Joe Bamberg mentioned that Yageo has been changing their sourcing strategy.
PIC16c84 was an early reprogrammable chip
Teardown of IBM PC junior
PKware zip
Intel has been dealing with the fallout of Meltdown and Spectre, which was apparently discovered by a 22 year old.
The amazing $1 micro
Chris has been using adafruit's Trinket M0, which ships with Circuit Python. It's great for troubleshooting, especially since Dave and Chris aren't debuggers (using things like the Black Magic Probe made by former guest Piotr)...we're more "printeffers"
Dave will be pulling out the network analyzer to try out his power supply. Power supplies rely heavily on control theory and inserting signals to see the resultant output is a useful analysis. Chris also recommends this animated GIF of a Fourier Transform to see what's going on inside a square wave signal (and why it can be used to approximate a network analyzer)
Travis Goodspeed released the Goodwatch. Dave thought it was just a calculator watch retrofit, but it actually has RF capabilities!
There are tons of good talks being released on YouTube from 34c3 (Chaos Computer Congress). Chris liked this one about decoding LoRa using GNUradio (which was actually from last year, 33c3)
Former guest Bil Herd narrated and many-time former guest Jeri Ellsworth produced this documentary on the Atari
The 3H Meetup has franchised to Seattle!
Chris will be in Amsterdam for The Things Conference and in Brussels for FOSDEM. Let him know if you'll be there!

Thanks to isipeoria for the printf picture

**An Interview with Richard Ginus** Jan 22, 2018
Show notes

Welcome, Richard Ginus of TWTG!

**Found out after the show, Chris and Richard will both be at The Things Network Conference in Amsterdam February 1st to 3rd!**

Richard is in Rotterdam in the Netherlands. There is a lot of focus on solar there. Chris recalled this beautiful National Geographic piece on (indoor) farming in the Netherlands.

In addition to designing with LoRa, Richard works on RC planes. When he put a LoRa module on a plane (which could "see" further than from the ground) he had a module that saw a tower over 30 km away (Antwerp, Utrect)

Past designs have included tracking cyclists during races, but the bandwidth needs make it difficult. Usually data transfers are about .3 kbps to 11 kpbs

There are many different types of LP WAN. Most are narrowband, LoRA is wideband

LoRa

Sigfox - open source, but only their network (multiple nodes)

NB-IOT - 3GPP, lots of penetration (50 cm underground)

Akiba has talked about 802.15.4 (also used in Zigbee) in past appearances on The Amp Hour. This is a point to point method of communicating. Chris saw Sure-Fi at CES, which also seemed to be point to point.

All LoRa radios operate in the ISM bands (location dependent) - 160 Mhz, 315, 433, 868, 968 MHz

On 868, the rule is you can only send 1% of the time (at least in the EU).

The stack was obtained on the GitHub from IBM, put on an m0

You do need a chip from Semtech in order to do this. It's SPI controlled.

There are different chips

Node chips - SX1272

Gateway chips - SX1301

GR (GNUradio) LoRa

Richard uses a HackRF for troubleshooting, which is why Chris got one as well. He mostly uses the waterfall diagram

LoRa uses CSS - Chirp Spread Spectrum

Doing this reduces multipath (echoes).

868 MHz has 8 few channels, each with 125 kHz of bandwidth.

Half duplex on LoRaWAN

Class A - uplink, listen for two downlink slots (one right after, one later)

Class B - two way devices, scheduled receive windows

Class C - Always listening

By default the packets are AES encrypted

There are two ways of attaching to a network

Over the air activation

Directly put in session keys (ABP - auth by personalization)

Systems are not symmetric. The gateways are passive (pass through devices), but there's more behind it

Network server

Application server

AT command interface to talk to the modules (like on ESP8266 or on cellular modules)

There is now hardware being sold by The Things Network

Uno

The Things Node

The Things Network is a shared "network of the people" who have gateways set up for devices to go through.

You can help by Wardriving - have a node send out a packet. TTN Mapper.org is a project to map new gateways. All you need is a device, TTN and a code.

Adaptive data rate allows devices to reach more gateways or save more power. Really it's about "knobs" you can turn. One main "knob" is spreading factor, which is the duration of chirp (more energy)

Coding rates (add more psuedorandom data and lengthens the packet) also allows more signal to be pulled from the noise.

Batteries are a huge issue still but with LoRa one of Richard's clients got 10 years on 11 Ah battery.

When multiple gateways receive a packet, it's up to the network server.

Updating firmware isn't not an option because it's mostly a unidirectional.

All LoRa devices speak FSK, which is European-centric.

Richard is working on trying to find new ways to create MQ gas sensors. Most have resistive heaters which are obviously not low power.

Tryst - light energy module for indoors

standards are defined by lora backends

Interested in working with Richard? Check out the TWTG.io careers page! Or shoot him an email. Or get in touch with him on hackaday.io.

Other images to help understand:

An Interview with Tim "Mithro" Ansell Jan 15, 2018

Show notes

Welcome, Tim “Mithro” Ansell!

Tim is on the show to discuss the Tomu, a new project currently funding on CrowdSupply. It's mentioned at the beginning of the show and continued around 1:13:00.
Tim is a software engineer (Back end/ front end) during the day and hardware engineer on the side.
He also started PyCon AU, which is coming up August 24-26, 2018 in Sydney (there is also LinuxConf.au which is in January). There is a large IoT section as well, usually attended by the micropython crowd, including founder Damien George.
Due to dyslexia in elementary school, Tim was told to use the spell check on his IBM XT 8088. This plus the "Dick Smith's Fun Way into electronics" sparked his love of hardware.
University of Adelaide
- His senior project was creating a phone exchange using a PIC with built in USB Interface. It has 8 ports connected to phones via standard RJ12 jacks and was all written in assembly.
We got into the idea of unit tests for schematics.
TimVideos
- The hardware
- This is a project targeting user groups and conferences
- History of the project
- Needs to be portable with "extreme debuggability"
- FAQ
- Was inspired by Bunnie's NETV - HDMI overlay
- They ended up using a Digilent board for early protos. Founder of Digilent (Clint Cole) was a guest on The Amp Hour in the past.
- Atlys
- Numato Opsis
- Current specs are 720p60, 1080p30 on the Spartan6
- Artix7 will be 1080p60
- Bunnie is doing NeTV2
- Tim's talk at 33c3
Tomu
- Currently funding on Crowdsupply
- Aims to replace something like the Yubikey Nano (though there's no crypto module on board this device)
- It has 6 mil space/trace so it can be made cheaply. Uses the Silicon Labs Happy Gecko EFM32HG309
- FIDO device
- Sean "xobs" Cross is heading up the project.
Training at Linux.conf.au - Jan 23rd
- This will take participants through the steps of creating an embedded soft processor in an FPGA. There will also be a Python framework that switches between different softcores.
- Cores discussed/explored
  - OpenRISC 1K
  - PicoRV32, which was mentioned last week on the show with Claire (nee Clifford) Wolf.
  - Lattice LM32
- They are using the Arty A7 board
- Soon "upy-fpga" will become "fupy"
- Gateware
Contact:
- Find Tim on the #TimVideos Freenode IRC channel as mithro
- Find him as @mithro on Twitter.
- As mentioned in the interview, if you contribute to the project Tim will send you a board for free!

An Interview with Claire (née 'Clifford') Wolf Jan 08, 2018

Show notes

Claire, formerly Clifford, took on a new name in December 2019. We decided to update the post.

Welcome, Claire Wolf (Twitter: @OE1CXW)

Claire's first open source project was RockLinux, started back in 1997
- Shell scripts, AWK scripts
- A fork of the project still is active as T2
OpenSCAD is an open source scripted 3D CAD program
- Metalab.at hackerspace
- Creating parametric models that can be modified easily in OpenSCAD.
FPGAs
- Claire started out with Xilinx because they offered HDL as the default.
- She did things like building CPUs, writing compilers and creating the SPL scripting language
- The Dragon book was her intro to writing a compiler
3D laser scanners / LIDAR
- Light is too fast
- Light is too slow
- Self driving cars will likely move to cameras in the future because of interference of multiple LIDAR systems on the road.
In 2008 she went back to university
- Her academics were overshadowed by focusing on missing questions here and there. So instead she focused on publishing papers
- Coarse-Grain Reconfigurable Architectures
  - "Methodology and Example-Driven Interconnect Synthesis for Designing Heterogeneous Coarse-Grain Reconfigurable Architectures. Johann Glaser and Clifford Wolf. In Jan Haase, editor, Models, Methods, and Tools for Complex Chip Design. Lecture Notes in Electrical Engineering. Volume 265, 2014, pp 201-221. Springer, 2013."
Yosys
- A framework for HDL synthesis and more
- Verilog 2005
- Reinforcement learning
- Logic Synthesis - turning verilog into a logic circuit
- Intocent
- File formats for logic circuits
  - edif
  - blif
  - verilog
  - json
Project IceStorm
- iCE40 from Lattice
- Documented the bitstream format
- mid-2015, complete open source toolchain
- Later added 8K, then ultra plus device

arachne-pnr - written by Cotton Seed
"Whenever you have a theory write a small program that checks if your theory is correct"
New versions will target Xilinx 7 parts
- Partial reconfiguration will allow an "FPGA within the FPGA, where the harness is made in vendor tools
- "Prototyping tools in ARM processor"
- Example: Logic analyzer trigger conditions
RISC V
- This is an open instruction set architecture (ISA) -- not open source
- Western Digital will be shipping 1B RISC V devices in 2019.
- The software tools is the hard part
- XKCD standards
- ARM put m0 and m3 on webpage

PicoRV32
- This was part of the subject of Claire's CCC talk this year.
- It's a fast, small processor, which reduces clock domain crossing
- It's used in the Berkeley Lawrence Nat'l lab synchrotron
Libxsvf
- Used in one of the control coils for the Large Hadron Collider
- Has the LHC Destroyed the world yet?
RISC V vs x86 is a red herring
Formal Verification
- This is the goal for Claire's company, SymbioticEDA.com
- The idea is to do hardware model checking and "prune the search tree as soon as possible"
- SAT/SMT solving
- SymbiYosis
- Yosys-SMTBMC
- Project IceStorm uses formal verification
riscv-formal
- Formally verify a processor against ISA
- This is actually what the latest CCC (34c3) talk was, End to End ISA Verification of a RISC V processor.
- Reactive synthesis (starting from random and seeing if it's a processor)
- Instead this is starting from a processor and running "all programs" against it
- Category of bugs:
  - Reading spec incorrectly
  - Function is different from what it usually does in one specific application
- New intel bug

The best way to reach Claire is on Twitter! @OE1CXW

Pedantic or Andrantic Jan 03, 2018

Show notes

The Amp Hour and Embedded join up to send a holiday letter to listeners!

I (Chris G) got totally fritzed out dealing with the new year and Chris and Elecia were awesome and edited AND did show notes this week. Not to mention Chris White’s new Ampbedded Crossover Theme! Wowsa! Props to them, I’m super lucky to have them as friends. Happy New Year!

Chris G is ever improving Contextual Electronics. Chris W has a new band: 12ax7. Elecia still has a book: Making Embedded Systems.

Amp Hour episodes mentioned in this one

372: Where Chris and Dave talk about 2017
304: Alexa jokes
281: The first Amp Hour / Embedded show, with call ins
256: The first time Chris W was on the Amp Hour
187: Elecia joined the Amp Hour for the first time

Embedded episodes mentioned:

We talked about teaching which led to:

Short mention of Dreyfus model of skill acquisition of which Chris G’s friend Mel did a great explanatory comic
Daniel Spalding’s How to Teach Adults (pdf)
Dan Luu’s Learning To Program post
Udacity’s Self Driving Car courses
Computer vision with Python OpenCV
Article on how the difficulty is the point of teaching literature
The new art and engineering Function Podcast
Hilarious World of Depression podcast
Books!
- Build Your Own Transistor Radio by Ron Quan
- The Hobbyist’s Guide to RTL-SDR by Carl Laufer
- Spineless by Juli Berwald about Jellyfish
- Lost Art of Reading Nature’s Signs by Tristan Gooley
- Into the Drowning Deep by Mira Grant (terrifying mermaids)
- Catseye by Andre Norton
- Teach Beyond Your Reach by Robin Neidorf
- Mastery by Robert Greene
- Understanding By Design by Grant Wiggins and Jay McTighe
- Making Learning Whole by David Perkins

Elecia got a JTrace Pro Cortex-M for herself for Christmas. Chris W got a Moog Werkstatt and an assortment of Teenage Engineering small synths. Chris G mostly got sweaters because Chicago is very cold.

Year End, 2017 Dec 18, 2017

Show notes

Our last show together in 2017!