Difference between revisions of "User:Bertrik Sikken"

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* reverse-engineering things (USB stuff, mp3 players), working on http://rockbox.org
 
* reverse-engineering things (USB stuff, mp3 players), working on http://rockbox.org
 
* studying bats and making electronics for recording/listening to bat sounds
 
* studying bats and making electronics for recording/listening to bat sounds
* software-defined radio
+
* radio stuff, in particular software-defined radio
  
  
New project ideas:
+
Projects I work(ed) on ([https://revspace.nl/index.php?title=User:Bertrik_Sikken&action=purge refresh]):
* Use two old satellite dishes to allow speech to be transferred over some distance
+
{{#ask:[[Category:Project]][[Project Contact::bertrik]]
** Figure out focal point
+
|?Project Status
** Create some kind of dish mount
+
|headers=show
* Create a RFM69HW TNC, based on code by flok
+
|link=all
** Remove 'flok' framing, make it comply with KISS protocol
+
|order=ASC,ASC
** Use 'infinite' package length mode to send typical TCP/IP frames (1500 bytes)
+
|sort=Project Status,Project Name
* Create a 'HabAlert' android app, see [[HabAlertApp]]
+
}}
* add opus audio codec support to squeezeboxserver and/or squeezelite
 
** an opus web radio stream already seems to be redirected to the client, but squeezelite crashes on it
 
* create code for remote control of my ZwaaiLicht
 
** implement wireless protocol for the NOMZ message ("\x4NOMZ") on address 0x66996699L (no ack)
 
** possibly implement a more capable protocol on a different pipe (with ack, learn about extra pipes on NRF24L01+)
 
** possibly split control of the light and the motor
 
* create a [[FrontDoorDisplay]]
 
** clearly indicates the RevSpace door bell
 
** show short scrolling text messages, e.g. to food delivery people
 
** remote control over NRF24, e.g. enable/display the display of messages, set the text to be displayed
 
  
  
Laser cutting:
+
== Project ideas ==
I would like to get more creative with the laser cutter, starting with cutting existing designs, for example:
+
This is a list of ideas I'm thinking about, but have not fully developed into an actual project yet.
* this [http://www.thingiverse.com/thing:36673 trebuchet]
+
 
* this [http://msraynsford.blogspot.nl/2013/10/project-46-catapult.html catapult] or the [http://msraynsford.blogspot.nl/2014/08/emf-camp-mini-catapult.html mini catapult]
+
Zo'n ding 3d printen: https://twitter.com/MeOwOser/status/1250879531830915073
* a cool looking [http://www.robives.com/blog/display_box_moving_gears box with gears]
+
 
* [http://www.instructables.com/id/MSRaynsfords-Marble-Machine-11-Kit/ mini marble machine]
+
=== 3d glasses ===
* [http://www.thingiverse.com/thing:297758 bee puzzle]
+
I got some 2nd hand 3d glasses, they look exactly like these ones:
 +
* GH-15 https://www.dhgate.com/product/g15-dlp-3d-active-shutter-glasses-96-144hz/213983026.html
 +
* Sintron https://www.amazon.de/Sintron-Kompatibel-TDG-BT500A-TDG-BT400A-Deutschland/dp/B015PCWMZ8
 +
The common name appears to be "G15-DLP".
 +
 
 +
A tear-down here:
 +
* https://blog.danman.eu/3d-shutter-glasses-teardown/
 +
 
 +
Interesting documents:
 +
* http://cmst.curtin.edu.au/wp-content/uploads/sites/4/2016/05/2012-28-woods-helliwell-cross-compatibility_of_shutter_glasses.pdf
 +
* http://cmst.curtin.edu.au/local/docs/pubs/2011-17-woods-helliwell-3D-Sync-IR.pdf
 +
 
 +
Someone claims he got something to work with some hacks:
 +
https://www.avsforum.com/threads/how-i-got-cheap-dlp-link-glasses-to-work-great.1887145/
 +
 
 +
=== Waterniveaumeter ===
 +
Op verschillende plekken in Gouda staat er water in de kruipruimte van huizen van bewoners.
 +
Kunnen we dat meten en inzichtelijk maken, voor bewoners, op een kaart bijvoorbeeld?
 +
 
 +
Idee:
 +
* in de kruipruimte plaats je een module die waterhoogte kan meten
 +
* de module bestaat uit een microcontroller en een afstandsmeter, die de waterhoogte bepaalt
 +
* de gegevens worden via WiFi doorgestuurd naar een centraal punt, waar de data wordt verwerkt en gevisualiseerd
 +
* op een webpagina kan je een overzicht zien van alle meters die online zijn
 +
* de meting wordt gedaan door bijv. een laser-afstandsmeter of een ultrasoon-afstandsmeter
 +
* voeding? lastig, hoe krijg je 5v naar een potentieel natte plek?
 +
* kosten? verwachting < E 40,-
 +
 
 +
In Gouda wordt op veel verschillende plekken de grondwaterstand gemeten, zie https://opendata.munisense.net/portal/wareco-water2/group/581/Gouda-KJ38A , maar:
 +
* geen visualisatie op de kaart, je ziet alleen de meetlokaties d.m.v. een icoontje!
 +
* geen meetpunten in Gouda noord!
 +
 
 +
=== Online bat detector ===
 +
Idea: use an ultrasonic microphone, connect it to a WebSDR, so people can tune into bat sounds remotely.
 +
 
 +
=== Blood pressure meter hacking ===
 +
Apparently some blood pressure monitors can be hacked.
 +
 
 +
My goal is to be able to extract the list of the last 100 measurements somehow, so you don't have to type them over manually.
 +
Either using bluetooth (serial), or by adding something like an ESP8266 to sniff internally an make it available over WiFi.
 +
 
 +
* bluetooth GATT profile for blood pressure monitors https://www.bluetooth.com/specifications/gatt/
 +
* hacking the UART on an Omron RS8 : https://blog.adafruit.com/2016/05/26/hacking-uart-to-an-omron-rs8-blood-pressure-sphygmomanometer/
 +
* https://hackaday.com/2015/10/11/push-blood-pressure-data-to-the-cloud-via-esp8266/
 +
* hacking a blood pressure monitor by monitoring i2c traffic to the EEPOM: https://www.edusteinhorst.com/hacking-a-blood-pressure-monitor/
 +
 
 +
=== Raspberry pi airplane tracking ===
 +
Apparently now you can also participate in MLAT tracking of planes that don't transmit GPS coordinates themselves.
 +
 
 +
=== APRS gateway ===
 +
http://qso365.co.uk/2017/02/a-guide-to-setting-up-an-aprs-receive-only-igate-using-a-raspberry-pi-and-an-rtl-sdr-dongle/
 +
 
 +
=== JQ6500 ===
 +
Small inexpensive modules that play mp3 from an internal flash. Could be nice for a custom door bell for example.
 +
 
 +
More info at:  
 +
* https://www.elecfreaks.com/wiki/index.php?title=JQ6500_Mini_MP3_Module
 +
* https://sparks.gogo.co.nz/jq6500/index.html
 +
 
 +
=== FPGA ===
 +
Cheap FPGA boards and nice applications:
 +
* https://bitbucket.org/appanp/artificial-neural-networks/wiki/Home/FPGAsAndNeuralNets.md#!sbcs-and-iot-boards
 +
* [http://nl.aliexpress.com/item/Altera-fpga-cycloneii-ep2c5t144-learning-board-development-board/872520721.html inexpensive ep2c5t144 board]  
 +
* http://land-boards.com/blwiki/index.php?title=Cyclone_II_EP2C5_Mini_Dev_Board
 +
 
 +
=== Neural networks on low-end hardware ===
 +
Investigate if you can run a powerful neural network on relatively low-end/cheap/low-power hardware. For example a Raspberry pi.
 +
A RPI runs Linux, run python, just like some common neural frameworks.
 +
Do we need hardware acceleration from the GPU and does the RPI GPU support that?
 +
 
 +
Read list:
 +
* https://www.zdnet.com/pictures/raspberry-pi-meets-ai-the-projects-that-put-machine-learning-on-the-35-board/
 +
* https://www.pyimagesearch.com/2017/12/18/keras-deep-learning-raspberry-pi/
 +
* https://www.indiegogo.com/projects/sipeed-maix-the-world-first-risc-v-64-ai-module#/
 +
* https://ai.intel.com/intel-neural-compute-stick-2-smarter-faster-plug-and-play-ai-at-the-edge/
 +
 
 +
Bought a MaixPy:
 +
* see https://maixpy.sipeed.com/en/
 +
* see https://www.youtube.com/watch?v=KResVuAIMb4
 +
* see http://educ8s.tv/sipeed-m1-dock-review/
 +
* interesting? https://www.instructables.com/id/Transfer-Learning-With-Sipeed-MaiX-and-Arduino-IDE/
 +
 
 +
=== mini word clock in dutch ===
 +
Basically an monochrome 8x8 word clock, in Dutch, showing local time in the Netherlands.
 +
 
 +
[https://github.com/bertrik/miniwordclock This git repo] has the current code.
 +
 
 +
See [https://plus.google.com/103276078656203197145/posts/7ki7rpJzk3a here for a demo] running on an arduino nano.
 +
 
 +
The plan is to run this from an ESP8266 instead of an arduino nano, so it can get the time from the internet using NTP.
 +
Andreas Spiess demonstrated on youtube how existing libraries on the ESP8266 can be used to do the local time (including summer-time) calculations.
 +
 
 +
=== Cypress PSOC5 ===
 +
Play with the Cypress PSOC5 platform, which combines a ARM Cortex-m3 processor with configurable analog blocks. I'm thinking of combining it with a 24 GHz doppler radar sensor, to process the signal and present it as a USB audio device (stereo signal contains I and Q parts). See [[RadarOnAStick]].
 +
 
 +
=== Simple Doppler motion sensors ===
 +
You can find basic doppler microwave motion sensors based on a single transistor, with some weird traces on the PCB very cheaply, for example
 +
* https://www.aliexpress.com/item/RCWL-0516-microwave-radar-sensor-module-Human-body-induction-switch-module-Intelligent-sensor/32708877914.html
 +
 
 +
Typically the microwave part of these consists of a single transistor with a rectangular area on one leg and a meandering trace (with lots of vias to the other side) on the other leg.
 +
The output of this circuit seems to go into a chip very much like the ones used in PIR sensors.
 +
 
 +
See also https://github.com/jdesbonnet/RCWL-0516 for a reverse engineering effort of these doppler radar modules.
 +
 
 +
=== Bare-bones Arduino bat detector ===
 +
This is an idea for a very basic heterodyne bat detector, doing signal processing on an Arduino, requiring minimal external components.
 +
 
 +
The basic principle of a heterodyne detector is that it just mixes (multiplies) the audio signal with a square wave, low-pass filters the result and puts it on a speaker.
 +
 
 +
Multiplying with a square wave can also be considered to be just alternatively inverting and not-inverting the signal.
 +
So if you sample an ultrasonic signal at twice the rate you want to multiply, you can just subtract odd samples from even samples and low-pass filter that.
 +
 
 +
How this can be done in an AVR Arduino:
 +
* sample the audio signal at twice the detection frequency, say 84 kHz. An AVR should just be able to do that.
 +
* apply a 1-pole IIR high-pass filter to remove DC bias, this takes one shift instruction and one addition.
 +
* multiply by the detection frequency, this means just inverting the odd samples.
 +
* low-pass filter the signal, this can be done using a moving average filter, say 16 samples long (first null at 5.25 kHz). Theoretically, averaging 16 samples should result in two bits extra accuracy. This operation takes some storage, an addition and a subtraction.
 +
* output the filtered signal using PWM, possibly at the same rate that we are sampling the input audio.
 +
 
 +
The microphone can be a 40 kHz piezo transducer, to keep it cheap (but also limited to 40 kHz).
 +
The pre-amplifier can be a single transistor with some resistors around it, providing about 40x gain.
 +
The arduino does the signal processing (mixing, low-pass filter) to shift the bat audio to human range.
 +
The speaker amplifier can just be a simple two transistor push-pull circuit, since the output from the Arduino is digital/PWM.
 +
 
 +
==== AVR Arduino sample rate ====
 +
As far as I understand, the ADC clock can be set to 1 MHz.
 +
Conversion takes 13 cycles, so this can be a problem to reach a sample rate above 80 kHz.
 +
 
 +
=== GPS repeater ===
 +
This idea is about experimenting with a cheap GPS repeater built out of an "active" GPS antenna.
 +
 
 +
The problem this solves is that often indoors you have no GPS reception, but you like to have some signal to experiment with (e.g. a LoRa tracker).
 +
 
 +
Plan:
 +
* get a cheap active GPS antenna from AliExpress (some as cheap as E2,- !), most just mention one frequency (1575.42 MHz)
 +
* get a bias-T circuit to feed it the supply voltage (e.g. from a KOPPLA) and pass the RF signal onto an indoor antenna
 +
* the indoor antenna may be as simple as a 1/4 wave coax dipole: center conductor sticking up (about 47 mm), coax shielding is divided into 3 of 4 ground radials sticking sideways
 +
* build it and test it with a smart phone, tracker hardware, etc.
 +
 
 +
See also:
 +
* [https://electronics.stackexchange.com/a/156488 Reradiating antena for GPS]
 +
 
 +
=== Indoor radar speed sign ===
 +
This idea about placing a simple IQ-output radar sensor indoors in the hacker space, do some basic signal processing on the IQ doppler signal and determine movement speed and direction, then display this on a LED display.
 +
This is of no immediate practical use other than fun, but helps me to gain a bit more experience with microwave radar sensors and eventually build a more effective setup for detecting/counting bats flying in and out of a roost.
 +
 
 +
Implement this on a PSOC5 platform or on the STM32 using Arduino.

Revision as of 22:30, 8 September 2020

User info Bertrik Sikken
Name Bertrik Sikken
Nick bertrik
Tagline heb ik niet

You can reach me at bertrik@sikken.nl or bertrik@gmail.com

Studied Electrical Engineering at Twente University.


Main interests:

  • reverse-engineering things (USB stuff, mp3 players), working on http://rockbox.org
  • studying bats and making electronics for recording/listening to bat sounds
  • radio stuff, in particular software-defined radio


Projects I work(ed) on (refresh):

 Project Status
FrontDoorDisplayAbandoned
HabAlertAppAbandoned
ISSOAbandoned
IbmPosDisplayAbandoned
Pico TrackersAbandoned
RadarOnAStickAbandoned
WifiLampAbandoned
A4PaperDispenserCompleted
BuildStatusTrafficLightCompleted
CJMCU-811Completed
CO2MeterHackingCompleted
CrawlSpaceSensorCompleted
DecodingLoraCompleted
DustSensorCompleted
ElectronicLoadCompleted
EspNowSkipCompleted
IntakefancontrollerCompleted
LichtKrantCompleted
LoRaGatewayCompleted
LoraBatBoxCompleted
LoraWanNodeCompleted
MHZ19Completed
MainsFrequencyCompleted
MiniSTM32F103ZECompleted
PowerLightCompleted
RC522HackingCompleted
RevRadioCompleted
STM32Completed
Secure iButtonCompleted
SoilHumiditySensorCompleted
StofAnanasCompleted
StofradarCompleted
TTNHABBridgeCompleted
VINDRIKTNINGCompleted
ZigbeeCoordinatorCompleted
Sensor-data-bridgeCompleted
AntiLostIn progress
AudioMothIn progress
CubeCellIn progress
EspAudioSensorIn progress
Esp32camIn progress
FMCWRadarIn progress
LoRa-E5-miniIn progress
LoraWanDustSensorIn progress
MainsFrequency2.0In progress
Msi2500SDRIn progress
Sim7020In progress
StereoBatRecorderIn progress
UltrasonicPlayerIn progress
EspNowAudioInitializing
... further results


Project ideas

This is a list of ideas I'm thinking about, but have not fully developed into an actual project yet.

Zo'n ding 3d printen: https://twitter.com/MeOwOser/status/1250879531830915073

3d glasses

I got some 2nd hand 3d glasses, they look exactly like these ones:

The common name appears to be "G15-DLP".

A tear-down here:

Interesting documents:

Someone claims he got something to work with some hacks: https://www.avsforum.com/threads/how-i-got-cheap-dlp-link-glasses-to-work-great.1887145/

Waterniveaumeter

Op verschillende plekken in Gouda staat er water in de kruipruimte van huizen van bewoners. Kunnen we dat meten en inzichtelijk maken, voor bewoners, op een kaart bijvoorbeeld?

Idee:

  • in de kruipruimte plaats je een module die waterhoogte kan meten
  • de module bestaat uit een microcontroller en een afstandsmeter, die de waterhoogte bepaalt
  • de gegevens worden via WiFi doorgestuurd naar een centraal punt, waar de data wordt verwerkt en gevisualiseerd
  • op een webpagina kan je een overzicht zien van alle meters die online zijn
  • de meting wordt gedaan door bijv. een laser-afstandsmeter of een ultrasoon-afstandsmeter
  • voeding? lastig, hoe krijg je 5v naar een potentieel natte plek?
  • kosten? verwachting < E 40,-

In Gouda wordt op veel verschillende plekken de grondwaterstand gemeten, zie https://opendata.munisense.net/portal/wareco-water2/group/581/Gouda-KJ38A , maar:

  • geen visualisatie op de kaart, je ziet alleen de meetlokaties d.m.v. een icoontje!
  • geen meetpunten in Gouda noord!

Online bat detector

Idea: use an ultrasonic microphone, connect it to a WebSDR, so people can tune into bat sounds remotely.

Blood pressure meter hacking

Apparently some blood pressure monitors can be hacked.

My goal is to be able to extract the list of the last 100 measurements somehow, so you don't have to type them over manually. Either using bluetooth (serial), or by adding something like an ESP8266 to sniff internally an make it available over WiFi.

Raspberry pi airplane tracking

Apparently now you can also participate in MLAT tracking of planes that don't transmit GPS coordinates themselves.

APRS gateway

http://qso365.co.uk/2017/02/a-guide-to-setting-up-an-aprs-receive-only-igate-using-a-raspberry-pi-and-an-rtl-sdr-dongle/

JQ6500

Small inexpensive modules that play mp3 from an internal flash. Could be nice for a custom door bell for example.

More info at:

FPGA

Cheap FPGA boards and nice applications:

Neural networks on low-end hardware

Investigate if you can run a powerful neural network on relatively low-end/cheap/low-power hardware. For example a Raspberry pi. A RPI runs Linux, run python, just like some common neural frameworks. Do we need hardware acceleration from the GPU and does the RPI GPU support that?

Read list:

Bought a MaixPy:

mini word clock in dutch

Basically an monochrome 8x8 word clock, in Dutch, showing local time in the Netherlands.

This git repo has the current code.

See here for a demo running on an arduino nano.

The plan is to run this from an ESP8266 instead of an arduino nano, so it can get the time from the internet using NTP. Andreas Spiess demonstrated on youtube how existing libraries on the ESP8266 can be used to do the local time (including summer-time) calculations.

Cypress PSOC5

Play with the Cypress PSOC5 platform, which combines a ARM Cortex-m3 processor with configurable analog blocks. I'm thinking of combining it with a 24 GHz doppler radar sensor, to process the signal and present it as a USB audio device (stereo signal contains I and Q parts). See RadarOnAStick.

Simple Doppler motion sensors

You can find basic doppler microwave motion sensors based on a single transistor, with some weird traces on the PCB very cheaply, for example

Typically the microwave part of these consists of a single transistor with a rectangular area on one leg and a meandering trace (with lots of vias to the other side) on the other leg. The output of this circuit seems to go into a chip very much like the ones used in PIR sensors.

See also https://github.com/jdesbonnet/RCWL-0516 for a reverse engineering effort of these doppler radar modules.

Bare-bones Arduino bat detector

This is an idea for a very basic heterodyne bat detector, doing signal processing on an Arduino, requiring minimal external components.

The basic principle of a heterodyne detector is that it just mixes (multiplies) the audio signal with a square wave, low-pass filters the result and puts it on a speaker.

Multiplying with a square wave can also be considered to be just alternatively inverting and not-inverting the signal. So if you sample an ultrasonic signal at twice the rate you want to multiply, you can just subtract odd samples from even samples and low-pass filter that.

How this can be done in an AVR Arduino:

  • sample the audio signal at twice the detection frequency, say 84 kHz. An AVR should just be able to do that.
  • apply a 1-pole IIR high-pass filter to remove DC bias, this takes one shift instruction and one addition.
  • multiply by the detection frequency, this means just inverting the odd samples.
  • low-pass filter the signal, this can be done using a moving average filter, say 16 samples long (first null at 5.25 kHz). Theoretically, averaging 16 samples should result in two bits extra accuracy. This operation takes some storage, an addition and a subtraction.
  • output the filtered signal using PWM, possibly at the same rate that we are sampling the input audio.

The microphone can be a 40 kHz piezo transducer, to keep it cheap (but also limited to 40 kHz). The pre-amplifier can be a single transistor with some resistors around it, providing about 40x gain. The arduino does the signal processing (mixing, low-pass filter) to shift the bat audio to human range. The speaker amplifier can just be a simple two transistor push-pull circuit, since the output from the Arduino is digital/PWM.

AVR Arduino sample rate

As far as I understand, the ADC clock can be set to 1 MHz. Conversion takes 13 cycles, so this can be a problem to reach a sample rate above 80 kHz.

GPS repeater

This idea is about experimenting with a cheap GPS repeater built out of an "active" GPS antenna.

The problem this solves is that often indoors you have no GPS reception, but you like to have some signal to experiment with (e.g. a LoRa tracker).

Plan:

  • get a cheap active GPS antenna from AliExpress (some as cheap as E2,- !), most just mention one frequency (1575.42 MHz)
  • get a bias-T circuit to feed it the supply voltage (e.g. from a KOPPLA) and pass the RF signal onto an indoor antenna
  • the indoor antenna may be as simple as a 1/4 wave coax dipole: center conductor sticking up (about 47 mm), coax shielding is divided into 3 of 4 ground radials sticking sideways
  • build it and test it with a smart phone, tracker hardware, etc.

See also:

Indoor radar speed sign

This idea about placing a simple IQ-output radar sensor indoors in the hacker space, do some basic signal processing on the IQ doppler signal and determine movement speed and direction, then display this on a LED display. This is of no immediate practical use other than fun, but helps me to gain a bit more experience with microwave radar sensors and eventually build a more effective setup for detecting/counting bats flying in and out of a roost.

Implement this on a PSOC5 platform or on the STM32 using Arduino.