Bench experiment using LoRa transceivers on the 70cm ham band (~433 MHz) as IF radios, up and down converting to/from the 3cm (~10GHz) ham band.
Inspired by work being done at Open Research Institute (https://www.openresearch.institute/)
It could be really interesting to have some LoRa APRS iGate stations/beacons on at 10GHz to promote experimentation. (https://github.com/lora-aprs/LoRa_APRS_iGate)
The primary goal is to be able to roughly calibrate some signal sources in the 8.4GHz to 10GHz range with known calibrated equipment at lower frequencies. I have a Tektronix RSA306B Spectrum Analyzer, but a receiver with the appropriate coverage would work.
Signal paths (really need a diagram!)
Uncalibrated 10.5 GHz Source : 30dB Attenuator : High Pass Filter : Mixer RF IN Calibrated Oscillator at 5GHz : Frequency Doubler : Mixer LO IN Mixer IF Out : Spectrum Analyzer (centered at 500MHz)
Tektronix RSA306B Spectrum analyzer (good to 6 GHz) https://www.tek.com/spectrum-analyzer/rsa306
Aaronia BPSG 6 Signal Generator (I have the OEM version – good to 6 GHz) https://aaronia.com/signal-generators/bpsg-series-compact/
Mini-Circuits shopping list:
VHF-7150+ High pass filter https://www.minicircuits.com/WebStore/dashboard.html?model=VHF-7150%2B
ZX05-24MH-S+ Doubly balanced mixer https://www.minicircuits.com/WebStore/dashboard.html?model=ZX05-24MH-S%2B
ZX90-2-50-S+ Frequency multiplier https://www.minicircuits.com/WebStore/dashboard.html?model=ZX90-2-50-S%2B
141-6SM+ 6″ cables https://www.minicircuits.com/WebStore/dashboard.html?model=141-6SM%2B
Bird 30dB Attenuator
Uncalibrated 10.5GHz signal source https://www.amazon.com/Microwave-10-525GHz-Doppler-Detector-arduino/dp/B089KG2TK9
Reference article about the above source http://www.arrl.org/files/file/QEX_Next_Issue/2015/May-Jun_2015/Wadsworth.pdf
Presentation
Make your robot drive straight (ok, well, straighter) using the MPU-6050 6-Degrees-of-Freedom accelerometer/gyro.
This is another presentation given to the Nashua Robot Builders.
Here’s the Arduino code: _2020Bot_MUP6050.ino.zip
Please note… the Arduino code isn’t up to my usual standards, but it will show you a few things. Pay attention to the required libraries (links are in the comments).
Here’s a zip file for the Apple Keynote version: Driving Straight and Turning
Euclid Presentation
Euclid presentation for the Nashua Robot Builders.
Sorry, this is definitely one of those “you had to be there” type presentations… The feature list slides might be the only decipherable section.
Phew! That was amazing!
I had a blast at Bay Area Maker Faire building 2020 Bots all day Saturday and Sunday. Once an hour, a couple attendees got a chance to build their own 2020 Bot and take it home with them.
I just updated the 2020 Bot Arduino Library to include a couple motor control examples: https://github.com/robojay/_2020Bot_Library
One uses the delay() function between motions. This is great for ease of understanding, but not so great to use in practice. The delay() function blocks the robot from doing most other tasks until the time expires.
The second example uses millis() and a timestamp to step through the motions. This lets the robot do other important tasks, such as blinking the LED, while still controlling motions.
Proximity sensing for your robot.
When you build a robot, it’s nice to have layers of sensors. You can think of the layers either top down (maybe starting with a 3D laser scanner), or from the bottom up (are my motors stalled?). Proximity sensing sits on one of the lower layers, and generally is used as “Hey, there’s something near me, and it might be in general direction X”.
Using infrared LEDs and detectors is an inexpensive and common approach to basic proximity sensing.
I did a presentation on this topic for the Nashua Robot Builders. You can find the slides and demo code at https://github.com/robojay/IrProximityDemo
Once you’ve built your 2020 Bot and played around with it a bit, the next step is writing your own programs. The 2020 Bot uses an Arduino Nano micro controller. A simple web search will turn up plenty of references. Here’s a good link to get you started:
Official Nano Getting Started guide from Arduino: https://www.arduino.cc/en/Guide/ArduinoNano
Here is a hookup diagram and a wiring checklist to go along with the 2020 Bot video instructions. The diagram has a couple breadboard locations that are different than what are called out in the video and checklist, but they are functionally equivalent.
Click on each image to download PDF versions:
This probably qualifies as my first real robot. Still works after 20+ years.
I built it as part of the final project in my grad school Artificial Intelligence course. The professor made sure I understood the project was a software project, and not to get hung up on the hardware side (fortunately, being an electrical engineer in a comp-sci class made that a little easier).
Here’s my final report, along with all the typos intact…
http://www.robojay.us/wp-content/uploads/2017/03/jfrancis_robot_1993.pdf