More distractions and an electronics build

Dev boards falling from the sky

I love the fact that radiosondes are described as

“ARM/STM32 Development boards literally falling from the sky”

EEVblog #1207 - ARM Dev Boards Falling From The Sky!

• also a bunch of stuff discussed here
  • https://www.eevblog.com/forum/blog/eevblog-1207-arm-dev-boards-falling-from-the-sky!/

STM32 Development Boards (literally) Falling From The Sky - linux.conf.au

Radiosonde reception on UV-K5

Tried receiving radiosonde signal with my Quansheng UV-K5 at 401.500MHz but it seems the sound coming out of the speaker, was not good enough quality to use sondedump to decode? maybe the “acoustic coupling” between the output speaker of the UV-K5 and the microphone of the Mac with outside noise is not good enough?

Or maybe the transmission band is too wide? The UV-K5 has an FM wide/narrow setting. I used wide but am not sure how wide that is? on the internet I have found that braodcast FM can be 75kHz wide? and a wide FM setting on a radio can be 25kHz whilst a narrow setting is 12.5kHz, but I have seen something suggesting as narrow as 5kHz. I could not seem to find a specification for the Quansheng UV-K5 for how wide the wide FM is either.

• Reddit: Wide vs narrow FM

From previous experiments with the RTL-SDR USB dongle using GQRX software, I know I can adjust the width of the reception and it was wide enough to get sondedump to decode the signal. I have an idea for a couple of experiments for tomorrow or next time I have a chance to listen to a radiosonde.

Experiments in listening and decoding radiosonde

• determine the width of the required signal using laptop and GQRX

  1. setup laptop with RTL-SDR USB dongle and decode using sondedump
  2. adjust the width of the input to see when sondedump fails to process data
  3. record sound for comparison to UV-K5

• determine if UV-K5 can decode using sondedump via “audio coupling”

  1. try with a nearer signal
  2. potentially try with 2 radios, each tuned up and down the band to emulate a wider band? not sure if this will work
  3. record the sound check for quaulity and compare to RTL-SDR

On recylding radiosondes

Not trying to get ahead of myself but this is a cool article with some internals etc

• http://www.om3bc.com/docs/rs41/rs41_en.html
• 
• 

ESP32 signal processing

What are the limits of the ESP32 and sound?

• https://dronebotworkshop.com/esp32-i2s/ another RS41 specific decoding library
• https://github.com/bazjo/RS41_Decoding
• which mentions FSK Frequency-shift Keying https://en.wikipedia.org/wiki/Frequency-shift_keying

Finally isn’t it just APRS?

• https://github.com/nakhonthai/ESP32IGate

  ESP32IGate is a APRS Internet Gateway + TNC Built In that is implemented for Espressif ESP32 processor.

• https://www.rpc-electronics.com/esp32-aprs-tracker.php

  The ESP32-APRS Tracker is an all new APRS Tracker meant for the 21st century. We started with the powerful ESP32 WROOM module and built the platform on it’s vast array of built-in peripherals. Adding a high quality, fast locking GPS, sensors and other devices, we have created a small form factor, feature rich APRS Tracker/Digipeater/iGate/Modem that will fit your APRS operating needs.

  

• did I post this already?

  Receiving APRS using Baofeng UV-5R and ESP32 - Ryan Kinnett

• https://hackaday.com/2021/06/15/aprs-implemented-at-low-cost-and-small-size/
  • 
  • https://www.curiouselectron.com/?p=595
  • code and design https://repo.curiouselectron.com/curiousmuch/arrow-firmware

  • Arrow - TNC with Bluetooth and 2M Radio - curiousmuch

    

  • but what is an Arrow?

  

  • not something you can buy but you need to make it

  • repo.curiouselectron.com Arrow-Schematic.pdf

  

  • right using a CC1200 - Low power and high performance wireless transceiver Sub-1 GHz RF Transceivers - sounds like it is good for packet radio and streaming data over RF?
    • which appart from a pretty heavy data sheet has a security vulnerability

    Absence of Frame Counter Validation

    The TI WiSUN® stack did not include logic to check the frame counter of incoming packets… This allows attackers to capture network packets and resend those packets. The receiving device will process the packet as if it was sent by the original source of the packet.

  • a 2 board? development kit from digikey for ~$200
    • CC1200EMK-420-470
    • SimpleLink™ CC1200 Transceiver, ISM 420MHz ~ 470MHz Evaluation Board

    

    The Cc1200Emk-420-470 Evaluation Module Kit For 420Mhz To 470Mhz, Can Be Used In Conjunction With The Cc1200 Development Kit To Evaluate The Operation Of The Cc1200 In The Mentioned Frequency Range. The Cc1200 Is A Fully Integrated Single Chip Radio Transceiver Designed For High Performance At Very Low Power And Low Voltage Operation In Cost Effective Wireless Systems. All Filters Are Integrated, Removing The Need For Costly External Saw And If Filters. The Device Is Mainly Intended For The Industrial, Scientific And Medical And Short Range Device Frequency Bands At 164Mhz To 190Mhz, 410Mhz To 475Mhz And 820Mhz To 950Mhz. The Cc1200 Provides Extensive Hardware Support For Packet Handling, Data Buffering, Burst Transmissions, Clear Channel Assessment, Link Quality Indication And Wake On Radio. The Cc1200 Main Operating Parameters Can Be Controlled Via An Spi Interface. In A Typical System, The Cc1200 Will Be Used Together With A Microcontroller And Only Few External Passive Components

    • but there seem to be CC1101 433Mhz 10mW transciever related boards for ~$3 - note this is a trnasciever as opposed to a lot of 433MHz boards that are either TX or RX
      • https://electropeak.com/cc1101-moduale-10mw
    • Texas Instruments LAUNCHXL-CC1310 Dev Board, Launchpad ~$70
      • https://au.mouser.com/ProductDetail/Texas-Instruments/LAUNCHXL-CC1310
    • a LoRa 915MHz model is ~$20 for comparison
      • https://littlebirdelectronics.com.au/products/lora-fsk-transceiver-module-915mhz-rfm97cw

  • this did allow me to find this intruiguing device FM Walkie Talkie Circuit Board Transceiver All-in-One Module FM Transmitter Receiver Module 7 Frequency 27-480MHz DC3.3-6V for only ~$7

    

  • also found some more solid looking 433MHz modules like
    • RF TRANSCEIVER MODULE FOR ARDUINO PROJECTS ~$15

Code practice circuit

I prototyped a qiuck version using a 555 on a breadboard - sounds better than the 1k transformer one I have so will go with a proper build tomorrow.