Sunday, March 1, 2020

New Technology for 2020 ~ The ZL2CTM Teensy 3.5 SDR Rig

An SDR Radio In a Microcontroller.

3/3/2020 ~ Problem Solved 

A cure for Coronavirus? Hey Mikey are you watching this blog? 

My Calabrian Grandmother had a bag of old folk remedies that were not many by count; but did cure a variety of illnesses. When I was about 8 years old I got some sort of rash on my arms and despite seeing the doctor it would not go away. 

It was summertime and as kids do I was scratching and picking at the scabs --it got worse. By chance we were visiting with "Nonna" and she immediately said: I know how to fix that! 

She made a poultice out of beaten eggs and flowers of Sulphur and spread it over the infected area. Next she ripped up an old soft bedsheet and covered the area in what looked like a mummy wrap. Her stern words: leave that on for 24 hours! Boom the next day I removed the wrap and the rash was gone!

When I next saw my Grandma, I showed her my arms and she said "good". I then asked what was that stuff. She replied --I don't know; but this is what we did in the old country when people had rashes. Thinking back --it must have been a crude form of a sulfa drug. But I do know that Flowers of Sulphur as far back as 2000 years ago was used to treat skin conditions. "Nonna" knows Best!

So "Nonna" I am sure has a cure for Coronavirus using Italian Penicillin.

If it were only that simple...

A Message to Mikey: Don't discount any possibility for a cure. 


Problem Solved...

Firstly all due credit to Charlie Morris ZL2CTM and his pioneering work in developing an SDR Radio in the form of a Teensy 3.5 microcontroller. I first saw his work nearly three years ago and Charlie, a true gentleman, readily shared his code and schematics with me.

[ZL2CTM has now moved up to the much more powerful Teensy 4.0 (about 5X the power of the Teensy 3.5 in terms of processor speed) and the use of a very nice 240 X 320 Color TFT display. ]

I did add a few bits and pieces to his original work; but never quite achieved the results he did with the Teensy 3.5. It was at that point that I branched off and took the RF hardware parts and mated those with a Raspberry Pi2, Pi3, the ASUS Tinker Board and now a Linux Mint 64 machines. All of these several implementations use the Quisk Software from N2ADR. This approach has been documented on my website at

The acquisition of a Teensy 4.0 prompted me to go back and revisit the Teensy 3.5 implementation, reasoning that I should really get that that to work first, before heading off to the Teensy 4.0. 

I was 100% sure of the RF hardware as it has been used with the Single Board Computers and the "Big Dude" Linux Mint 64 machine. So now the focus is the Teensy 3.5 and the CODEC Board and the all important ZL2CTM's code.

Dusting off the original Teensy 3.5 and CODEC Board I managed to smoke both which once again proves haste makes for waste. I had a spare Teensy 3.5 and a CODEC board which were recently installed in my original PC Board assembly. The results were not unlike what I saw two years ago. 

My earlier experience identified that there were issues with opposite sideband suppression on very strong signals. These prior tests saw this condition on receive and transmit.  When I transmitted on it, the 40M SDR police shouted at me that here was a component albeit not as strong, on the opposite side band. At that time I had conferred with ZL2CTM on what I saw; but he did not see this issue on his set up. So what ever it was the issue was only being seen at N6QW.

It is so nice when you are able to replicate circuit performance and here we were again. The same problem of two years ago was documented in the recently posted video which is now on you tube.

But yesterday I changed the Hilbert coefficients from 70 in the older code I was using and replaced those with the 100 coefficients found in Zl2CTM's latest code used with the Teensy 4.0. 

These coefficients come from the FREE Iowa Hills Software program that essentially define the digital filter curves (they have variants for Low, High and Band Pass Digital Filters). I believe the original digital filters were either 2.7 or 2.8 kHz. 

I also took another look at the Teensy 3.5/CODEC board just to make sure all was snug and tight since I had just replaced the Teensy 3.5 and the CODEC Board.

The Moment of Truth arrived and the above video shows the results. The issue seems to have ben resolved!


People are saying we are in a #Trump Slump so keep this guy shown below in your prayers. Your life may depend on him. For those of you who may not know this man, he is the Coronavirus Czar designated by our emperor (with a small e) to take charge of the US response to this terrible global scourge. 

We now have a statistically significant number of cases with many newly identified this past weekend. People are now saying that there are likely six deaths in Washington State associated with the virus.

These USA cases represent a turning point as a large number of the infected individuals did not travel to the Far East nor were they in direct contact with known infected persons. The CDC uses a clever term calling these instances  "community based" meaning the cases just sprung  up in the community. 

It is also posited that the cluster of infected individuals in Washington State may have been exposed as far back as 6 weeks ago. The disease vector will undoubtedly escalate in a geometric progressive fashion much like the rabbits in the famous Fibonaci sequence versus a simple linear expansion .

I have a package of parts in my garage that were shipped directly from China to me. I may never open that sealed bag!

What will happen if the Coronavirus shows up in Florida or New Jersey.  Imagine for a moment the person that has to tell the emperor (with a very small e) that he cannot visit Mara Del Lago or Bedminster. BTW the first case was just identified in Florida . There goes that planned golfing weekend. 

 The US Chief Responder to Coronavirus.
His Name is Mike Pence and has a day job as Vice-President to the emperor  (with a very small e). 


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