STEMlab RED PITAYA SDR Transceiver Build Part 3

 

In the last instalment of my Stemlab Red Pitaya SDR transceiver project, I completed the design and build of the receiver front‑end module, which includes an RF pre‑amp, bandpass filters, and a digital attenuator. This module improves the Red Pitaya’s receiving performance and adds an extra layer of protection to the Pitaya’s ADC input.

With the new receiver front‑end built and tested, I’ve thoroughly enjoyed listening to the HF bands and evaluating the enhanced performance of the Red Pitaya when integrated with the superb Thetis software.

If you are not familiar with the Thetis software, it is an advanced SDR client originally developed for the Apache Labs ANAN transceivers, and it’s become a popular choice for Red Pitaya‑based SDR projects. It provides a highly configurable interface, low‑latency DSP, powerful filtering, and excellent visualization tools. With features like adaptive noise reduction, customizable panadapter displays, and flexible transmit/receive profiles, Thetis brings out the full potential of the Red Pitaya hardware and offers a polished, professional operating experience.

To continue documenting my SDR transceiver build, this post covers the design and construction of a dedicated controller that enhances and complements the Red Pitaya module, the heart of the project.

STEMlab RED PITAYA SDR Transceiver Build Part 2

Now that the Stemlab Red Pitaya 125-14 module has been modified for use as an SDR (software defined radio), it is time to design and build a front end module with filtering, RF amplification and digital attenuation.

The Red Pitaya board has very wideband, high-speed ADC's that will digitize everything from DC up to tens of MHz and while this is desirable for a software-defined radio receiver, it is not without some downsides.

Building an SDR transceiver with the STEMlab Red Pitaya.

 

The Red Pitaya board itself is a compact, open‑source FPGA‑based test and measurement platform. It’s often described as a Swiss‑army knife for electronics because it can act as an oscilloscope, signal generator, spectrum analyzer, VNA, logic analyzer, and more. It is fully open-source and widely used in industry, education, RF labs and hobbyist electronics.

Irwell Transceiver Update & Red Pitaya SDR

 

It has been just over nine months since I made a post on my blog or provided any updates on the "Irwell HF Multimode Transceiver" project that I have been designing and developing for what feels like an eternity.

In my last blog post, I provided details of the multimode modulator I built for the "Irwell" transceiver. This tested out okay, but I was unable to carry out any on-air testing, as I had yet to design and build the required transmitter amplifier stages needed to get the transceiver on the air. Fast forward nine months later, and I am somewhat embarrassed to admit that I still haven't designed the transmitter amplifier stages!

In my defence I can substantiate and justify what, on the surface, may appear to be a lack of progress or abandonment on my part, so here goes: 

1. I have been busy working on a modular homebrew SDR transceiver project based on the Red Pitaya (AKA Stemlab) FPGA microcontroller board, and I wanted to get this project working, and to the point it also required transmit amplification, the idea being I would design a transmitter amplifier module that  can be used with this project and the "Irwell HF Multimode Transceiver".
   

2.  I found it neccessary to improve my software programming skills in order that I could expand and improve the Irwell VFO software and also produce software for a controller board I designed for the SDR transceiver. This has been a HUGE time sync but worth the investment of time!

So there you have it this is where I am upto, the "Irwell HF Multimode Transceiver" has been updated with some significant software changes and I now have two transceiver projects near to completion with both requiring some transmit RF amplification.

Next I want to start documenting my Red Pitaya homebrew SDR transceiver build and once I have done that I will do a post on the "Irwell" software development changes that I have made, but for now here is a quick screen grab that shows the new software in operation.

The new software contains dedicated band tables, and as you can see from the image above the transceiver has ventured into the Darkside by introducing channelized CB Radio bands. The new software also includes dedicated bandtables for the Shortwave bands, HF air aviation and HF Marine bands, and of course, Amatuer radio. The Bands and CB channels are scrolled through using an additional mechanical rotary encoder.

Thats it for this short blog post, until next time... 

 

 

73's From Andy G6LBQ

Its all about the Radio Ga Ga...

 

 

A Multimode Radio Transceiver Modulator

Following on from the last blog post that I made in July 2024, I present the progress I have made with the microphone preamplifier stages for the Irwell HF Transceivers modulator.

As per usual time has moved on and I have been sidetracked by other projects but with that said, the Irwell HF Transceiver project is and has always been a long-term project.

Since my last update, I have produced and developed various prototype circuits in a bid to get the modulator finished, some of which are illustrated below.