Introduction WSPR is part of a suite of communication protocols developed by Dr. Joseph Taylor K1JT, a Nobel Prize winning pulsar researcher (Ref.1). He applied the latest signal processing techniques from his astronomical research to the reception of very weak amateur radio signals. Amateur radio operators can work at signal to noise ratios bordering on… Continue reading RTL-SDR for WSJT-X WSPR
L Band Dish Antenna Testing with NanoVNA
Introduction In previous posts I have tested the various HF & VHF antennas that I have using the versatile NanoVNA (Ref.4/5/6). In the last post I decided to try pushing the NanoVNA beyond it’s spec of 1.5GHz to test my Inmarsat Patch antenna (Ref.1). In this post I will test the L band microwave dish… Continue reading L Band Dish Antenna Testing with NanoVNA
Si5351 Clock Generator Programming
Introduction Six years ago I designed a zero IF direct conversion receiver to be used with my HF Radio Ebook (Ref.1). For flexibility, I used an IQ VFO. At the time, the best choice for my VFO was the Si514. In order to get coswct & sinwct waveforms, I had to run the VFO at… Continue reading Si5351 Clock Generator Programming
Inmarsat Patch Antenna Testing with NanoVNA
Introduction In previous posts I looked at receiving Inmarsat satellite signals (Ref.1/2). I used an L band dish and patch antenna. I was wondering what the overall SWR of these antennas looked like, so I decided to test them with the NanoVNA. The NanoVNA that I purchased was spec’d to 1.5GHz, but I guessed that… Continue reading Inmarsat Patch Antenna Testing with NanoVNA
FEC Forward Error Correction on GNU Radio
Introduction In previous posts I examined the possible use of OFDM for HF messaging (Ref.1/2/3) and for voice (Ref.4). I introduced several channel models using Scicos: an 8 channel discrete model and a 64 channel model using IFFT/FFT. In this post I will focus on using FEC Forward Error Correction to improve the transmission performance.… Continue reading FEC Forward Error Correction on GNU Radio