Jeremy Clark – Page 23 – Telecommunications, Navigation & Electronics

HF Messaging with OFDM_b

Introduction In previous posts I examined the possible use of OFDM for HF messaging (Ref.1) and for voice (Ref.2). I introduced several channel models using Scicos. In this post I will expand my Scicos 8 channel model to a 64 channel model generated by IDFT. OFDM IFFT/FFT 64Ch Model In order to obtain the benefits… Continue reading HF Messaging with OFDM_b

Lunar Distance – DST to EST

Introduction Saturday November 5th was an ideal evening to measure a Lunar from my balcony. It was unseasonably warm at 20degC and I had just removed all the gear, as my balcony is going to be rebuilt for the third time in five years, so I might as well enjoy the last few jack hammer… Continue reading Lunar Distance – DST to EST

RTL-SDR for VHF Marine Scanner on SDR#

Introduction Recently I was approached for advice on frequency scanning. My first thought was a traditional approach of starting at the base frequency, stepping by the channel spacing and doing a power evaluation. If greater than a threshold, then hold and attempt a decode. Before building a prototype in GNU Radio, I thought I would… Continue reading RTL-SDR for VHF Marine Scanner on SDR#

HF Messaging with OFDM_a

Introduction Communications for blue water sailors is extremely important. Reliable satellite communications for voice, email and GRIB weather files has become common place. This service is expensive, however, depending on usage. HF communications for voice & email is another alternative. This has the conventional drawbacks of propagation reliability, connectivity and bandwidth. There are several commercial… Continue reading HF Messaging with OFDM_a

RTL-SDR for HF WWV Propagation

Introduction Recently I was in Costa Rica (Ref.1) and I used WWV to set my watch for UTC time to accurately read my sextant. We tend to take time for granted now with the Internet & GPS, but time stations like WWV still provide an essential service. WWV (Ref.2) can also be used to study… Continue reading RTL-SDR for HF WWV Propagation