Introduction In previous posts I examined the possible use of OFDM for HF messaging (Ref.1/2) and for voice (Ref.3). I introduced several channel models using Scicos: an 8 channel discrete model and a 64 channel model using IFFT/FFT. In the last post I concentrated on the IFFT transmitter. In this post I will focus on… Continue reading HF Messaging with OFDM_c
Category: Telecommunications
Telecommunications: Propagation, HF, VHF, UHF, uWave
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
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