diario SWL I-56578 Antonio

An unidentified FSK 41.6 Bd/200 Hz signal on 11592.0 kHz (CF), reminiscent of — but not quite matching — the Russian Navy's well-known T-600/CIS-36-50 family.

A consolidated technical reference on the 75 bps STANAG-4415/MS-110A waveform observed on 18503.0 kHz, combining the physical-layer characterization from [1] with the framing findings from [2].

A follow-up to the 75 bps serial tone (4415/110A) from Cyprus post [1] A friend and colleague pointed me to a few mailing list posts regarding receptions on 18503.0 kHz, shared by the users F1GOC, Kosmod, Linkz, and mco.

Cyprus has long been synonymous, in the utility monitoring community, with a single name: Akrotiri (DHFCS/RAF).

Following up on the initial analysis of the UK Defence High Frequency Communications Service (DHFCS) transmissions on 16289.5 kHz [1] (observed in both 800 Bd / 800 Hz FSK and STANAG-4285 modes), further analysis of extended raw bitstream captures has pro…

Analysis and TDoA geolocation of an unusual binary FSK transmission recorded on 16.2 MHz, highlighting its modulation properties, bitstream framing, and identification as part of the UK DHFCS network in St.

This post provides a breakdown of an HF diplomatic link between Tunisian MFA nodes using a modified MS-110A waveform.

This post presents a technical analysis of an HF radio intercept recorded on July 22.

This is not the first time I have had the opportunity to study the 300Bd/500Hz FSK waveform (of Russian/CIS origin), which I have encountered in different configurations — for instance, with 255/366-bit framing, or with reversal preambles transmitted at 1…

In the world of HF, spectral efficiency is usually the gold standard.

Following my previous post, a colleague reached out asking for clarification on the real-world, non-simulated operations of Data Terminal Equipment (DTE, typically a host PC) and Data Circuit-terminating Equipment (DCE, the HF modem).

The idea for this post stems from an interesting RAN (Royal Australian Navy) fleet broadcast originating from the MHFCS (Modernised High Frequency Communications System) utilized by the ADF (Australian Defence Force).

These signals were captured on 14430.0 kHz (USB) by my colleague ANgazu, who kindly shared them with me.

[Update April 3, 2026]: Further analysis of the OFDM-241 waveform has revealed additional parameters.

While monitoring the UHF band, my friend Kosmod successfully captured and shared a series of military satellite 2400 Bd bursts on 252.2525 and 253.6460 MHz.

Dealing with phase ambiguity and bit shifting in a demodulated BPSK/QPSK bistream are two of the most common obstacles that prevent you from actually understanding what the transmitter sent. 1.

Disclaimer: The following analysis is based on empirical observation of HF traffic and does not represent an official specification.

The signal captures used for this post were recorded a few days ago on 6369.0 kHz (USB) and kindly provided by my friend Kosmod; below is my analysis, which took inspiration from some observations just shared by Kosmod.

The purpose of this post is to report test transmissions heard on 6963.0 kHz USB and logged during the first week of February by both Kosmod (who sent them to me for analysis) and ANgazu (whose signal was reported by KA0KA and published on the radiofrecue…

A great thanks to my friend Kosmod who breakdown a Citadel II encrypted bitstream and saw that the Initialization Vector (IV) composed of 96 bits, 3 times repeated, is followed by a 64-bit field, this one also 3 times repeated.

FSK 100Bd/600 signal (thanks to KarapuZ) A few days ago my friend KarapuZ posted an interesting recording of a 100Bd/600 FSK signal which turned out to be a message structured according to MEROD-IND (Message Entry Read Out Device, Indian variant) message-…

For background read the previous post I ended the previous post hoping to recover new transmissions to understand more about the used application-layer protocol, and somehow this happened: my friend Kosmod indeed kindly sent me several transmissions he re…

This is a casual catch while I was exploring the 14 MHz band (14963.5 KHz/USB to be precise): the data transmission occurred after the usual MS-141A 3-way handshake between the ALE nodes 101 (caller) and 102 (called).

Some days ago my friend cryptomaster sent me an interesting recording dated December 4, 2025 about a test of new communications equipment conducted in the Russian Federation.

A few days ago I was casually watching the 4 MHz band when an unusually long STANAG-4538 (3G-HF) transmission on 4561.0 KHz/USB caught my attention and I decided to record it for later analysis.

Interesting and unknown (at least for me) FSK transmission in 800Bd/850Hz mode sent to me by my friend cryptomaster.