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Accurate calibration of your receiver and sound card is necessary for good results with the weak signal modes in use at LF. Modern receivers with master oscillators that are synthesized to provide all conversion frequencies greatly simplify the process. This article describes a method of making the necessary measurements and adjustments to an ICOM R75 receiver and a sound card, using the ARGO software

Noise Meter software for the noise meter tool by G8KBB that measure noise using a PC sound card and calculate noise figures by means of a calibrated noise source.

Soundmodem is a free software defined dual-port Packet-Radio TNC that implement a soundcard as a modem and supports AX.25 protocol. Soundmodem has been tested on Windows XP, Vista, 7, 8, 10 and has proved stable in operation. The Soundmodem may be used to build EMCOMM, APRS, BBS, Node station, for satellites

iSpectrum is a free spectrum analyzer for MacOS that allows you to display live audio in a standard frequency plot, waterfall display or in a stereo oscilloscope view. Used by ham radio operators, audiofiles, musicians, and Sound Technicians.

This wiki is intended to help identify radio signals through example sounds and waterfall images. Most signals are received and recorded using a software defined radio

The MT-63 modem, constructed around a high speed DSP processor, either in a dedicated external DSP unit like the Motorola EVM, or in PC software using the PC sound card, transmits 64 tones spaced 15.625 Hz apart, in the 1 kHz bandwidth.

Demonstrates the _RoMac Automatic CW Identifier 2012_ software, a Windows application designed to automate station identification and provide a tuning pulser. It can send CW identification via a sound card's audio output or by keying a radio's manual CW jack using a serial port's DTR line. The software also supports CAT commands for various Kenwood, Yaesu, Flex, and Elecraft radios, enabling automatic mode and frequency changes for ID transmission. It integrates with USB audio-capable radios like the Icom 7300 and Yaesu FT-991, simplifying connectivity with a single USB cable. The application features a fully programmable interface, adjustable CW speed from **5 to 35 WPM**, and ID intervals from **5 to 30 minutes**. The integrated "Pulse Tuner" function allows for safe amplifier and antenna tuner adjustments by sending short audio tones or rapid CW keying, with an adjustable duty cycle from 1% to 100%. It offers compatibility with a wide range of transceivers and amplifiers, and a schematic for a basic sound card interface is included for users without existing setups.

MT-Hell software for 16 bit Soundblaster cards. Sends seven parallel tones with careful dot shaping for minimum interference, and transmits a very nice sound by G3PPT

AudioXplorer is a sound analyzer software designed for Mac OSX, provide a real-time analysis window where you can visualize the sound spectrum and sonogram

Demonstrates the fundamental principles for connecting a personal computer to a ham radio transceiver, specifically for utilizing sound card-based digital mode software like those in the MM Hamsoft suite. It details the basic hardware setup, emphasizing the use of shielded leads and proper audio routing from the radio's output to the sound card's input, and from the sound card's output to the radio's microphone or data input. The resource highlights the critical need for transmit attenuation, suggesting a 100:1 voltage divider to prevent overdriving the transmitter's audio stage, and mentions the optional addition of ferrite beads and decoupling capacitors for RFI mitigation. The guide also points to external resources for more detailed pin-outs and interface schematics, such as a specific QSL.net page, and recommends consulting the help files within MM Hamsoft programs for interfacing specifics. It underscores that while the process is straightforward, understanding the audio level management and proper cabling is key to successful operation. The author, VE5KC, provides practical advice drawn from common issues encountered by operators setting up digital mode stations.

The Utility DXers Forum (UDXF) provides a centralized platform for exchanging news and information concerning utility radio stations and signals operating within the 0 to 30 MHz spectrum. It specifically excludes broadcasting, pirate, and amateur radio transmissions, concentrating instead on a diverse array of other signals. The resource details the types of stations covered, including maritime coastal and ship stations, aeronautical ground and aircraft communications (voice, HFDL, Selcalls, Volmet), military operations, various beacons (NDB, driftnet, propagation, pirate, high-frequency), fax transmissions, numbers stations, diplomatic communications, clandestines, and other unusual signals. Further content addresses radar systems such as Over-the-Horizon, Ocean Wave, and CODAR, alongside ionosondes, chirpsounders, ALE-systems, Selcall-systems, and tone calls. Experimental stations and standard frequency and time stations are also within its scope. The forum also acknowledges utility radio-related amateur events like the International Lighthouse Weekend and Night of Nights, providing a broader context for listeners. The site offers sections for modes, hardware, software, a utility radio archive, digital BC & HF conditions, and a utility radio club archive, along with QSLs and pennants.

Fifty-three digital modes, including PSK31, RTTY, and JT65, are explored in this resource, providing detailed descriptions of their underlying technologies and typical use cases. It covers error correction methods like ARQ in PACTOR and FEC in JT65, alongside modulation schemes such as FSK and PSK. The content highlights the evolution of digital communication from traditional TNC-based systems to modern sound card implementations, emphasizing the role of personal computers in advancing these modes. Specific modes like AMTOR, PACTOR, and G-TOR are discussed, noting their baud rates and error correction capabilities. For instance, AMTOR operates at 100 baud, while PACTOR offers 200 baud with Huffman compression. The article also delves into newer modes like MFSK16, which uses 16 tones and continuous Forward Error Correction, and Olivia, capable of decoding signals 10-14 dB below the noise floor. Each mode's bandwidth, speed, and resilience to propagation challenges are examined, such as MT63's 1 KHz bandwidth and 100 WPM rate, or Hellschreiber's 75 Hz bandwidth and 35 WPM text rate. The resource also lists predominant USA HF digital frequencies for bands like 160, 80, and 40 meters, specifying segments for PSK31, RTTY, SSTV, and Packet. It includes links to freeware and shareware sound card software such as Digipan, FLDigi, and MixW, enabling amateurs to experiment with these modes.

Windows free sound recorder. What you save is what you hear ! Small utility program to capture and save any sound played by your computer. Audio recorded can be converted in MP3 format.

Analyzing 433 MHz radio signals from common wireless devices, such as temperature sensors and remote controls, involves understanding **On-Off Keying (OOK)** modulation. This resource details the process of capturing these signals using a Software Defined Radio (SDR) like Gqrx and then visually inspecting the captured audio data in a sound editor such as Audacity. It differentiates between **Pulse Width Modulation (PWM)** and Pulse Position Modulation (PPM) encoding schemes, illustrating how to identify and decode binary data by eye based on pulse and gap durations. The article provides a step-by-step walkthrough for decoding a wireless thermometer's data, correlating bit patterns with known temperature, humidity, and channel values. It also demonstrates decoding an RF remote control's button presses, highlighting the constant and varying parts of the transmitted packets. The content further introduces automated decoding using tools like RTL_433, explaining its capabilities in parsing various device protocols and showing how to interpret its output, including modulation type and decoded data. Specific examples include analyzing Prologue sensor protocol specifications from RTL_433's source code and noting common operating frequencies like 433.92 MHz in Europe and 915 MHz in the US.

The **Nilex Morse Tutor** is an HTML5 web application designed to teach Morse code reception, adapting to user proficiency by adding new characters as readiness is detected. It prioritizes practice on less familiar letters, numbers, symbols, words, and phrases, while minimizing repetition of already mastered elements. The program offers multiple learning orders, including "Q7ZG..." (Ward/Jim's), "KMRS..." (PU5EPX/Koch), "KMUR..." (lcwo.net), "AENT..." (CWops CW Academy), "TEAN..." (Stephen C Phillips), "ANET..." (Vic VE3YT), and "ETI5..." (Ham Whisperer), alongside an alphabetical option. Users can customize the learning experience by enabling or disabling automatic progression, and selecting specific content categories such as numbers, symbols, words, phrases, QSO bits, Ham Radio Bands, X+Y=Z math, and units. Audio settings are adjustable for volume, speed (WPM), tone frequency, and keyshape/keying envelope, allowing for a personalized auditory environment. The interface provides visual feedback with blue bars indicating practice emphasis and gray bars for reserved characters, with clickable bars for manual character selection. Developed by "Nosey" Nick Waterman, VA3NNW, this tutor is based on earlier versions by Jim Wilson and a 1977 QST article. A significant October 2019 rewrite incorporated a new WebAudio sound library by AwesomeAidenW, improving offline functionality and mobile support. The content library was expanded to include 3000 top Google words, 2284+ General Service List words, ISO country codes, capital cities, US states, Canadian provinces, UK counties, common names, periodic table elements, quotes, Q-codes, electronic components, ham abbreviations, and example call signs. The software is distributed under the GNU GPL V2 license.

MLog 0.8d is a freeware logging software designed for Windows operating systems (NT, 98, ME, 2000, XP) that facilitates the logging, management, and analysis of amateur radio QSOs. It features a customizable input mask for rapid contest logging, a robust search function for existing contacts, and immediate data storage in CSV format to prevent data loss. The software also includes a double-check mechanism against reference logs during callsign entry, integrated DXCC information, and a "magic field" for streamlined data input, all within a single-window interface. Key functionalities include graphical QSL card management via _QSL-Collection_, CW output through soundcard or PC speaker, and direct access to _Radio Amateur Callbook_ data. MLog supports transceiver control via _Ham Radio Deluxe_ URLs, offers a detailed world map with locator conversions, and can launch _VOACAP_ through _HamCap_. It provides extensive data analysis options for QSLs, _Locator_ large fields, _DOKs_, _DXCCs_, QSO counts, and user-defined contest evaluations, alongside flexible import/export capabilities for various log formats.

DecoAlert 1.0 Beta is a companion application designed to enhance the digital mode operating experience, specifically for FT8, FT4, and FT2. It operates by monitoring UDP data streams from primary decoding software like _Decodium_ and _WSJT-X_ on port 2237. The software provides real-time, priority-based audio alerts using WAV sounds for various conditions, including All Time New Ones (ATNO), new DXCC entities per band/mode, user-defined watchlist callsigns, new Maidenhead grid squares, and LoTW-active stations. It also highlights previously worked stations (B4) and integrates live DX spots from Telnet clusters, offering a comprehensive suite of tools for serious digital mode operators. The application features a built-in SQLite database for tracking worked stations and integrates with LoTW user lists to identify confirmed contacts. A DX Cluster client supports multiple Telnet servers, providing a broad view of propagation. PSKReporter statistics are available by band and mode, offering insights into signal paths. The QSO log viewer includes search and filter capabilities, while an _OpenStreetMap_ (OSM) interface visualizes spot locations, aiding in situational awareness. DecoAlert requires Windows 10/11 (64-bit) and compatible digital mode software configured to send UDP data.

Sita is a small tool that permanently records an input of the sound card into the working memory and repeats the last 10 seconds if needed. This is ideal for connecting the radio to the Line In of the sound card and, if you have not understood something, to have the last 10 seconds repeated.

CWoip (CW over internet protocol) Full Duplex morse code audio with high fidelity sound. Allow to conduct morse code CW over the internet. Fast, Full Break-in Qsk, due to low latency, free software. With the ability to conduct an audio CW QSO between 2 to 100 iCW OPS

The Greencube Terminal Program enhances communication with the Greencube/IO-117 satellite by enabling message exchange via a PC's soundcard and integrating with multiple loggers like ACLog and Cloudlog. It supports new contact identification through an ADIF file, featuring a color-coded "Dupelist" for tracking unconfirmed contacts and grids. The software is compatible with voice notifications for efficient satellite communication management.

The N7YG Digital Engine, functions as a streamlined digital modem, supporting **PSK**, **RTTY**, and **MFSK** modes. It eliminates many ancillary logging and awards features found in other software, focusing instead on providing a dedicated digital interface. The software is specifically engineered to complement the N3FJP logging suite, offering a simple digital modem with a floating waterfall display that can coexist on the same screen as the logger. The application includes support for PSK Reporter, EXTFSK, TinyFSK, and K1EL Winkey FSK, enhancing its utility for various digital operations. Key features comprise a separate waterfall window, a main GUI with operational controls, receive and transmit display areas, and 10 Macro Buttons across 10 user-definable macro banks, totaling 100 macros for general and contesting use. Configuration options include sound card selection, digital gain (0-32767), AFC Level (0-100), AFC Width (in Hz), and COM Port TX keying for VOX/SignaLink or direct port control. Input and Output Mixer buttons provide direct access to OS audio mixer controls for precise level adjustments. The software is digitally signed with a security certificate, aiming to prevent conflicts with antivirus programs.