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Demonstrates _Freq51_ and _Specgrm2_, two analysis programs from the Biomedical Ultrasonics Laboratory at the University of Michigan, available for DOS or Linux. The _Spectrum Analyser (Freq51)_ provides power spectrum levels as a function of frequency, configurable for absolute values (e.g., dB re 1 volt) with sound card calibration. _Spectrogram (Specgrm2)_ generates a real-time, full-screen spectrogram (sonagram) with various color options. These programs analyze incoming signals in real time, not stored files, and offer extensive settings for sampling rate, FFT points, and averaging time, making them highly versatile for acoustic analysis. The DOS version of _Freq51_ and _Specgrm2_ can operate under Windows 95, requiring users to configure sound card switches via a text file. The resource also briefly mentions other acoustic analysis software like Gianni Pavan's DOS-based bioacoustic tools, _Gram_ by R.S. Horne for Windows, _SASLab_ (Light and Pro versions), _Cool Edit_, and _GoldWave_, providing a comparative overview of available tools for real-time and file-based spectral analysis and waveform manipulation.

SDR# (read SDR Sharp) is a high performance Software Defined Radio application. SDR sharp is a fully featured SDR capable of handling samplerates from kHz level soundcards up to multi hundred MHz dedicated samplers, thanks to its multi-core architecture.

Constructing a digital interface for the Elecraft K2 transceiver, this resource details the "Fat Wire" design by WG4S. It demonstrates how to integrate a sound card for digital modes, outlining specific connections to the K2's microphone jack and internal audio path. The author shares practical insights from his build, including the use of _RG-62_ coax for its flexible braid and the strategic placement of components like the 2.2K resistor and _2N2222_ transistor. The guide provides a breakdown of the interface's internal wiring, specifying connections for AF In (pin 1), AF Out (pin 5), PTT (pin 2), and Ground (pin 7) on the K2's microphone connector. It also covers the external connections to a laptop's headphone and line-in jacks, along with a DB-9 connector for PTT control via _DTR_ or RTS lines. The author notes that his laptop's headphone output level was sufficient for the K2, negating the need for an attenuator. Reflecting on the design, the author, Dan WG4S, acknowledges a later suggestion to house the components directly within the DB-9 shell for a more compact build. This iterative feedback highlights the ongoing evolution of DIY ham radio projects and the community's collaborative spirit in refining designs.

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.

This article aims to help promote the proper configuration for having a clean signal on the waterfall to avoid interference to other users and also to vastly increase the effectiveness of your signal.

The recognition of telegraphy masked by noise at 40 and 80 signs/min telegraphy speed was studied in 10 normal-hearing subjects at different sound pressure levels (25-85 dB SPL in steps of 5 dB) as well as at different test frequencies (2000, 1000, 800, 630, 500 and 250 Hz). The ability to recognize the signs varied with varying SPL. Recognition for most of the subjects was best at an SPL close to 70 dB. All subjects improved their recognition as the frequency was lowered to 500 Hz, some even at 250 Hz. These facts should be taken into consideration when training telegraphy operators as well as in the construction of radio receivers to permit listening at low frequencies. Furthermore, the critical ratio was calculated at the different test frequencies.

Single-sideband (SSB) radio enhances spectral efficiency but poses challenges with audio intelligibility, particularly in noisy conditions. A microphone audio compressor addresses these issues by dynamically managing the audio signal’s dynamic range. It amplifies quiet sounds and attenuates loud ones, ensuring consistent audio levels for improved clarity. Benefits include increased intelligibility, higher average power, and reduced spurious emissions. While essential for optimal SSB performance, careful parameter adjustment is crucial to balance natural sound quality and effective communication across various operating modes.

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.

Demonstrates an **Arduino-based** solution for the Icom IC-7300 transceiver, specifically addressing the operational inconvenience of switching between a CW paddle and a straight key. The project leverages the IC-7300's **CI-V bus** (Computer Interface 5) to provide instant keyer type selection and two preset power levels, bypassing the rig's menu system which otherwise requires eight button presses. This implementation utilizes the 3.5mm CI-V connector, leaving the USB port free for CAT control and the internal soundcard, a critical design choice for integrated station setups. The system's utility is particularly evident for CW operators who frequently alternate between keying methods during contesting or general operating. The article details the hardware setup, including an Arduino Nano, a 3.5mm jack for CI-V, and pushbuttons for control. An update in 2023 expanded the project to incorporate an 8-button Nintendo controller, enhancing user interface flexibility and demonstrating the adaptability of the initial design for further customization and feature integration.