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A technical Description of HamSphere
2024-04-10 20:59
Registered: 14 years ago
Posts: 1,250

Technical Description of HamSphere

HamSphere is a sophisticated virtual amateur radio communication system that operates through a network of robust servers, each dedicated to generating a virtual ionosphere sampled at 192 kHz, providing a bandwidth of 96 kHz per band.

In HamSphere, each operator is equipped with both an RX (receive) and TX (transmit) oscillator, also known as a Variable Frequency Oscillator (VFO). These oscillators are capable of fine-tuning frequencies between 1 kHz to 100 kHz on both RX and TX sides.

The TX signal undergoes modulation with Software Defined Radio (SDR) algorithms on the server-side, using audio from the operator. This modulation, either Upper Sideband (USB) or Lower Sideband (LSB), results in a Single Sideband (SSB) modulated TX signal fed to the mixer, mixing it with all other TX signals, creating what we refer to as the "Sphere". It's important to note that operating near the edges of the feasible bandwidth, such as < 3 kHz or > 93 kHz, may cause distortion according to the Nyquist theorem.

So in short, the "Sphere" serves as the consolidation of all transmitted signals within the system. With a sample rate of 196 kHz, the system and "Sphere" provide a feasible bandwidth of 96 kHz. Within the "Sphere," the modulated TX signals blend, creating a cohesive transmission environment.

On the RX side, the RX VFO is directly mixed with the "Sphere" and subsequently downsampled to 8 kHz. At this stage, Software Defined Radio (SDR) filters are applied to extract the audio, which is then fed to the user's transceiver software, also known as thin clients, ensuring a seamless and immersive experience for all operators.

A key aspect of HamSphere's realism lies in its continuous integration of propagation data. RX and TX signals are constantly fed with propagation data obtained from dedicated calculation servers. These servers analyze geographical data such as Sun Spots Numbers, Solar Flux values, continents and oceans, using VOACAP software, enhancing the simulation's authenticity.

The propagation model leverages Numerical Electromagnetic Code (NEC) designed antennas, which are seamlessly integrated into the VOACAP calculation engine. This integration allows for the constant calculation of propagation circuits between all operators within the system. The propagation servers work with a matrix of latitudes and longitudes for all operators. Every second, multiple propagation servers collaborate to calculate each matrix point for all users, ensuring real-time adjustments for changes such as antenna modifications or azimuth adjustments.

In essence, HamSphere's technical architecture is designed to provide users with a highly realistic virtual amateur radio communication experience. By leveraging advanced modulation techniques, continuous propagation data analysis, and seamless signal processing, HamSphere delivers an unparalleled simulation of real-world radio operations.
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