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HamSphere Technology

Quite often I get a question about HamSphere and how it works.

Not many operators realize that HamSphere is constructed on real radio concepts such as local oscillators, mixers, filters, agc’s, balanced modulators, carrier wave suppression etc.

About 10 years ago I started contemplating a crazy concept of simulating SSB-signals on the Internet. Of course back then the CPU power was not enough to achieve such thing, but eventually in late 2007 I started writing the first  embryo for HamSphere on a 4-core Intel server.

The concept is simple. I give each logged in Ham a digital local  oscillator (LO) that can be tuned between 1-99 kilohertz. The LO is then modulated with Amplitude Modulation (AM) by the operator’s  microphone audio. The AM signal is fed through a carrier wave  suppression module leaving a Double Side band (DSB) signal.

The DSB signals from all operators on the system are mixed in a mixer and re-sampled at 192 kHz. That output of that mixer is the ”HamSphere”, which is a melting pot with all signals mixed together.

On the receiver side I inject the LO (1-99 kHz) into a balanced  direct mixer which is also fed with the “HamSphere” signal. The product of that mixer creates an (Intermediate Frequency) IF which is actually carrying the audio product. The IF is then filtered with  a 3.8 or 2.8 kHz filter to get rid of the digital artifacts and then fed to the speaker.

This whole digital concept above is acting like a real shortwave radio or actually a SDR (Software Defined Radio).

The “HamSphere” is constantly reshaped using real so called  QSB-envelopes that I have prerecorded from real shortwave signals on different bands. That is how I can explain the QSB (fading) on the signals that you hear on HamSphere.

Another concept of HamSphere is the fact that when you swirl the VFO know the voices turn into ”Donald Duck” voices, just like a SSB receiver. Well, the reason for that is that it is the same thing, except HamSphere uses Double Side Band instead.
Below I have pasted a diagram of the HamSphere system.

73
Kelly
5B4AIT
www.hamsphere.com

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