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Indeed, I am using OFDM [1], which uses several carriers, each modulated via QAM [2]. [1] https://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplex
by roman_zeyde 8y ago
Indeed, I am using OFDM [1], which uses several carriers, each modulated via QAM [2].
[1] https://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexing https://en.wikipedia.org/wiki/Orthogonal_frequency-division_...
[2] https://en.wikipedia.org/wiki/Quadrature_amplitude_modulation https://en.wikipedia.org/wiki/Quadrature_amplitude_modulatio...
- viraptor 8y agoI'm a bit confused. How does QAM work with audio if you have only one channel rather than I/Q? Are you using multiple frequencies for that?
- roman_zeyde 8y agoQAM is using both carrier's amplitude and phase to encode information, so I/Q can be thought as [1]: I = amplitude*cos(phase) Q = amplitude*sin(phase) [1] http://whiteboard.ping.se/SDR/IQ http://whiteboard.ping.se/SDR/IQ
- viraptor 8y agoI'm just sitting here and staring at this sentence: "The modulated signal rides on a carrier of a given frequency, but the base band signal got no fixed frequency at all. Because of this, we have the possibility to encode the two-dimensional I/Q signal onto the one-dimensional RF signal without losing anything." I may need to sleep on it...