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the whole "direct modulation" concept isn't well defined, a SSB transceiver is just a frequency converter with side-band selection, the sound input and output is just a frequency shifted copy of the RF signal it doesn't really get more direct than that, and I'd argue that SSB isn't even a modulation form since it's literally just transverting voice (or whatever you want) frequencies into RF it's as flexible as it can be, you can literally transmit any modulation you want within the channel bandwidth with SSB radios last month I made a weather-fax FM demodulator in a DSP, the input is the output from an SSB receiver if you wanted to directly modulate the RF you might go a bit further and do I/Q modulation, but that requires a DC coupled signal and you can achieve the same result with both methods. it just happens that if you're building a radio these days it's cheaper and more convenient to use an I/Q complex modulator and demodulator instead of an SSB one, and a lot of RF signal processing is easier to do in the complex plane
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Mar 31, 2023 16:36
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| # ¿ May 9, 2024 06:54 |
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