It’s well known that the most important speech information is between 300 and 3000 Hz. Energy outside that range makes the speech sounds nicer, but doesn’t help intelligibility much. Analog modes such as SSB exploit this by band limiting the speech so that the transmitter power is used just to punch through information in the narrow bandwidth that matters.
With digital speech the RF bandwidth is not directly linked to the bandwidth of the decoded speech. For example FreeDV 700D uses around 1100 Hz of RF bandwidth, but the decoded speech has energy covering most of the 0 to 4000 Hz range.
8-6-2021 (August 6, 2021) is the Snakiest day of the year and it’s also this year’s CircuitPython Day! The day highlights all things CircuitPython and Python on Hardware. See you there!
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.