Tinkerer and classic computing fanatic Gus Gorman has introduced again a basic of the roadwarrior’s on-the-move arsenal: an acoustic coupler, designed to pair a computing system with a landline phone handset.
“A kind of items of tech that I’ve at all times actually wished is an acoustic coupler,” Gorman explains, referring to a classic piece of {hardware} that related a pc to a phone line by actually cradling a landline handset with a microphone to its speaker and a speaker to its microphone — that means no wires have been required, and it might even be used with payphones. “Sadly, they do not make them any extra.”
The answer, aside from scouring the public sale websites and hoping for a suitable and still-functional itemizing to look: constructing a brand new one, utilizing a 3D-printed housing and a USB microphone and speaker set. “The practical purpose I used to be taking pictures for was about 300bps [bits per second],” Gorman explains, “with minimal typos.” The invoice of supplies, too, was designed to be minimal: a $6 miniature USB microphone in a single finish and a $12.50 USB speaker within the different, designed for connection to an exterior system.
“At my home I’ve my very own PBX [Private Branch Exchange] arrange,” Gorman explains of the place the acoustic coupler will discover its use. Testing, nevertheless, revealed that acoustic coupler design is trickier than it might appear: whereas authentic {hardware} would possibly attain 300bps with out issue, Gorman’s recreation hits about 100bps earlier than errors creep into the transmitted textual content.
The {hardware}’s of little use with out software program, after all, and for this Gorman put collectively a bulletin board system (BBS) based mostly on Kamal Mostafa’s minimodem, a software-based frequency-shift keying (FSK) modulator/demodulator (modem) suitable with USB audio units.
AcousticBBS, based mostly on minimodem, is provided with the acoustic coupler’s STL to supply a contemporary twist on classic boards. (📷: Gus Gorman)
“One other cool factor that I would prefer to see,” Gorman suggests of the place the challenge might go sooner or later,” is a Raspberry Pi cyberdeck model of [this] with an acoustic coupler. One thing else I need to attempt doing is as an alternative of utilizing the telephone strains to transmit this data is to do a radio model with walkie-talkies or one thing.”
Extra data is accessible on Gorman’s YouTube channel, whereas the STL file for the acoustic coupler housing and the supply code for the BBS can be found on GitHub beneath an unspecified open supply license.
