3 ms·
I really like how you can figure out the phone number dialed with the representation of the DTMF tones. This was basically an audio coordinate system (or just a
by antiterra 6y ago
I really like how you can figure out the phone number dialed with the representation of the DTMF tones. This was basically an audio coordinate system (or just a 2D array): an X tone and a Y tone played at the same time.
The upper component has three positions representing the columns on a phone keypad.
The lower four positions represent the rows.
For example, zeros are represented by upper tone 2 for the middle column (2,5,8,0) and lower tone 4 for the bottom row (*,0,#).
- yaml-ops-guy 6y agoThis was basically an audio coordinate system (or just a 2D array): an X tone and a Y tone played at the same time. Auditory....Vectors? (Thinking aloud)
- pwg 6y agoYou have also just described how the old analog touch tone phones actually generated the tones. Each column of buttons generated a different tone per column, and each row also generated another tone per row. A given button when pressed activated a column and a row to generate the two tones associated with that button.
- antiterra 6y agoYes, that's what my intent was.
- Jtsummers 6y agohttps://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_sign... There was a fourth column (A,B,C,D) meant for menu selection, and for the US military to indicate call precedence. Also used for various kinds of system automation and signaling but not accessible directly.
- flemhans 6y agoAnd they sounded _weird_. Almost spacey.
- lozf 6y agoGenerate them all with: sox -n dtmf-1.wav synth 0.1 sine 697 sine 1209 channels 1 sox -n dtmf-2.wav synth 0.1 sine 697 sine 1336 channels 1 sox -n dtmf-3.wav synth 0.1 sine 697 sine 1477 channels 1 sox -n dtmf-4.wav synth 0.1 sine 770 sine 1209 channels 1 sox -n dtmf-5.wav synth 0.1 sine 770 sine 1336 channels 1 sox -n dtmf-6.wav synth 0.1 sine 770 sine 1477 channels 1 sox -n dtmf-7.wav synth 0.1 sine 852 sine 1209 channels 1 sox -n dtmf-8.wav synth 0.1 sine 852 sine 1336 channels 1 sox -n dtmf-9.wav synth 0.1 sine 852 sine 1477 channels 1 sox -n dtmf-0.wav synth 0.1 sine 941 sine 1209 channels 1 sox -n dtmf-star.wav synth 0.1 sine 941 sine 1336 channels 1 sox -n dtmf-pound.wav synth 0.1 sine 941 sine 1477 channels 1 sox -n dtmf-A.wav synth 0.1 sine 697 sine 1633 channels 1 sox -n dtmf-B.wav synth 0.1 sine 770 sine 1633 channels 1 sox -n dtmf-C.wav synth 0.1 sine 852 sine 1633 channels 1 sox -n dtmf-D.wav synth 0.1 sine 941 sine 1633 channels 1 sox -n dtmf-us-busy.wav synth 10 sine 480 sine 620 channels 1 sox -n dtmf-rbt-US.wav synth 10 sine 440 sine 480 channels 1 sox -n dtmf-uk-us-dialtone.wav synth 11 sine 350 sine 440 channels 1 sox -n dtmf-uk-busy.wav synth 10 sine 400 channels 1 # needs cadence sox -n dtmf-uk-ringback synth 10 sine 400 sine 450 channels 1 sox -n dtmf-eur-dialtone.wav synth 10 sine 425 channels 1 sox -n dtmf-eur-busy.wav synth 10 sine 425 channels 1 # needs cadence sox -n dtmf-eur-ringback.wav synth 10 sine 425 channels 1 # needs cadence
- antiterra 6y agoI had forgotten about those! I had a phreaking program[1] with those on the C-64. They called the DTMF utility 'Silver Box.' Turns out: https://en.wikipedia.org/wiki/Silver_box https://en.wikipedia.org/wiki/Silver_box [1] It was this one: https://commodore.software/images/jdownloads/screenshots/telephone%20phreak%20utility.jpg https://commodore.software/images/jdownloads/screenshots/tel...
- grishka 6y agoWhere I'm from we used pulse dialing. I remember being so proud of myself for figuring out that the number of pulses the phone sent represented the digit you're dialing.