Terence Eden on Nostr: What's the maximum speed you could transmit data using DTMF on a basic voice line? ...
What's the maximum speed you could transmit data using DTMF on a basic voice line?
There are 16 discrete symbols (0-9, *,#,A-D) which means you can use hex-encoded data.
Standard rate is 80ms (40ms for the tone and a 40ms space).
But the fastest decoders can work with 25ms (20 tone, 5 space).
That's 40 hex symbols per second.
So approx 1KB per minute.
There are 16 discrete symbols (0-9, *,#,A-D) which means you can use hex-encoded data.
Standard rate is 80ms (40ms for the tone and a 40ms space).
But the fastest decoders can work with 25ms (20 tone, 5 space).
That's 40 hex symbols per second.
So approx 1KB per minute.