Detection of ultrasonic side channels in mobile devices with Python?
Grant Edwards
grant.b.edwards at gmail.com
Wed Feb 28 21:51:44 EST 2018
On 2018-03-01, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> The bandwidth normally used for voice grade telephone traffic is closer
> to 6kHz (say 300Hz to 6.3kHz)
Wow, that's pretty high -- where was that?
Back when I was designing telephony electronics in US in the late
80's, POTS bandwidth was 3KHz: 300-3.3K. That same bandpass spec was
used for the audio stages in the first couple generations of AMPS
cellular mobile phones.
The Codecs used in digital telephony (e.g. a T1 trunk) used 7-bit
converts with 8KHz sampling, which means a cutoff frequency below
4KHz.
--
Grant
More information about the Python-list
mailing list