Detection of ultrasonic side channels in mobile devices with Python?

[Grant Edwards]

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