4 Jun
2019
4 Jun
'19
7:58 p.m.
On Mon, 3 Jun 2019, David Ranch wrote:
(6) A RTTY, data or multiplexed emission using a
specified digital code
listed in ?97.309(a) of this part may be transmitted. The symbol rate must not
exceed 56 kilobauds. A RTTY, data or multiplexed emission using an unspecified
digital code under the limitations listed in ?97.309(b) of this part also may
be transmitted. The authorized bandwidth is 100 kHz.
56 kilobauds is because the Telebit Trailblazer existed; it used OFDM
and 6 "baud" carriers.
We've never pushed the limits like wireline did. We should be able to
cram 33.6 kbit/s through 0-4 kHz just like the phone modems did. It was
possible to achieve 14.4 kbit/s bidirectionally with modems through a
full-duplex telephone patch.
Hack apart the resistor bridge, TX to modulator, RX to demodulator, send
the command to start data, and the command to answer. It'd have to be a
full-duplex link, four radios involved, but that's 33.6 kbit/s
bidirectional with 175 ms of modem delay or so. Good luck finding
schematics today however.
--
Kris Kirby, KE4AHR
Disinformation Architect, Systems Mangler, & Network Mismanager