In days past, the telephone companies ran an analog carrier system of 24
SSB channels with what was called a pilot tone at a reduced level. The
pilot was indeed a carrier reference that was PLL to the office master
clock.
These 0-4 Khz channels could get off on the receiving end, but a
"satellite doppler" type tracking circuit PPL to the incoming pilot tone
kept everything in the pass band of the specific crystal filters for
each channel. Bear in mind we expected pilot error in the CPS range,
rather than 10s or 100s of cycles.
I would think one can design this to work with today's digital
components rather than use the "rock solid" crystal filters this L
Multiplex phone equipment did back in the day.
Connect the pilot tone receive PLL to control the receive RF
oscillator. I suspect it would work if the barn door was not too wide
for the PLL to lock on. May get expensive if you have to use the
crystals from yesteryear.
73
Jim WA4IVM
On 1/10/2014 2:28 PM, Kevin Muenzler, WB5RUE wrote:
I doubt that it would be useful because the tolerances are extremely high in
DTMF so if you are only a few Hz off the tones won't lock. FM might be ok
but certainly not SSB. FM itself has its own problems on HF so that might
not be useable either.
Kevin Muenzler, WB5RUE
Grid-EL09uf
Eagle Creek Observatory
http://www.eaglecreekobservatory.org
I'd be unstoppable if it weren't for law enforcement and physics
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Robert Bruninga
Sent: Friday, January 10, 2014 11:10 AM
To: [email protected]
Cc: [email protected]
Subject: [amsat-bb] DTMF on HF?
Has anyone had any experience with any success at DTMF working on HF for
some rudimentary commands?
I know tuning is critical as well as inter-tone noise must be way down.
Just thought maybe someone has experimented with it.
Bob, WB4aPR
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