I'm working on transforming the keyer into an FSK generator as we speak.
Question about default values. Default tones will be 2125 mark/2295 space,
trivially invertible or resettable for AMTOR, etc. What about envelope
rise/fall times?
Based on a little experimentation here it appears that the best approach is
to seesaw between a pair of tone generators rather than slewing the tone
freq on a single generator. This should help bandlimit spurious products
at the transitions. It's also easier to program. However it does imply
crossfading mark/space. That suggests 4ms rise/fall times. Make sense
to the RTTY mavens here?
Thanks
Frank
AB2KT
Ron Kolarik wrote:
Thanks Bob, no hurry it was only a wish. Gotta love the guru's
on this group.
I just got a note that the TAPR Reflock II should be available
in about month......pictures and more information here:
http://gref.cfn.ist.utl.pt/cupido/reflock.html
Ron K0IDT
----- Original Message -----
From: "Robert McGwier" <[EMAIL PROTECTED]>
To: "[EMAIL PROTECTED] Biz" <flexradio@flex-radio.biz>
Sent: Tuesday, August 02, 2005 12:12 PM
Subject: [Flexradio] "Real" FSK
Real FSK is possible with outboard programs but will involve some
serious surgery. Basically, the "straight keyer" must be modified to
send space rather than silence when the data pin not on. This will
involve the construction of a new block of code fsk.c to do this.
Otherwise, it will call the same functions and change the tone. We need
to use the data pin since the RTTY programs do not bit bang this. The
data will be clocked to us by the RTTY app calling the real or virtual
com port and loading its "send" register with the data. I do not yet
know if the virtual com port can be opened for baudot as the 16550 UART can.
This will be in some future version but requires more work than simply
flipping a switch. I sent Eric RTTY mode enabled. This enabled RTTY
receive where you can set the variable filter to what you like.
The transmit filter is the LSB and the receive filter is the users
discretion. The LSB transmit filter allows you to move your tones up
with your AFSK code (MMTTY, Writelog, etc.). When in RTTY mode, the
leveler for the microphone is out of the circuit. You may use this
for PSK as well. Reverse is not yet enabled. This will be in 1.4.5
probably next week. I have other fish to fry for a week.
Bob
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