Kok Chen <chen@mac.com> wrote ..
>
> On Feb 8, 2013, at 10:01 AM, ham@n0sq.us wrote:
>
> > Already tried reversing the polarity.
> >
> > Joe Subich, W4TV <lists@subich.com> wrote ..
> >>
> >> Lee.
> >>
> >> Check the RTTY Polarity menu in your TS-2000. It probably needs to be
> >> set to REVERSE. IIRC, the KAM takes care of that but your serial port
> >> interface would not.
>
> Lets see if we can drill down a little bit.
>
> If I am reading this correctly, you are
>
> 1) transmitting FSK through MMTTY, using EXTFSK,
No. I'm using MMTTY with N1MM logging software.
> 2) receiving through a second receiver with a KAM.
Yes.
> 3) and the KAM tuning meter shows that you have centered the two tones
> correctly.
Yes.
>
> And, when you transmit, your transmitter keys properly, and you can hear
> diddles
> (instead of a single tone) coming from the receiver. I also assume that the
> receiver
> and KAM can copy signals off the air?
Yes.
>
> Correct so far?
>
> If so, your transistor circuits are working. And EXTFSK may be working (read
> on).
>
> You said that you have tried reversing polarity, is that at the receiver (KAM
> end)
> or at the MMTTY end?
I reversed polarity in the TS2000 (MMTTY + N1MM software). The Kam+ is
connected to a TS450.
>
> If you are trying to reverse at the KAM end, do not do it by using the FSKinv
> command
> on the KAM. That one controls the KAM transmit direction. Instead, turn the
> KAM's
> INVerse state on and off. (FSKinv and INVerse are different commands, one to
> control
> the transmit and one to control the decoding)
>
> If that makes it work, and you can copy off the air signals on the KAM without
> inverting, you will need to invert MMTTY's output (see if MMTTY has an EXTFSK
> invert
> setting, or if the transmitter has an FSK invert setting).
>
> If you hear modulation through MMTTY's EXTFSK, and you still cannot copy by
> reversing
> the KAM, there is one more thing that is possible: you are throwing too many
> errors
> when using EXTFSK. EXTFSK is really a hack, where the computer attempts to
> send
> the bits out every 22 millisecond. If there is any timing latency in the OS,
> the
> output will not be close enough to the 22 millisecond bit periods that the KAM
> expects at the receiving end. Unfortunately, you need an oscilloscope to tell
> you
> exactly what is happening.
I haven't tried EXTFSK yet. But, I do have access to an oscilloscope.
>
> With most computers, the latency is around one tenth of a bit time (people
> will
> have more problems copying you when you are weak, but they will copy you fine
> when
> you are loud, so most people don't even know they have a problem, they just
> think
> the receiving end has a crummy demodulator). But if you have an old, slow
> machine,
> it could be bad enough that few characters get through.
>
> If that is your case, some of your choices are: change software, use the K4DSP
> FSKit to convert AFSK to FSK, or just change to using AFSK transmit.
I want to try fldigi but it doesn't seem to have support for the TS2000.
>
> BTW, you did not tell us what the KAM is printing while all of this is going
> on...
> is it printing nothing, is it printing complete gibberish, or is it printing a
> bunch of weird but repeating characters during diddles, or is it printing
> correct
> characters now and then? Telling us that can help zeroing in on the problem.
It's printing gibberish due to noise and nothing when receiving a signal. I can
hear the diddles in the TS450 speaker so I'm receiving at least that much.
>
> 73
> Chen, W7AY
>
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