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FSK Help

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WS6X

FSK Help

I'm wondering if any one in this esteemed group is successfully using the K3
/ microKeyer II / MixW combo in FSK mode (I'm not interested in AFSK.). If
so, would you kindly contact me off list.

I am particularly looking for help in keeping the K3 and MixW in the
"non-inverted" state.

I know I should be addressing the MixW group but the moderator over there
gets excited if you even THINK about mentioning hardware. :(

Thanks,

Jim, WS6X

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John E. Reiser

Re: FSK Help

Hi Jim,

I'm sorry, I don't know the answer to your question. (Someone out there
surely does). I'm new to digi-modes. Started when I got my K3 in
mid-February. Since then I have worked 102 countries in RTTY and PSK-31. I
use MMTY and Digipan.

But, I have a question for you, being a neophyte. Why are you not
interested in AFSK? Does FSK work better in some way? Let me say, I have
been very pleased with AFSK so far. I have worked almost any station that I
could hear/print so far.

Is it worth the bother to wire up a cable for FSK? Why is it better than
AFSK?

Many thanks and 73,

John, W2GW

----- Original Message -----
From: "WS6X" <[hidden email]>
To: <[hidden email]>
Sent: Monday, July 21, 2008 7:29 PM
Subject: [Elecraft] [K3] FSK Help

> I'm wondering if any one in this esteemed group is successfully using the
> K3
> / microKeyer II / MixW combo in FSK mode (I'm not interested in AFSK.). If
> so, would you kindly contact me off list.
>
> I am particularly looking for help in keeping the K3 and MixW in the
> "non-inverted" state.
>
> I know I should be addressing the MixW group but the moderator over there
> gets excited if you even THINK about mentioning hardware. :(
>
> Thanks,
>
> Jim, WS6X
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
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> Elecraft web page: http://www.elecraft.com
>

James C. Hall, MD-2

RE: FSK Help

Hi Jim:

Interfaces like the MK II (I have the MK) because of its construction
reverses the polarity of RTTY (FSK) signals. All radios with this and other
interfaces should be set to reversed polarity. This will of course cause any
AFSK you might do to be inverted but that's why you have the check switch in
MixW ! :)

73, Jamie
WB4YDL

----- Original Message -----
From: "WS6X" <[hidden email]>
To: <[hidden email]>
Sent: Monday, July 21, 2008 7:29 PM
Subject: [Elecraft] [K3] FSK Help

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Joe Subich, W4TV-3

RE: FSK Help

In reply to this post by WS6X

> I'm wondering if any one in this esteemed group is
> successfully using the K3 / microKeyer II / MixW combo in FSK
> mode (I'm not interested in AFSK.). If so, would you kindly
> contact me off list.
>
> I am particularly looking for help in keeping the K3 and MixW
> in the "non-inverted" state.

All of the microHAM interfaces work properly with the K3 and
MixW when configured as shown in the MixW Set-up guides that
are available for download through the "Download Documents"
link in microHAM Router's Help menu starting with Router 5.

In general, the K3 should be operated in "FSK D." MixW should
have the PTT&CAT dialog set so "Default digi mode" is RTTY and
DIG (Yaesu) is = LSB. "FSK center fq" should be set to 2210
if you are using the standard 2125/2295 Hz tones. The "Inv"
box must not be checked in microHAM Router.

73,

... Joe Subich, W4TV
microHAM America
http://www.microHAM-USA.com
http://groups.yahoo.com/group/microHAM
[hidden email]

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of WS6X
> Sent: Monday, July 21, 2008 7:29 PM
> To: [hidden email]
> Subject: [Elecraft] [K3] FSK Help
>
>
> I'm wondering if any one in this esteemed group is
> successfully using the K3 / microKeyer II / MixW combo in FSK
> mode (I'm not interested in AFSK.). If so, would you kindly
> contact me off list.
>
> I am particularly looking for help in keeping the K3 and MixW
> in the "non-inverted" state.
>
> I know I should be addressing the MixW group but the
> moderator over there gets excited if you even THINK about
> mentioning hardware. :(
>
> Thanks,
>
> Jim, WS6X
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

Julian, G4ILO

Re: FSK Help

In reply to this post by John E. Reiser

John Reiser-3 wrote

But, I have a question for you, being a neophyte. Why are you not
interested in AFSK? Does FSK work better in some way? Let me say, I have
been very pleased with AFSK so far. I have worked almost any station that I
could hear/print so far.

That's a good question. I don't know the answer either. I cannot see the point of using FSK if a sound card is available. It will make no difference at the other end of the contact, and at your end it means that you have to tune in the signal you are working to the exact frequency you are transmitting on, instead of just clicking on it in a waterfall and letting AFC take care of it.

Some people use an external RTTY terminal unit and I have heard claims that they can decode better than sound card programs. I can't argue with that, since I have never done a comparison, but if true I would have thought it was due to a deficiency in the decoding software. I would have thought that DSP was capable of doing a better decoding job than any analog frequency discriminator circuit.

Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html

John E. Reiser

Re: FSK Help

Thanks gentlemen for the replies to my question about the relative merits of
FSK and AFSK. You gave me lots of good and helpful info.

Jim, WS6X, I didn't mean to hijack your thread.

73, John, W2GW

----- Original Message -----
From: "Julian, G4ILO" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, July 22, 2008 4:00 AM
Subject: Re: [K3] [Elecraft] FSK Help

>
>
>

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Jerry Flanders

Re: FSK Help

In reply to this post by Julian, G4ILO

True FSK does not require that following amplifier stages be linear.
Any distortion or non-linearity with AFSK will result in a "dirtier"
signal, which will have a negative impact on other stations working
nearby in frequency.

Since no amplifier is perfect, one can always argue that FSK is
likely to be the cleanest mode and is best if band crud is a consideration.

Jerry W4UK

At 04:00 AM 7/22/2008, you wrote:

>John Reiser-3 wrote:
> >
> >
> > But, I have a question for you, being a neophyte. Why are you not
> > interested in AFSK? Does FSK work better in some way? Let me say, I have
> > been very pleased with AFSK so far. I have worked almost any station that
> > I
> > could hear/print so far.
> >
> >
>That's a good question. I don't know the answer either. I cannot see the
>point of using FSK if a sound card is available. It will make no difference
>at the other end of the contact, and at your end it means that you have to
>tune in the signal you are working to the exact frequency you are
>transmitting on, instead of just clicking on it in a waterfall and letting
>AFC take care of it.
>
>Some people use an external RTTY terminal unit and I have heard claims that
>they can decode better than sound card programs. I can't argue with that,
>since I have never done a comparison, but if true I would have thought it
>was due to a deficiency in the decoding software. I would have thought that
>DSP was capable of doing a better decoding job than any analog frequency
>discriminator circuit.
>
>-----
>Julian, G4ILO

Simon (HB9DRV)

Re: FSK Help

Why that - enquiring minds etc. ?

Simon Brown, HB9DRV

--------------------------------------------------
From: "Jerry Flanders" <[hidden email]>

> True FSK does not require that following amplifier stages be linear.

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Jerry Flanders

Re: FSK Help

Shifting a constant carrier back and forth does not require linearity
in later stages - for the same reason that CW does not.

FSK goes back to at least the WW2 era. In the "olden days" class C
amplifiers were used for FSK.

Jerry W4UK

At 10:29 AM 7/22/2008, you wrote:

>Why that - enquiring minds etc. ?
>
>Simon Brown, HB9DRV
>
>--------------------------------------------------
>From: "Jerry Flanders" <[hidden email]>
>
>>True FSK does not require that following amplifier stages be linear.
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Joe Subich, W4TV-3

RE: FSK Help

In reply to this post by Julian, G4ILO

The following settings appear to work properly with MixW
and the K3:

In MixW XCVR/CAT ...
CAT = Kenwood
Model = Elecraft K2
CW is LSB (check)
Default digi mode = RTTY
CW Pitch = <your Pitch>
FSK center fq = 2210
Cat correction (Hz)
Digi = -2210

"FSK center fq" will be (Mark + shift/2) and the CAT correction
for digi modes will be -FSK Center fq.

Unfortunately, MixW does not seem to maintain separate center
frequencies by mode so it's necessary to change TX and RX
Frequency when you change modes (Mode Settings).

With this configuration the frequency shown on the waterfall will
be incorrect by shift/2 (it will read the FSK center frequency)
but the frequency in the log will be correct (Mark frequency).

If your choice is AFSK (AFSK A in the K3), the same configuration
applies with one change ... Check "AFSK in place of FSK" in the
MixW CAT configuration dialog. "FSK Center fq" is not used.

73,

... Joe, W4TV

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Jim Brown-10

Re: FSK Help

In reply to this post by Jerry Flanders

On Tue, 22 Jul 2008 10:49:27 -0400, Jerry Flanders wrote:

>Shifting a constant carrier back and forth does not require linearity
>in later stages - for the same reason that CW does not.

Hmmm. Well, yes and no. Shifting a carrier in frequency results in
switching transients (clicks). If these are amplified non-linearly, their
relative level can increase. These clicks are easily heard in a K3 when
close to a relatively strong RTTY signal, even one coming from another
K3.

The comment that FSK avoids the audio distortion produced by a sound card
is quite correct. However -- sound card distortion can often be reduced
significantly by operating the sound card about 6 dB down from its max
output.

73,

Jim K9YC

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Ed Muns, W0YK

RE: FSK Help

In reply to this post by John E. Reiser

> But, I have a question for you, being a neophyte. Why are
> you not interested in AFSK? Does FSK work better in some
> way? Let me say, I have been very pleased with AFSK so far.
> I have worked almost any station that I could hear/print so far.
>
> Is it worth the bother to wire up a cable for FSK? Why is it
> better than AFSK?

RTTY transmission using FSK or AFSK is a personal preference and some people
are very outspoken with their opinion about which is "best". There are
advantages of each method and equally excellent results have been achieved
with either, i.e., equally difficult DX has been worked with either method
and major RTTY contests have been won with either method.

AFSK uses the PC soundcard which is often being used anyway for reception
with software decoders. A standard audio cable is used where FSK requires a
special keying cable identical to that used for CW keying. The audio level
of the soundcard audio tones must be set to drive the transmitter adequately
but not over-drive it. Since the MARK and SPACE RF frequencies are derived
from audio tones run through the SSB portion of the radio, the software can
dither those audio frequencies to automatically change the MARK/SPACE RF
frequencies providing dynamic zero-beating. In most radios, the VFO dial
frequency is the suppressed carrier frequency of the SSB signal. Thus, the
actual MARK frequency will differ from this by whatever the current audio
tone frequency is being used, which may be moving around due to the
automatic frequency feature. Since PSK31 typically uses soundcard audio
generation for transmission via the SSB mode, the same hardware (cabling)
setup can be used for RTTY. Finally, some older radios do not have a FSK
keying input, so the only choice is AFSK. This typically means that the IF
filtering available on receive is the wider SSB filters.

FSK is direct keying of the transmitter just like CW. The VFO dial
frequency is the MARK frequency and unambiguous when exchanging QRV
frequencies. Since the transmitter creates the two MARK/SPACE RF
frequencies, there is no worry about audio level adjustments or remembering
to turn SSB compression off. Some will argue that the FSK signal is cleaner
than AFSK, but with modern radios this difference is seldom an issue. Since
automatic TX frequency dithering is not possible with FSK, there is less
chance to inadvertently transmit at an offset. Radios with FSK keying
typically provide narrow IF filtering similar to CW.

FSK is clearly simpler from an overall hardware/software system standpoint,
and therefore less likely to have unintentional problems. But many argue
that AFSK is "simpler" because it doesn't require the special keying cable.
Yet another religious debate within our hobby.

73,
Ed - W0YK

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WS6X

RE: FSK Help

-----Original Message-----
From: Ed Muns [mailto:[hidden email]]
Sent: Tuesday, July 22, 2008 9:34 AM
To: 'John Reiser'; 'WS6X'
Cc: [hidden email]
Subject: RE: [Elecraft] [K3] FSK Help

> But, I have a question for you, being a neophyte. Why are
> you not interested in AFSK? Does FSK work better in some
> way? Let me say, I have been very pleased with AFSK so far.
> I have worked almost any station that I could hear/print so far.
>
> Is it worth the bother to wire up a cable for FSK? Why is it
> better than AFSK?

>>>>Thanks, Ed, for your succinct treatise on the FSK vs. AFSK question.
Just so the group doesn't think I was ignoring John and his question, I had
actually replied direct to John, off-reflector last evening.

And while I'm at it, thanks to all who responded to my original question. I
have acknowledged everyone who responded on, or off list.

73,

Jim, WS6X

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Jerry Flanders

Re: FSK Help

In reply to this post by Jim Brown-10

>On Tue, 22 Jul 2008 10:49:27 -0400, Jerry Flanders wrote:
>
> >Shifting a constant carrier back and forth does not require linearity
> >in later stages - for the same reason that CW does not.
>Then, at 12:06 PM 7/22/2008, Jim Brown wrote:Hmmm. Well, yes and no.
>Shifting a carrier in frequency results in
>switching transients (clicks).

The transition time constant has to be reasonable, of course, just as
CW keying on/off transitions are smoothed to reduce click levels.
This is all taken care of (hopefully) in the rig design. It is not a
consideration for an appliance operator, which most of us are these days.

Back when guys were modding their rigs to add FSK to them (and some
did, 30-40 years ago) this might have been a problem. The early AFSK
units had problems, too, if the tone transitions were made without
regard to phase. It was a big deal to get a phase-continuous
transition in the early/mid 70's, IIRC.

Unless an operator can do some tests on his sigs to verify quality he
is generally better off using FSK for the sake of band crud reduction.

Jerry W4UK

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