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K3: FSK-D vs AFSK

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Jim AB3CV

K3: FSK-D vs AFSK

I played a bit with FSK-D and AFSK today. I was able to get FSK-D to decode
and display on the PC via the K3 Utility Terminal tab.

While listening to T32C working a split RTTY pack I realized that trying to
figure out which was the most recent worked station was a bit more difficult
than doing it for CW, especially since the UP distance was 8-9Khz.

I thought AFSK and display of the sigs on the PC screen might be of benefit
but after putting it all together I realized that the bandwidth of the audio
out would limit the spectrum to less than 4Khz.

So what's the benefit of AFSK over FSK-D?

Any suggestions for finding the last station worked in a pack?

TIA

Jim ab3cv
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Don Wilhelm-4

Re: K3: FSK-D vs AFSK

Jim,

It all depends on your software application(s). If you are using the K3
Utility display, then the only practical choice is FSK-D. If you are
using MMTTY, you have your choice between AFSK and FSK. FSK will
require a "one transistor keying circuit", while AFSK requires
connection to your computer soundcard.
AFSK is used like any other digital mode - set the audio level to 4-5
bars on the K3 ALC meter, and you will achieve copyable transmit by the
other end. If instead, you construct the FSK keying device and use
FSK-D, there is no worry about audio levels. The end result is the
same, the receiving station can tell no difference.

If you are doing other digital modes, you probably have the soundcard
connection to the K3 in place, and AFSK will be a natural extension, but
if your data mode operation is restricted to RTTY, you may find the
FSK-D selection more to your liking.

73,
Don W3FPR

On 10/12/2011 9:34 PM, Jim Miller wrote:

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w0mu

Re: K3: FSK-D vs AFSK

In reply to this post by Jim AB3CV

FSK is super simple to get going. No adjustments of audio etc. Let the
K3 do all the work. MMAVARI allows you when using N1MM to have up to 24
decoders going at the same time. While they may say up 2-10 the
decoders are probably only seeing the bandwidth of the radio which could
be 6k with the filtering etc. The P3 will easily show you the
activity. Not who worked the DX. You can tune around and listen for
the proper timing or run two instances of your RTTY program and tune
with the 2nd vfo in hopes of spotting the last worked station.

That said..........

When I get on from J6 and operate RTTY I will have the decoders going so
it would be better to stake out a freq and call instead of trying to run
around the pileup. I think you will see more of this in the future.
Very cool technology at work!

Mike W0MU

J6/W0MU November 21 - December 1 2011 CQ WW DX CW
W0MU-1 CC Cluster w0mu.net

On 10/12/2011 7:34 PM, Jim Miller wrote:

> I played a bit with FSK-D and AFSK today. I was able to get FSK-D to decode
> and display on the PC via the K3 Utility Terminal tab.
>
> While listening to T32C working a split RTTY pack I realized that trying to
> figure out which was the most recent worked station was a bit more difficult
> than doing it for CW, especially since the UP distance was 8-9Khz.
>
> I thought AFSK and display of the sigs on the PC screen might be of benefit
> but after putting it all together I realized that the bandwidth of the audio
> out would limit the spectrum to less than 4Khz.
>
> So what's the benefit of AFSK over FSK-D?
>
> Any suggestions for finding the last station worked in a pack?
>
> TIA
>
> Jim ab3cv
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Iain MacDonnell - N6ML-2

Re: K3: FSK-D vs AFSK

In reply to this post by Jim AB3CV

The choice between AFSK and FSK is really about how you transmit, not
how you receive. With FSK, you feed an on/off signal to the K3 to
shift frequency, where with AFSK you send audio tones. You can
increase the receive bandwidth in FSK D mode just as you can in AFSK A
mode.

If you have KRX3, you can use a stereo sound card and two instances of
MMTTY - one configured to look at the left audio channel (main RX) and
the other the right channel (Sub-RX), and tune around with VFO B, in
split mode, looking for "the other guy", and then taking his
frequency.

73,

~iain / N6ML

On Thu, Oct 13, 2011 at 1:34 AM, Jim Miller <[hidden email]> wrote:

Joe Subich, W4TV-4

Re: K3: FSK-D vs AFSK

In reply to this post by w0mu

> While they may say up 2-10 the decoders are probably only seeing the
> bandwidth of the radio which could be 6k with the filtering etc.

MMVARI will only work with audio frequencies up to 3 KHz. The 6 KHz
filter (4.2 KHz max audio frequency in the K3) would be a waste. You
are better served by using the 2.7 or 2.8 KHz filter with FC=1.60 and
BW=2.80 if you plan to use multiple decoders in MMVARI.

73,

... Joe, W4TV

On 10/12/2011 10:19 PM, W0MU Mike Fatchett wrote:

> FSK is super simple to get going. No adjustments of audio etc. Let the
> K3 do all the work. MMAVARI allows you when using N1MM to have up to 24
> decoders going at the same time. While they may say up 2-10 the
> decoders are probably only seeing the bandwidth of the radio which could
> be 6k with the filtering etc. The P3 will easily show you the
> activity. Not who worked the DX. You can tune around and listen for
> the proper timing or run two instances of your RTTY program and tune
> with the 2nd vfo in hopes of spotting the last worked station.
>
> That said..........
>
> When I get on from J6 and operate RTTY I will have the decoders going so
> it would be better to stake out a freq and call instead of trying to run
> around the pileup. I think you will see more of this in the future.
> Very cool technology at work!
>
> Mike W0MU
>
> J6/W0MU November 21 - December 1 2011 CQ WW DX CW
> W0MU-1 CC Cluster w0mu.net
>
>
> On 10/12/2011 7:34 PM, Jim Miller wrote:
>> I played a bit with FSK-D and AFSK today. I was able to get FSK-D to decode
>> and display on the PC via the K3 Utility Terminal tab.
>>
>> While listening to T32C working a split RTTY pack I realized that trying to
>> figure out which was the most recent worked station was a bit more difficult
>> than doing it for CW, especially since the UP distance was 8-9Khz.
>>
>> I thought AFSK and display of the sigs on the PC screen might be of benefit
>> but after putting it all together I realized that the bandwidth of the audio
>> out would limit the spectrum to less than 4Khz.
>>
>> So what's the benefit of AFSK over FSK-D?
>>
>> Any suggestions for finding the last station worked in a pack?
>>
>> TIA
>>
>> Jim ab3cv
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Jim AB3CV

Re: K3: FSK-D vs AFSK

It looks like I could use my KXR3/Split and feed the LR audio from the K3 to
two instances of MMTTY (or something) and then use CW memories to do the
sending rather than fiddling with the transmit audio and the misc beeps from
windows.

Is that correct?

Jim ab3cv
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w0mu

Re: K3: FSK-D vs AFSK

Yes. Exactly. The computer interface is like a memory keyer for RTTY.
It is more flexible if you have a computer close by and who doesn't
these days. Most logging programs even have RTTY built in so you can
send directly from your logging program. I use CommCat and I know many
others support RTTY and Data modes.

Mike W0MU

J6/W0MU November 21 - December 1 2011 CQ WW DX CW
W0MU-1 CC Cluster w0mu.net

On 10/12/2011 10:23 PM, Jim Miller wrote:
> It looks like I could use my KXR3/Split and feed the LR audio from the
> K3 to two instances of MMTTY (or something) and then use CW memories
> to do the sending rather than fiddling with the transmit audio and the
> misc beeps from windows.
> Is that correct?
> Jim ab3cv
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Barry

Re: K3: FSK-D vs AFSK

In reply to this post by Jim AB3CV

Jim AB3CV wrote

Any suggestions for finding the last station worked in a pack?

One of the problems with RTTY pileups, as with the other modes, is many people call endlessly. That makes it difficult, as you won't hear (or see) just one signal when it's time for the caller to xmit a report.

I'm sure I'm in the minority using this technique, but I've worked RTTY long enough to be able to recognize the sound of my callsign, CQ and 599 in my head. Being a high speed CW guy probably helps, too.

When I tune with VFO B in DUAL mode, listening for the responding station, besides having the display, I listen for 599 599.

Barry W2UP