The "correct" frequency in HSMS 
 By Steve, Ko0u



At 09:33 AM 8/29/97 -0700, you wrote:


I had hoped to see more discussion on the correct frequency thread.
We need to resolve something as I now find myself explaining where
I'll really be listening and xmitting on every sked.

I personally am in favor of tuning the radio to the actual sked
frequency and expecting the tone to be above that frequency. It
seems to me that if you can expect someone to put a note zero beat
with a freq they can just as easily put it 1500/2000Hz above a
frequency. With most OPs using audio xmitted CW it seems simple to
go to the actual sked frequency and then xmit a tone on USB that
will be above that frequency.

That's describing it in a pretty complicated way; and besides, it's not the
way it works!!

Consider when you whistle into your microphone at pitch A: the receiver must
be tuned to the same frequency as the transmitter to receive the whistle at
pitch A, NOT above the transmitted frequency!

So if you key a tone into the mike jack, it's exactly the same: you will
receive the tone at the correct frequency only when the receiver is tuned to
the same frequency as the transmitter.

But in OUR case, we adjust our receivers to put the tone at the frequency
that our recording method requires. For example, with SBMS, you need to
record at a high tone pitch since there is no downconverter function and
thus, the tone frequency gets divided by the same ratio as the playback
speed; the same is true of using a simple analog or digital tape recorder
with no downconverter. With the German DTR or MS_DSP, however, you can use
ANY tone pitch since both techniques have the ability to set the output tone
to whatever you want. So actually, with MS_DSP or the DTR, NEITHER the
actual transmitted/received frequency NOR the recorded tone pitch are
relevant since you purposely adjust the actual output tone frequency for
whatever you want to listen to.

   To me it just makes sense that when
   a sked is being run on .110 that you tune to .110. Without discussion
   of the subject four out of five of my sked partners have assumed the
   above method. So to me this method seems a bit more intuitive.

The ONLY reason this whole issue came up in the first place was because a
few of us remembered that SOME radios shift the frequency readout between CW
and SSB; and we were concerned whether that meant we also had to shift the
VFO to account for that fact (oh yes: there was another reason, too: what
happened when one station was actually keying the radio while the second
station used tone injection). 

It's rather simple to remember: on SSB, your dial reads the "zerobeat"
frequency. If your dial changes when you go into CW mode, then it is likely
that it is showing a "correction" so that when you tune in a CW tone at the
same frequency as, typically, your radio's sidetone, then your dial will
show the "zerobeat" frequency. The amount of shift that the readout shows is
not really important, but it should be about the same amount as your
sidetone frequency, whether your radio receives CW on USB or LSB.

BUT THE WHOLE ISSUE IS IRRELEVANT WHEN YOU USE A KEYED TONE TO YOUR MIKE JACK!!

  So far only four people have commented on the subject. Two on each
  side of the issue. Alf, with Eu HSCW experience, was in favor of
  being zero beat on the sked frequency, I believe. He certainly has
  more experience that I.

I saw his comments and was confused by them; personally, I need more time to
consider what he's saying before comment.

  Can we get some more discussion. Comments from others. Perhaps it
  doesn't really matter and we should just vote and pick one. What
  do you think?????????????

I think we should, again, emulate the Europeans, who never seem to mention
the issue: It is NOT an issue with keyed tones!

If anyone still thinks that it IS, then please answer ONE relevant question
for me: how come NO EMEers ever mention it when setting skeds?? After all,
moonbounced signals are FAR weaker than the pings/bursts that we hear, and
they HAVE to be within a few hundred hertz of the other guy/gal or they may
not ever find him/her. This is why the popularity of AF9Y's FFTDSP; it shows
you exactly where that super-weak signal really is so you can tune it in
with all of your filters in-line.

73, Steve Ko0U/1


At 10:30 AM 8/29/97 -0700, Alf wrote:

  If you are making a CW sked, one publishes the actual frequency, not one
  2kHz lower. Why should HSMS be any different? 

No, one publishes the frequency at which one sets his DIAL! Why? Because
that is the same frequency at which the other op will set his dial when he
receives your CW at the same pitch. The ONLY exception, and one which is
almost NEVER accounted for, is when one radio or the other does NOT correct
the dial readout between CW/SSB. Then, that radio is indicating the actual
"zerobeat" frequency, and the OWNER of that radio has to make allowances for
that fact.

Look at it this way: almost all of us like to listen to CW at a pitch
somewhere between 500 and 1000 Hz (EMEers may like it lower, or even MUCH
lower). Manufacturers have, for some time now, designed their radios so that
you do not have to change your dial in order to hear someone else on CW at
the same pitch as your own sidetone. But in reality, your actual frequency
HAS been shifted...by the amount of your sidetone.

See my other missive in response to Jay for my reasoning on not having to
discuss tone frequency when using keyed tones into the mike jacks.

In the special case of one op using keyed tones while the other op uses
direct CW keying, THEN there is the possibility of considerable offset
between the two radios. Assume, for example, that the injected tone is 1
kHz, while the offset of the keyed radio is 800 Hz (the amount of the
sidetone, and thus the built-in shift by the manufacturer). I bet only a
pair of very careful observers will note that the two signals happen to be
200 Hz apart in frequency!

Now, say the keyed tone is actually 2 kHz (that guy/gal intends to go like a
bat outta hell at 2500+ lpm!), while the other radio is still being
CW-keyed; then there will be a 1200 Hz difference in frequency which will be
rather noticeable to everybody!

This is what happened to myself and W8WN when he first started using MS_DSP
0.41 while I was still keying my radio directly. But it didn't take me long
to find Shel's signal, as loud as he usually is!

73, Steve Ko0U/1







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