CW / CW Reverse

CW / CW Reverse

Post by CJ » Mon, 21 Feb 2000 04:00:00

Does anyone know where the concept that CW is "normal" when tuned LSB
style, i.e. pitch increases as one tunes higher in frequency, and
"reversed" when tuned USB style?

I ask the question because my own operating preference has always been
for the "reversed" tuning. I do a fair amount of VHF/UHF weak signal
operating where it is important to be able to switch between USB and CW
with an absolute minimum of retuning at either end of the contact. In
addition, although my memory may be faulty, I am quite certain that I
always tuned CW that way -- even back in the days when it didn't make
much difference because I didn't have a receiver with good enough
selectivity to make much of a difference. And when I got more modern
equipment, it was Yaesu and it tuned my way.

Then I encountered ICOM and Kenwood equipment that sometimes couldn't be
made to tune CW USB style or didn't work as well when it could. I
remember once seeing a rather involved modification for a TS-700, I
think it was, to make it do CW USB style.

Well, this is not earth shattering and I hope I don't start another
endless thread, but if you think you know I'd like to hear from you.
Maybe its just various Japanese engineers' whims.

73, CJ K0CJ

 
 
 

CW / CW Reverse

Post by N4BU » Tue, 22 Feb 2000 04:00:00


I have a question of a similar nature.  I've never understood why USB signals
seem to be on the "lower" side of the signal and the opposite is true of LSB
signals.  In other words, when I tune away from a USB signal (Donald Duck's
voice gets higher pitched), I am tuning down in frequency and the reverse is
true of LSB.  It would seem that when I'm listening to USB, tuning "up" in
frequency would cause the pitch to get higher and higher.

Am I confusing the pitch of the sound of the voice with the "direction" I'm
tuning?  Perhaps this is a silly question, but I've not been able to resolve
this seeming paradox yet.

73,

Barry - N4BUQ

Quote:>Does anyone know where the concept that CW is "normal" when tuned LSB
>style, i.e. pitch increases as one tunes higher in frequency, and
>"reversed" when tuned USB style?

>I ask the question because my own operating preference has always been
>for the "reversed" tuning. I do a fair amount of VHF/UHF weak signal
>operating where it is important to be able to switch between USB and CW
>with an absolute minimum of retuning at either end of the contact. In
>addition, although my memory may be faulty, I am quite certain that I
>always tuned CW that way -- even back in the days when it didn't make
>much difference because I didn't have a receiver with good enough
>selectivity to make much of a difference. And when I got more modern
>equipment, it was Yaesu and it tuned my way.

>Then I encountered ICOM and Kenwood equipment that sometimes couldn't be
>made to tune CW USB style or didn't work as well when it could. I
>remember once seeing a rather involved modification for a TS-700, I
>think it was, to make it do CW USB style.

>Well, this is not earth shattering and I hope I don't start another
>endless thread, but if you think you know I'd like to hear from you.
>Maybe its just various Japanese engineers' whims.

>73, CJ K0CJ

 
 
 

CW / CW Reverse

Post by VA2PTC, Eri » Tue, 22 Feb 2000 04:00:00

AM signal is composed of tree part : two sides bands and a carrier.
Generally, AM signal is present as an frequency who you simply vary the
"power" level (sorry to cutoff tech's words).

In real world, your voice is compose of mix of many many freq combine
together to make your natural sound.  Low, med and high pitch notes.  AM
generate a carrier (tunning freq) and two frequency band (your voice) each
side of the carrier.  The Lower band part is similar to the upper band part.
50% of the transmit power is consume by carrier each band consume 25% of the
transmitted power.

If you filter out the carrier you have DSB (double side band) and if you
filter out one band you've get single side band then put all you precious
watts in this single part.  Note : the upper band is similar to lower side
band (mirror copy).  In SSB you put all the power to the message and nothing
to the carrier.

The receiver have to "decode" the signal by regenarating the AM.  First you
inject the carrier (tunning the receiver) into the SSB and make a duplicate
of de Side band.  With this regenarate AM you put it in a AM receiving part
Voil ! voice again

In USB if you raise the tunning freq, the receiver made a copy of "reduced"
band = cave sound.  Since you made a "copy line"  (injected carrier) highier
then needed, you chop a part of the signal.  One part is over the copy line
and one part is under the copy line. (The needed copy line must be under the
entire USB message to make a complete copy of the USB + LSB)

The part over this "copy line" is shifted down in freq and the part under
the "copy line" will substract itself to the copy result.

When you lower the tunning freq, you have all the massage but you "push it"
far of the carrier in the high pitch note make a hole in the lower voice
note.

In LSB, you have similar but reverse effect

In CW, the voice message is composed of one frequency (the tone).  In USB,
tunning up made the copy line close of the CW tone ; lower the tone and
lowering the tunning lower the copy line then raising the tone.  Mirror
effect in LSB

I hope it,s may help
--
Eric, VA2PTC
Jonquire, Qubec

(418) 695-4619 tl et fax
Pour m'crire:
retirez le mot JUNK de mon adresse e-mail

 
 
 

CW / CW Reverse

Post by N4BU » Wed, 23 Feb 2000 04:00:00

Eric,
Thanks for the detailed reply.  This certainly gives me something to think
about.  Does this explanation hold true for product detectors?

Thanks,

Barry - N4BUQ

>AM signal is composed of tree part : two sides bands and a carrier.
>Generally, AM signal is present as an frequency who you simply vary the
>"power" level (sorry to cutoff tech's words).

>In real world, your voice is compose of mix of many many freq combine
>together to make your natural sound.  Low, med and high pitch notes.  AM
>generate a carrier (tunning freq) and two frequency band (your voice) each
>side of the carrier.  The Lower band part is similar to the upper band part.
>50% of the transmit power is consume by carrier each band consume 25% of the
>transmitted power.

>If you filter out the carrier you have DSB (double side band) and if you
>filter out one band you've get single side band then put all you precious
>watts in this single part.  Note : the upper band is similar to lower side
>band (mirror copy).  In SSB you put all the power to the message and nothing
>to the carrier.

>The receiver have to "decode" the signal by regenarating the AM.  First you
>inject the carrier (tunning the receiver) into the SSB and make a duplicate
>of de Side band.  With this regenarate AM you put it in a AM receiving part
>Voil ! voice again

>In USB if you raise the tunning freq, the receiver made a copy of "reduced"
>band = cave sound.  Since you made a "copy line"  (injected carrier) highier
>then needed, you chop a part of the signal.  One part is over the copy line
>and one part is under the copy line. (The needed copy line must be under the
>entire USB message to make a complete copy of the USB + LSB)

>The part over this "copy line" is shifted down in freq and the part under
>the "copy line" will substract itself to the copy result.

>When you lower the tunning freq, you have all the massage but you "push it"
>far of the carrier in the high pitch note make a hole in the lower voice
>note.

>In LSB, you have similar but reverse effect

>In CW, the voice message is composed of one frequency (the tone).  In USB,
>tunning up made the copy line close of the CW tone ; lower the tone and
>lowering the tunning lower the copy line then raising the tone.  Mirror
>effect in LSB

>I hope it,s may help
>--
>Eric, VA2PTC
>Jonquire, Qubec

>(418) 695-4619 tl et fax
>Pour m'crire:
>retirez le mot JUNK de mon adresse e-mail

 
 
 

CW / CW Reverse

Post by Bubb » Fri, 25 Feb 2000 04:00:00

I think the easy answer is that in the old days cw receivers just injected
the BFO on the low side and 'walla!' a standard was decided -- newer rigs
just copied the convention.  As you say, it really doesn't matter which side
you inject the BFO, it just affects the apparent frequency of the tuned
signal.

cheers


> Does anyone know where the concept that CW is "normal" when tuned LSB
> style, i.e. pitch increases as one tunes higher in frequency, and
> "reversed" when tuned USB style?

> I ask the question because my own operating preference has always been
> for the "reversed" tuning. I do a fair amount of VHF/UHF weak signal
> operating where it is important to be able to switch between USB and CW
> with an absolute minimum of retuning at either end of the contact. In
> addition, although my memory may be faulty, I am quite certain that I
> always tuned CW that way -- even back in the days when it didn't make
> much difference because I didn't have a receiver with good enough
> selectivity to make much of a difference. And when I got more modern
> equipment, it was Yaesu and it tuned my way.

> Then I encountered ICOM and Kenwood equipment that sometimes couldn't be
> made to tune CW USB style or didn't work as well when it could. I
> remember once seeing a rather involved modification for a TS-700, I
> think it was, to make it do CW USB style.

> Well, this is not earth shattering and I hope I don't start another
> endless thread, but if you think you know I'd like to hear from you.
> Maybe its just various Japanese engineers' whims.

> 73, CJ K0CJ