Can anyone direct me to some good understandable references on single
sideband frequency modulation? I have no real practical reason for
wanting to know about this. It is interesting to me in a "mathetical"
sort of way. Of course, that is dangerous for me because my brain gets
very stubborn when I try to do math. Such ideas as "negative
frequency" kind of send my mental faculties into total shutdown.

But I read schematic very well. It is a visual language I can usually
understand. Seems like years ago there was an article on SSB FM in Ham
Radio. That would probably be a good start. If anyone can send me a
copy of that article I would be much appreciative.

Thanks in advance

Bruce kk7zz

www.elmerdude.com

No such thing that I have ever heard of.
For an easy explanation of the modulation modes -- see URL:
http://www.williamson-labs.com/480_mod.htm

Perhaps you were thinking of commercial FM broadcasting -- there is a
baseband FM signal, a 19kHz pilot carrier, and a DSB suppressed signal at
38kHz.
All this yields stereo FM
Baseband is left plus right channel
the DSB signal is left minus right -- so after demodulation, adding them
gives Left and Right channels

--
73 From The KeyBoard In The Wilderness
"Bruce Kizerian" wrote in message
om...
Can anyone direct me to some good understandable references on single
sideband frequency modulation? I have no real practical reason for
wanting to know about this. It is interesting to me in a "mathetical"
sort of way. Of course, that is dangerous for me because my brain gets
very stubborn when I try to do math. Such ideas as "negative
frequency" kind of send my mental faculties into total shutdown.

But I read schematic very well. It is a visual language I can usually
understand. Seems like years ago there was an article on SSB FM in Ham
Radio. That would probably be a good start. If anyone can send me a
copy of that article I would be much appreciative.

Thanks in advance

Bruce kk7zz

www.elmerdude.com

No such thing that I have ever heard of.
For an easy explanation of the modulation modes -- see URL:
http://www.williamson-labs.com/480_mod.htm

Perhaps you were thinking of commercial FM broadcasting -- there is a
baseband FM signal, a 19kHz pilot carrier, and a DSB suppressed signal at
38kHz.
All this yields stereo FM
Baseband is left plus right channel
the DSB signal is left minus right -- so after demodulation, adding them
gives Left and Right channels

--
73 From The KeyBoard In The Wilderness
"Bruce Kizerian" wrote in message
om...
Can anyone direct me to some good understandable references on single
sideband frequency modulation? I have no real practical reason for
wanting to know about this. It is interesting to me in a "mathetical"
sort of way. Of course, that is dangerous for me because my brain gets
very stubborn when I try to do math. Such ideas as "negative
frequency" kind of send my mental faculties into total shutdown.

But I read schematic very well. It is a visual language I can usually
understand. Seems like years ago there was an article on SSB FM in Ham
Radio. That would probably be a good start. If anyone can send me a
copy of that article I would be much appreciative.

Thanks in advance

Bruce kk7zz

www.elmerdude.com

Thanks everyone

Sometimes I really get curious and want to know about something.

I haven't seen the Ham Radio article, but I'm thinking if the whole
idea had any merit it would be a popular mode by now.

Bruce kk7zz

www.elmerdude.com

Sometimes I really get curious and want to know about something.

I haven't seen the Ham Radio article, but I'm thinking if the whole
idea had any merit it would be a popular mode by now.

Bruce-

It has been about 35 years since I had a class in school where SSB-FM was
discussed. I recall that if you derive the equations for both AM and FM SSB,
they are identical for practical purposes if the FM signal has low deviation
(low modulation index?).

Looking at Two Meter FM, the deviation typically peaks at about 5 KHz. If you
listen to your local repeater with an SSB rig such as the IC-706, it will be
obvious that it isn't a clean signal! However, a 3 KHz deviation FM signal on
HF (below 29 MHz) will sound much cleaner when tuned as SSB, and you may not
notice it isn't AM-SSB.

With this in mind, consider that AM-SSB and FM-SSB might just be two ways to
generate an SSB signal, assuming you use a filter to eliminate the carrier and
other sideband.

By the way, an IC-706, especially one with the TCXO, often has a more accurate
frequency read-out than a typical Two Meter rig. Therefore you can use it to
check a repeater's frequency by tuning it as if it were an SSB station while
someone is speaking. It is easy enough to check the IC-706 against WWV on HF.

73, Fred, K4DII

Fred McKenzie wrote:
It has been about 35 years since I had a class in school where SSB-FM was
discussed. I recall that if you derive the equations for both AM and FM
SSB, they are identical for practical purposes if the FM signal has low
deviation (low modulation index?).

You're probably thinking of AM vs. narrow band FM. Although the equations
look very similar on paper and the MAGNITUDE spectrum is identical, the
phase spectrum is different in that -- in the phasor domain -- AM always
sits at 0 degrees and just grows and shrinks with modulation (overmodulation
pushes it over to 180 degrees, BTW). NBFM, on the other hand, still has the
carrier at 0 degrees but grows and shrinks along the imaginary axis. Hence
the angle of the phasor is small but time-varying (which implies that the
instantaneous frequency is varying as well -- but of course you already knew
that since we called this whole mess 'frequency modulation'). The angle is
about 15 degrees for a modulation index of 0.3 (what my notes claim as a
good cutoff for NBFM) and about 5 degrees at 0.1.

See the message I posted earlier tonight for a discussion of whether or not
you can recover NBFM with an envelope detector as of course one often does
with AM (the difficulty is due to that phasor's wiggling...). I think not,
but there's plenty I don't have a clue about... yet!

What's the modulation index on two meters anyway?

---Joel Kolstad
....who does know that a wideband FM receiver has no problem whatsoever
receiving NBFM...

Looking at Two Meter FM, the deviation typically peaks at about 5 KHz.
If you listen to your local repeater with an SSB rig such as the IC-706,
it will be obvious that it isn't a clean signal! However, a 3 KHz
deviation FM signal on HF (below 29 MHz) will sound much cleaner when
tuned as SSB, and you may not notice it isn't AM-SSB.

You're probably thinking of AM vs. narrow band FM. Although the equations
look very similar on paper and the MAGNITUDE spectrum is identical, the
phase spectrum is different

Joel-

Perhaps that is what I'm remembering. Now, if you use a filter to eliminate
the other sideband, the higher frequency components and the carrier, don't you
have a nearly identical remainder?

See the message I posted earlier tonight for a discussion of whether or not
you can recover NBFM with an envelope detector

Somehow I missed that one. It seems that AOL does not post messages in the
order in which they were originated!

I think we are in agreement that you can't recover FM modulation with just an
envelope detector, but there is another approach. Again, you need a filter,
but maybe one that is not as sharp as above. If you tune the radio so the
carrier is just outside the passband, an amplitude variation will occur as the
signal slides up and down the shoulder of the filter. The result is a pseudo
AM signal that is detected by the envelope detector. I recall that this
approach is called "slope detection".

73, Fred, K4DII

Fred McKenzie wrote:
Perhaps that is what I'm remembering. Now, if you use a filter to
eliminate the other sideband, the higher frequency components and the
carrier, don't you have a nearly identical remainder?

At that point I don't think you could tell the difference since there's no
longer any local phase reference (i.e., the carrier) to compare with. I
suppose this is why your SSB-AM rig is able to (somewhat) receive low
frequency (and thereby presumably narrowband) FM broadcasts; this is what
you were saying in your last post, correct?

I think we are in agreement that you can't recover FM modulation with
just an envelope detector

Yes, at least you can't recover a signal that directly corresponds to what
you transmitted. It does appear that you can recover the signal's square,
however, so this approach might be useful for, e.g., remote command
transmissions. (But probably just for the novelty of having said you did
it... since it's probably not much harder to build the slope detector you
describe!)

---Joel

Fred McKenzie wrote:
Perhaps that is what I'm remembering. Now, if you use a filter to
eliminate the other sideband, the higher frequency components and the
carrier, don't you have a nearly identical remainder?

At that point I don't think you could tell the difference since there's no
longer any local phase reference (i.e., the carrier) to compare with. I
suppose this is why your SSB-AM rig is able to (somewhat) receive low
frequency (and thereby presumably narrowband) FM broadcasts; this is what
you were saying in your last post, correct?

I think we are in agreement that you can't recover FM modulation with
just an envelope detector

Yes, at least you can't recover a signal that directly corresponds to what
you transmitted. It does appear that you can recover the signal's square,
however, so this approach might be useful for, e.g., remote command
transmissions. (But probably just for the novelty of having said you did
it... since it's probably not much harder to build the slope detector you
describe!)

---Joel

You're probably thinking of AM vs. narrow band FM. Although the equations
look very similar on paper and the MAGNITUDE spectrum is identical, the
phase spectrum is different

Joel-

Perhaps that is what I'm remembering. Now, if you use a filter to eliminate
the other sideband, the higher frequency components and the carrier, don't you
have a nearly identical remainder?

See the message I posted earlier tonight for a discussion of whether or not
you can recover NBFM with an envelope detector

Somehow I missed that one. It seems that AOL does not post messages in the
order in which they were originated!

I think we are in agreement that you can't recover FM modulation with just an
envelope detector, but there is another approach. Again, you need a filter,
but maybe one that is not as sharp as above. If you tune the radio so the
carrier is just outside the passband, an amplitude variation will occur as the
signal slides up and down the shoulder of the filter. The result is a pseudo
AM signal that is detected by the envelope detector. I recall that this
approach is called "slope detection".

73, Fred, K4DII