On Tue, 04 Oct 2005 10:39:59 GMT, (Peter Newman)
said in rec.radio.scanner:

On 29 Sep 2005 21:18:12 -0700, wrote:

there has to be some other modes that normal scanners wouldn't decode.
any thoughts?

ISB, DSB ?

Any receiver that will receive SSB will also receive DSB, since both
sidebands are the same. ISB too, but only 1 at a time.

On Wed, 05 Oct 2005 21:18:23 -0400, Al Klein
wrote:

On Tue, 04 Oct 2005 10:39:59 GMT, (Peter Newman)
said in rec.radio.scanner:

On 29 Sep 2005 21:18:12 -0700, wrote:

there has to be some other modes that normal scanners wouldn't decode.
any thoughts?

ISB, DSB ?

Any receiver that will receive SSB will also receive DSB, since both
sidebands are the same. ISB too, but only 1 at a time.
Only if the IF is narrow enough to keep the other sideband out,
otherwise you get both at once.....

On Thu, 06 Oct 2005 20:37:32 -0700, matt weber
said in rec.radio.scanner:

On Wed, 05 Oct 2005 21:18:23 -0400, Al Klein
wrote:

On Tue, 04 Oct 2005 10:39:59 GMT, (Peter Newman)
said in rec.radio.scanner:

On 29 Sep 2005 21:18:12 -0700, wrote:

there has to be some other modes that normal scanners wouldn't decode.
any thoughts?

ISB, DSB ?

Any receiver that will receive SSB will also receive DSB, since both
sidebands are the same. ISB too, but only 1 at a time.
Only if the IF is narrow enough to keep the other sideband out,
otherwise you get both at once.....

A SSB receiver is one that has a bandwidth narrow enough to receive
only 1 sideband. If it's 6 KHz wide it's a DSB receiver. (Yes,
almost any ham receiver is either SSB or DSB, depending on the filter
you have running at the moment.)

Of course finding DSBSC signals on the air today is a bit difficult.
(They used to be much more prevalent, but ARC5s are expensive antiques
today, not cheap transmitters. And is there still 1 operational
DSB-100?)

Al Klein wrote:

On Thu, 06 Oct 2005 20:37:32 -0700, matt weber
said in rec.radio.scanner:

On Wed, 05 Oct 2005 21:18:23 -0400, Al Klein
wrote:

On Tue, 04 Oct 2005 10:39:59 GMT, (Peter Newman)
said in rec.radio.scanner:

On 29 Sep 2005 21:18:12 -0700, wrote:

there has to be some other modes that normal scanners wouldn't decode.
any thoughts?

ISB, DSB ?

Any receiver that will receive SSB will also receive DSB, since both
sidebands are the same. ISB too, but only 1 at a time.
Only if the IF is narrow enough to keep the other sideband out,
otherwise you get both at once.....

A SSB receiver is one that has a bandwidth narrow enough to receive
only 1 sideband. If it's 6 KHz wide it's a DSB receiver. (Yes,
almost any ham receiver is either SSB or DSB, depending on the filter
you have running at the moment.)

Of course finding DSBSC signals on the air today is a bit difficult.
(They used to be much more prevalent, but ARC5s are expensive antiques
today, not cheap transmitters. And is there still 1 operational
DSB-100?)

You can't assume that any filter over 3kHz or so is symetrical about the
'carrier' frequency just because that is the normal configuation of consumer
equipment.

Just for fun I am currently listening to an LSB conversation on 3763 kHz with
a 7.5 kHz filter and I cannot hear any sign of the conversation on 3765 - but,
the noise is a bit higher due to the wider filter. I wouldn't normally do this
but just had to try it. Of course, if I select DSB or ISB I get both signals,
although the 3765 conversation is inverted and shifted in frequency.

I don't know how much DSB is still on the air but a quick google search for
"double side band' gets over 12 million hits. It may not be encountered in
normal voice communications on HF and scanner frequencies but it is hiding in
other places and frequencies from a quick look at some of the hits.

Dave

On Sat, 08 Oct 2005 21:17:44 -0400, Dave Holford
said in rec.radio.scanner:

You can't assume that any filter over 3kHz or so is symetrical about the
'carrier' frequency just because that is the normal configuation of consumer
equipment.

You can't assume that any given SSB signal will fit in a 3 KHz
bandwidth, just because all current signals do.

But I can assume that all filters currently in production are
symmetrical about the center frequency within 10% - because they all
are.

Just for fun I am currently listening to an LSB conversation on 3763 kHz with
a 7.5 kHz filter and I cannot hear any sign of the conversation on 3765 - but,
the noise is a bit higher due to the wider filter. I wouldn't normally do this
but just had to try it. Of course, if I select DSB or ISB I get both signals,
although the 3765 conversation is inverted and shifted in frequency.

With what receiver and which filter? What kind of detector? I can
design any number of receivers that will do what you claim, but that
doesn't negate the fact that the standard filtered superhet SSB
receiver will receive a signal on the "wrong" sideband if the filter
is wide enough and the detector is set correctly.

I don't know how much DSB is still on the air but a quick google search for
"double side band' gets over 12 million hits. It may not be encountered in
normal voice communications on HF and scanner frequencies but it is hiding in
other places and frequencies from a quick look at some of the hits.

I said DSBSC, not DSB. There's loads of DSB on the air today, it's
just not DSBSC.

Al Klein wrote:

On Sat, 08 Oct 2005 21:17:44 -0400, Dave Holford
said in rec.radio.scanner:

You can't assume that any filter over 3kHz or so is symetrical about the
'carrier' frequency just because that is the normal configuation of consumer
equipment.

You can't assume that any given SSB signal will fit in a 3 KHz
bandwidth, just because all current signals do.

But I can assume that all filters currently in production are
symmetrical about the center frequency within 10% - because they all
are.


Certainly most current crystal filters are symmetrical about the centre frequency,
as are most people symmetrical about the centre (externally at least, and I'm not
going to quibble about the orientation since I'm sure you know what I mean) - I
wrote 'carrier' frequency.

I'm not sure about current mechanicals (somewhere I have an old Collins filter
catalog with asymmetrical SSB curves).



Just for fun I am currently listening to an LSB conversation on 3763 kHz with
a 7.5 kHz filter and I cannot hear any sign of the conversation on 3765 - but,
the noise is a bit higher due to the wider filter. I wouldn't normally do this
but just had to try it. Of course, if I select DSB or ISB I get both signals,
although the 3765 conversation is inverted and shifted in frequency.

With what receiver and which filter? What kind of detector? I can
design any number of receivers that will do what you claim, but that
doesn't negate the fact that the standard filtered superhet SSB
receiver will receive a signal on the "wrong" sideband if the filter
is wide enough and the detector is set correctly.


As I stated in my first posting, a Winradio.

The rest of the paragraph is true if you are talking about 'the standard filtered
superhet SSB receiver' provided that it is also fitted with AM filters which can be
used in the SSB mode - not universally true. I can do it with my TS-450 but not my
IC-706 for example. Not all receivers have the ability to select mode and filter
independently.



I don't know how much DSB is still on the air but a quick google search for
"double side band' gets over 12 million hits. It may not be encountered in
normal voice communications on HF and scanner frequencies but it is hiding in
other places and frequencies from a quick look at some of the hits.

I said DSBSC, not DSB. There's loads of DSB on the air today, it's
just not DSBSC.

True, my mistake in assuming DSBRC or DSBSC.

Here I am trying to make a simple point that one should not assume that just
because a situation is common in one's own experience it is universal; and I make
an assumption - Hoist with my own Petard!

And, I can't help noting how a simple point can grow into a complex discussion of
differing views - I guess that's how politics and the law got started!

Dave

On Sun, 09 Oct 2005 10:50:22 -0400, Dave Holford
said in rec.radio.scanner:

Al Klein wrote:

But I can assume that all filters currently in production are
symmetrical about the center frequency within 10% - because they all
are.

Certainly most current crystal filters

Mechanical filters, ceramic filters, lumped-constant filters, op-amp
filters ... any discrete piece of hardware that's supposed to pass a
band of frequencies in the IF of a modern (within the last 40 years or
so) receiver.

are symmetrical about the centre frequency,
as are most people symmetrical about the centre (externally at least, and I'm not
going to quibble about the orientation since I'm sure you know what I mean) - I
wrote 'carrier' frequency.

If you put the carrier (no need for tics - carrier whether suppressed
or not) at the center of the filter's bandpass, the filter is
symmetrical about the carrier - if you put the carrier outside the
bandpass of the filter are you going to claim that bandpass filters
don't pass signals? The filter is symmetrical about any signal
centered in the bandpass if the filter has a symmetrical bandpass - by
definition.

I'm not sure about current mechanicals (somewhere I have an old Collins filter
catalog with asymmetrical SSB curves).

Within 10%? None of mine were ever that distorted, although some of
the Collins filters were about the most asymmetrical filters I've ever
seen. They were designed that way. But the receivers were designed
to work with "asymmetrical" filters.

Just for fun I am currently listening to an LSB conversation on 3763 kHz with
a 7.5 kHz filter and I cannot hear any sign of the conversation on 3765 - but,
the noise is a bit higher due to the wider filter. I wouldn't normally do this
but just had to try it. Of course, if I select DSB or ISB I get both signals,
although the 3765 conversation is inverted and shifted in frequency.

With what receiver and which filter? What kind of detector? I can
design any number of receivers that will do what you claim, but that
doesn't negate the fact that the standard filtered superhet SSB
receiver will receive a signal on the "wrong" sideband if the filter
is wide enough and the detector is set correctly.

As I stated in my first posting, a Winradio.

Oh, you mean that a DSP is capable of not hearing the opposite
sideband. Nothing to do with filters. "Filtering" isn't always done
by "filters".

The rest of the paragraph is true if you are talking about 'the standard filtered
superhet SSB receiver' provided that it is also fitted with AM filters which can be
used in the SSB mode - not universally true. I can do it with my TS-450 but not my
IC-706 for example. Not all receivers have the ability to select mode and filter
independently.

And my Honda can't receive ISB either. If we're comparing fruits,
chickens don't count.

On Sun, 09 Oct 2005 10:50:22 -0400, Dave Holford
wrote:

With what receiver and which filter? What kind of detector? I can
design any number of receivers that will do what you claim, but that
doesn't negate the fact that the standard filtered superhet SSB
receiver will receive a signal on the "wrong" sideband if the filter
is wide enough and the detector is set correctly.


As I stated in my first posting, a Winradio.


Yes, the WinRadio G303 and G313 appear to be the only commercially
available eceivers with genuine ISB and DSB modes. The DSB is actually
so good that you can receive standard AM with it and can hardly hear
any difference (i.e. the digital BFO inserts the carrier spot on
frequency, like with synchronous AM mode).

I did an interesting experiment with my G303e/PD by using stereo
speakers in DSB mode on an AM broadcast station, and you can actually
hear a phase difference variation between the two sidebands. This
causes an amazing "floating in space" audio sensation.

Peter