Michael Black wrote:
) writes:
Michael Black wrote:

I glanced at it and maybe missed something, but DSB is AM. And
he certainly says it at the outset, and when he's talking about the
components he's talking about 2 sidebands and a carrier.

Now, "DSB" often has fallen into the meaning of "DSB with no carrier",
but technically one should specifically define that there is no carrier.
snip
Michael

Back in 1972 when I took my FFC 2nd and 1st class exams DSB was defined
as the sidebands with a supressed carrier. A signal with both sidebands
and the
carrier was simply AM with a BW disgnator. .Now that diffintion may
have slipped
over the years, but from my perspective AM means both sidebands, with a
carier
DSB means both sidebands without the carrier, and ISB means two
different
sidebands with no carrier. I only have received the later, ISB, a very
few times
mainly on ancient STL links.

It might be useful to check out what the ITU says these days about
"AM", both sidebands with carrier", and for this conversation, "DSB"
being both sidebands without the carrier.

Terry

Are you arguing semantics, or understanding?

It is not sematics, but generally agreed upon definitions.

The post I replied to was almost outraged by that PDF's useage of "DSB".
I couldn't figure out whether he was just fussing over words (and thus
why was he so outraged?), or really does believe that DSB is not AM.

Because people have become sloppy about the words, some of all
these conversations about "better AM detectors" is limited. Because
people are searching for something that really isn't all that different
from what's already available. That PDF talks in terms of how
synchronous detectors get too much hype, yet the author turns around
and uses everything a "synchronous detector" has except the actual
synchronization. But the synchronization isn't actually what provides
the potentially improved reception, it's just a means of compensating
for some side effects.

I never got around to replying, but a few months ago someone started
a thread here where he stated something like "So I gather the carrier
is more likely to fade when selective fading is happening". I haven't
a clue whether the carrier is more likely to fade than the sidebands, but
once the carrier fades in relationship to the sidebands you're going to
start having reception problems, and once the carrier completely fades
you won't be able to recover the modulation. The carrier is the key
part to demodulation. But a more universal understanding of "amplitude
modulation" would show right away that you can't demodulate a DSB
signal unless a carrier is sent along, or generated locally at the receiver
end, and selective fading can mean that a DSBc signal sent from the
transmitter may be a DSBsc (Double SIdeband suppressed carrier) by the
time it reaches the receiver.

So in this sort of talk, you'd better start being specific about what
you are talking about. Since DSB (with or without a carrier) and
SSB (with or without a carrier) are "AM", then you really need to
stop using "AM" to only mean DSBc.

Hence DSB in the PDF is more descriptive than AM. Is he confused?
I don't think so. In his opening paragraph he says "Note: DSB (Double
Sideband full-carrier) and SSB (single sideband suppressed carrier) are
both amplitude modulation". He defines the term as he is about to
use them, so there is no confusion. He needs to use the DSB rather
than a more generic "AM" because he is very much thinking in terms
of two sidebands (even if he turns around and removes one). The
fact that there are two sidebands rather than one may be more significant
than whether or not there is a carrier.

Since he defined his terms to begin with, any subsequent useage of
"DSB" is taken care of. But, again, even if that was not the case,
his useage is fine, because whether or not a carrier is sent is
irrelevant to his discussion. It's easy to get a locally generated
"carrier", and if it's just one sideband it's done all the time, with
a bit of mistuning. But with two sidebands, it's far harder. Hence
you can either determine where the locally generated carrier needs to
be from the the redundant sidebands, or strip off one sideband so it
becomes SSB and placing the carrier becomes much easier.

Maybe he should have gone with DSBc to show that he is talking about
a DSB signal with carrier, but that is hardly a confusion of AM and DSB.

As for common useage of so many of these terms, nobody had to specify
how many sidebands and whether a carrier went with it until they
started to use a subset of that stuff. Look in early articles about
SSB and it was pretty common for them to be most specific, ie SSBsc (SSB
suppressed carrier). It's only later that it simply became SSB. Nobody
really thought of sending DSB without a carrier until SSB came along,
and there too it was not uncommon to see it referred to as DSBsc.

I just don't buy the argument that nobody thought about DSB. DSB is
naturally generated from a mixer if the audio signal is zero mean.
[Again, it is best to talk about modulation schemes by discussion
modulators.] Remember, AM exists because the demod is cheaper, not
because it is any easier to generate that say DSB. AM and DSB use the
same hardware.

Michael

To get to the meat of the problem, the only utility in any of these
demod schemes is if you can narrow band the signal. That is, just
because you can build a demodulator that can use both sidebands without
need of the carrier, it doesn't mean the quality of the signal will be
any better. Wider bandwidth signals are more prone to atmospheric
effects, i.e. fading. Thus if you are going to do synchronous
detection, you need to receive one side band, period.

Brenda Ann wrote:
wrote in message
ups.com...

wrote:
Michael Black wrote:

I glanced at it and maybe missed something, but DSB is AM. And
he certainly says it at the outset, and when he's talking about the
components he's talking about 2 sidebands and a carrier.

Now, "DSB" often has fallen into the meaning of "DSB with no carrier",
but technically one should specifically define that there is no
carrier.
snip
Michael

Back in 1972 when I took my FFC 2nd and 1st class exams DSB was defined
as the sidebands with a supressed carrier. A signal with both sidebands
and the
carrier was simply AM with a BW disgnator. .Now that diffintion may
have slipped
over the years, but from my perspective AM means both sidebands, with a
carier
DSB means both sidebands without the carrier, and ISB means two
different
sidebands with no carrier. I only have received the later, ISB, a very
few times
mainly on ancient STL links.

No arguments from me. That was how I was taught in college, though ISB
was never a topic.


ISB (with carrier) has been around for a while. It was used in one of the
original AM Stereo experiments. I believe it was Kahn that was using it. The
only station I know of personally that used it commercially was XETRA, and
it actually didn't do too badly, but you needed either a special receiver or
two radios to tune the two sidebands to receive stereo. It was not a
compatible system though in the sense that on a single standard AM radio,
you only heard the channel (perhaps with some spillover depending on tuning)
that the radio was designed to demodulate.

When you study communications in a university, it tends to be pure
theory rather than some specific protocol. While this seems
counter-intuitive, understanding the theory means you can figure out
some proprietary standard when the time comes. The only exceptions that
come to mind would be something like duobinary modulation, which I
think was a GTE patent, though it was treated as something generic. So
getting back to ISB, it never came up, though by your description it is
a matter of pulling out the sideband independently. So if you
understand SSB, ISB would follow.

On Sun, 03 Dec 2006 01:10:52 GMT, Telamon
wrote:


clarification.

Looks to me that acronym DSB does not define the carrier condition.
That's why the dash and more letters.
FCC EMISSION DESIGNATORS
Detailed List
Last Rev. 1998


WARC-79, the World Administrative Radio Conference that rewrote many
of the world's radio regulations, adopted a new system of emission
classification. The traditional A (Amplitude), F (Frequency), and P
(Pulse) was intuitive, but limited and clumsy when dealing with new
modes.

The world's radio bodies, including the FCC, gradually phased in the
new system until today it completely replaces the old one.

The formula for the new designations, loosely from ITU radio
regulations 264 through 273, and Appendix 6, Part A, is:

[BBBB]MNI[DM],

where

[] means optional when writing emission specs.


[BBBB] = Necessary Bandwidth (shown in FCC records, but is often
omitted elsewhere)

Uses a letter and three numbers. The letter goes where the decimal
point should be placed, and denotes a magnitude:

H Hz
K kHz
M MHz
G GHz

Some common bandwidths a

400 Hz 400H
2.4 kHz 2K40
12.5 kHz 12K5
6 MHz 6M00



M = Modulation Type

N None
A AM (Amplitude Modulation), double sideband, full carrier
H AM, single sideband, full carrier
R AM, single sideband, reduced or controlled carrier
J AM, single sideband, suppressed carrier
B AM, independent sidebands
C AM, vestigial sideband (commonly analog TV)

F Angle-modulated, straight FM
G Angle-modulated, phase modulation (common; sounds like FM)

D Carrier is amplitude and angle modulated

P Pulse, no modulation
K Pulse, amplitude modulation (PAM, PSM)
L Pulse, width modulation (PWM)
M Pulse, phase or position modulation (PPM)
Q Pulse, carrier also angle-modulated during pulse
W Pulse, two or more modes used

X All cases not covered above


N = Nature of modulating signal

0 None
1 Digital, on-off or quantized, no modulation
2 Digital, with modulation
3 Single analog channel
7 Two or more digital channels
8 Two or more analog channels
9 Composite, one or more digital channel, one or more analog

X All cases not covered above


I = Information type

N None
A Aural telegraphy, for people (Morse code)
B Telegraphy for machine copy (RTTY, fast Morse)
C Analog fax
D Data, telemetry, telecommand
E Telephony, voice, sound broadcasting
F Video, television
W Combinations of the above

X All cases not covered above


[DM] = additional details, not used by FCC, optional elsewhere

D = Detail


RTTY/modems:

A Two condition code, differing numbers or durations (Morse)
B Two condition code, same number and duration, no error check
C Two condition code, same num & dur, error check
D Four condition code, 1 or more bits per condition
E Multi condition code, 1 or more bits per condition
F Multi condition code, conditions may combine

Audio:

G Broadcast quality (mono)
H Broadcast quality (stereo/multichannel)
J Commercial quality
K Commercial quality, analog freq inversion or band scrambling
L Commercial quality, FM pilot tone (i.e. Lincomprex)

Video:

M Monochrome
N Color


W Combination

X All cases not covered above



M = Multiplex type

N None
C Code division
F Frequency division
T Time division
W Combination of above

X All other types



-----------------------------------------------------------------------


Converting Between Old & New Systems


-----------------------------------------------------------------------


USE OLD NEW

Pure carrier A0,F0 N0N
Morse telegraphy (by ear) A1 A1A
Modulated CW Morse A2 A2A
AM voice A3 A3E
SSB, suppressed carrier A3J J3E
SSB, reduced carrier A3R R3E
SSB, full carrier A3H H3E
Television A5 C3F

RTTY (F.S.K.) F1 F1B
RTTY (A.F.S.K.) F2 F2B
FM voice (Narrowband) F3 F3E, 20K0F3E


Packet Data/Teleprinters
with Audio Sub-Carrier 20F2 20K0F2B

Data with Audio Sub-carrier 3F2 3K00F2D
6F2 6K00F2D
20F2 20K0F2D

Analog Voice 20F3 20K0F3E

Digital Voice 20F3Y 20K0F1E

Digital Facsimile without
Audio Sub-Carrier 20F4 20K0F1C

Digital Facsimile with
Audio Sub-Carrier 20F4 20K0F2C

Analog Facsimile 20F4 20K0F3C

Composite of Digital &
Analog Information 3F9 3K00F9W
6F9 6K00F9W
20F9 20K0F9W

Packet Data/Teleprinters
without Audio Sub-Carrier 20F9Y 20K0F1B

Digital Data 20F9Y 20K0F1D



LAND MOBILE EMISSIONS MICROWAVE EMISSIONS
old new old new old new
A0 N0N P0 P0N F9 F8W (If bw is less than
A1 A1A P9 P0N 50 convert to F2D)
A3 A3E A2J J2B F9Y F7W (If bw is less than
A3J J3E A3H H3E 50 convert to F2D)
A7J J8W A9J J9W F3 F3E
A9 A9W P1 P1D A9Y A7W
A9Y A1D F2Y F2D A5 A3F
F0 N0N A0H H0N A9 A8W
F1 F1B A7 A8D A5C C3F
F2 F2D F7 F8D F2 F2D
F3 F3E F5 F3F
F3Y F1E
F4 F3C
F9 F9W
F9Y F1D
A2H H2D
A2 A2D


----------------------------------------------------------------------

And here is the relevant section of FCC rules:

----------------------------------------------------------------------




From General Docket No. 80-739

Section 2.201 Emission, modulation, and transmission characteristics.


The following system of designating emission, modulation, and
transmission characteristics shall be employed.

(a) Emissions are designated according to their classification and
their necessary bandwidth.

(b) A minimum of three symbols are used to describe the basic
characteristics of radio waves. Emissions are classified and
symbolized according to the following characteristics:

(1) First symbol - type of modulation of the main carrier;

(2) Second Symbol - nature of signal(s) modulating the main
carrier;

(3) Third symbol - type of information to be transmitted.

NOTE: A fourth and fifth symbol are provided for additional
information and are shown in Appendix 6, Part A of the ITU Radio
Regulations. Use of the fourth and fifth symbol is optional.
Therefore, the symbols may be used as described in Appendix 6,
but are not required by the Commission.

(c) First Symbol - types of modulation of the main carrier:

(1) Emission of an unmodulated carrier N

(2) Emission in which the main carrier is amplitude-
modulated (including cases where sub-carriers are angle
modulated):
- Double-sideband A
- Single-sideband, full carrier H
- Single-sideband, reduced or variable level carrier R
- Single-sideband, suppressed carrier J
- Independent sidebands B
- Vestigial sideband C

(3) Emission in which the main carrier is angle-modulated:
- Frequency modulation F
- Phase modulation G

NOTE: Whenever frequency modulation "F" is indicated,
Phase modulation "G" is also acceptable.

(4) Emission in which the main carrier is amplitude and
angle-modulated either simultaneously or in a pre-
established sequence D

(5) Emission of pulses:*
- Sequence of unmodulated pulses P
- A sequence of pulses:
- Modulated in amplitude K
- Modulated in width/duration L
- Modulated in position/phase M
- In which the carrier is angle-modulated during the
period of the pulse Q
- Which is a combination of the foregoing or is
produced by other means V

(6) Cases not covered above, in which an emission consists
of the main carrier modulated, either simultaneously or
in a pre-established sequence, a combination of two or
more of the following modes: amplitude, angle, pulse W

(7) Cases not otherwise covered X

*Emissions where the main carrier is directly modulated by a
signal which has been coded into quantizied form (e.g.,
pulse code modulation) should be designated under (2) or
(3).

(d) Second Symbol- nature of signal(s) modulating the main
carrier:

(1) No modulating signal 0

(2) A single channel containing quantized or digital
information without the use of a modulating sub-
carrier, excluding time-division multiplex 1

(3) A single channel containing quantized or digital
information with the use of a modulating sub-carrier,
excluding time-division multiplex 2

(4) A single channel containing analogue information 3

(5) Two or more channels containing quantized or digital
information 7

(6) Two or more channels containing analogue information 8

(7) Composite system with one or more channels containing
quantized or digital information, to-gether with one or
more channels containing analogue information 9

(8) Cases not otherwise covered X

(e) Third Symbol - type of information to be transmitted:

(1) No information transmitted N

(2) Telegraphy - for aural reception A

(3) Telegraphy - for automatic reception B

(4) Facsimile C

(5) Data transmission, telemetry, telecommand D

(6) Telephony (including sound broadcasting) E

(7) Television (video) F

(8) Combination of the above W

(9) Cases not otherwise covered X

(f) Type B emission: As an exception to the above principles,
damped waves are symbolized in the Commission's rules and
regulations as type B emission. The use of type B emissions
is forbidden.

(g) Whenever the full designation of an emission is necessary,
the symbol for that emission, as given above, shall be
preceded by the necessary bandwidth of the emission as
indicated in Section 2.202 (b) (1).


Section 2.202 Bandwidths.

(b) Necessary bandwidths.

(1) The necessary bandwidth shall be expressed by three
numerals and one letter. The letter occupies the
position of the decimal point and represents the unit
of bandwidth. The first character shall be neither
zero nor K, M or G.

-

-end-

In article . com,
wrote:
I just don't buy the argument that nobody thought about DSB. DSB is
naturally generated from a mixer if the audio signal is zero mean.
[Again, it is best to talk about modulation schemes by discussion
modulators.] Remember, AM exists because the demod is cheaper, not
because it is any easier to generate that say DSB. AM and DSB use the
same hardware.

But there's something where a DSB local carrier has to be in phase with
the signal, otherwise there some sort of canceling effect from the two
sidebands. SSB doesn't have the problem, it just causes a pitch shift.

The only DSB I know of, (that isn't just treated as a cheap form of SSB,
where really only one sideband is used) is the L-R subcarrier in FM stereo
where they double the pilot tone to get an in phase carrier.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

Mark Zenier wrote:
In article . com,
wrote:
I just don't buy the argument that nobody thought about DSB. DSB is
naturally generated from a mixer if the audio signal is zero mean.
[Again, it is best to talk about modulation schemes by discussion
modulators.] Remember, AM exists because the demod is cheaper, not
because it is any easier to generate that say DSB. AM and DSB use the
same hardware.

But there's something where a DSB local carrier has to be in phase with
the signal, otherwise there some sort of canceling effect from the two
sidebands. SSB doesn't have the problem, it just causes a pitch shift.

I've done DSB generation in a baseband signal for a telemetry
application, similar to the FM stereo demod, i.e a pilot was provided.
However, say you had no pilot and you were simply tuning by hand.
Assume a simple mixer. If you were off a bit, the sound would be pretty
ugly, i.e. 1000hz would be a combination of 999hz and 1001Hz if you
were off by 1Hz in the local carrier. However, I could see this making
tuning very easy since if you were off a little, it would be clear that
the local carrier needed adjusting.


The only DSB I know of, (that isn't just treated as a cheap form of SSB,
where really only one sideband is used) is the L-R subcarrier in FM stereo
where they double the pilot tone to get an in phase carrier.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

Miso:

Eh, the author confuses DSB and AM. I wouldn't put much faith in
his/her analysis.

I wouldn't put much faith in someone who is confused over the gender of
the name 'Phil'. Ludicrous and a "poisoning the well" logic fallacy.

DSB never has a carrier. There is no such thing as DSB and DSB without
a carrier, just DSB.

http://www.atis.org/tg2k/_double-sid...nsmission.html
http://www.atis.org/tg2k/_double-sid...nsmission.html
http://www.atis.org/tg2k/_amplitude_modulation.html



Telamon:

Listening to AMBCB in the car where I don't have a sync detector and
home where I do sure makes me wish I had it in the car.

See my article "ferrite rods make poor car antennas".

The improvement in reception most radios have with sync detection is
huge not small and so the improvement is not open to argument.

Is SAM on your RX340 a huge improvement over SSB? (Yes it's a trap.)

Happy Holidays!
phil
http://groups.yahoo.com/group/phils_radio_articles/ [Files Only]

In article .com,
wrote:

Miso:

Eh, the author confuses DSB and AM. I wouldn't put much faith in
his/her analysis.

I wouldn't put much faith in someone who is confused over the gender of
the name 'Phil'. Ludicrous and a "poisoning the well" logic fallacy.

DSB never has a carrier. There is no such thing as DSB and DSB without
a carrier, just DSB.

http://www.atis.org/tg2k/_double-sid...nsmission.html
http://www.atis.org/tg2k/_double-sid...nsmission.html
http://www.atis.org/tg2k/_amplitude_modulation.html



Telamon:

Listening to AMBCB in the car where I don't have a sync detector and
home where I do sure makes me wish I had it in the car.

See my article "ferrite rods make poor car antennas".

Where? At Yahoo? I'm not a member.

The improvement in reception most radios have with sync detection is
huge not small and so the improvement is not open to argument.

Is SAM on your RX340 a huge improvement over SSB? (Yes it's a trap.)

SSB on the RX340 is superb. SAM works great most of the time. The SAM
does have the locking problem when you encounter rapid deep fades the
AGC system in the radio can't seem to handle properly. In those cases
you can usually fiddle with the programmable AGC settings to get an
acceptable response. Only other solution is to use an antenna less
susceptible to rapid fading. That would be one with larger cross
sectional area. The SAM can lock on very weak signals and is side band
selectable so with DSP filtering it usually makes adjacent channel
splatter disappear. SAM usually works like a champ.

You really get really excellent sound from this radio as you can
increase the bandwidth as conditions allow for SSB or AM.

--
Telamon
Ventura, California

wrote:
Miso:

Eh, the author confuses DSB and AM. I wouldn't put much faith in
his/her analysis.

I wouldn't put much faith in someone who is confused over the gender of
the name 'Phil'. Ludicrous and a "poisoning the well" logic fallacy.

"phil" is in the file name, not the document.


DSB never has a carrier. There is no such thing as DSB and DSB without
a carrier, just DSB.

Oh sure, you read it on the net, so it must be right. I stand by my
statements.

Just because a few people get it wrong on the net, doesn't make it
right. I've seen DSBAM used for AM, DSBSC used for DSB. Check out this
college text:
http://www.utdallas.edu/~mtacca/cour...-2006/Exp3.pdf
In the equation, you would have to add a DC bias in x(t) to produce AM.
Hence they are producing DSB, pure and simple.

http://www.atis.org/tg2k/_double-sid...nsmission.html
http://www.atis.org/tg2k/_double-sid...nsmission.html
http://www.atis.org/tg2k/_amplitude_modulation.html



Telamon:

Listening to AMBCB in the car where I don't have a sync detector and
home where I do sure makes me wish I had it in the car.

See my article "ferrite rods make poor car antennas".

The improvement in reception most radios have with sync detection is
huge not small and so the improvement is not open to argument.

Is SAM on your RX340 a huge improvement over SSB? (Yes it's a trap.)

Happy Holidays!
phil
http://groups.yahoo.com/group/phils_radio_articles/ [Files Only]

www.infowars.com Bypass Big Brother.

Shortwave Radios for sale.
cuhulin

Just because a few people get it wrong on the net, doesn't make it
right. I've seen DSBAM used for AM, DSBSC used for DSB. Check out this
college text:

i agree: version 2 will use "DSBc". why the logic fallacy? if you can
find errors in my analysis e-mail me. ~phil PS my name -is- in the
paper and 999/1001 Hz tones sound the -same-.