Guest
Ok - so if the carrier is surppressed, just how does a receiver
distinguish between stations ?
distinguish between stations ?
D
Don Bowey
Guest
On 11/24/07 7:11 PM, in article
66d5d58a-3c14-486c-8f91-4d3e91dae8d3@e6g2000prf.googlegroups.com,
"el_squid_2000@yahoo.com" <el_squid_2000@yahoo.com> wrote:
received sideband(s).
66d5d58a-3c14-486c-8f91-4d3e91dae8d3@e6g2000prf.googlegroups.com,
"el_squid_2000@yahoo.com" <el_squid_2000@yahoo.com> wrote:
By reinserting a reference frequency in the receiver to heterodyne with the
received sideband(s).
P
Phil Allison
Guest
<el_squid_2000@yahoo.com>
** You obviously have no idea how a radio receiver works.
Do some web searching.
....... Phil
** You obviously have no idea how a radio receiver works.
Do some web searching.
....... Phil
M
Michael Black
Guest
(el_squid_2000@yahoo.com) writes:
at all.
The term "carrier" comes from the early days of radio, and I've never
seen any articles about the topic from that period so I don't know how
they named it.
But it's a misnomer, since the name implies it carries something, when
in reality, it's not needed at all.
And the models that came from the early days of radio still persist
in many explanations, so it's no wonder it can be confusing. What
really sort of happened was that there was one explanation for "AM"
and another when "SSB" came along, when in reality a common explanation
fits all such signals.
So you have a standard "AM" broadcast transmitter. The carrier
signal is amplified up to the final output stage, and that stage is
plate modulated. That terminology suggests that the amplitude of
the carrier is varied, but in reality it's not. It's a mixing
process. That final stage that is plate modulated with audio is
actually a mixer. It translates the audio signal up to radio
frequencies, where all the original information is intact, it's merely
at a radio frequency. That mixing process generates two sidebands.
| | |
9.999MHz 10MHz 10.001MHz
The "carrier" is 10MHz. The audio signal is a 1KHz tone. The mixing
process results in the difference (the 9.999MHz signal) and the sum
(the 10.001MHz signal) at the output, ie the two sidebands.
It's more obvious with a fixed tone, but do the math on other audio
frequencies and you'll see the sidebands dance around that "carrier"
frequency.
Since it's a linear mixer, the audio amplitude of the modulating signal
remains at radio frequency, so each of those sidebands will rise and
fall as the audio modulating signal rises and falls.
Some of the mixup about how the carrier must actually vary in amplitude
surely derives from the fact that if you put a simple RF voltmeter on
the output of the transmitter, the signal would go up and down with
the modulating signal. But since that voltmeter can't select between
a sideband or the carrier, it sees the complete amplitude of all three
signals, and thus it looks like the carrier level is varying.
It's only incidental that the carrier is also present at the antenna.
It's there because the modulated stage is unbalanced, so the carrier
signal feeds through to the output. But since you've also translated
the modulating signal to RF, those sidebands, you no longer need the
carrier to send it along.
"DSB", in this case double sideband with suppressed carrier, uses
a balanced modulator stage to mix the audio signal with the "carrier".
The result is the two sidebands, but the unneeded "carrier" is not present
at the output. Like this:
| |
9.999MHz 10MHz 10.001MHz
"SSB", and more specifically single sideband with suppressed carrier, goes
a step further. Since both sidebands are mirror images of each other,
only one is needed to convey the modulating signal, so the transmitter
removes one of the sidebands, and the mixing process is balanced so
there's no "carrier" at the output. Like this:
|
9.999MHz 10MHz 10.001MHz
or this
|
9.999MHz 10MHz 10.001MHz
depending on whether the transmitter sends lower or upper sideband
(ie the sum or the difference between the "carrier" and the modulating
audio signal).
All three variants of amplitude modulation have their pros and cons.
"AM", ie double sideband with a carrier, is really easy to demodulate.
A simple diode will do the deed, and tuning is easy. (Note, that
demodulator that seems to create a varying DC voltage to match
the modulating signal is in reality a mixer, mixing the carrier
from the incoming signal with its sidebands, which converts the radio
frequency sidebands back down to audio.)
"DSB", ie double sideband with no carrier, gets rid of the carrier, which
wastes power (since it's not actually needed), and since it's not there,
it can't beat against a carrier from some other station on almost the
same frequency, which results in odd tones coming out of the receiver.
"SSB", ie single sideband with no carrier, puts all the transmitted
power in one sideband, which is all that's needed to convey what's
in the modulating signal.
But, since the demodulation of all three is about mixing the RF
sideband(s) back down to audio, at some point the receiver needs
a signal on the "carrier" frequency to beat against the sideband(s)
and mix it back down to audio. With "AM", the carrier is there, and
as I pointed out, few even think in terms of a mixing process at
the receiver.
But when the "carrier" is not sent out from the transmitter, one
has to create a "carrier" at the receiver end. The problem then
arises of where to put the locally generated "carrier". Because
if it's not in the right place, the demodulated signal will not
be an exact replicant of the original modulating signal.
With "SSB", that means you will have audio that is low or high pitched,
though you can tune the locally generated "carrier" so it sounds about
right, the human brain will know. And the brain will tolerate a certain
level of "off frequency".
"DSB" is trickier, because the locally generated "carrier" has to be
in exactly the right place, ie right between the sidebands. Otherwise,
that 9.999MHz signal will not translate back down to the original 1KHz,
it will be at 1.1KHz, say. But, the upper sideband will not translate
to 1KHz either, it will land at at zero Hertz, you won't hear it. But,
since the two sidebands do not mix back down to the same frequency, they
will not clash, and the receiver output will not be listenable.
The simplest way to fix that is to put a filter in the receiver to
knock out one of the sidebands, so the rest of the receiver sees an
"SSB" signal. There's no difference between stripping off the signal
at the transmitter or at the receiver (well in terms of demodulating
that signal).
But then you lose one advantage of sending two sidebands, which is
the redundancy of the two sidebands. If you use a demodulator that
makes use of both sidebands, then interference to one will not be a problem,
and fading to one will not be a problem.
So if the receiver is not stripping off one sideband, the locally generated
"carrier" has to use information from those sidebands to tune it to
the exact frequency. Various methods exist to do that, going from
simple to complicated.
But despite the complications, all three types of amplitude modulated
signals are demodulated by a mixer and a "carrier". It's clear in an
"SSB" receiver, where the mixer is usually called a product detector,
and you see the locally generated "carrier" in the form of the BFO,
beat frequency oscillator. The methods to demodulate "DSB" use that
same basic notion of a product detector and BFO, with added circuitry
to automatically tune the BFO to the exactly needed frequency.
No to try to figure out your question, a receiver can differentiate
between signals because the various sidebands of a signal are on different
frequencies.
Michael
That's like asking what makes an apple an orange, ie no sense
at all.
The term "carrier" comes from the early days of radio, and I've never
seen any articles about the topic from that period so I don't know how
they named it.
But it's a misnomer, since the name implies it carries something, when
in reality, it's not needed at all.
And the models that came from the early days of radio still persist
in many explanations, so it's no wonder it can be confusing. What
really sort of happened was that there was one explanation for "AM"
and another when "SSB" came along, when in reality a common explanation
fits all such signals.
So you have a standard "AM" broadcast transmitter. The carrier
signal is amplified up to the final output stage, and that stage is
plate modulated. That terminology suggests that the amplitude of
the carrier is varied, but in reality it's not. It's a mixing
process. That final stage that is plate modulated with audio is
actually a mixer. It translates the audio signal up to radio
frequencies, where all the original information is intact, it's merely
at a radio frequency. That mixing process generates two sidebands.
| | |
9.999MHz 10MHz 10.001MHz
The "carrier" is 10MHz. The audio signal is a 1KHz tone. The mixing
process results in the difference (the 9.999MHz signal) and the sum
(the 10.001MHz signal) at the output, ie the two sidebands.
It's more obvious with a fixed tone, but do the math on other audio
frequencies and you'll see the sidebands dance around that "carrier"
frequency.
Since it's a linear mixer, the audio amplitude of the modulating signal
remains at radio frequency, so each of those sidebands will rise and
fall as the audio modulating signal rises and falls.
Some of the mixup about how the carrier must actually vary in amplitude
surely derives from the fact that if you put a simple RF voltmeter on
the output of the transmitter, the signal would go up and down with
the modulating signal. But since that voltmeter can't select between
a sideband or the carrier, it sees the complete amplitude of all three
signals, and thus it looks like the carrier level is varying.
It's only incidental that the carrier is also present at the antenna.
It's there because the modulated stage is unbalanced, so the carrier
signal feeds through to the output. But since you've also translated
the modulating signal to RF, those sidebands, you no longer need the
carrier to send it along.
"DSB", in this case double sideband with suppressed carrier, uses
a balanced modulator stage to mix the audio signal with the "carrier".
The result is the two sidebands, but the unneeded "carrier" is not present
at the output. Like this:
| |
9.999MHz 10MHz 10.001MHz
"SSB", and more specifically single sideband with suppressed carrier, goes
a step further. Since both sidebands are mirror images of each other,
only one is needed to convey the modulating signal, so the transmitter
removes one of the sidebands, and the mixing process is balanced so
there's no "carrier" at the output. Like this:
|
9.999MHz 10MHz 10.001MHz
or this
|
9.999MHz 10MHz 10.001MHz
depending on whether the transmitter sends lower or upper sideband
(ie the sum or the difference between the "carrier" and the modulating
audio signal).
All three variants of amplitude modulation have their pros and cons.
"AM", ie double sideband with a carrier, is really easy to demodulate.
A simple diode will do the deed, and tuning is easy. (Note, that
demodulator that seems to create a varying DC voltage to match
the modulating signal is in reality a mixer, mixing the carrier
from the incoming signal with its sidebands, which converts the radio
frequency sidebands back down to audio.)
"DSB", ie double sideband with no carrier, gets rid of the carrier, which
wastes power (since it's not actually needed), and since it's not there,
it can't beat against a carrier from some other station on almost the
same frequency, which results in odd tones coming out of the receiver.
"SSB", ie single sideband with no carrier, puts all the transmitted
power in one sideband, which is all that's needed to convey what's
in the modulating signal.
But, since the demodulation of all three is about mixing the RF
sideband(s) back down to audio, at some point the receiver needs
a signal on the "carrier" frequency to beat against the sideband(s)
and mix it back down to audio. With "AM", the carrier is there, and
as I pointed out, few even think in terms of a mixing process at
the receiver.
But when the "carrier" is not sent out from the transmitter, one
has to create a "carrier" at the receiver end. The problem then
arises of where to put the locally generated "carrier". Because
if it's not in the right place, the demodulated signal will not
be an exact replicant of the original modulating signal.
With "SSB", that means you will have audio that is low or high pitched,
though you can tune the locally generated "carrier" so it sounds about
right, the human brain will know. And the brain will tolerate a certain
level of "off frequency".
"DSB" is trickier, because the locally generated "carrier" has to be
in exactly the right place, ie right between the sidebands. Otherwise,
that 9.999MHz signal will not translate back down to the original 1KHz,
it will be at 1.1KHz, say. But, the upper sideband will not translate
to 1KHz either, it will land at at zero Hertz, you won't hear it. But,
since the two sidebands do not mix back down to the same frequency, they
will not clash, and the receiver output will not be listenable.
The simplest way to fix that is to put a filter in the receiver to
knock out one of the sidebands, so the rest of the receiver sees an
"SSB" signal. There's no difference between stripping off the signal
at the transmitter or at the receiver (well in terms of demodulating
that signal).
But then you lose one advantage of sending two sidebands, which is
the redundancy of the two sidebands. If you use a demodulator that
makes use of both sidebands, then interference to one will not be a problem,
and fading to one will not be a problem.
So if the receiver is not stripping off one sideband, the locally generated
"carrier" has to use information from those sidebands to tune it to
the exact frequency. Various methods exist to do that, going from
simple to complicated.
But despite the complications, all three types of amplitude modulated
signals are demodulated by a mixer and a "carrier". It's clear in an
"SSB" receiver, where the mixer is usually called a product detector,
and you see the locally generated "carrier" in the form of the BFO,
beat frequency oscillator. The methods to demodulate "DSB" use that
same basic notion of a product detector and BFO, with added circuitry
to automatically tune the BFO to the exactly needed frequency.
No to try to figure out your question, a receiver can differentiate
between signals because the various sidebands of a signal are on different
frequencies.
Michael
J
John Popelish
Guest
el_squid_2000@yahoo.com wrote:
around where the carrier would be. The modulation produces
side bands on one or both sides of that carrier frequency.
The passes band includes both the carrier and the
sideband/s. If the carrier is missing, the sideband/s still
fit through that same pass band.
Receivers select a band of RF frequency to pass, centered
around where the carrier would be. The modulation produces
side bands on one or both sides of that carrier frequency.
The passes band includes both the carrier and the
sideband/s. If the carrier is missing, the sideband/s still
fit through that same pass band.
B
Bob Masta
Guest
On Sat, 24 Nov 2007 19:11:57 -0800 (PST), el_squid_2000@yahoo.com
wrote:
of multiplying two sinusoids, if you used a plain old multiplier,
would be signals at the sum and difference frequencies, and
none at either of the original frequencies. The only difference
with AM is there is effectively a constant added to the signal input
so that it never goes through zero, which means the carrier is
always present. If you looked at a spectrum of the broadcast
signal when there is only a pure sine signal input to the modulator,
you'd see 3 peaks: The carrier frequency, the carrier plus the
signal, and the carrier minus the signal.
In a real broadcast, there are of course many input frequencies,
but the above still holds. The side peaks become bands whose
width is the bandwidth of the incoming signal. Let's say the
signal covers a 5 kHz bandwidth (I think this is typical for broadcast
AM). Then a station at 1 MHz would have sidebands extending
5 kHz to either side, down to 995 kHz and up to 1005 kHz. The next
station on the dial will be at least 10 kHz away (farther, in
practice). so the sidebands will not overlap. If the carrier is
removed (say by using a multiplier instread of an AM modulator)
the sidebands stay in the same positions and don't interfere.
You can see how AM sidebands and multipliers work with my
free Daqarta signal generator and your Windows sound card.
(You don't have to purchase anything: The signal generator
continues to work after the trial period, along with most everything
else except inputs... which you don't need for these experiments.)
You can see waveform, spectrum, and spectrogram of the signal,
and play around with modulation depth and type. The only difference
compared to a broadcast situation is that the carrier will be in the
audio range as well. So, for example, you can set the carrier to
10 kHz and try modulating signals between 0 and 5 kHz, giving
sidebands from 5 kHz to 15 kHz. This is actually an advantage over
RF, since things are proportionally more spread out and easier to see
on the spectrum display.
Note that Daqarta's AM modulator works a bit differently from
that in a transmitter (see the Help for full details): When you
set Depth to 200% you get pure multiplication, which is the
supressed-carrier condition.
If you have any trouble with this, I'd be glad to answer questions.
Best regards,
Bob Masta
DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!
wrote:
The AM process is really a form of multiplication The result
of multiplying two sinusoids, if you used a plain old multiplier,
would be signals at the sum and difference frequencies, and
none at either of the original frequencies. The only difference
with AM is there is effectively a constant added to the signal input
so that it never goes through zero, which means the carrier is
always present. If you looked at a spectrum of the broadcast
signal when there is only a pure sine signal input to the modulator,
you'd see 3 peaks: The carrier frequency, the carrier plus the
signal, and the carrier minus the signal.
In a real broadcast, there are of course many input frequencies,
but the above still holds. The side peaks become bands whose
width is the bandwidth of the incoming signal. Let's say the
signal covers a 5 kHz bandwidth (I think this is typical for broadcast
AM). Then a station at 1 MHz would have sidebands extending
5 kHz to either side, down to 995 kHz and up to 1005 kHz. The next
station on the dial will be at least 10 kHz away (farther, in
practice). so the sidebands will not overlap. If the carrier is
removed (say by using a multiplier instread of an AM modulator)
the sidebands stay in the same positions and don't interfere.
You can see how AM sidebands and multipliers work with my
free Daqarta signal generator and your Windows sound card.
(You don't have to purchase anything: The signal generator
continues to work after the trial period, along with most everything
else except inputs... which you don't need for these experiments.)
You can see waveform, spectrum, and spectrogram of the signal,
and play around with modulation depth and type. The only difference
compared to a broadcast situation is that the carrier will be in the
audio range as well. So, for example, you can set the carrier to
10 kHz and try modulating signals between 0 and 5 kHz, giving
sidebands from 5 kHz to 15 kHz. This is actually an advantage over
RF, since things are proportionally more spread out and easier to see
on the spectrum display.
Note that Daqarta's AM modulator works a bit differently from
that in a transmitter (see the Help for full details): When you
set Depth to 200% you get pure multiplication, which is the
supressed-carrier condition.
If you have any trouble with this, I'd be glad to answer questions.
Best regards,
Bob Masta
DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!
J
Jamie
Guest
el_squid_2000@yahoo.com wrote:
transmitter generating the side band offsets.
Solution of side band transmissions allows one to concentrate it's
use of space all in a useable window unlike AM.
--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
at the receiver that zero beats to the original signal used at the
transmitter generating the side band offsets.
Solution of side band transmissions allows one to concentrate it's
use of space all in a useable window unlike AM.
--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
D
Don Bowey
Guest
On 11/25/07 9:25 AM, in article sci2j.242$cb1.210@newsfe07.lga, "Jamie"
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
suppressed carrier would have been.
topic), occupies the same bandwidth as a double sideband with carrier
signal.
Bandwidth is reduced by half, by suppressing one of the two sidebands.
>
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
That's what he said.
That is correct.
There are no sideband offsets. They still bracket, precisely, where the
suppressed carrier would have been.
Not at all. A signal of two sidebands with the carrier suppressed (The
topic), occupies the same bandwidth as a double sideband with carrier
signal.
Bandwidth is reduced by half, by suppressing one of the two sidebands.
>
J
Jamie
Guest
Don Bowey wrote:
comes to side band signals for the transmitter.
Think about it../
--
"I'd rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
My comparison to AM was for power efficiency of use when it
comes to side band signals for the transmitter.
Think about it../
--
"I'd rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
T
terryS
Guest
On Nov 25, 5:29 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
(band-width) of frequency spectrum.
Single sideband, without carrier (SSB) occupies half bandwidth.
Correct?
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
Double sideband signal with or without a carrier occupies same amount
(band-width) of frequency spectrum.
Single sideband, without carrier (SSB) occupies half bandwidth.
Correct?
D
Don Bowey
Guest
On 11/25/07 12:29 PM, in article nVk2j.80$4D7.58@newsfe06.lga, "Jamie"
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
now you are trying lie out of it.
Part of your post:
bandwidth.
If anyone is trying to "pull this to one side," it's you.
I see you pulling this crap on other posters, but you won't get by with it
here. The best you can is STFU and go study the topic. And while I'm at
it, the OP didn't ask about power efficiency anyhow. What you did was
typical of someone who doesn't know crap about what they are posting about.
Think about it real good.
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
I thought about it. I think your reply to the OP contained bad errors, and
now you are trying lie out of it.
Part of your post:
....says nothing about power efficiency. "Space" in your statement means
bandwidth.
If anyone is trying to "pull this to one side," it's you.
I see you pulling this crap on other posters, but you won't get by with it
here. The best you can is STFU and go study the topic. And while I'm at
it, the OP didn't ask about power efficiency anyhow. What you did was
typical of someone who doesn't know crap about what they are posting about.
Think about it real good.
D
Don Bowey
Guest
On 11/25/07 3:32 PM, in article
8ad5f6ed-85b8-4df9-8a6a-e0af87b0df1a@e10g2000prf.googlegroups.com, "terryS"
<tsanford@nf.sympatico.ca> wrote:
Single sideband, with or without carrier (SSB) occupies half bandwidth.
A carrier has no bandwidth.
8ad5f6ed-85b8-4df9-8a6a-e0af87b0df1a@e10g2000prf.googlegroups.com, "terryS"
<tsanford@nf.sympatico.ca> wrote:
Yes
No, not quite.
Single sideband, with or without carrier (SSB) occupies half bandwidth.
A carrier has no bandwidth.
J
Jamie
Guest
Don Bowey wrote:
I see you're just like some one else here. (no names mentioned)
It's obvious if you can't read between the lines, you're not any
better than those you speak of, Who ever they maybe..
Go play some where else, your petty bull shit is not welcome here.
And I do not withdraw anything I said since there is nothing wrong with
what I said. If you really think other wise, you do have a problem with
reading or, your just looking to be an ass, if that is that case, do it
elsewhere.
I can't speak for the rest here but I can say this, your little kiddy
acts do not impress me at all.
Grow the fuck Up!
--
"I'd rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
I see you're just like some one else here. (no names mentioned)
It's obvious if you can't read between the lines, you're not any
better than those you speak of, Who ever they maybe..
Go play some where else, your petty bull shit is not welcome here.
And I do not withdraw anything I said since there is nothing wrong with
what I said. If you really think other wise, you do have a problem with
reading or, your just looking to be an ass, if that is that case, do it
elsewhere.
I can't speak for the rest here but I can say this, your little kiddy
acts do not impress me at all.
Grow the fuck Up!
--
"I'd rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
D
Don Bowey
Guest
On 11/25/07 5:12 PM, in article Q1p2j.168$yU1.2@newsfe05.lga, "Jamie"
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
correct and so am I: You are too ignorant to accept when you make a
mistake. You hope to bury it rather than have the OP get a correct,
meaningful answer,
see it.
information and then spew it out to screw-up beginners who ask questions.
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
Where do I go to read Good Ass? Or did you mean something else?
Sure, no names mentioned because you're a chicken shit coward. He was
correct and so am I: You are too ignorant to accept when you make a
mistake. You hope to bury it rather than have the OP get a correct,
meaningful answer,
I read fine, and I understand the language just fine, and I know BS when I
see it.
Smoke screen. You really think this will fool someone?
Again...Smoke screen. You really think this will fool someone?
I'm reasonably certain the ass has exposed himself.
If you were a little impressed with your betters, you might be better off.
By the way, your gutter language use means YOU LOSE.
You are too ignorant for words. You lurk and lurk and collect half-correct
information and then spew it out to screw-up beginners who ask questions.
J
Jamie
Guest
Don Bowey wrote:
Ignorant, you took the works out of my mouth.
--
"I'd rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
Ignorant, you took the works out of my mouth.
--
"I'd rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
M
Michael A. Terrell
Guest
Jamie wrote:
Pervert.
It looks like you've had both.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
Pervert.
It looks like you've had both.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
T
The Captain
Guest
el_squid_2000@yahoo.com wrote:
demodulate a particular type of modulation.
In the case of a suppressed carrier transmission, be it single side band
(SSB) or dual sideband (not used much) the receiver is tuned to the
sideband which is transmitted. In the case of SSB, the sideband covers
the same spectrum as half an unsuppressed transmission, minus the
bandwidth used the carrier.
Normally, a phased lock loop is used to restore a replica of the carrier
in the receiver and a balanced bridge is used for demodulation.
Distinguishing between "stations" is achieved by accurately tuning to
the narrow transmitted frequency spectrum and filtering out other
transmissions.
Sean
A receiver is tuned to a particular frequency and is designed to
demodulate a particular type of modulation.
In the case of a suppressed carrier transmission, be it single side band
(SSB) or dual sideband (not used much) the receiver is tuned to the
sideband which is transmitted. In the case of SSB, the sideband covers
the same spectrum as half an unsuppressed transmission, minus the
bandwidth used the carrier.
Normally, a phased lock loop is used to restore a replica of the carrier
in the receiver and a balanced bridge is used for demodulation.
Distinguishing between "stations" is achieved by accurately tuning to
the narrow transmitted frequency spectrum and filtering out other
transmissions.
Sean
T
The Captain
Guest
Jamie wrote:
technical question and all you can do is bicker and insult each other.
I dropped back into this group to see if things had improved at all, but
they obviously haven't. It's still the same old backbiting and ego trips.
To hell with the lot of you.
By the way, the development that my company was working on, the circuit
that I designed that doubles the range and speed of DSL; the company is
fully funded, the invention is patented and it is selling to telephone
companies as I write this. So to those of you who said that I was not
intelligent enough to invent such a circuit and in the vernacular that
you seem so addicted to on this newsgroup; - - - -
Nah, you're not worth it.
Sean
maturity in a kindergarten playground. He asked a relatively simple
technical question and all you can do is bicker and insult each other.
I dropped back into this group to see if things had improved at all, but
they obviously haven't. It's still the same old backbiting and ego trips.
To hell with the lot of you.
By the way, the development that my company was working on, the circuit
that I designed that doubles the range and speed of DSL; the company is
fully funded, the invention is patented and it is selling to telephone
companies as I write this. So to those of you who said that I was not
intelligent enough to invent such a circuit and in the vernacular that
you seem so addicted to on this newsgroup; - - - -
Nah, you're not worth it.
Sean
D
Don Bowey
Guest
On 12/11/07 8:45 PM, in article 475f6763$0$2346$4c368faf@roadrunner.com,
"The Captain" <Captainvonfolter@yahoo.com> wrote:
Don't let the door whop you in the backside on your way out.
"The Captain" <Captainvonfolter@yahoo.com> wrote:
Back at you, too,
B.S.
Whoever said it, was likely correct.
My, my!
Don't let the door whop you in the backside on your way out.
M
Michael A. Terrell
Guest
The Captain wrote:
If it's patented, then post the patent numbers.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
If it's patented, then post the patent numbers.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida