Asking about Amplitude Shift Keying

M

MRW

Guest
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:
http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!
 
MRW wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:
http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!
Click to expand...
Try drawing such a case. How would a receiver interpret
the resulting signal?
 
On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) > s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!
Click to expand...
OK I'm probabbly being an idiot here... But is that picture right?
You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?

George H.
 
On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?
Click to expand...
---
Yeah.
---

You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?
Click to expand...
---
No; in this case the presence of a carrier denotes a transmission of a
"1", say, and the length of time the carrier is ON defines how many 1's
will be transmitted.

Conversely, the absence of a carrier denotes the transmission of a zero
and the length of time there is no carrier defines how many zeros will
be transmitted.


JF
 
On Wed, 17 Feb 2010 13:32:35 -0800, George Herold wrote:

On Feb 17, 3:45 pm, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold





ggher...@gmail.com> wrote:
On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude
Shift Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?

---
Yeah.
---

You don't want the carrier to go to zero amplitude do you?  Isn't this
like AM radio?

---
No; in this case the presence of a carrier denotes a transmission of a
"1", say, and the length of time the carrier is ON defines how many 1's
will be transmitted.

Conversely, the absence of a carrier denotes the transmission of a zero
and the length of time there is no carrier defines how many zeros will
be transmitted.

JF- Hide quoted text -

- Show quoted text -

Thanks John, That makes sense... sorta. Not the most 'robust' way to
send data. Lose of the carrier means a zero... or that you've just lost
the carrier.
Click to expand...
'xactly. But a very _easy_ way to send data -- just turn the transmitter
on and off.

--
www.wescottdesign.com
 
On Feb 17, 3:45 pm, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold





ggher...@gmail.com> wrote:
On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) > >> s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?

---
Yeah.
---

You don't want the carrier to go to zero amplitude do you?  Isn't this
like AM radio?

---
No; in this case the presence of a carrier denotes a transmission of a
"1", say, and the length of time the carrier is ON defines how many 1's
will be transmitted.

Conversely, the absence of a carrier denotes the transmission of a zero
and the length of time there is no carrier defines how many zeros will
be transmitted.

JF- Hide quoted text -

- Show quoted text -
Click to expand...
Thanks John, That makes sense... sorta. Not the most 'robust' way to
send data. Lose of the carrier means a zero... or that you've just
lost the carrier.

George H.
 
On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?
You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?

George H.
Click to expand...
I think I'd call that on-off keying. For amplitude-shift keying, I'd
expect one or more intermediate levels, not just off and on. Perhaps
full amplitude and 50% (or a couple more intermediate levels to encode
multiple bits in each interval.)


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
On Wed, 17 Feb 2010 15:50:21 -0800, Peter Bennett
<peterbb@somewhere.invalid> wrote:

On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?
You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?

George H.

I think I'd call that on-off keying.
Click to expand...
---
Agreed, but, taken to the lowest level of ASK, zero carrier and some
level of carrier defines the difference between mark and space.
---

For amplitude-shift keying, I'd
expect one or more intermediate levels, not just off and on. Perhaps
full amplitude and 50% (or a couple more intermediate levels to encode
multiple bits in each interval.)
Click to expand...
---
Using ASK in the way you describe it, what would you expect the maximum
data transfer rate to be?

JF
 
"Peter Bennett" <peterbb@somewhere.invalid> wrote in message
news:310pn5pctm9t6a4l6433ukmgdhv58m244p@news.supernews.com...
On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?
You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?

George H.

I think I'd call that on-off keying. For amplitude-shift keying, I'd
expect one or more intermediate levels, not just off and on. Perhaps
full amplitude and 50% (or a couple more intermediate levels to encode
multiple bits in each interval.)
Click to expand...
The loss would be a constant power drain on the battery of say, a
wireless mouse or keyboard.



--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
On Wed, 17 Feb 2010 19:03:21 -0600, John Fields wrote:

On Wed, 17 Feb 2010 15:50:21 -0800, Peter Bennett
peterbb@somewhere.invalid> wrote:

On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right? You
don't want the carrier to go to zero amplitude do you? Isn't this like
AM radio?

George H.

I think I'd call that on-off keying.

---
Agreed, but, taken to the lowest level of ASK, zero carrier and some
level of carrier defines the difference between mark and space. ---

For amplitude-shift keying, I'd
expect one or more intermediate levels, not just off and on. Perhaps
full amplitude and 50% (or a couple more intermediate levels to encode
multiple bits in each interval.)

---
Using ASK in the way you describe it, what would you expect the maximum
data transfer rate to be?

JF
Click to expand...

Do you mean when it's working correctly, or most of the time?


--
www.wescottdesign.com
 
John Fields wrote:
On Wed, 17 Feb 2010 15:50:21 -0800, Peter Bennett
peterbb@somewhere.invalid> wrote:

On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?
You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?

George H.

I think I'd call that on-off keying.

---
Agreed, but, taken to the lowest level of ASK, zero carrier and some
level of carrier defines the difference between mark and space.
---

For amplitude-shift keying, I'd
expect one or more intermediate levels, not just off and on. Perhaps
full amplitude and 50% (or a couple more intermediate levels to encode
multiple bits in each interval.)

---
Using ASK in the way you describe it, what would you expect the maximum
data transfer rate to be?

JF
Click to expand...
WWVB gets one baud.


--
Greed is the root of all eBay.
 
On Thu, 18 Feb 2010 11:36:23 -0500, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

John Fields wrote:

On Wed, 17 Feb 2010 15:50:21 -0800, Peter Bennett
peterbb@somewhere.invalid> wrote:

On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?
You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?

George H.

I think I'd call that on-off keying.

---
Agreed, but, taken to the lowest level of ASK, zero carrier and some
level of carrier defines the difference between mark and space.
---

For amplitude-shift keying, I'd
expect one or more intermediate levels, not just off and on. Perhaps
full amplitude and 50% (or a couple more intermediate levels to encode
multiple bits in each interval.)

---
Using ASK in the way you describe it, what would you expect the maximum
data transfer rate to be?

JF

WWVB gets one baud.
Click to expand...
---
Yeah, but its not ASK in the sense that one level defines a 1 and
another defines a 0, it's more like PWM with a carrier floor and the
length of time the transmitter stays at the low floor level before it
gets keyed on to full power out determines whether the bit sent is a 1
or a zero.

http://tf.nist.gov/stations/wwvbtimecode.htm

http://en.wikipedia.org/wiki/WWVB#Modulation_Format

Pretty damn clever, in my book...

JF
 
John Fields wrote:
On Thu, 18 Feb 2010 11:36:23 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:


John Fields wrote:

On Wed, 17 Feb 2010 15:50:21 -0800, Peter Bennett
peterbb@somewhere.invalid> wrote:

On Wed, 17 Feb 2010 11:44:01 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

On Feb 16, 1:22 am, MRW <mr.whate...@gmail.com> wrote:
Hello group,

I posted a screen capture of an image showing a basic Amplitude Shift
Key modulation:http://imgur.com/Ahwya.jpg

The image shows the a diagram and equation. The equation is ASK(t) =
s(t)*sin(2*pi*f*t). I assume s(t) is the baseband signal and
sin(2*pi*f*t) is the carrier frequency.

In the image, is it possible for s(t) to have a higher frequency as
sin(2*pi*f*t)? Please explain.

Thanks!

OK I'm probabbly being an idiot here... But is that picture right?
You don't want the carrier to go to zero amplitude do you? Isn't this
like AM radio?

George H.

I think I'd call that on-off keying.

---
Agreed, but, taken to the lowest level of ASK, zero carrier and some
level of carrier defines the difference between mark and space.
---

For amplitude-shift keying, I'd
expect one or more intermediate levels, not just off and on. Perhaps
full amplitude and 50% (or a couple more intermediate levels to encode
multiple bits in each interval.)

---
Using ASK in the way you describe it, what would you expect the maximum
data transfer rate to be?

JF

WWVB gets one baud.

---
Yeah, but its not ASK in the sense that one level defines a 1 and
another defines a 0, it's more like PWM with a carrier floor and the
length of time the transmitter stays at the low floor level before it
gets keyed on to full power out determines whether the bit sent is a 1
or a zero.

http://tf.nist.gov/stations/wwvbtimecode.htm

http://en.wikipedia.org/wiki/WWVB#Modulation_Format

Pretty damn clever, in my book...
Click to expand...

Especially when you consider when they first used it. A 10 dB carrier
reduction to modulate the carrier in the early days of electronics, and
was used to control clocks all over the country. A lot of metrology
labs used a Fluke VLF receiver & WWVB for their frequency standard,
until GPS based systems replaced it. I still have my Fluke receiver,
but I will need to build a new PLL 10 MHz standard.

BTW, I found my homebrew copper 60 KHz loop for WWVB yesterday. I
finally feel well enough to start cleaning out the small shop building,
so I can get back to the bench. :) It is only 18 * 28 feet, but it
suffered the least hurricane damage a few years ago. I tossed out a
truckload of damaged cardboard boxes and very rusty hardware. I have a
fairly clear shot towards WWVB from here, unlike the last place I lived.


--
Greed is the root of all eBay.
 
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