quadrature detector & SSB
 

How to use quadrature detector to demodulate cw and ssb. I want to use
AD607 in simple project. There is Quadrature detector on "the end" with
two outputs I&Q - and internal phase shifter. How to detest SSB simplest
way?

73

mac

quadrature detector & SSB
 

On 2006-07-04, MAc wrote:
How to use quadrature detector to demodulate cw and ssb. I want to use
AD607 in simple project. There is Quadrature detector on "the end" with
two outputs I&Q - and internal phase shifter. How to detest SSB simplest
way?

If it does all that, you just have to choose USB, LSB or AM by chosing
sum, difference or magnitude of the IQ output.

--
Ben Jackson

http://www.ben.com/

quadrature detector & SSB
 

Ben Jackson napisa³(a):
On 2006-07-04, MAc wrote:
How to use quadrature detector to demodulate cw and ssb. I want to use
AD607 in simple project. There is Quadrature detector on "the end" with
two outputs I&Q - and internal phase shifter. How to detest SSB simplest
way?

If it does all that, you just have to choose USB, LSB or AM by chosing
sum, difference or magnitude of the IQ output.

Thank you

what frequency should be for Local oscilator?

MAc

quadrature detector & SSB
 

It's not that easy Ben.....

The I-Q demodulator in this chip doesn't include the required 90 deg audio
phase shift network. That's usually one of the toughest parts of any
phasing-type detector. Also, the LO phase balance is specified as 1.2 deg
and the amplitude balance is specified as 0.2 dB. These imbalances would
combine to give an opposite sidenabd rejection of less than 40 dB, maybe 35
dB. Not too good by modern standards.

Furthermore, the detector circuits only work at IF frequencies, not RF
frequencies. This implies that the internal mixer would have to be used in a
downconversion mode, resulting in a requirement for an image-reject bandpass
filter at the mixer input and some measure of bandpass filtering at the
mixer output.

On top of all this, the LO noise floor is only -100 dBc/Hz, which would
probably cause pretty bad reciprocal mixing under crowded band conditions.

All things considered, I think that by the time one made this chip do what
it has to do for SSB/AM, one would be better off starting from scratch with
more conventional components.

Joe
W3JDR


"Ben Jackson" wrote in message
...
On 2006-07-04, MAc wrote:
How to use quadrature detector to demodulate cw and ssb. I want to use
AD607 in simple project. There is Quadrature detector on "the end" with
two outputs I&Q - and internal phase shifter. How to detest SSB simplest
way?

If it does all that, you just have to choose USB, LSB or AM by chosing
sum, difference or magnitude of the IQ output.

--
Ben Jackson

http://www.ben.com/

quadrature detector & SSB
 

W3JDR napisa³(a):
It's not that easy Ben.....

The I-Q demodulator in this chip doesn't include the required 90 deg audio
phase shift network. That's usually one of the toughest parts of any
phasing-type detector.

What will be if I treat "I" mixer as a typical product detector. Will it
work?

MAc

quadrature detector & SSB
 

To clarify - the idea is to build very simple receiver - Not "play with
quadrature detector". AD607 look simply and small

quadrature detector & SSB
 

MAc wrote:
To clarify - the idea is to build very simple receiver - Not "play with
quadrature detector". AD607 look simply and small

Andy writes:

While I agree with everything MAC wrote, I think a point is being
missed.
A Quadrature detector is normally used only for FM demodulation. It
accomplishes this by limiting the signal and applying it to one port
of a 90deg detector. If the limited signal is shifted 90 degrees
(narrow
band), the quad detector will detect FM... If the limited signal is
shifted
ZERO degrees, the quad detector will detect AM, and in a much more
linear way than a diode type detector......

With CW, there would be no signal to zero beat with, and no audio
note would be formed.... Exactly the same with SSB....all the output
would be "DC"...

Mac's explanation is correct for an IQ detector... In this case a
local
signal EQUAL to the suppressed carrier of the SSB signal has to
be supplied..... I don't know how a local carrier can be synchronized
to
a SSB carrier that, if done really well, doesn't exist......

In Homodyne receivers, it is easy, since the transmit signal can be

the LO signal..... Otherwise, it has to be "guessed" at..... With
really
really really stable local oscillators, the guess can be really close,
and
the difference will creat an error that is so small it doesn't
matter... But,
since you don't know the incident phase of the received signal, you
have to do both I and Q and shift the IF by 90 degrees and sum (or
difference, depending whether you want USB or LSB) the outputs of
the two channels...... For SSB detection, the RF port is NOT shifted,
the LO port is both 0 and 90 degrees, and the IF port ( I and Q) are
shifted 90 and combined........

It is a hell of a lot easier to "approximate" the LO, and shift it
manually
until Donald Duck starts sounding human.... In older SSB rigs, this was

called a "clarifier" control..... It isn't necessary in many modern
systems
with really really really good TCXOs and stuff....

Just my two cents worth.... If anyone disagrees, I'd be happy to
learn from them where my explanation is wrong..... but I warn you,
it ain't far wrong.... cause it worked for me for many many years
in designing receivers for both commercial and military products
....:)))))

Andy in Eureka, W4OAH ( retired comm/radar engineer and ham for 45
years )

quadrature detector & SSB
 

AndyS wrote:
A Quadrature detector is normally used only for FM demodulation.

Yes.

but (from Analog Devices):
"...Applications of the AD607 include narrowband systems with a high
first IF (21.4 MHz to 300 MHz) and a second IF at 10.7 MHz, 455 kHz, or
450 kHz. These include Dual Conversion IS136, GSM, TETRA, and MSAT
Receivers; and Single or Dual Conversion VHF and HF AM, SSB, CW, or QPSK
Receivers... "

But :-) I did not find any SSB application :-( So I need an example.




Just my two cents worth.... If anyone disagrees, I'd be happy to
learn from them where my explanation is wrong..... but I warn you,
it ain't far wrong.... cause it worked for me for many many years
in designing receivers for both commercial and military products
...:)))))


Andy Thanks for your cents, rather dollars.

PS there is internal quadrature pll in ad607.

MAc

quadrature detector & SSB
 

Andy Thanks for your cents, rather dollars.

PS there is internal quadrature pll in ad607.

MAc


Andy responds;

Ok.. I admit that I didn't go find the AD607 and study it before
replying
to Mac... However,,, I'll bet you a dollar that the fellow who wrote
the
app note that Mac refers to has a hell of a lot less experience than
either Mac or myself..... not that I would expect a young app note
writer to overstate the applications of his product ( big damn grin
)...
The AD606 really makes a great tie-tac if you glue an alligator clip
to it, tho I've never actually seen one for sale... :)))))))

if the gilbert cell, or single ended long tailed pair multiplier
used as a
quad detector allows external coupling to the ports, it can be used as
a BFO for CW or SSB,..., HOWEVER, having a limiting stage in the
linear path of such a device is NOT a great idea.... Sure, it can be
made
to work, but..... well, heck... I've built a LOT of things that were
really
bad ideas, and I try not to duplicate them again, or tell others about

them.... especially in app notes that I've made input to......
I've seen the MC3372 used as an SSB receiver in either Ham Radio
or some such.... and I never seriously considered doing it myself since
the limitations were so obvious....

An 811A can be used a a product detector also, but the
manufacturers
don't advertise it as such,...... because it is a REALLY BAD idea....
If a fellow wants a simple CW/SSB receiver, a much better idea is to
use something like an NE602..... I've done that, for a home project ,
and
it works OK,..... but certainly not something I'd try to produce as a
receiver for Bendix, Texas Instruments, or Raytheon...... There's a
limit
to how far one should stretch an application.....

Thanks Mac, for your input. I bet we agree on almost
everything.....

Andy W4OAH

quadrature detector & SSB
 

Ok.. I admit that I didn't go find the AD607 and study it before
replying.....

.....HOWEVER, having a limiting stage in the
linear path of such a device is NOT a great idea
---------------------

Andy,

You really should go and read the data sheet on the AD607.

1) It's a linear component with no limiter stages
2) It has an "I-Q" detector, not a "quadrature detector".

Comparing it to the MC3372, or any other FM detector chip, is as far off
base as comparing it to an 811.

However, having said all that, I think we would agree that there are better
and simpler solutions for amateur SSB and AM applications.


Joe
W3JDR


"AndyS" wrote in message
oups.com...

Andy Thanks for your cents, rather dollars.

PS there is internal quadrature pll in ad607.

MAc


Andy responds;

Ok.. I admit that I didn't go find the AD607 and study it before
replying
to Mac... However,,, I'll bet you a dollar that the fellow who wrote
the
app note that Mac refers to has a hell of a lot less experience than
either Mac or myself..... not that I would expect a young app note
writer to overstate the applications of his product ( big damn grin
)...
The AD606 really makes a great tie-tac if you glue an alligator clip
to it, tho I've never actually seen one for sale... :)))))))

if the gilbert cell, or single ended long tailed pair multiplier
used as a
quad detector allows external coupling to the ports, it can be used as
a BFO for CW or SSB,..., HOWEVER, having a limiting stage in the
linear path of such a device is NOT a great idea.... Sure, it can be
made
to work, but..... well, heck... I've built a LOT of things that were
really
bad ideas, and I try not to duplicate them again, or tell others about

them.... especially in app notes that I've made input to......
I've seen the MC3372 used as an SSB receiver in either Ham Radio
or some such.... and I never seriously considered doing it myself since
the limitations were so obvious....

An 811A can be used a a product detector also, but the
manufacturers
don't advertise it as such,...... because it is a REALLY BAD idea....
If a fellow wants a simple CW/SSB receiver, a much better idea is to
use something like an NE602..... I've done that, for a home project ,
and
it works OK,..... but certainly not something I'd try to produce as a
receiver for Bendix, Texas Instruments, or Raytheon...... There's a
limit
to how far one should stretch an application.....

Thanks Mac, for your input. I bet we agree on almost
everything.....

Andy W4OAH

quadrature detector & SSB
 

AndyS napisa?(a):
I bet we agree on almost
everything.....

Generally Yesss

But (always but) :-))))

I never used mc3372 as ssb rx, but permanently used mc3362.
But... - mc3362 id dual conversion RX and i used second mixer as a
product detector leaving original fm detector "out of business".
I am not good in quadrature detectors, and i don't know what
(technically) is mixer (rather mixers) in ad607. I have only 1 piece of
IC, it's surface mount, and I'm afraid, that if I use it in my test
board I will have nothing to use in my receiver.

Of course I used ne602/612 in many constructions, (genetally trx with
switched BFO/VFO - Atlas idea), but this time the idea is to use as low
elements as possible to build a rx with "quite good" performance.

Serious (other or better ;-) ) idea in my wokshop is TGX with1st mixer
on fst3125 with companion of ad600 IF ampli (only one) in typical
application (application note with simple ad590 and one transistor AGC)
- not this "high performance agc system from Exp. Methods...

On the other hand - it is the best way in our HAM life - to use parts in
the way, which was not inntended by "creators". It's a part of our love
to ham radio :-)

Nice and inspirating talk Andy. Greetings from Poland

MAc
sp9mrn

quadrature detector & SSB
 

W3JDR wrote:
Andy,

You really should go and read the data sheet on the AD607.


Andy replies,

You're right. I should have dug a little further before I started
rattling off "the world according to Andy"....
When the OP started with the "quadrature det" question and
the reply was concerning I/Q , I just jumped right in...

Sorry I wasted your time......

Andy W4OAH

quadrature detector & SSB
 

MAc wrote:.
I have only 1 piece of
IC, it's surface mount, and I'm afraid, that if I use it in my test
board I will have nothing to use in my receiver.

Andy writes:

God how I hate surface mount.... It used to be that I could send
away for a freebee, or buy a chip from Digikey, and get normal,
civilized, 1/10 lead spacing pins that I could use in a socket, or
use the pins as tie point for "dead bug".....
I could build a circuit up as fast as I could go and the connecting
of the parts together was an insignificant part of the process...

NOW, for the last several years, all freebees I have received have
been surface mount. I have to work under a magnifying glass, with
a special thingy for my soldering iron, and use small pieces of copper
wire strand that I get out of lamp cord to expand the chip to the point
where I can actually attach resistors and capacitors.... it takes more
time
to expand the surface mount than to build the rest of the circuit... As
a
result, I lose enthusiasm a lot......

I have a few things that I have done with surface mount, but I long
for the good old days...... Fortunately, I have about 30 years of
accumulated freebees that I haven't gotten around to using, and can
usually come up with a way to build something.... However, the miracle
chips (as I call them) that Analog Dev, and others, are coming out with
are just too damn much trouble for me.......


If anyone here has some SIMPLE solutions for the surface mount thing,
that does NOT include making a custom PC board, I'd like to learn
about them.....

Andy in Eureka, Texas

quadrature detector & SSB
 

AndyS wrote:

If anyone here has some SIMPLE solutions for the surface mount thing,
that does NOT include making a custom PC board, I'd like to learn
about them.....

Take a look at Surfboards, stocked by Digi-Key:

http://dkc3.digikey.com/PDF/T062/1634.pdf

Dana K6JQ

quadrature detector & SSB
 

"MAc" wrote in message
...
How to use quadrature detector to demodulate cw and ssb. I want to use
AD607 in simple project. There is Quadrature detector on "the end" with
two outputs I&Q - and internal phase shifter. How to detest SSB simplest
way?

73

mac

With all that...

AD607 does NOT have a "quadrature detector". It has an "I & Q demodulator".
BIG difference. You must read the datasheet and app notes to use it
correctly. It is capable of demudulating many types of modulation. [typo
accepted]

73, Steve, K9DCI

quadrature detector & SSB
 

Steve N. napisa³(a):

AD607 does NOT have a "quadrature detector". It has an "I & Q demodulator".
BIG difference. You must read the datasheet and app notes to use it
correctly. It is capable of demudulating many types of modulation. [typo
accepted]

My mistake, I undersand. But datasheet says nothing more exept "it is
possible to detect ssb with ad607"

Thanks
MAc

quadrature detector & SSB
 

MAc wrote:
Steve N. napisa³(a):

AD607 does NOT have a "quadrature detector". It has an "I & Q
demodulator".
BIG difference. You must read the datasheet and app notes to use it
correctly. It is capable of demudulating many types of modulation.
[typo
accepted]


My mistake, I undersand. But datasheet says nothing more exept "it is
possible to detect ssb with ad607"

Thanks
MAc

Do a search on the phasing method of SSB reception, then the "Weaver"
method. Either of those should get you a block diagram showing what to
do with the I and Q outputs.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

quadrature detector & SSB
 

I never tried to use this chip as an SSB detector, but I did design an AM
sync detector a couple of years back. I remember that I had to limit the
input level to around 30uV when used in the fashion, but it wasn't bad for
that purpose.

Pete

"MAc" wrote in message
...
AndyS wrote:
A Quadrature detector is normally used only for FM demodulation.

Yes.

but (from Analog Devices):
"...Applications of the AD607 include narrowband systems with a high first
IF (21.4 MHz to 300 MHz) and a second IF at 10.7 MHz, 455 kHz, or 450 kHz.
These include Dual Conversion IS136, GSM, TETRA, and MSAT Receivers; and
Single or Dual Conversion VHF and HF AM, SSB, CW, or QPSK Receivers... "

But :-) I did not find any SSB application :-( So I need an example.



Just my two cents worth.... If anyone disagrees, I'd be happy to
learn from them where my explanation is wrong..... but I warn you,
it ain't far wrong.... cause it worked for me for many many years
in designing receivers for both commercial and military products
...:)))))


Andy Thanks for your cents, rather dollars.

PS there is internal quadrature pll in ad607.

MAc

quadrature detector & SSB
 

"MAc" wrote in message
...
Steve N. napisa³(a):

AD607 does NOT have a "quadrature detector". It has an "I & Q
demodulator".
BIG difference. You must read the datasheet and app notes to use it
correctly. It is capable of demudulating many types of modulation.
[typo
accepted]

My mistake, I undersand. But datasheet says nothing more exept "it is
possible to detect ssb with ad607"

Thanks
MAc

OK MAc,
All I know is the I & Q modulator and demodulators are the industry
standard in commercial radios like the ones my company designs. I hrae that
you can get anything you want. I'm too far away from the current designs to
know anything specific.
A Google resulted in this , but it doesn't appear to be a complete how-to.
http://www.merrimacind.com/rfmw/02intro_modulators.pdf

Perhaps someone can explain how to "I & Q" to get SSB, etc.

Good luck 73, K9DCI

quadrature detector & SSB
 

Perhaps someone can explain how to "I & Q" to get SSB, etc.


The simplest way I found - is to use an ear in companion of brain - :-)
I am serious - look for "binaural DC receiver" (Exp. Methods in RF
design) when one can see, that "i" is and "q" are simply amplified and
feed headphones. Thats all. But then we have still problem with lsb/usb.

Thanks for link.

MAc
sp9mrn

quadrature detector & SSB
 

On Fri, 7 Jul 2006 17:28:54 -0500, "Steve N."
wrote:


"MAc" wrote in message
...
Steve N. napisa³(a):

AD607 does NOT have a "quadrature detector". It has an "I & Q
demodulator".
BIG difference. You must read the datasheet and app notes to use it
correctly. It is capable of demudulating many types of modulation.
[typo
accepted]

My mistake, I undersand. But datasheet says nothing more exept "it is
possible to detect ssb with ad607"

Thanks
MAc

OK MAc,
All I know is the I & Q modulator and demodulators are the industry
standard in commercial radios like the ones my company designs. I hrae that
you can get anything you want. I'm too far away from the current designs to
know anything specific.
A Google resulted in this , but it doesn't appear to be a complete how-to.
http://www.merrimacind.com/rfmw/02intro_modulators.pdf

Perhaps someone can explain how to "I & Q" to get SSB, etc.

Good luck 73, K9DCI


Havent looked much at the AD part but... it's a mixer
(actually two of them).

See articles by KK7B and Breed. Basically the I (inphase)
and Q (quadrature) mixers are fed with RF at 90 degree relation to
each other. The resulting output is then put through a 90degree
delay (use 3rd order allpass networks for that) and sum or difference
the result and you have a phasing SSB/CW reciever. If you can keep
the phase and amplitude errors better than 1% (easy with modern parts)
you get 40+ db of alternate sideband suppression. All the work is
done in the audio range so Opamps are good for this or DSP. Look up
R2, MIniR2, or R2pro for more details. Summary is if you delay the
Q path by 90degrees and add the result there will be a frequency(s)
where the results add to each other and as you get past zero beat they
will subtract from each other.

One note on alternate sideband suppression, 40db is pretty good
sounding, 50db is achieveable and 60db is tough.

I've built a SSB transceiver using the KK7B miniR2 design and opposite
sideband suppression is 45db or so and it sounds far better on the air
than the typical minimal RX with a 4 crystal ladder filter. I run a
MiniR2 and T2 (phasing TX) on 6m with a 6W output. Gets rave reviews
for clean signal and it's very good TRX for DX.


Allison

quadrature detector & SSB
 

Hi -

The best not-terribly-mathematical place to get started probably is a
Popular Electronics (of all places) article from '82 called "Build a
Synchronous Detector for AM Radio" by Dave Hershberger.


Chuck