Thanks Tom,
I do have that article, and that circuit is similar to
the quasi-sync detector that I developed a couple of weeks ago. The appnote
that i have describes a design that I believe was created by one of the
application engineers at AD. This is a really cool circuit, because it is
optimized for 455kHz. I've got the board layout almost done...........maybe
later this week, I will have it built up.
I've bumped up the overload point on the receiver to 80,000uv, so it isn't
too bad now. Measured distortion with either the envelope detector or the
current version of the sync detector is .4% @ 300uV, but there is still
something I don't like about the sound of that sync detector. If I were to
try to market the receiver with the current sync detector, it would get shot
down by anybody who was unfortunate enough to buy it. Still more work to do
in this area. One fellow from Norway suggested that I have an I.F. output on
the radio, so that folks can use their own sync detector. I could do that,
but my goal is to design a sync detector that is better than anything else
on the market, regardless of price. Hopefully, I will be able to do it.

Pete

tom Holden wrote in message
om...
"Pete KE9OA" wrote in message [snip]
this into production, so the next step is to design a sync detector,
using
an Analog Devices AD607. The folks at AD were nice enough to send me a
workable application circuit, but unfortunately, this is going to
require a
four layer board, so I am not going to be able to etch the boards at
home
with this one. Not a bad thing in itself, but I am going to have a board
house do the prototype boards.

[snip]

Pete, here's an article on using the AD607 as a sync demod:
http://home.att.net/~wa1sov/technical/sync_det.html

73, Tom

Pete KE9OA wrote:

...my goal is to design a sync detector that is better than anything else
on the market, regardless of price. Hopefully, I will be able to do it.

I appreciate you're striving for the best Pete but I think most everyone
on this group would be very satisfied if the sync' works like the R8B or
AOR-7030.

BTW- The sync' should be double sideband in addition to sideband
selectable.


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I am not sure how to do the selectable sideband function, but I can figure
it out, I will sure throw that function in. I just ordered some samples of
the high speed op-amp that is used for squaring up the signal to the phase
detector. They should be in on Wednesday. I am doing two versions of the
detector...........one of them will use an AD op-amp, while the other will
use a Burr-Brown device. This sync detector will have two ceramic bandpass
filters in the signal chain.........one of them will be between the mixer
output and the I.F. input, while the other will be between the I.F. output
and the demodulator input. It shoud be a low-noise system. AD specifies this
configuration as having an MDS of -90dBm. I will be feeding in a -20dBm
signal, so the earlier stages of the receiver will have more than enough
takeover gain. If there is enough interest in the circuit design, I will
post the AD application note up on my website.
Thanks for encouragement!

Pete

starman wrote in message
...
Pete KE9OA wrote:

...my goal is to design a sync detector that is better than anything
else
on the market, regardless of price. Hopefully, I will be able to do it.

I appreciate you're striving for the best Pete but I think most everyone
on this group would be very satisfied if the sync' works like the R8B or
AOR-7030.

BTW- The sync' should be double sideband in addition to sideband
selectable.


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(John Crabtree) on 12/21/03 wrote:

snip

I have just dug out an article:
Trevor Wheatley (of Surrey Electronics), "AM synchronous
demodulator",
Electronics and Wireless World, Sept 1989, pp858-860

snip

Adriano Tencati kindly pointed out to me that the author is Trevor Brook (of
Surrey Electronics Ltd)

Apologies to all.

73 John KC0GGH

"Pete KE9OA" on 12/30/03 wrote:

I am not sure how to do the selectable sideband function, but
I can figure it out, I will sure throw that function in. I just
ordered some samples of the high speed op-amp that is used
for squaring up the signal to the phase detector. They should
be in on Wednesday. I am doing two versions of the detector...........one of
them will use an AD op-amp, while the
other will use a Burr-Brown device. This sync detector will have
two ceramic bandpass filters in the signal chain.........one of
them will be between the mixer output and the I.F. input, while
the other will be between the I.F. output and the demodulator
input. It shoud be a low-noise system. AD specifies this
configuration as having an MDS of -90dBm. I will be feeding in
a -20dBm signal, so the earlier stages of the receiver will have
more than enough takeover gain. If there is enough interest in
the circuit design, I will post the AD application note up on my
website.
Thanks for encouragement!

Pete

You have some options as to how to provide selectable sideband in the
synchronous detector:

1. You can do it with passband tuning and move the signal carrier to the edge
of the IF filter passband. IIRC this is the way that you can select the
sideband in the AOR7030. I suspect that doing this will cause some phase
distortion to the carrier if you place it on the edge of the passband. To what
extent this matters I do not know.

2. Once you have the I and Q signals from a quadrature detector, you can use
all-pass networks to phase the outputs and then add or subtract as necessary.
Sony did this with the ICF-2010. Trevor Brook in his Electronics and Wireless
World article did this as well.

One issue with this approach is that the level of opposite sideband reduction
is dependent upon the quality and number of stages in the phasing networks.
IIRC Sony only achieve ca. 25db of opposite sideband reduction. The quality of
phasing networks has been discussed in the ham radio literature re. the
generation of SSB signals. It is possible to design simple networks which are
'OK' over the range 300 to 3000Hz.

Once you have the Q output, it then should be very straightforward to offfer
quadrature detection as well, where you null out the strongest station on the
frequency to which the detector has locked.

Which ever way you might choose, there are inevitable compromises. Another
issue is what audio bandwidth is necessary in an AM receiver. Some time ago,
in Short Wave Magazine (UK), John Wilson showed the spectrum analyser display
of a BBC MW broadcast station. It was tightly filtered above 4+ kHz to stay
with the allowed channel. Many AM stations also process their signals..

I like your idea of having two ceramic filters before the synchronous detector.
I see that the oscillator in the AD607 has a wide tuning range, and it would
be very unhelpful if it locked to the 'wrong' signal. As a contrast the synch
oscillator in the ICF-2010, which is also used as the BFO, can only be moved a
small frequency eg. 3 kHz (please do not quote me on this - I did measure it
once) either side of 455kHz.

I must admit that I am still intrigued by the idea in Brook's article of having
using the sync. oscillator as a BFO and restricting it to a very narrow (+/-
20Hz ?) locking range. One could then listen normally with envelope detection,
turn on the BFO to get ECSS detection, and then once one has obtained a zero
beat, turn it to sync mode. However it is not something which I would wish to
put into a general purpose radio.

Let me register my interest in seeing the AD application note on your web site.
If you want a copy of the Brook article, please contact me off list.

73 John KC0GGH

Thanks John...........that will be good.

Pete

John Crabtree wrote in message
...
"Pete KE9OA" on 12/30/03 wrote:

I am not sure how to do the selectable sideband function, but
I can figure it out, I will sure throw that function in. I just
ordered some samples of the high speed op-amp that is used
for squaring up the signal to the phase detector. They should
be in on Wednesday. I am doing two versions of the
detector...........one of
them will use an AD op-amp, while the
other will use a Burr-Brown device. This sync detector will have
two ceramic bandpass filters in the signal chain.........one of
them will be between the mixer output and the I.F. input, while
the other will be between the I.F. output and the demodulator
input. It shoud be a low-noise system. AD specifies this
configuration as having an MDS of -90dBm. I will be feeding in
a -20dBm signal, so the earlier stages of the receiver will have
more than enough takeover gain. If there is enough interest in
the circuit design, I will post the AD application note up on my
website.
Thanks for encouragement!

Pete

You have some options as to how to provide selectable sideband in the
synchronous detector:

1. You can do it with passband tuning and move the signal carrier to the
edge
of the IF filter passband. IIRC this is the way that you can select the
sideband in the AOR7030. I suspect that doing this will cause some phase
distortion to the carrier if you place it on the edge of the passband. To
what
extent this matters I do not know.

2. Once you have the I and Q signals from a quadrature detector, you can
use
all-pass networks to phase the outputs and then add or subtract as
necessary.
Sony did this with the ICF-2010. Trevor Brook in his Electronics and
Wireless
World article did this as well.

One issue with this approach is that the level of opposite sideband
reduction
is dependent upon the quality and number of stages in the phasing
networks.
IIRC Sony only achieve ca. 25db of opposite sideband reduction. The
quality of
phasing networks has been discussed in the ham radio literature re. the
generation of SSB signals. It is possible to design simple networks which
are
'OK' over the range 300 to 3000Hz.

Once you have the Q output, it then should be very straightforward to
offfer
quadrature detection as well, where you null out the strongest station on
the
frequency to which the detector has locked.

Which ever way you might choose, there are inevitable compromises.
Another
issue is what audio bandwidth is necessary in an AM receiver. Some time
ago,
in Short Wave Magazine (UK), John Wilson showed the spectrum analyser
display
of a BBC MW broadcast station. It was tightly filtered above 4+ kHz to
stay
with the allowed channel. Many AM stations also process their signals..

I like your idea of having two ceramic filters before the synchronous
detector.
I see that the oscillator in the AD607 has a wide tuning range, and it
would
be very unhelpful if it locked to the 'wrong' signal. As a contrast the
synch
oscillator in the ICF-2010, which is also used as the BFO, can only be
moved a
small frequency eg. 3 kHz (please do not quote me on this - I did measure
it
once) either side of 455kHz.

I must admit that I am still intrigued by the idea in Brook's article of
having
using the sync. oscillator as a BFO and restricting it to a very narrow
(+/-
20Hz ?) locking range. One could then listen normally with envelope
detection,
turn on the BFO to get ECSS detection, and then once one has obtained a
zero
beat, turn it to sync mode. However it is not something which I would
wish to
put into a general purpose radio.

Let me register my interest in seeing the AD application note on your web
site.
If you want a copy of the Brook article, please contact me off list.

73 John KC0GGH

John Crabtree wrote:

"Pete KE9OA" on 12/30/03 wrote:

I am not sure how to do the selectable sideband function, but
I can figure it out, I will sure throw that function in. I just
ordered some samples of the high speed op-amp that is used
for squaring up the signal to the phase detector. They should
be in on Wednesday. I am doing two versions of the detector...........one of
them will use an AD op-amp, while the
other will use a Burr-Brown device. This sync detector will have
two ceramic bandpass filters in the signal chain.........one of
them will be between the mixer output and the I.F. input, while
the other will be between the I.F. output and the demodulator
input. It shoud be a low-noise system. AD specifies this
configuration as having an MDS of -90dBm. I will be feeding in
a -20dBm signal, so the earlier stages of the receiver will have
more than enough takeover gain. If there is enough interest in
the circuit design, I will post the AD application note up on my
website.
Thanks for encouragement!

Pete

You have some options as to how to provide selectable sideband in the
synchronous detector:

1. You can do it with passband tuning and move the signal carrier to the edge
of the IF filter passband. IIRC this is the way that you can select the
sideband in the AOR7030. I suspect that doing this will cause some phase
distortion to the carrier if you place it on the edge of the passband. To what
extent this matters I do not know.

2. Once you have the I and Q signals from a quadrature detector, you can use
all-pass networks to phase the outputs and then add or subtract as necessary.
Sony did this with the ICF-2010. Trevor Brook in his Electronics and Wireless
World article did this as well.

One issue with this approach is that the level of opposite sideband reduction
is dependent upon the quality and number of stages in the phasing networks.
IIRC Sony only achieve ca. 25db of opposite sideband reduction. The quality of
phasing networks has been discussed in the ham radio literature re. the
generation of SSB signals. It is possible to design simple networks which are
'OK' over the range 300 to 3000Hz.

Once you have the Q output, it then should be very straightforward to offfer
quadrature detection as well, where you null out the strongest station on the
frequency to which the detector has locked.

Which ever way you might choose, there are inevitable compromises.
snipped

Pete,

I'm not sure if you mentioned it but I assume you're working with an
I.F. of 455-Khz? The Drake-SW8 and it's clone the Sat-800, implement the
sync' detector in the second I.F. at 455-Khz while the Drake-R8x does it
at 50-Khz. It's basically the same circuit in both receivers, just
operating at different I.F.'s.
FWIW- I vote for the I/Q method for selectable sideband sync' detection.
It seems like the elegant solution to me.


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It looks pretty good............I should take a look at my Drake schematics.
I hope they aren't using those impossible to get chips, you know, the ones
that all of the radio manufacturers have bought up!
Anyway, I got the AD607 board layout completed, but it required four layers.
I am going to try to reduce it to two layers, at least for the 1st article,
so I can build it up this weekend. Too bad that Analog Devices doesn't
internally bias their chips, the way that Philips does. With the quagmire if
external biasing resistors, this chip reminds me more of something like the
OLD,OLD MC1496, which came out in the last century, not the modern day chip
that it is touted as being.
I do have the AD607 Eval Board, but that thing is harder to use than just
doing my own board layout. I can understand why the manufacturers of those
external sync boards charge so much money. Quite a bit of development time.
I am still shooting for the 100 to 125 dollar range for this board, if I can
get it into existance!

Pete

starman wrote in message
...
John Crabtree wrote:

"Pete KE9OA" on 12/30/03 wrote:

I am not sure how to do the selectable sideband function, but
I can figure it out, I will sure throw that function in. I just
ordered some samples of the high speed op-amp that is used
for squaring up the signal to the phase detector. They should
be in on Wednesday. I am doing two versions of the
detector...........one of
them will use an AD op-amp, while the
other will use a Burr-Brown device. This sync detector will have
two ceramic bandpass filters in the signal chain.........one of
them will be between the mixer output and the I.F. input, while
the other will be between the I.F. output and the demodulator
input. It shoud be a low-noise system. AD specifies this
configuration as having an MDS of -90dBm. I will be feeding in
a -20dBm signal, so the earlier stages of the receiver will have
more than enough takeover gain. If there is enough interest in
the circuit design, I will post the AD application note up on my
website.
Thanks for encouragement!

Pete

You have some options as to how to provide selectable sideband in the
synchronous detector:

1. You can do it with passband tuning and move the signal carrier to
the edge
of the IF filter passband. IIRC this is the way that you can select the
sideband in the AOR7030. I suspect that doing this will cause some
phase
distortion to the carrier if you place it on the edge of the passband.
To what
extent this matters I do not know.

2. Once you have the I and Q signals from a quadrature detector, you
can use
all-pass networks to phase the outputs and then add or subtract as
necessary.
Sony did this with the ICF-2010. Trevor Brook in his Electronics and
Wireless
World article did this as well.

One issue with this approach is that the level of opposite sideband
reduction
is dependent upon the quality and number of stages in the phasing
networks.
IIRC Sony only achieve ca. 25db of opposite sideband reduction. The
quality of
phasing networks has been discussed in the ham radio literature re. the
generation of SSB signals. It is possible to design simple networks
which are
'OK' over the range 300 to 3000Hz.

Once you have the Q output, it then should be very straightforward to
offfer
quadrature detection as well, where you null out the strongest station
on the
frequency to which the detector has locked.

Which ever way you might choose, there are inevitable compromises.
snipped

Pete,

I'm not sure if you mentioned it but I assume you're working with an
I.F. of 455-Khz? The Drake-SW8 and it's clone the Sat-800, implement the
sync' detector in the second I.F. at 455-Khz while the Drake-R8x does it
at 50-Khz. It's basically the same circuit in both receivers, just
operating at different I.F.'s.
FWIW- I vote for the I/Q method for selectable sideband sync' detection.
It seems like the elegant solution to me.


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On Tue, 30 Dec 2003 07:08:46 GMT, "Pete KE9OA"
wrote:

I am not sure how to do the selectable sideband function, but I can figure
it out, I will sure throw that function in.

On my bench as I type this is a nearly completed audio phase shift
network for KK7B's R2pro. It is designed for handling the 90 degree I
and Q phase shifts for audio from below 300 Hz to at least 4 kHz.

Yes, it uses 1% components for the resistors and capacitors. However,
it's built with commonplace operational amplifiers. With just an
amplitude balance pot, one should be able to achieve opposite sideband
rejection ratios of at least 50 dB. If you really want to get the
very best out of it, one could reach rejection ratios of 60 dB, though
KK7B says that maintaining this performance over typical room
temperature shifts is probably more trouble than it's worth.

To put this sort of performance in perspective, most consumer SSB
receivers audio noise floors would mask the opposite sideband.


Jake Brodsky, AB3A
"Beware of the massive impossible!"

I remember doing something with one of AD's quadrature modulators, using an
AD9854 as the LO source. I came up with a circuit that would give 50dB
opposite sideband suppression from 4MHz to 1.5GHz. I don't know if Motorola
ever applied for a patent for that circuit. I guess that circuit could also
work. It sounds like you have taken a sound approach.

Pete

Jake Brodsky wrote in message
...
On Tue, 30 Dec 2003 07:08:46 GMT, "Pete KE9OA"
wrote:

I am not sure how to do the selectable sideband function, but I can
figure
it out, I will sure throw that function in.

On my bench as I type this is a nearly completed audio phase shift
network for KK7B's R2pro. It is designed for handling the 90 degree I
and Q phase shifts for audio from below 300 Hz to at least 4 kHz.

Yes, it uses 1% components for the resistors and capacitors. However,
it's built with commonplace operational amplifiers. With just an
amplitude balance pot, one should be able to achieve opposite sideband
rejection ratios of at least 50 dB. If you really want to get the
very best out of it, one could reach rejection ratios of 60 dB, though
KK7B says that maintaining this performance over typical room
temperature shifts is probably more trouble than it's worth.

To put this sort of performance in perspective, most consumer SSB
receivers audio noise floors would mask the opposite sideband.


Jake Brodsky, AB3A
"Beware of the massive impossible!"