A
Alan Horowitz
Guest
Is there a place in modern technique for regeneration (Q-multiplication)?
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J
Joerg
Guest
Hi Alan,
use some cheap mixer chip, filter with a crystal at a frequency where it
is low enough in cost and then mix back to where the signal needs to be.
Also, I believe the art of such fine analog schemes is to a large extent
lost. Younger engineers often wouldn't even know what you mean by that
question. Thinking back to my days back at the university, have we ever
been taught regen or Q-multiplication? Nope.
Regards, Joerg
http://www.analogconsultants.com
spared me the expense of a crystal filter. Nowadays it is possible toIs there a place in modern technique for regeneration (Q-multiplication)?
Last time I used it was, oh, about 30 years ago. It worked great and
use some cheap mixer chip, filter with a crystal at a frequency where it
is low enough in cost and then mix back to where the signal needs to be.
Also, I believe the art of such fine analog schemes is to a large extent
lost. Younger engineers often wouldn't even know what you mean by that
question. Thinking back to my days back at the university, have we ever
been taught regen or Q-multiplication? Nope.
Regards, Joerg
http://www.analogconsultants.com
J
John Smith
Guest
"Alan Horowitz" <alanh_27@yahoo.com> wrote in message
news:1e3670a7.0410281434.70887cc7@posting.google.com...
believe I saw that some of the 433 MHz ISM band receivers use either
regenerative or superregenerative detectors. They are tiny and have
sensitivities better than -106 dBm.
There has been new work on superregens (September/October 2000). An article
was published in QEX, a ham radio journal. The first file at
http://www.arrl.org/tis/info/vhfproj.html is that article but it requires
membership to get it. However, on the same Web page, I see another that
appears to be available without membership. It is An Ultra-Simple VHF
Receiver for 6 Meters .
You can probably contact the ARRL and buy a reprint of the first article. It
is well worth it. The author, Charles Kitchin, says the gain in a superregen
detector is about a million. He discusses his discovery of shaping the
quenching waveform so that selectivity is not lost. And he says it is
possible to receive FM and NBFM as well as AM. It is a very enlightening
article.
I plan to build a superregen to play with. After I get one going, I think I
will try to make it work at 450 MHz. Like some other posters here, I built
my previous regen 40 years ago.
Cheers,
John
news:1e3670a7.0410281434.70887cc7@posting.google.com...
I guess that depends on the application. I don't know how true it is, but IIs there a place in modern technique for regeneration (Q-multiplication)?
believe I saw that some of the 433 MHz ISM band receivers use either
regenerative or superregenerative detectors. They are tiny and have
sensitivities better than -106 dBm.
There has been new work on superregens (September/October 2000). An article
was published in QEX, a ham radio journal. The first file at
http://www.arrl.org/tis/info/vhfproj.html is that article but it requires
membership to get it. However, on the same Web page, I see another that
appears to be available without membership. It is An Ultra-Simple VHF
Receiver for 6 Meters .
You can probably contact the ARRL and buy a reprint of the first article. It
is well worth it. The author, Charles Kitchin, says the gain in a superregen
detector is about a million. He discusses his discovery of shaping the
quenching waveform so that selectivity is not lost. And he says it is
possible to receive FM and NBFM as well as AM. It is a very enlightening
article.
I plan to build a superregen to play with. After I get one going, I think I
will try to make it work at 450 MHz. Like some other posters here, I built
my previous regen 40 years ago.
Cheers,
John
A
Alan Horowitz
Guest
John Larkin <jjlarkin@highSNIPlandTHIStechPLEASEnology.com>
Selectivity at the upper decades of Mhz is cheap nowadays? Where do I
buy one of these flea-market tuneable multi-ganged, several-octave
HF-VHF preselectors?
I wasn't thinking of regenerative detectors. I was thinking of a
tuneable front-end preselector which would emulate the Q
characteristics of a crystal-lattice bandpass filter.
don't we have nowadays, high-power, low-noise FETs which are almost as
good as the vacuum tubes made in the late 60's, early 70's.
Stability? RF stability is like aircraft stability.... if your
design and implementation are excellent, it would be hard to get into
an unstable area of operation.
Rarely, if ever. Gain and selectivity are cheap nowadays, and
regeneration trades them for stability.
Selectivity at the upper decades of Mhz is cheap nowadays? Where do I
buy one of these flea-market tuneable multi-ganged, several-octave
HF-VHF preselectors?
I wasn't thinking of regenerative detectors. I was thinking of a
tuneable front-end preselector which would emulate the Q
characteristics of a crystal-lattice bandpass filter.
don't we have nowadays, high-power, low-noise FETs which are almost as
good as the vacuum tubes made in the late 60's, early 70's.
Stability? RF stability is like aircraft stability.... if your
design and implementation are excellent, it would be hard to get into
an unstable area of operation.
J
Joerg
Guest
Hi John,
Direct DSP would be prohibitively expensive at VHF. Probably you'd have
to assemble an array the size of a large pizza and call the power
company before turning it on.
Regards, Joerg
http://www.analogconsultants.com
Selectivity at the upper decades of Mhz is cheap nowadays? Where do I
buy one of these flea-market tuneable multi-ganged, several-octave
HF-VHF preselectors?
Only using conversion - filter - conversion back. Otherwise it's cavity
resonators and beaucoup Dollars.
Or SAWs, or ceramic resonators, or DSP stuff.
But the first wto ar not tunable. At least not without using sandpaper ;-)
Direct DSP would be prohibitively expensive at VHF. Probably you'd have
to assemble an array the size of a large pizza and call the power
company before turning it on.
Regards, Joerg
http://www.analogconsultants.com
J
Jim Gerrie
Guest
"Alan Horowitz" <alanh_27@yahoo.com> wrote in message
news:1e3670a7.0410291230.a1b0e18@posting.google.com...
with Pin diodes and Fets. but it is at least 10 to 100 times wider.
news:1e3670a7.0410291230.a1b0e18@posting.google.com...
Ham fest, build your own, can get more than 10:1 over frequency.John Larkin <jjlarkin@highSNIPlandTHIStechPLEASEnology.com
Rarely, if ever. Gain and selectivity are cheap nowadays, and
regeneration trades them for stability.
Selectivity at the upper decades of Mhz is cheap nowadays? Where do I
buy one of these flea-market tuneable multi-ganged, several-octave
HF-VHF preselectors?
Can get to a xal selectivity at all. You can do an elecrically tuneableI wasn't thinking of regenerative detectors. I was thinking of a
tuneable front-end preselector which would emulate the Q
characteristics of a crystal-lattice bandpass filter.
with Pin diodes and Fets. but it is at least 10 to 100 times wider.
don't we have nowadays, high-power, low-noise FETs which are almost as
good as the vacuum tubes made in the late 60's, early 70's.
Stability? RF stability is like aircraft stability.... if your
design and implementation are excellent, it would be hard to get into
an unstable area of operation.
K
Ken Smith
Guest
In article <bzzgd.2281$zx1.304@newssvr13.news.prodigy.com>,
Joerg <notthisjoergsch@removethispacbell.net> wrote:
[...]
Doing an ADC that has very many bits is tricky at high frequencies. You
would end up with a combination ADC and spaceheater.
How about a large copper tube as a wave guide and a plunger driven by an
electric motor? You can get sharp peaks out of such things. The bad part
is you never get just one peak. Perhaps using two or more you can arrange
it so that only one peak lines up in both (all three).
--
--
kensmith@rahul.net forging knowledge
Joerg <notthisjoergsch@removethispacbell.net> wrote:
[...]
Thats the easy part. First, you have to run the signal through an ADC.Direct DSP would be prohibitively expensive at VHF. Probably you'd have
to assemble an array the size of a large pizza and call the power
company before turning it on.
Doing an ADC that has very many bits is tricky at high frequencies. You
would end up with a combination ADC and spaceheater.
How about a large copper tube as a wave guide and a plunger driven by an
electric motor? You can get sharp peaks out of such things. The bad part
is you never get just one peak. Perhaps using two or more you can arrange
it so that only one peak lines up in both (all three).
--
--
kensmith@rahul.net forging knowledge
K
Ken Smith
Guest
In article <cluc19$jbb$1@newshost.mot.com>,
Steve Nosko <suteuve.nosukowicuz@moutouroula.com> wrote:
--------------------------------
! !
--- !
--- C1 !
R1 ! R2 ! \ !
---/\/\/\------+------/\/\/\/----+---! K >----- +----
! ! / E1
!
---
--- C2
!
GND
Feed this circuit into spice with
R1 = R2 = 1 Ohm
C1 = C2 = 1 Farad
Try the circuit with K= 0.5 1 2 and 2.7 2.8 and 2.9
See what happens to the 0.03Hz to 0.3Hz band as you raise the gain and
hence the positive feedback.
--
--
kensmith@rahul.net forging knowledge
Steve Nosko <suteuve.nosukowicuz@moutouroula.com> wrote:
No I mean positive. Lets take the simplest example:"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:cls6o5$urr$2@blue.rahul.net...
In article <1e3670a7.0410281434.70887cc7@posting.google.com>,
Alan Horowitz <alanh_27@yahoo.com> wrote:
Is there a place in modern technique for regeneration (Q-multiplication)?
Most RC+opamp filters include some sort of positive feedback.
Umm. Er Don't you mean negative?
--------------------------------
! !
--- !
--- C1 !
R1 ! R2 ! \ !
---/\/\/\------+------/\/\/\/----+---! K >----- +----
! ! / E1
!
---
--- C2
!
GND
Feed this circuit into spice with
R1 = R2 = 1 Ohm
C1 = C2 = 1 Farad
Try the circuit with K= 0.5 1 2 and 2.7 2.8 and 2.9
See what happens to the 0.03Hz to 0.3Hz band as you raise the gain and
hence the positive feedback.
--
--
kensmith@rahul.net forging knowledge
N
N. Thornton
Guest
"John Smith" <kd5yikes@mindspring.com> wrote in message news:<E8kgd.10431$KJ6.993@newsread1.news.pas.earthlink.net>...
I think its possible it might become popular technology again. The
advantage of high gain per cost is attractive, and it has other
benefits. Stability is the prime issue: it can be controlled by low
frequency quenching, which can of course be adaptive. The question now
is whether a simple scheme can be devised that ensures consistent
stability and gain with small quench control circuit cost. If solid
stability is achieved, the rf emission problem is eliminated at the
same time. If its achieved at minimal cost, it may be a winner.
I know I've seen it used in some modern receiver chips, but damned if
I can remember the details.
NT
"Alan Horowitz" <alanh_27@yahoo.com> wrote in message
news:1e3670a7.0410281434.70887cc7@posting.google.com...
Is there a place in modern technique for regeneration (Q-multiplication)?
I think its possible it might become popular technology again. The
advantage of high gain per cost is attractive, and it has other
benefits. Stability is the prime issue: it can be controlled by low
frequency quenching, which can of course be adaptive. The question now
is whether a simple scheme can be devised that ensures consistent
stability and gain with small quench control circuit cost. If solid
stability is achieved, the rf emission problem is eliminated at the
same time. If its achieved at minimal cost, it may be a winner.
I know I've seen it used in some modern receiver chips, but damned if
I can remember the details.
NT
N
N. Thornton
Guest
"Guillaume Soro" <nospam@nospam.com> wrote in message news:<2udho9F269uimU1@uni-berlin.de>...
expensive. For most of the 30s the reaction set was still the prime
configuration, superhets stayed in the luxury bracket for some while.
Anyone that built a superhet in 1925 had to be rich.
NT
Although superhets were conceived early on, they were absurdly"Alan Horowitz" <alanh_27@yahoo.com> wrote in message
news:1e3670a7.0410281434.70887cc7@posting.google.com...
Is there a place in modern technique for regeneration (Q-multiplication)?
Yes, there are some kits available to build, seen them somewhere on the net.
There is also quenched regen. which works better than just regeneration.
Regen has the best sensitivity, but poor selectivity
It was popular in the first radios 1910 to 1925, then the superhets came
in, with better stability, but cost more.
expensive. For most of the 30s the reaction set was still the prime
configuration, superhets stayed in the luxury bracket for some while.
Anyone that built a superhet in 1925 had to be rich.
NT
P
Paul Keinanen
Guest
On Fri, 29 Oct 2004 22:33:43 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:
If we are talking about amateur band systems only, using suitable
high-Q front end band pass filtering (helical or cavity resonators),
you can limit the bandwidth to a few hundred kHz (e.g. the SSB or
satellite band). Then you only need a sampling frequency of the order
of 1 MHz and undersample (decimate) it and process it at that sampling
frequency.
Paul OH3LWR
<notthisjoergsch@removethispacbell.net> wrote:
Why ?Direct DSP would be prohibitively expensive at VHF. Probably you'd have
to assemble an array the size of a large pizza and call the power
company before turning it on.
If we are talking about amateur band systems only, using suitable
high-Q front end band pass filtering (helical or cavity resonators),
you can limit the bandwidth to a few hundred kHz (e.g. the SSB or
satellite band). Then you only need a sampling frequency of the order
of 1 MHz and undersample (decimate) it and process it at that sampling
frequency.
Paul OH3LWR
K
Ken Smith
Guest
In article <puh6o0lpvkiotq4pbsgtin4ptv4g17h732@4ax.com>,
Paul Keinanen <keinanen@sci.fi> wrote:
[...]
area of the sample and hold. The device that does the sampling, must be
fast so there are a lot of sqrt(Hz) included. The sampling will alias the
high frequency noise from the device down.
You are better off to mix down to a lower frequency using something that
acts multiplying sinewaves so that there are no high frequency components
to cause the mixing of high frequency components. You can make sample and
hold circuits that act this way but you need more than one to make it work
right.
--
--
kensmith@rahul.net forging knowledge
Paul Keinanen <keinanen@sci.fi> wrote:
[...]
This method tends to increase noise unless something clever is done in theIf we are talking about amateur band systems only, using suitable
high-Q front end band pass filtering (helical or cavity resonators),
you can limit the bandwidth to a few hundred kHz (e.g. the SSB or
satellite band). Then you only need a sampling frequency of the order
of 1 MHz and undersample (decimate) it and process it at that sampling
frequency.
area of the sample and hold. The device that does the sampling, must be
fast so there are a lot of sqrt(Hz) included. The sampling will alias the
high frequency noise from the device down.
You are better off to mix down to a lower frequency using something that
acts multiplying sinewaves so that there are no high frequency components
to cause the mixing of high frequency components. You can make sample and
hold circuits that act this way but you need more than one to make it work
right.
--
--
kensmith@rahul.net forging knowledge