On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough to
overlaod and flatten out the selectivity.

Could you recommend a good introduction to the theory of the regenerative
receiver (and superregen)?

thanks,
Tobin

Tobin Fricke wrote:

On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough
to overlaod and flatten out the selectivity.


Could you recommend a good introduction to the theory of the
regenerative receiver (and superregen)?

thanks,
Tobin


I'll recommend a little book that is readily available. "Secrets of
Homebuilt Regenerative Receivers" by C.F. "Rock" Rockey. Its a Lindsay
Publications book.
Rockey does a good job at simplifying the simple Basically the
concept of a regen is feeding the output back into the input for
reamplification. Theoretically its a somewhat infinite process in that
the reamplification continues repeating itself resulting in very high
gain at the particular frequency the set is tuned to and thats also
where the selectivity improvement comes from.
Its similar to oscillation in a tube.

The coupling issue mentioned by Allison is related in the sense that
heavy antenna loading will decrease the circuit Q and consequently
decrease its selectivity as the regenerative signal makes its round-trip
thru the circuit. That opens the window for strong stations that are
well off frequency to easily overload the circuit as a whole due to the
high magnitude of amplification. You'll see some circuits with direct
antenna connections to the tank circuit (bad)...some use a separate
antenna winding on the coil (better) some use capacitive coupling to
the tank...some use a combination of both.

Easy enough to build one for grins...might not be as stable as you would
want for your decoding project but would be a good, fun exercise just
the same.

GL,
Bill

On Tue, 24 Jan 2006 17:20:35 GMT, "Michael A. Terrell"
wrote:

Joel Kolstad wrote:

"xpyttl" wrote in message
...
However, depending on where you are, you can typically only hear WWVB for a
small part of the day.

Does a bigger antenna help? Or is there just so much more background noise
than signal that it's a lost cause?

Hmm... isn't the data rate something like 1bps? Maybe they could do some
direct sequence spreading at 100Hz or so and improve the link margin a handful
of dB... :-)

If the problem is more or less random noise, what is the point of
spreading the transmit signal, since the same noise density would
appear in a specific bandwidth after despreading.

And lose the ability to be used as a frequency standard?

The GPS signal is DSSS and it can be used as a time and/or frequency
standard.

Paul

On Tue, 24 Jan 2006 20:06:22 -0800, Tobin Fricke
wrote:

On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough to
overlaod and flatten out the selectivity.

Could you recommend a good introduction to the theory of the regenerative
receiver (and superregen)?

thanks,
Tobin
You may want to consider this little regen receiver project. The board
for it is available from Far Circuits for around $5, or you could make
your own board.
http://www.electronics-tutorials.com...o-receiver.htm

Mike

On Tue, 24 Jan 2006 20:06:22 -0800, Tobin Fricke
wrote:

On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough to
overlaod and flatten out the selectivity.

Could you recommend a good introduction to the theory of the regenerative
receiver (and superregen)?

thanks,
Tobin

I Don't have any but I'd look on the net as there are gobs of circuits
with explanation. However the best explaied ones may be the older
tube designs.

Allison

On Tue, 24 Jan 2006 19:43:45 -0800, Tobin Fricke
wrote:

On Tue, 24 Jan 2006, wrote:

For wwv I consider DC the least useful. One approach I've also tried

What do yo umean by "least useful"?

I consider recieving AM transmissions with a system more optimum a
less than desireable thing unless the LO is locked (PLL) to the source
and thats a lot of complication.


is 9.6mhz crystal LO and use 455khz if can retuned to 400khz. that
works and uses fairly easy to get parts. That allows a diode
detector for zero beat against external sources and copy of the audio
without beats.

What is the 400 kHz used for?

IF amplifer as in superhet style of reciever.

Allison

"Tobin Fricke" wrote in message
F.Berkeley.EDU...

I don't see any articles on WWV receivers there... Does anything look
familiar: http://www.njqrp.org/data/qrp_homebrewer.html

Sorry, I meant "Homebrewer" rather than "QRP Home brewer". The AmQRP rag
rather than the now-defunct NJQRP mag.

...

Paul Keinanen wrote:

The GPS signal is DSSS and it can be used as a time and/or frequency
standard.

So, you want everyone still using WWVB for a frequency standard to
spend wads of cash to convert?

--
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

Allison wrote:
[Regens]
The trick with regens is to couple as loosely as possible.

And, to the original poster (Tobin), don't take anything I wrote as
being bad about regeneratives being a great first receiver project.
They are a wonderful first receiver project. Just don't do it to
receive one particular station, do it instead to receive all the
interesting stuff going on.

Tim.

From: (Mark Zenier) on Tues, Jan 24 2006 7:13 pm

xpyttl wrote:
"John S." wrote in message

Are you looking to decode the data transmissions or listen to the voice
signals. If the former it may take something more sophisticated
because you will have to feed a decoder.

Well, the 60 kHz WWVB transmissions were designed to be decoded, and there
are a fair number of projects out there to do just that. However, depending
on where you are, you can typically only hear WWVB for a small part of the
day.

For information on the WWV, WWVH, WWVB time codes and signal
strength, go to: http://tf.nist.gov/timefreq/index.html

From the coverage diagrams (every 2 hours), most of the
contiguous states of the USA get sufficient signal from
WWVB in any 24-hour period. That has been observed here
(Los Angeles County) using a 2 1/2 foot diameter loop;
distance to Ft. Collins is roughly 800 miles (?).

By actual test, my LaCrosse radio wris****ch was able to
sync on WWVB on an auto trip to Wisconsin and back over
September to October. Typically such radio watches only
begin checking/syncing after midnight local time. The
internal quartz timing oscillator remains stable (for
time indication) within one second in 24 hours.

Radio clocks are consumer electronics items that typically
cost $20 to $30 (depending on display size and extras such
as local temperator). If all that is wanted is automatic
time setting, it may not be a good return on time
investment to build one's own automatic-setting clock.
Those radio clocks aren't much good for zero-beating a
local frequency standard except: If the local standard
is counted down to 1-second pulses for comparison with
the radio clock (arduous process to check).

The same time code is in the WWV HF signals as a 100 Hz, One Baud, pulse
duration modulated subcarrier tone. If you've only got a communications
grade speaker in your receiver, you may not notice it.

There was once a KIT for a WWV time code receiver (Heathkit?).
As memory serves, it cost about $400 just for the kit! That
was in much older days before 25-cent 74LS00 chips.

The original requestor wanted a WWV receiver, presumably to
zero-beat a local crystal standard. ANY HF receiver will do
for that, but preferrably one whose S-Meter can show very
slow beats (well below 100 Hz). As another suggested, a
cheapo import SWL receiver can do that, adding only a
metering connection to the internal AGC line (for the slow
zero beat). Bandwidth of the IF is not of great importance
since the time-frequency bands are wider than the usual
cheapo receiver IF bandwidth.

In the northern Los Angeles area, I've never had a problem
picking up either WWV or WWVH on 5, 10, or 15 MHz, even with
a few feet of hook-up wire as an antenna. That's over a 42
year residence in this same house here. The time ticks are
good for checking progressive aging of local frequency
standards which are counted down to 1 second output...that
compared with the time tick in delay...and delay change (to
indicate very slow changes in the local frequency standard).

The time tick method was once the ONLY precise way to check
out local L.A. frequency standards when WWV was located
back east. That preciseness was to better than 1 part per
million.

A simple TRF arrangement tuned to 5 MHz will do the trick
for a receiver used solely for zero-beating and hearing the
voice announcements and time ticks. The interstage tuning
will be stable enough to pick up WWV or WWVH. To get 10
or 15 MHz carriers, add a mixer to the antenna input with
a local oscillator of 5 and 10 MHz. A local frequency
standard can supply that; no extra LO crystals required.
Four stages tuned to 5 MHz with Q = 100 will result in an
overall TRF/IF bandwidth of about 20 KHz, quite adequate
for WWV/WWVH.