Buck:

Aegean Park Press has reprinted Navy OPNAV 20 - 26 under the title "Direction Finding". It is a summary of what was
done and how as of 1947. Pretty complete summary of WW2 techniques. Aegean has a web site for descriptions and sales.
Note the spelling.

--
Crazy George
the ATTGlobal.net is a SPAM trap. Use the att dot biz account.
"Buck" wrote in message ...
In WWII the allies were able to pinpoint the locations of German HF
transmissions very accurately. They were able to pinpoint the
locations of U-boats, etc. when they transmitted. (or so I have been
led to believe).

What methods did they use to do this? Is it something duplicatable
with Radio Amateurs in general or does it require some special type
equipment?


I hear lots of amateurs describing interference and other problems on
HF, but no one seems to be triangulating the offending stations. I am
guessing that the real secret was in their communications with the
'spotters' to triangulate the positions.

Any suggestions?

Thanks

--
73 for now
Buck
N4PGW

RB wrote:

Brings back scenes from old WWII movies....

Small loops are still used and seem to be very effective for DF. I think that
the ARRL antenna book provides information in this direction. One system I
saw used a short ferrite dipole array.

In most cases, DF sets displayed their goniometer outputs on a CRT or as
signal strength on a meter. In this case, the dots and dashes melded into
a continous output because of the persistence of the CRT or the AGC delay
of the receiver.

The first DF equipment I used on the ships was WWII vintage and very
effective on any type of signal.

Irv VE6BP
--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/index.html
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--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

On Thu, 17 Feb 2005 23:32:36 +0000, "M. J. Powell"
wrote:

U-boats used HF for reporting back to base in Lorrient, but MF for talk
among themselves in the Wolfpack. It was this that was DFed by the
shipborne CRT DF.


By 'this', I assume you mean MF?

Thanks

--
73 for now
Buck
N4PGW

"RB" ) writes:

Wonder if loop antennas were what they really used, and how good they were?
The spies generally used cw. How do you get a fix on the short dots and
dashes?


With AGC turned off, just listen for the null in the signal as the loop is
rotated.

Intellgence agencies when they did HFDF used huge antenna arrays
called CDAAs (Circular Disposed Antenna Arrays). They were also known
as Wollenwebbers (presumably after an inventor). These arrays were
often very large, and sometimes were affectionally known as "elephant
cages." The diameter of these arrays could be as small as 50-60 feet
for a tactical unit to several hundred feet for large fixed sites in a
secure area. Each circle had many vertical elements.
They measured time difference of arrival by measuring the wavefront
timing on each antenna in the array as the wave passed through the
array. A computer then collated this information to calculate a
bearing. The readouts varied depending upon the era. Some were
digital, some were on an oscillicsope. I'm not quite sure how the
really early ones worked (before my time). The results of several
stations were then combined to get a "fix." Contrary to popular
belief, their accuracy had significant error factors so despite many
requests from military commanders who wanted to drop ordinance on a
target, you really couldn't do that based solely on HFDF. HFDF was
really originally intended for open ocean surveillance against things
like German subs in both WW I and WW II.
You could get a rough idea where a signal was coming from and then
you would have to sent a destroyer or aircraft to actually locate the
sub. There are other types of HFDF antennas as well, but none can
give pin point accuracy unless you are mobile and close in as in
transmitter hunts. As long at there was energy, you could get a
bearing be it a sustained carrier or a single dit. You would have to
rely on other externals (callsigns, radio finger printing etc) to
figure out who was sending a given signal.

W3JT


On 18 Feb 2005 06:29:34 GMT, (Martin Potter)
wrote:


"RB" ) writes:

Wonder if loop antennas were what they really used, and how good they were?
The spies generally used cw. How do you get a fix on the short dots and
dashes?


With AGC turned off, just listen for the null in the signal as the loop is
rotated.

In message , RB
writes
Brings back scenes from old WWII movies where the Germans were closing in on
an Allied spy, with a suitcase radio set, sending from an upstairs flat, in
the dark of night. Vans crawling along with loop antennas on the roof, and
guys inside with comm gear and headphones telling the driver where to go,
etc.

Wonder if loop antennas were what they really used, and how good they were?

They were simple and with a good null. Only with arrays will you get a
better null.

The spies generally used cw. How do you get a fix on the short dots and
dashes?

Just swing the loop for minimum signal.

Mike

In message , Irv Finkleman
writes
RB wrote:

Brings back scenes from old WWII movies....

Small loops are still used and seem to be very effective for DF. I think that
the ARRL antenna book provides information in this direction. One system I
saw used a short ferrite dipole array.

In most cases, DF sets displayed their goniometer outputs on a CRT or as
signal strength on a meter. In this case, the dots and dashes melded into
a continous output because of the persistence of the CRT or the AGC delay
of the receiver.

I don't think there was a swinging goniometer with the CRT DF set. The
output of the two loop aerials fed the X and Y plates respectively so
that the trace appeared at the right angle and the bearing was read from
the screen.

Mike

In message , Buck
writes
On Thu, 17 Feb 2005 23:32:36 +0000, "M. J. Powell"
wrote:

U-boats used HF for reporting back to base in Lorrient, but MF for talk
among themselves in the Wolfpack. It was this that was DFed by the
shipborne CRT DF.


By 'this', I assume you mean MF?

Sorry for vagueness. Yes, they used the lower frequencies for short
ranges, probably because the LF didn't travel far. (But far enough for
the RN)

Mike

"M. J. Powell" wrote:

In message , Irv Finkleman
writes
RB wrote:

Brings back scenes from old WWII movies....

Small loops are still used and seem to be very effective for DF. I think that
the ARRL antenna book provides information in this direction. One system I
saw used a short ferrite dipole array.

In most cases, DF sets displayed their goniometer outputs on a CRT or as
signal strength on a meter. In this case, the dots and dashes melded into
a continous output because of the persistence of the CRT or the AGC delay
of the receiver.

I don't think there was a swinging goniometer with the CRT DF set. The
output of the two loop aerials fed the X and Y plates respectively so
that the trace appeared at the right angle and the bearing was read from
the screen.

Mike

There were a number of different types of DF sets. Some, as you
point out had x and y
plates connected to the loops, another had a mechanically rotating gonio.
We had one for radar detection which used horns with crystal detectors in
it which went to x and y plates (through amps). The HFDF used loops feeding
a mechanically rotating gonio with output to a crt.

Irv


--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/index.html
Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm
Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

All about DF, sense antennas, nulls, etc
http://www.avweb.com/news/avionics/183233-1.html

Side note -- A WWII B-24 bomber (Lady Be Good) ran out of fuel because they
were not sure of the DF readings --that is -- if they were going toward or
away from the home station. Crashed in the Libyan desert -- all of the crew
perished after walking as far as 85 miles in the desert.

See URL:
http://www.qmfound.com/lady_be_good_...r_recovery.htm

----------------------------------

On our Navy planes in the 50's we had two ARN-6 - ADF (Direction Finders),
100-1750 KHz
In conjunction with Loran -- we usually knew where we were. (;-)

But also the Navigator would take periodic sextant readings (weather
permitting) thru a bubble on top of the aircraft

No GPS in those days.(;-(

On one of the squadrons flights -- a circuit breaker blew and refused to be
reset -- avionics were off -- the crew flew dead reckoning most of the rest
of the flight.


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Help The New Hams
Someone Helped You
Or did You Forget That ?



"Irv Finkleman" wrote in message
...
"M. J. Powell" wrote:

In message , Irv Finkleman
writes
RB wrote:

Brings back scenes from old WWII movies....

Small loops are still used and seem to be very effective for DF. I think
that
the ARRL antenna book provides information in this direction. One system
I
saw used a short ferrite dipole array.

In most cases, DF sets displayed their goniometer outputs on a CRT or as
signal strength on a meter. In this case, the dots and dashes melded
into
a continous output because of the persistence of the CRT or the AGC
delay
of the receiver.

I don't think there was a swinging goniometer with the CRT DF set. The
output of the two loop aerials fed the X and Y plates respectively so
that the trace appeared at the right angle and the bearing was read from
the screen.

Mike

There were a number of different types of DF sets. Some, as you
point out had x and y
plates connected to the loops, another had a mechanically rotating gonio.
We had one for radar detection which used horns with crystal detectors in
it which went to x and y plates (through amps). The HFDF used loops
feeding
a mechanically rotating gonio with output to a crt.

Irv


--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/index.html
Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm
Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada