In message , David G. Nagel
writes
And your problem is?
Being of German descent with relatives in Germany, I feel that the
German people got what they deserved. Actions by the Luftwaffe were
just as horrific in London, Warsaw, Stalingrad and Antwerp to name a few.
The Luftwafe had similar devices to locate their targets in England
with the same results when their systems were captured by British
Military Intelligence (what an oxymoron).

Do you consider Prof. R.V. Jones to be an oxymoron? Or any other kind of
moron?

Mike

And your problem is?

we ain't got one,,, we won!
So I hear?

Buck, N4PGW wrote:
"Is it something duplicable with Radio Amateurs in general or does it
require some special type of equipment?"

Much British success in WW-2 in eavesdropping on German transmissions
had as much to do with information processing as it had to do with its
interception.

Germans used an "Enigma Machine" which was easily reset for a new code.
They often changed the code and it was quite complicated. Germans used
the machines to encode and decode their confidential messages. Early in
the war, an Enigma Machine was captured. British code experts worked
long, hard, and smartly to determine how the machine worked and broke
its codes. Afterwards, the British were silent parties on the German`s
war partyline. The British sometimes feigned ignorance so as not
announce their access to Germany`s most secret information. It was a big
factor in victory.

Stationary direction finding can take the directional antenna arrays
used for transmitting and use them for receiving insteaad. Reciprocity
means that the reception pattern is identical to the transmitting
pattern. I have no idea what the British did in their enemy reception
stations in WW-2. For HF, they could have used Yagi-Uda`s on rotators
and indicators. They also could have used crossed loops or Adcocks,
feeding a goniometer and not rotated the antenna. Terman shows how this
is done on page 1051 of his 1955 edition.

During the "Cold War", when I worked in HF broadcasting, Radio Free
Europe diligently monitored, recorded, and processed broadcasts from
behinnd the "Iron Curtain". All the Communist news and commentary that
was fit to broadcast from their point of view. To pick the desired
transmissions from among the babble, some RFE receiving stations had the
appearance of medium-wave multi-tower broadcast stations. Towers were
tuned and phased to null interference and to grab the desired
transmission. Other stations used sizeable loops. Some had air for a
core and some had huge ferrite cores. Whatever proved best was used in
any case..

Hams can surely use directional antenna systems.

Best regards, Richard Harrison, KB5WZI

In message , Richard
Harrison writes
Buck, N4PGW wrote:
"Is it something duplicable with Radio Amateurs in general or does it
require some special type of equipment?"

Much British success in WW-2 in eavesdropping on German transmissions
had as much to do with information processing as it had to do with its
interception.

snip

Stationary direction finding can take the directional antenna arrays
used for transmitting and use them for receiving insteaad. Reciprocity
means that the reception pattern is identical to the transmitting
pattern. I have no idea what the British did in their enemy reception
stations in WW-2. For HF, they could have used Yagi-Uda`s on rotators
and indicators.

Too broad a beam. Loop zeros are sharper.

They also could have used crossed loops or Adcocks,
feeding a goniometer and not rotated the antenna.

Correct.

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.

Mike

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

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

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

"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