Tutorial About SuperDF:

Comparing SuperDF with Several Common RDF Systems

Notes:

Click to down load as a GIF Image. Its name is Compare.GIF.

In general, the more X's an RDF has below it in the chart, the more versatile it is. A ? indicates the author does not have that information.

				-------------- TYPE OF RADIO DIRECTION FINDER --------------
				SuperDF	Vector	 beam	Little	Adcock	Loop	Doppler	 OAR
----------- FEATURE -----------		Finder		L-Per
Unambiguous			   X		   X	   X			   X	   X
Ignores Multipath in motion	   X			   X			   X	   X
Electronic detection		   X			   X			   X	   X
Detects multipath on foot	   X	   X		   X	   X	   X
Vertical or Horizontal		   X	   X	   X	   X		   X	
Kit available			   X	   ?					   X
Assembled available		   X	   X	   X	   X	   ?	   ?	   X	   X
Adjustment free hunting 	   X	   X					   X	   X
Very sensitive			   X		   X	   X			
Highly accurate			   X			   X	   X
Well documented and supported	   X	   ?		   ?			   ?	   ?
Use with any NBFM receiver	   X	   X					   X
S-Meter NOT required		   X	   X					   X	   X
Attenuator NOT required		   X	   X					   X	   X
Very wide frequency coverage	   X	   X			   X		   X	   X
Fast response			   X	   X		   X			   X	   X
Easy maintenance		   X	   ?	   X	   ?	   X	   X	   ?	
Affordable			   X	   X	   X	   X	   X	   X	   X
Easy to use			   X	   X		   X			   X	   X
Eyes-free operation		   X	   X
Automatic									   X	   X
Practical for mobile in motion	   X			   X			   X	   X
Practical for On-foot		   X	   X	   X	   X	   X	   X
Practical for Base		   X	   X	   X	   X	   X		   X	   X

Below are a collection of important comments about particular systems in the chart.

Vector Finder

• User must pick out a tone and rotate antenna to null it to zero to obtain the bearing. This is difficult to do with a modulated or noisy signal.
• Ambiguous. Can't tell if a bearing is towards or away from the transmitter.
• Not able to sort out the strongest path in multipath.

Beam

• Small beams have a rather broad front lobe; not accurate.
• Have multiple lobes to confuse the hunter.
• Awkward on foot.
• Fragile (unless specially built).

L-Per

• Covers only 6 MHz (with adjustment).
• Crystal controlled.

Adcock

• No commercial source (known by the author).
• Cannot obtain accurate bearing on weak signals.

loop

• Must rotate in both Azimuth and Elevation to get good null.
• Null washes out in multipath.
• Rather insensitive.
• Tends to be limited in frequency range for good performance.

Doppler

• Fully automatic RDF.
• Cannot hunt horizontal signals.
• Tends to be insensitive.

OAR & similar

• Fully automatic RDF.
• Cannot hunt horizontal signals.
• Very expensive.
• Very fast response.
• Very complex electronics. (Difficult maintenance.)

BMG Engineering, Inc. holds a patent on the SuperDF, and has been manufacturing and marketing it since 1981.

Contact Information

George (Russ) Andrews, K6BMG

BMG Engineering, Inc.

9935 Garibaldi Avenue

Temple City, CA

91780

USA



Phone:  1(626)285-6963

FAX:	1(626)285-1684  (dedicated line, automatic)

Web:    http://users.aol.com/bmgenginc

(31 Jan 1996)

Send E-mail to grandrews@aol.com. (A message window will open.)
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