4Rohde
&
Schwarz
R&S®DDF255 Digital
Direction Finder
5
Effective
measurements
in line with ITU
r6
High-precision correlative interferometer
DF
method using multi-element DF antennas
(VHF/UHF/SHF)
In the VHF/UHF/SHF range, the R&S®DDF255 uses the
correlative interferometer DF method (see page 14). In
contrast to other direction finders using simple amplitude
comparison methods, the R&S®DDF255 offers signifi
-
cantly higher DF accuracy up to class A in line with ITU
recommendations.
This high DF accuracy relies on the precise measurement
of the phase angles between the reference antenna ele
-
ment and the other elements. Measuring the phase differ
-
ence between two signals normally requires two coherent
receive paths. For this reason, most interferometer direc
-
tion finders on the market use at least two receivers. With
the R&S®DDF255, the two receive paths are coherently
linked in the DF antenna using a patented method from
Rohde
&
Schwarz.
In the HF range, the Watson-Watt DF method is used. The
special advantage of this method is that small DF antennas
can be deployed. This makes the R&S®DDF255 also suit
-
able for mobile direction finding in this frequency range