TELE-TECH & - AmericanRadioHistory.Com

F
A
Optical Radar
EIMAC Vacuum Switches
for high- voltage switching
in severe environments.
In explosive atmospheres and high altitude
airborne conditions, Eimac vacuum switches
operate reliably and safely.
Used extensively in air and ground
mobile applications, the small size and fast
closing time of Eimac vacuum switches
make them ideal for antenna changeover.
They handle RF peak potentials up to
20kv in this service, and 1.5 amps at 5kv
in DC switching service.
Eimac single pole double throw vacuum
switches are available in four types,
including one for pulse service.
If you have a switching problem,
write our Application Engineering
Department for further information.
EITEL - McCULLOUGH, INC.
S A N B R U N O C A L I
O R N I
The World's Largest Manufacturer of Transmitting Tubes
(Continued from page 191)
ly by the "pick -up" device on the
radar indicator.
B. Noise. The 1P21 photo- multiplier
tube is a natural noise generator.
The white noise (or grass)
can be varied in intensity by varying
the level of ambient light. Almost
any signal -to -noise ratio desired
can be achieved.
C. Target Size. Since the size of
the target image on the radar indicator
resulting from the signals it
receives from the "pick -up" device
will be proportional to the size of
the light spot, larger targets are
simulated by larger spots.
D. Simulation of Altitude and
IFF. Future plans involve simulation
of altitude and IFF in addition
to range and azimuth by means of
modulation of the target lights.
This is still in the experimental
stage however.
Nonlinear Relation Between
Range and Time
The time delay between the sending
and receiving of a pulse from a
radar antenna to a target is directly
proportional to the range of the
target. Unfortunately this linear
relation does not exist between
time and range in the present simulated
system. As has been pointed
out previously in the simulated system
R =h tan, ì. =h tan 20.)t. Now
for small angles (). = 20 °) the approximation
tan A = ), is quite
sufficiently accurate, and if the
"pick-up" device is removed sufficiently
far from the screen no problem
arises. However, if space is
limited and /or optical problems become
serious at great distances,
other solutions must be found.
One simple solution would be to
use a non -linear scale on the face of
the radar screen. However, this
would introduce a degree of unreal -
ism. Several schemes are now under
consideration. One method involves
producing a sweep voltage
shaped like the tangent curve instead
of the conventional sawtooth
curve. Different methods for generating
the tangent curve are now
in the experimental stage but a
few show good promise of success.
192 For product information, use inquiry card on pages 209 -210. Tele-Tedi & ELECTRONIC INDUSTRIES June 1956