Radar System Engineering

622 EXAMPLES OF RADAR SYSTEM DESIGN [SEC. 1514
(containing the i-f amplifier, the detector, and a video output stage), the
automatic frequency control unit, and the low-voltage power supply for
these circuits, are also mounted in this unit. The detailed design of this
receiver is treated in Sec. 12.10.
The synchronizer unit includes the primary timing circuits, and the
sweep, range-mark, and intensifier circuits. On its front panel are the
operating controls for the system. This unit serves as a cable junction
box, and its use in this capacity has enabled the set to be designed with a
total of only seven cables. Since the circuits are designed to allow for
cable capacitance and for voltage drops, any of these cables can be as
long as 25 ft. Separation of the synchronizer power-supply unit from
the synchronizer itself permits the latter to be small enough to be conveniently
used as the main control box. It can be mounted with the
control panel either vertical or horizontal, as each installation may
demand.
The indicator unit contains a video amplifier, in addition to the
cathode-ray tube and its deflection yoke and focus magnet.
The synchronizer power supply provides the necessary voltages for
the indicator and the synchronizer.
Performance oj the AN/.4 PS-lO.—The completed set shows performance
meeting the initial requirements. Scope-map comparisons
that display the usual overland performance of the set at low and medium
altitude are shown in Figs. 15”11 and 15.12. The blanked-out sectors
abeam are due to shadows cast by the engine nacelles of the C-47 aircraft
in which the set was installed. Figure 15.12 was taken while a special
experimental antenna of 30-in. horizontal aperture was in usc; thus the
azimuth resolution and range pcrformante are better than those attained
with the standard 18-in. antenna.
The performance of the set with 3-cm beacons is especially good
because careful attention was paid to the radar-beacon problem in design.
The major changes involved in switching from search to beacon operation
are:
1. Change of pulse length from 0.8 to 2.2 psec.
2. Change of PRF from 810 to 405 pps.
3. Change of TR-switch resonant frequency from the magnetron
frequency to the beacon frequency.
4. Change from search to beacon local oscillator.
5. Change from search to beacon AFC. (Sec. 12.7.)
6. Stretching of beacon reply pulses in the video amplifier.
A broadband ATR tube is used primarily to pass beacon signals with
minimum loss, and a wider i-f band than necessary for optimal signal-to-