-13- 
Figure 8 is a block diagram of the transformation circuits as used in 
ARES. It can be seen that each of the transformation error signals is applied 
to a separate modulator. 
Y SCAN 
IN 
X SCAN 
IN 
,Y SCANNER 
HYBRID 
.X SCANNER 
HYBRID 
1ST ORDER TRANSFORMATION 
ERROR SIGNALS IN 
2ND ORDER TRANSFORMATION 
ERROR SIGNALS IN 
Figure 8.- Pattern transformation circuits (7.0). 
Modulators are a type of multiplier in which the input signals are the 
factors and the output signal is their product. Of the two input signals to 
a modulator, one input, called the control, varies slowly with time or remains 
constant. The other input, called the carrier, is generally a repetitive wave 
form of relatively high frequency. 
In the modulators shown, the transformation error signals constitute the 
control inputs whilst the carrier inputs are derived from the scanning wave 
forms . It will be observed that the outputs of all the modulators are added 
together in two groups which constitute the AX and AY signals described 
earlier. 
It may be demonstrated that each of the modulators in the transformation 
circuits controls the addition of a AX or AY signal to produce one of the 
prime transformations listed in Figure 1. The action of the modulators and 
the subsequent additions and subtractions of their output signals are simple, 
mathematical operations and produce their effects regardless of the nature of 
the scanning pattern employed. However, owing to the simple nature of the 
waveforms involved in the production of the crossed diagonal pattern, the de 
sign of the modulators is considerably simplified over what might be required 
for other patterns.