With a 42-foot length of this cable, a determination of the attenuation characteristics versus frequency was also made (see Figure 5-3). It is shown in this illustration that the cable starts to attenuate at approximately 5 Mc/sec, and exhibits a 3 dB attenuation at approximately 20 Mc/sec. The attenuation then falls with a continually increasing negative slope, and has an attenuation factor of 16 dB at a frequency of 100 Mc/sec.

. The transient pulse characteristics for this cable are shown in Figure 5-4. Note that the rise time of the pulse at the receiving end of this cable is 25 nsec (uncorrected), or 22 nsec. (corrected), for the same sending end pulse rise time of 7. 7 nsec (corrected). If this cable is considered as a single time constant system, the upper 3 dB frequency is calculated to be:

0, 35 = 0. 35

7 t 22 x 10"9

сл I 05

ги INPUT PULSE SWEEP SPEED: 0.2Msec/cm	INPUT PUI. SE SWEEP SPEED: 20nsec/cm

0.01 0.1 1.0 10.0 100 FREQUENCY IN MEGACYCLES/SEC

Figure 5-3. Gain Versus Frequency — Prototype Cable

,r INPUT PULSE

1 ; SWEEP SPEED: 0.2/zsec/cm

m INPUT PULSE

SWEEP SPEED: 20nsec./cm