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CHARACTERISTICS OF THE ELECTRONIC SUBSYSTEM

5. 2. 1 Required Bandwidth

The required bandwidth of the subsystem is dependent upon the bandwidth of the information to be processed. The shape of the information pulse that is available from both the in-core and the out-of-core detectors has been described previously. The expression given was:

І =

0 d ( 1 — — amperes, T T /

where

Po =

charge of either sign/unit length of track in the gas 1 — oul | ,

cm /

d =

gas gap (cm),

T =

transit time of the electron or positive ion across the gas gap (seconds), and

t =

time after pulse initiation (seconds).

In the above expression, the time required to accelerate the ion pairs to their average drift velocity is assumed to be negligible. This information pulse is applied to the interconnecting cable for transmission to the remote amplifier input.

In the out-of-core subsystem, the interconnecting cable is modified RG-6A/U coaxial cable. Because of the almost ideal transmission characteristics of the RG-6A/U cable (attenuation/100 ft = 2. 9 dB at 100 Me), the information pulse is transmitted to the amplifier input essentially unchanged in shape. For the in-core subsystem, the interconnecting cable is 40 feet of stainless steel — quartz — stainless steel prototype in-core cable in addition to the RG-6A/U mentioned above. The transmission characteristics of the prototype in-core cable are far from ideal. * The attenuation

For an experimental comparison of these cables, see Section V.

per 100 feet of the prototype in-core cable is, typically, 6 dB/100 ft at 22 Me. This high frequency attenuation causes an increase in the rise time of the information pulse from on the order of 10 nsec to 0. 15 psec. The upper and lower frequency breakpoints of the electronic subsystem are made to conform to the requirements of this information pulse.