a. break signals are effective only on short lines.
b. reactive constants of long transmission lines distort the telegraph pulses.
c. short transmission lines minimize the complexity of system configuration.
d. resistance in long transmission lines causes signal pulse distortion.
14. A polar telegraph system requires the use of complex equipment because
a. signal pulses must be sensed by a receiving polar relay.
b. a break system is required to interrupt the current flow.
c. signal pulses consisting of oppositely flowing current are affected differently by line constants.
d. special components must be included to overcome the effects of telegraph distortion caused by line
15. What is one characteristic of the output signal from any VF telegraph transmitting terminal that is passing
a. The signal amplitude never varies.
b. The signal always shifts frequency.
c. The signal is modulated by dc pulses.
d. The frequency of the signal always remains constant.
16. Although the on-off keying method of ac telegraphy is basically simple, its operation is hampered by its
a. slow speed of transmission.
b. dependence on the type of dc loop.
c. rising noise level during no-tone intervals.
d. changes in signal level from tone to no-tone intervals.
17. The method generally preferred for tone telegraphy (teletypewriter) consists of
a. keying the carrier on for mark and off for space.
b. keying the carrier on for space and off for mark.
c. varying the carrier amplitude in accordance with pulse amplitude changes.
d. shifting the carrier to one frequency for mark and another frequency for space.