13 2-28.   Synchronous teletypewriter systems are characterized by which of the following features when compared to asynchronous systems? 1.   Internal timing signals are always used 2.   Only the start-stop element must be transmitted 3.   Only the intelligence elements must be transmitted 4.   Signal quality determines receiver line signal condition 2-29.   When you are referring to the unit of teletypewriter signaling speed, the reciprocal of the time (in seconds) of the shortest signal element is described by which of the following terms? 1.   Unit code 2.   Baud rate 3.   Bits per second 4.   Words per minute 2-30.   The teletypewriter condition where current flow represents a mark and no current flow represents a space occurs in which of the following types of operation? 1.   Polar 2.   Arctic 3.   Biased 4.   Neutral 2-31.   You are using neutral keying and the teletypewriter type hammer continually strikes the type box but there is no printing or type box movement across the page.  What is the name of this condition? 1.   Debugging 2.   Running open 3.   Baudot blanking 4.   Decoding at random 2-32.   Of the following equipment which one changes teletypewriter dc pulses to mark and space modulation for the transmitter carrier wave? 1.   A comparator 2.   A modulator 3.   A converter 4.   A keyer 2-33.   To change an rf signal to do pulses for teletypewriter operation, you must use a receiver and what other piece of equipment? 1.   A keyer 2.   A converter 3.   A comparator 4.   A demodulator 2-34.   A tone-modulated radio teletypewriter system uses what modulation method to change dc mark and space impulses into audio electrical impulses? 1.   Amplitude 2.   Frequency 3.   Phase 4.   Pulse 2-35.   In a basic tone-modulated radio teletypewriter system, separation of the audio signal from the carrier is accomplished by what process? 1.   Conversion 2.   Modulation 3.   Selection 4.   Detection 2-36.   In a radio-frequency-carrier shift system, what equipment is the source of radio- frequency excitation voltages? 1.   The inverter 2.   The converter 3.   The comparator 4.   The transmitter keyer