What term describes a wide-bandwidth communications system in which the RF carrier frequency varies according to some predetermined sequence?

Spread spectrum communication.

The signal of a specific frequency is sent over much larger bandwidth, using various frequency-jumping methods.

From the Committee on National Security Systems (CNSS), CNSS Instruction No. 4009, "National Information Assurance (IA) Glossary":

"Telecommunications techniques in which a signal is transmitted in a bandwidth considerably greater than the frequency content of the original information. Frequency hopping, direct sequence spreading, time scrambling, and combinations of these techniques are forms of spread spectrum."

For more info, please see NI site, for article on Understanding Spread Spectrum for Communications

Also, see ScienceDirect site, for article on Spread Spectrum Communications

And, see Wikipedia's article on Spread spectrum

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Name two types of spread spectrum systems used in most RF communications applications?

Direct Sequence and Frequency Hopping.

Direct Sequence Spread Spectrum (DSSS) occurs when radio frequency and some other signal are combined to simulate radio noise in a bandwidth.

Frequency Hopping Spread Spectrum (FHSS) is a method of randomly changing radio frequencies for short periods of time while transmitting

See QSI net site for article on Technical Comparison of Frequency Hopping and Direct Sequence Spread Spectrum, and sub pages on DSSS and FHSS.

See Wikipedia's article on Frequency-hopping spread spectrum

Solid info on Resources Systems Analysis Cadence site for a comprehensive article on
Comparing FHSS vs. DSSS

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What is the term used to describe a spread spectrum communications system where the center frequency of a conventional carrier is altered many times per second in accordance with a pseudo-random list of channels?

Frequency hopping.

The question is the definition of the right answer. Read the question again.

Frequency Hopping Spread Spectrum (FHSS) is a method of randomly changing radio frequencies for short periods of time while transmitting

See QSI net site for article on Technical Comparison of Frequency Hopping and Direct Sequence Spread Spectrum, and sub pages on DSSS and FHSS.

See Wikipedia's article on Frequency-hopping spread spectrum

Solid info on Resources Systems Analysis Cadence site for a comprehensive article on
Comparing FHSS vs. DSSS

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A TDMA radio uses what to carry the multiple conversations sequentially?

Separate time slots.

The frequency switching is so fast that it gives each participant the illusion of having a dedicated line for communication. This is done by using defined time slots. The separate signals carrying voice are sent sequentially.

For more info, please see Wikipedia's article on Time-division multiple access

Also, see Radio Academy for video and article on THE DIFFERENCE BETWEEN FDMA AND TDMA

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Which of the following statements about SSB voice transmissions is correct?

They normally use J3E emissions, which consists of one sideband and a suppressed carrier.

The answer is the definition of SSB voice band.

A single side band is the lower portion of the band. The upper portion and the carrier frequency are suppressed. Thus, all the transmission power is concentrated on only a single side band, instead of being spread between LSB, USB, and the carrier.

The ITU classifies various types and methods of using frequencies. The J3E is composed of :

J = single sideband with suppressed carrier.

3 = a single channel with analog info
E = telephony signal, to be received and understood by human ear such as speech or music.

For more info on Types of radio emissions see Wikipedia.

For info on SSB, see Ham Radio School site, article Single Sideband Advantages (G2A06)

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What are the two most-used PCS (Personal Communications Systems) coding techniques used to separate different calls?

CDMA and GSM.

CDMA (Code Division Multiple Access) and GSM (Global System for Mobiles) are two major radio systems used in cell phones.

CDMA uses Code Division Multiple Access technology.

GSM uses FDMA (Frequency Division Multiple Access) and TDMA (Time Division Multiple Access).

For more info, please see Geeks for Geeks site, article Difference between GSM and CDMA

Also, see Android Authority site article on GSM vs CDMA — What's the difference

Solid info from Verizon site, article What are Phone Bands (GSM, CDMA) and Why Do They Matter?

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