Modulating binary data onto a sinusoidal carrier wave is similar to analog modulation in that:

1. Modulating binary data onto a sinusoidal carrier wave is similar to analog modulation in that:
2. a. binary "0s" and "1s" modulate carrier amplitude, frequency, or phase angle depending upon the modulation method
3. b. with ASK (amplitude shift keying), binary data is represented by changes in the amplitude of the sinusoidal carrier wave
4. c. with FSK (frequency shift keying), binary data is represented by changes in the frequency of the sinusoidal carrier wave
5. d. with PSK (phase shift keying), binary data is represented by changes in the phase angle of the sinusoidal carrier wave
6. e. all of the above are correct

10 points  

QUESTION 2

1. Hartley's Law represents the relationship between a signals symbol rate (baud rate) and data rate, given the number of levels (M) that a single symbol can take on.
2.  True
3.  False

10 points  

QUESTION 3

1. Select the correct statement(s) regarding the relationship between symbol rate (baud rate) and data rate.
2. a. an electrical symbol where M=4, tells you that the symbol can be one of four different values
3. b. there is always a one-to-one relationship between baud and data rate; therefore, a symbol that can be one of four values (e.g., M=4, where M{ -2.5v, -1v, +1v, +2.5v}) always means that baud rate will equal data rate
4. c. when M=1, baud rate equals data rate
5. d. all of the above are correct

10 points  

QUESTION 4

1. If M=8, then the number of bits that can be represented by a single symbol is: (hint: N=log2M)
2. a. 2
3. b. 3
4. c. 4
5. d. 6

10 points  

QUESTION 5

1. QAM (quadrature amplitude modulation) incorporates both ASK and FSK techniques.
2.  True
3.  False

10 points  

QUESTION 6

1. When using ASK, FSK or PSK techniques, how can we increase data rate?
2. a. by decreasing M and increasing baud rate
3. b. Hartley's Law tells us that baud rate will always equal data rate when using ASK, FSK or PSK
4. c. by increasing M, we can increase the data rate when compared to the baud rate
5. d. by increasing M, we can increase the baud rate when compared to the data rate

10 points  

QUESTION 7

1. Line coding (i.e., binary data coded in to an electrical signal) produces a baseband signal, whereas ASK, FSK and PSK techniques create a "passband" signal.
2.  True
3.  False

10 points  

QUESTION 8

1. In selecting a line coding technique, we need to consider the need for receive clock synchronization, and how much frequency bandwidth is occupied by the resulting signal. What is true about the Manchester line coding technique.
2. a. Manchester occupies less frequency spectrum (i.e., frequency bandwidth), than simpler line coding techniques such as NRZ
3. b. Manchester ensures signal transitions for each bit sent, thus helping to ensure receive clock synchronization; however, it occupies twice the frequency bandwidth compared to NRZ
4. c. Manchester ensures greater receive clock synchronization and efficient bandwidth usage compared to NRZ
5. d. there are no true statements listed above

10 points  

QUESTION 9

1. 4B5B differs from line coding techniques in that is ensures that strings of consecutive "1s" and "0s" do not exist prior to being line coded. Select the correct statement(s) regarding 4B5B.
2. a. since 4B5B eliminates long string of logical "1s" and "0s", simpler line coding techniques such as NRZ can be used.
3. b. since one bit out of every five bits sent is not real information, the data link suffers from a 1/5 or 20% overhead cost (i.e., reduction in data throughput)
4. c. only 80% of the data sent using 4B5B is real information
5. d. all of the above are correct statements

10 points  

QUESTION 10

1. Analog information can be converted into digital data using techniques such as PCM (pulse code modulation). Select the correct statement(s).
2. a. in order to convert an analog signal that consists of an infinite number of values, it must be sampled using the Nyquist sampling theorem
3. b. digitized analog signals always experience quantization loss
4. c. signal aliasing is experienced when sampling falls under the recommended Nyquist sampling rate
5. d. all of the above are correct

10 points  

QUESTION 11

1. You want to capture a live music concert and covert it into digital format for transmission. The human ear has a frequency bandwidth of approximately 20,000 Hz. Select the best sampling rate and bit depth.
2. a. fs=40,000 samples/s, Bit depth = 1 bit per sample
3. b. fs=40,000 samples/s, Bit depth = 16 bit per sample
4. c. fs=10,000 samples/s, Bit depth = 16 bit per sample
5. d. fs=20,000 samples/s, Bit depth = 1 bit per sample

10 points  

QUESTION 12

1. Uncompressed voice grade digital signals require a link that can support 64 kbps data rate capacity. As such, methods are used to minimize digital files for transmission and storage. Select the following technique(s) that can be used. 
2. a. use of DPCM, where only changes between samples are sent
3. b. use of either lossy or lossless digital compression techniques
4. c. use of sophisticated algorithms that remove redundant bytes
5. d. all of the above

10 points  

QUESTION 13

1. The bit error rate (BER) of a communications link is influenced by:
2. a. transmission power
3. b. modulation method
4. c. noise
5. d. all of the aove

10 points  

QUESTION 14

1. CRC (cyclic redundancy check) is a stronger error detection method than simple parity checking.
2.  True
3.  False

10 points  

QUESTION 15

1. ARQ (automatic repeat request) is considered a forward error correction (FEC) technique.
2.  True
3.  False

10 points  

QUESTION 16

1. Identify the digital timing method used where the receiver synchronizes its own local clock using the incoming data stream.
2. a. asynchronous
3. b. synchronous
4. c. isochronous
5. d. plesiochronous

10 points  

QUESTION 17

1. Which multiplexing method can be used by analog systems?
2. a. frequency division multiplexing (FDM)
3. b. time division multiplexing (TDM)
4. c. either FDM or TDM
5. d. neither FDM or TDM

10 points  

QUESTION 18

1. Time division multiplexing (TDM) and frequency division multiplexing (FDM) can be used in tandem together.
2.  True
3.  False

10 points  

QUESTION 19

1. Calculate the data rate capacity for a 2400 baud signal where there are M=8 levels per symbol.
2. a. 2400 bps
3. b. 4800 bps
4. c.  7200 bps
5. d. 9600 bps

10 points  

QUESTION 20

1. What is the Nyquist sampling rate for a signals frequency bandwidth equal to 88 kHz?
2. a. fs ≥ 88,000 sample/s
3. b. fs ≥ 176,000 sample/s
4. c. fs ≥ 176 sample/s
5. d. fs ≥ 176E6 sample/s