This is the Coaching materials in Digital and Data Communications Part 3 as one topic in ECE Board Exam taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies (EST), Communications Books, Journals and other Communications References. This particular Coaching Notes in Communications Engineering has random Questions and Answers in random topics. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.
Digital and Data Communications Coaching Materials Part 3
137. ARQ is used to:
correct bit errors *
138. VRC is another name for:
Parity*
139. Run-length encoding is used to:
compress data *
140. When messages are intended for all the subscribers on the network it is called ____.
Broadcasting
141. When messages are intended for a specific group of subscribers in the network it is called _____.
Multicasting
142. Refers to the structure of the data within the message, which includes the sequence in which the data is sent
Syntax
143. Refers to the meaning of each section of data.
Semantics
144. It is an object or procedure considered by an authority of by general consent as a basis for comparison
Standard
145. The process of adding or removing protocol data unit called ____.
Encapsulation / decapsulation
146. The OSI layer that is responsible for the transmission of bits.
Physical layer
147. The OSI layer that manages traffic on the link.
Data link layer
148. The OSI layer that has inter-host communication.
Session layer
149. The OSI layer that accepts and structures the message for the application.
Presentation
150. The OSIL layer that serves as an interface for the user to the network.
Application layer
151. The OSI layer that is task with the end-to-end accountability through a network.
Network layer
152. The OSI layer that ensures and controls the end-to-end integrity of data message, by providing reliable, transparent transfer of data.
Transport layer
153. A system that allows personal computer to access files, print to a local printer, and have and use one or more disk and CD drives.
Local operating system
154. It describes the layout or appearance of a network, it describes how the computers, cables and other components within the data communications network are interconnected bot physically and logically.
Network topology
155. The typical SNA topology is
Hierarchical Topology *
156. Typical PBX configuration is
Star Topology *
157. Topology which is relatively immune to bottlenecks.
Mesh Topology *
158. It is a network access method used primarily with LANs configured in a ring topology using either baseband or broadband transmission formats.
Token passing
159. Topology of the Classical Ethernet system.
Bus *
160. ____ are omnipresent lack-and-white stripped stickers that seem to appear on virtually ever consumer item.
Bar codes
161. Classification of bar codes that has gaps or space between characters and each character within the bar code is independent of every other character.
Discrete code
162. A classification of bar code that does not include spaces between characters.
Continuous code
163. A classification of bar code that stores data in two dimensions in contrast with a conventional linear bar code, which stores data long only one axis.
2D code
164. One of the most popular code which consists of 36 unique codes representing 10 digits and 26 uppercase letters.
Code 39 or Code 3 of 9 or 3 of 9 Code
165. Code 39 is an example of what type of bar code.
Discrete code
166. Classifications of errors where two or more non-consecutive bits within a given data string are in error.
Multi-bit errors
167. Classification of errors where two or more consecutive bits within a given data string are in error.
Burst error
168. The message that never arrives at the destination or one that arrives but is damaged to the extent that it is unrecognizable.
Lost message
169. A message that is not recognized at the destination that contains one or more transmission errors.
Damaged message
170. Determine the noise margin for an RS 232 interface with driver signal voltages of +/- 6V
3V and 19V
171. The specs of the old Bell type 103 modem were:
300 bps, full-duplex, FSK *
172. The ITU is under the auspices of:
the U.N. *
173. High-speed modems equalize the line to compensate for:
uneven phase and frequency response *
174. The bits send to allow equalization are called:
a training sequence *
175. The V.90 standard is issued by:
the ITU *
176. It describes the function of a family of interchange circuits.
V.24 *
177. Protocol use to connect packet switching networks.
X.75 *
178. The output rate of CCITT V.26.
1200 bauds *
179. Technique that allows corrections of data of the receiver.
FEC *
180. MNP2, MNP3, MNP4 and MNP10 are all:
error-correction protocols *
181. MNP5 and V.42 bits are both:
data-compression schemes *
182. In RS-232, flow control is done using:
RTS/CTS handshake & XON/OFF characters
183. The official name for RS-232C is:
EIA-232D *
184. What is the signal rate of RS-232 normally used as an interface between DTE and DCE?
20 kbps *
185. In RS-232, a modem would be:
a DCE *
186. In RS-232, a personal computer would be:
a DTE *
187. On a DB-9 RS-232 connector, signal ground is pin:
5 *
188. On a DB-25 RS-232 connector, signal ground is pin:
7 *
189. RS-232C has how many pins?
25 pins *
190. RS-232 signal rate when used as an interface between DTE and DCE?
20 kbps *
191. The minimum lines required for RS-232 are:
TD, RD, and signal ground *
192. Hardware flow control uses:
RTS and CTS *
193. Which voltage represents a binary zero on an RS-232 data pin:
+15 volts or +12 volts or +9 volts
194. A “splitter” at the subscriber end is not required for:
ADSL lite *
195. Synchronous data transported by asynchronous modems is called ____.
Isochronous
196. Synchronous modems cost more than asynchronous modems because ______.
They must contain clock recovery circuits *
197. The Bell system 103 compatible modems is capable of duplex operation over two-wire telephone lines at a bit rate of ____.
300 bps
198. Asynchronous modes use what modulation techniques?
ASK or FSK
199. Speed of asynchronous modems
less than 2400 bps
200. Mode of transmission in PDN, wherein the data are transferred from source to the network then to the destination in an asynchronous data format?
Start/stop *
201. The bell system 202 modem is an asynchronous 1200-baud transceiver utilizing FSK with a transmission bit rate of
1200 bps
202. Synchronous modes use what modulation technique?
PSK and QAM
203. Asynchronous data modulation.
FSK *
204. Digital modulation scheme modems commonly used
PSK *
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