Signal Frequency, Analog And Digital Signals, And Periodic Signal Characteristics
Problem Question
The frequency (referred as f) is the rate of repetition of the signal. It can be defined as cycles/second, or Hertz (referred as Hz) (Stallings, 2009). Its equivalent factor is the time- period (referred as T) of the signal and time period is the amount of time taken by the signal for one repetition
Hence, T = 1/f
Given Fundamental frequency=1000 Hz
Therefore period=1/1000 Second
T=0.001 second.
Source: (Stallings, 2009)
Analog and digital signals are electromagnetic representations of Analog and digital data.
Analog electromagnetic signal: is a constantly fluctuating electromagnetic signal that may be broadcasted through various media, depends upon frequency.
Digital electromagnetic signal: is an arrangement of voltage pulsations that may be transferred through a Cu (copper) wire media (Semantics Scholar, 2010).
Differentiation can be illustrated as follows:
|
Analog signal transmission(AST) |
Digital signal transmission (DST) |
|
|
Analog electromagnetic signal (referred as AES) |
AES is processed using amplifiers for both of AST and DST. |
When AES need to process digital data then it is propagated using repeaters. |
|
Digital electromagnetic signal (referred as DES) |
DES is not used for AST |
For DST, DES is propagated using repeaters. |
Periodic signal characteristics are as follows:
- Amplitude: it is the instantaneous value of the signal at specified time.
- Frequency: The frequency (referred as f) is the rate of repetition of the signal. It can be defined as cycles/second, or Hertz (referred as Hz).
- Phase: it is a degree of the comparative position in time in a single period of any periodic signal (Stallings, 2009).
For Sine waves, wavelength is inversely relational to the frequency (f) of the signal. The relationship equation, which tells the relation between frequency and wavelength for Sine waves, is:
λ f=c
Where λ= wavelength,
f = frequency
c= speed of the signal travelling
This relationship results in many facts about its speed and velocity by providing information regarding phase velocity as well as group velocity (Bi, et al., 2016).
Source: (Stallings, 2009)
For generating better signal design, it depends upon transmitted power near the mid of the transmitted bandwidth. Thus, distortion ought to be less in the receiving side signal spectrum. To get better signal spectrum, bandwidth is adjusted according to above graph while shaping the transmitted signal spectrum (Bi, et al., 2016).
The fall of signal strength with the distance travelled by the signal is called attenuation. As a result of attenuation, the signals become round and smaller than their original size. Moreover, attenuation of the signal wave can further lead rapidly to the damage of the info contained by the wave of propagated signal (Stallings, 2009).
Solution 2.1
The extreme rate at which data or information can be transferred over a specified communication pathway, or network, under specified states is referred as the channel capacity. There are four factors which are relating to each other for increasing effective channel capacity, they are as follows:
- Data rate
- Error rate
- Noise
- Bandwidth (Stallings, 2009)
Transmission media is of two types as: guided or unguided. In guided media, the signal waves will be guided alongside any solid media, such as copper (Cu) coaxial cable, optical fiber, copper (Cu) twisted pair.
Unguided media also referred as wireless transmission as they provide a way of transferring electromagnetic wave signals but guiding of them is absent. Examples of unguided media are atmosphere and outer space (Agarwal & Zeng, 2015).
Wide area networks (WANs) and Local area networks (LANs), and both are the illustrations of communications networks.
Key differences between WAN and LAN is as follows:
- The space of the LANs is too small comparative to that of WANs, like a single building or a group of buildings.
- The LANs are owned by the same firm, which is holding attached devices. Conversely, in case of WANs, this is a rarest case, or in any case a significant portion of the network possessions are not owned by the firm which is using WAN.
- LANs internal data rate is much greater than those of WANs (Delony, 2017).
Circuit switching was initially designed to operate within voice traffics but presently it is also used for data transmission. Circuit-switching technology is important because of its use to convey voice traffic. One of the key limitations of circuit switching technology is that there must be essentially no broadcast delay and surely no deviation in delays. Signal transmission rate must be constant, as transmission and response both occur at the similar signal rate. These requirements are essential in circuit switching network. Moreover, the excellence of the established signal must be adequately high to deliver minimum value of intelligibility (Agarwal & Zeng, 2015).
Poor video quality comes under End-user performance expectations which are referred as QoS streaming services requirements. A unique feature of one-way video is the lack of conversational elements requirements. Thus, the delay requirements are not so strict. Still, if the user is not getting the appropriate quality data then following Multimedia services QoS requirements should be checked:
- Data transfer rate
- Amount of symmetry
- Key performance factors: Packet loss at session layer, start-up delay and transport delay variation (CiscoPress, 2006)
Key function of the network access layer is data exchange amid an end user system like workstation, server and the network hub to which the user is attached. It is a bottom-lined layer of TCP/IP model, which provides network link between sender and receiver of the system (Goralski, 2017). The Network Access layer contains the procedures of interfacing the network hardware and accessing transmission media. Below Network Access layer of the TCP/IP, there is a complex interaction of hardware, software, and transmission-media terms. To form base of the Network Access layer, there are different kinds of physical networks having their own pacts. Some examples of these physical networks types include:
- Wireless networks
- Ethernet
- Token bus
- Fiber distributed data interface (referred as FDDI)
- PPP (referred as Point-to-Point Protocol)
Review Questions
Responsibility of the transport layer is to maintain end-to-end communication across the whole computer network. Transport layer performs the tasks related to data reliability as well as correct sequencing. It is the fourth layer of the open system interconnect (refereed as OSI) model which provides transparent, reliable data transfer amid endpoints. Transport layer is having two protocols of TCP and UDP and these protocols provide host-to-host communication services (Goralski, 2017).
TCP/IP is a concept based on Internet and is the frame to develop a full range of computer communications standards. In general, these communications standards involve three representatives: applications, networks and computers. It is a set of rules that administrates the link between computer systems and Internet.
TCP/IP uses five relatively independent layers to organize the communication tasks. These five layers of TCP/IP suite are as follows:
- Physical layer
- Internet Layer
- Network access layer
- Application layer
- Transport layer or host-to-host layer
For effective communication, each unit of the whole system must have an exclusive address. Moreover, each communication process having a host must have a unique address; this enables the transport layer or host-to-host protocol (TCP) to transmit data to the appropriate process.
TCP/IP is non-proprietary and is not organised from single company. Therefore, the IP suite can be altered easily according to the situation. Moreover, it is well suited with all operating systems, so it can interconnect with any specified system. The IP suite is also attuned with all kinds of computer networks and hardware (Stallings, 2009).
Routers are used in internetworking among different sub networks. Key functions of router are as follows:
- Providing a link amid sub networks
- Providing routing and data delivery among processes on end user systems associated with different networks.
Router is a device, which is used to connect two or more than two networks. The router use an IP (referred as internet protocol), that is a without link protocol operates at third layer of the Open system interconnect (referred as OSI) model. Moreover, a router can be seen as a processor that links two networks and its main function is to transmit data from one network side to another that is from the source to the endpoint system. As we know that, an Intermediate System (IS) is used to connect either similar or dissimilar networks, hence a router functions at third layer of the OSI architecture and routes packets amid potentially diverse networks (Stallings, 2009).
References:
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Anon., 2010. Analog and Digital Signals, Time and Frequency Representation of Representation of Signals Signals. [Online]
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[Accessed 29 09 2018].
Stallings, W., 2009. Wireless communications & networks. s.l.:Pearson Education India.