What is ADC & How is ADC Processed?

The mean of ADC stands for Analogues to Digital Converter. The process of analogue to digital conversion is outlined in some ways. Computers individually process digital information, they command digital input, therefore, if an analogue input is distributed to a laptop, ADC  is needed. The terminology of analogue is defined has a nonstop valued signal, such as temperature or speed, with unlimited potential values in between, in another case, an analogue signal can be used to measure changes in light, sound, pressure or temperature. An analogues microphone can transform sound waves into an analogue signal. The terminology of digital is also labelled as a signal refer to an electrical signal that is transformed into a pattern of bits. A digital signal has a separate value at each sampling point. “ADC may also be used to converts audio streams. For examples, if you want to record sounds from a  microphone, the audio must be converted from the microphone’s analogue signal into a digital signal that the computer can understand” (Techtermscom, 2018). This is the reason why sound cards have an analogue audio input also demand an ADC that transfers the incoming audio signal to a digital format.

What is sampling?

Sampling is a method of taking an adequate range of separate values at a point on a waveform that will state the form of the wave. “The sampling frequency (or sample rate) is the number of samples per second in a sound, For example: if the sampling frequency is 44100 hertz, a recording with a duration of 60 seconds will contain 2,646,000 samples”(Humuvanl, 15 April 2015). I noticed the more samples you take, the more accurately you will outline the waveform. It transfers an analogue signal into strings of impulses, all indicating amplitude of the signal at a given point.

What is Quantization?

Quantization is a method that transfers sampled signal into an estimated quantized signal which contains only a limited number of voltage levels. Each sampled value at the input of the quantizer is estimated to the closest average voltage level. “the process of digitizing the range is called quantization”(sisuutee, unknown).

This are sampling and quantization diagram examples:-

Diagram1  “Figure 5.8 Quantized wave”(Digital Sound & Music,2014)

In this diagram show how an analog signal gets quantized. The blue line represents analog signal as the red one represents the quantized signal. Both sampling and quantization result in the loss of information. The value of a quantizer output depends upon the number of quantization levels used. The separate amounts of the quantized output are called representation level. The spacing between the two adjacent representation levels is called a step-size.

Diagram 2 “Figure 5.9 Quantized wave”(Digital Sound & Music,2014)”

 in this diagram the green lines in the graph shows error resulting from quantization. This shows that the error keep on a regular pattern that changes in cycle with the real correct sound wave. The error wave creates sound itself.

The contrast between the originals examples and the quantized examples comprises adjusting error. The lower the bit depth, the more qualities potentially should be adjusted.

What is PCM and how it works?

 PCM stands for Pulse Code Modulation. PCM is used to change analogue audio signals (symbolised by waveforms) into a digital audio signal, which are symbolised by 1’s and 0’s. analogue voice data must be converted into a sequence of binary digits before they can be transferred. “After these PCM data streams reach their destination, they are demultiplexed, broken back down into individual data streams, and demodulated, whereby the modulation procedure is applied in reverse to recreate the original binary numbers” (Techopediacom, 2018).

Sources of noise in the ADC

Noise is one of the important AC specifications of an ADC.

Noises come in many different ways such as broadband current noise, which is temperature-dependent noise affected by the physical movement of charge electrical conductors. erupted Noise, which is the low frequency in nature and caused by device faults, making it random and accurately unpredictable.

The usual causes of signal noise are noise addition, which can happen anywhere in the system and at any physical location in which the network is unprotected. It can be the result of several factors at any location on the network, examples of the cause of signals can be:-

•          Poor wiring applies – poorly wired networks, such as those not using protected twisted- pair and conduit, are more open to ambient electrical noise.

•          Long wire picks up radio frequency- long part of the wire effectively act as transmitters, they pick up radio waves and transfers them to electrical signals, adding to the additional noise in the system.

•          Close relationship to other electrical equipment such as devices or wires placed closely to electrical equipment that makes strong compelling pitches, such as generators, motors, or power lines, this objects can pick up some of that obstruction, which can add to the movement in communication signals.

Sources of Errors in ADC

There are three different type of errors in ADC, which are:-

•          offset error is described as a continuous change, over the complete range of the ADC, between the real output value.

•          Gain error is described as the change of the drop of the real output values and the ultimate output values. Total system gain error contains any gain errors from preamplifiers, attenuators, or signal transducers.

•          DNL error- DNL stands for differential Non-Linearity. Is the role of each ADC’s individual design. It is not possible to remove its effects with adjustment.

I am against this argument because of few reasons such as CD-quality audio resolution uses 16 bits for each sample. The sample rate is 44.1khz. this is regularly defined as only 16/44.1k. This converts into a simple powerful range of roughly 96 dB, and an analogy bandwidth speed is around 22 kHz which technology overrun these long ago, and today the most widely recognized piece bit depth is 24 bits, and the sample rates of 192 kHz and past are conceivable 24/192k. The individuals who manage professional sound system once in a while experience 44.1 kHz as a sample rate alternative. It has been expanded to a more logical 48 kHz rate, yielding more high-frequency extension. Most DSPs utilize a 48 kHz sample rate and 24-bits(24/48k).

“24-bit audio gives you a theoretical dynamic range of 144 dB, as opposed to 96 dB with 16-bit audio”(Resoundsoundcom,2014)

Expanding the digital sound resolution beyond what is required can strain playback and recording systems and power bargains that contains lower channel counts, more storage area, a heavier managing load for your DSP, and bigger required bandwidth for flowing.  Using 16 bits wouldn’t give you more dynamic range meaning that the signal to noise won’t be better has 24 bits.

Task 2

In this task, I have explained the screenshots of what and how the HTTP commands works.

This screenshot contain information about what the head method is and what it is used for. we also know “HEAD requests are useful for checking what a GET request will return before actually making a GET request — like before downloading a large file or response body”(Cody reichert, 2017).

This screenshot contain information about what the POST & GET method are and what they are used for. another way of describe POST would be “ to create a resource on the server “

Another way to describe GET would be “ To retrieve a resource from the server”(Guru99,2018).

This screenshot contain information about what the DELETE method is and what they are used for.

Another way to describe DELETE method would be “ To remove a resource from the server” (Guru99,2018).

This screenshot shows how a DELETE method operation. This method will be invoked whenever we want to delete an existing string value from our list of Tutorials via the DELETE method.

Create a new user with a POST request to /users

With the user id returned from the POST, make a DELETE request to /users/{{userid}}

A subsequent GET request to /users/{{userid}}

www.guru99.com/restful-web-services.html

Task3

What is a packet switched?

The packet switch is a way of sending data whereby the information is separated into packets. Each packet is given a header containing data of the destination. Each packet is sent through the system to the destination using this data. In the end, the data has to be collected from the received packages.

how does packet switch operate?

Information is transferred in short packets. “Typically an upper bound on packet size is 1000 octets”(Abel Willis, 2016). If a station has a longer message to dispatch it, splits it up into a series of small packets. Each packet currently contains part of the user’s information and some control information. The control information should at least contain ended address, source address, store and forward- packets are received stored temporarily and sent on to the next node.

Advantages of the packet switch

•    Bandwidth used to full possible

•    Devices of various speeds will communicate

•    Not affected by line failure (redirects signal)

•    Availability- no waiting for a direct connection to become available

•    During a disaster, when the public telephone network might stop working, emails and texts can still be sent via packet switching

Disadvantages of packet switching

•    Under heavy use, there can be a delay

•    Data packets can get lost or become corrupted

•    Protocols are needed for a reliable transfer

•    Not so good for some types data streams(e.g. real-time video streams can lose frames due to the way packets arrive out of sequence)

what is a Circuit switching?

This is a way of transmitting data and communicating, usually through the telephone system. Circuit-switched is a type of network in which a physical path is taken for and dedicated to a solo connection between two end-points in the system for the period of the connection. Normal voice phone service is circuit-switched.

 A circuit switch needs a dedicated line, meaning that the line must be active the entire time of the transmission. Electrical telegraphs, in their time, work by sending an electrical signal across a long wire(Robert pepper, 2012). When the current is active, it could be worked into code by pressing the telegraph key. When the current is not active, the wire stayed simply a wire.

How does a circuit switching operate?

Circuit switching between two stations is separated into three steps; the formation of the circuit, conversation and disconnect the circuit.

Circuit switch works with a set route between the stations involved is founded so that they can connect, then the station involved can exchange data by interacting and receiving data through the circuit already established. This data transfer links to the second stage of circuit switching, after an uncertain period, the connection is finally shut by the act of one of the communication stations.

Advantages of circuit switching

•    The circuit is committed to the phone no impedance, no sharing

•    Guaranteed the full transfer speed for the term of the cell

•    Guaranteed quality of service

Disadvantages of circuit switching

•    Inefficient – the equipment possibly is used for a considerable limitation of the call, if no information is being sent, the devoted line still stays open.

•    It sets aside a moderately long opportunity to set up the circuit.

•    During a disaster, the system may end up unsteady or unavailable

•    It was essentially created for voice movement as opposed to information traffic.

The packet switch is simpler, better and cheaper than circuit switch. Meanwhile, all the bandwidth can be used at once, a packet switch is more useful because it doesn’t need to manage a set number of connections that may not be using all data transmission. Packet switch also requires a less confusion structure that can simply answer parts of the system failures, which makes it faster and more affordable to include new hubs at whatever point they’re required.

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the packet switch will profit the country if the population increases in future, In term of reliable, a packet switch isn’t an issue because when the accepting comes to look at the packets, it can quickly identify if one is missing and request for that resent. however, on the other hand, the circuit-switch system has no component to resend lost information, if the information is lost on a circuit switch system, it is lost for good, as a result, packet switch system will, in general, will be more reliable for the country in present and future in their vehicle of information.

References

Techtermscom. 2018. Techtermscom. [Online]. [6 November 2018]. Available from: https://techterms.com/definition/adc

Humuvanl. 15 April 2015. Humuvanl. [Online]. [6 November 2018]. Available from: http://www.fon.hum.uva.nl/praat/manual/sampling_frequency.html

Sisuutee. unknown. Sisuutee. [Online]. [6 November 2018]. Available from: https://sisu.ut.ee/sites/default/files/imageprocessing/files/digitizn.pdf

Jennifer, B.U.R.G.P.I. 2014. Digital Sound & Music. [Online]. [9 November 2018]. Available from: http://digitalsoundandmusic.com/5-1-2-digitization/ 

Resoundsoundcom. 2014. RESOUNDSOUND. [Online].[12 November 2018]. Available from: http://www.resoundsound.com/sample-rate-bit-depth/

Cody Reichert. 2017. Assertible. [Online]. [12 November 2018]. Available from: https://assertible.com/blog/7-http-methods-every-web-developer-should-know-and-how-to-test-them

Guru99. 2018. Guru99. [Online]. [12 November 2018].Available from: www.guru99.com/restful-web-services.html

Guru99. 2018. Guru99. [Online]. [12 November 2018].Available from: www.guru99.com/restful-web-services.html

Techopediacom. 2018. Techopediacom. [Online]. [12 November 2018]. Available from: https://www.techopedia.com/definition/24128/pulse-code-modulation-pcm

Abel Willis. 2016. Slideplayercom. [Online]. [12 November 2018]. Available from: https://slideplayer.com/slide/11552228/

Robert pepper. 2012. Getvoipcom. [Online]. [12 November 2018]. Available from: https://getvoip.com/library/how-packet-switching-works/