Comparison of ADSL2+ router and cable modem router

This document compares ADSL2+ router and cable modem router for lone interfacing. It discusses the modulation type, error control strategy, modulation bit rate, and more.

Name of the Student
Name of the University
Author Note

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Assignment Answers
Part-A
1.1. Matlab code for the given bit pattern 01001, encode this data using ASK, FSK and PSK
%matlab code for digital modulation(ask, fsk and psk)
f=5;
f2=10;
x=[0 1 0 0 1] % input signal ;
nx=size(x,2);
i=1;
while i<nx+1
t = i:0.001:i+1;
if x(i)==1
ask=sin(2*pi*f*t);
fsk=sin(2*pi*f*t);
psk=sin(2*pi*f*t);

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else
ask=0;
fsk=sin(2*pi*f2*t);
psk=sin(2*pi*f*t+pi);
end
subplot(3,1,1);
plot(t,ask);
hold on;
grid on;
axis([1 10 -1 1]);
title('Amplitude Shift Key')
subplot(3,1,2);
plot(t,fsk);
hold on;
grid on;
axis([1 10 -1 1]);
title('Frequency Shift Key')

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subplot(3,1,3);
plot(t,psk);
hold on;
grid on;
axis([1 10 -1 1]);
title('Phase Shift Key')
i=i+1;
end

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2.
Answer
(a) A=2, f=2.5, =0o
(b) A=7, f=.08, =180o

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Answer 3
SQUARE KILOMETRE ARRAY

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Executive Summary
The SKA is a project which is used for radio astronomical purposes. SKA consists of
various radio telescopes. The main of this report is to discuss about the wireless communication
features of this project and its impact on radio astronomy due to the size and height of antennas.
SKA is very important for radio astronomical purpose as it helps to obtain information from
various astronomical bodies through radiation of electromagnetic waves.

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Table of Contents
SQUARE KILOMETRE ARRAY..................................................................................................6
Introduction....................................................................................................................................10
Discussion......................................................................................................................................10
Wireless communication features..............................................................................................10
Size and height of the antennas used in the SKA......................................................................11
Communication frequency bands of SKA.................................................................................11
Conclusion.....................................................................................................................................11
References......................................................................................................................................12

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Introduction
Square Kilometer Array (SKA) is a project related to the radio telescope, which is
proposed to be built in South Africa and Australia with the help of 10 other countries (Grainge
et al. 2017). The project will make the surveying of the sky very easy. This report will discuss
the wireless communication features of this project and its impact on radio astronomy due to the
size and height of antennas.
Discussion
. The project of SKA is so huge that it would require an area of one square kilometer. The
enormous size will make this system 50 times more sensitive than the other radio which is
currently used for sky surveying procedure.
Wireless communication features
Square kilometer array works on the principle of radio astronomy. SKA holds an upper
edge over the other telescopes as SKA can work with signals at longer wavelengths giving a
clear vision of space even during the poor weather on earth ("www.skatelescope.org ", 2019).
The radio telescope used in the SKA project helps to receive radio waves in the ground and it is a
special kind of antenna. The radio waves are propagated from the astronomical radio sources
through the medium of space. The development of radar technologies helped in the development
of the radio telescopes (Combes 2015). The electromagnetic spectrum which is emitted by the
astronomical objects have a radio frequency portion. The radio portion of that electromagnetic
spectrum is obtained by the radio telescopes.

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Size and height of the antennas used in the SKA
In Australia the SKA have 512 base stations, each station having 250 individual antennas. The
total count of antennas exceed 130,000, creating a maximum baseline of 65km. The South
African SKA project will add 133 antennas to the existing count of 64-dish MeerKAT precursor
telescope.
The SKA project uses three different kind of antennas which are arranged on the ground in five
giant spiral arms. Every antenna have some high frequency band, the higher part of that
frequency band uses antennas of 15 m diameter (Tingay et al. 2013). The middle and lower band
of the antennas are used for observing large areas of sky continuously.
Communication frequency bands of SKA
The completion of the first two phases of SKA project will make the SKA capable of
providing frequency coverage in between 50Hz and 1.4GHz continuously. The dish based array
covers about 1.2 GHz to 10 GHz making it the most capable design for SKA. After the
completion of the third phase of SKA, it will be capable of providing frequency up to 30GHz
(Hotan et al. 2014). The LFAA, which will be deployed in SKA by 2020 have the lowest
frequency from 50 MHz to 350 MHz .
Conclusion
It can be concluded from the above report that SKA is a very important prospect in the
field of radio astronomy. It is huge project consisting of several antennas. The telescopes used
for astronomical purposes are those antennas which receive high quality image by extracting the

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electromagnetic spectrum from the received wave coming from the astronomical objects. The
project is still in research and development phase.

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References
Combes, F. (2015). The Square Kilometer Array: cosmology, pulsars and other physics with the
SKA. Journal of Instrumentation, 10(09), C09001.
Grainge, K., Alachkar, B., Amy, S., Barbosa, D., Bommineni, M., Boven, P., Braddock, R.,
Davis, J., Diwakar, P., Francis, V. and Gabrielczyk, R., 2017. Square Kilometre Array:
The radio telescope of the XXI century. Astronomy Reports, 61(4), pp.288-296.
Hotan, A.W., Bunton, J.D., Harvey-Smith, L., Humphreys, B., Jeffs, B.D., Shimwell, T., Tuthill,
J., Voronkov, M., Allen, G., Amy, S. and Ardern, K., 2014. The australian square
kilometre array pathfinder: System architecture and specifications of the boolardy
engineering test array. Publications of the Astronomical Society of Australia, 31.
Tingay, S.J., Goeke, R., Bowman, J.D., Emrich, D., Ord, S.M., Mitchell, D.A., Morales, M.F.,
Booler, T., Crosse, B., Wayth, R.B. and Lonsdale, C.J., 2013. The Murchison widefield
array: The square kilometre array precursor at low radio frequencies. Publications of the
Astronomical Society of Australia, 30.
What is Radio Astronomy? - SKA Telescope. (2019). Retrieved from
https://www.skatelescope.org/radio-astronomy/

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Part B
Answer 3.
Comparison of ADSL2+ router and cable modem router for lone interfacing
ADSL2+ router
(TP LINK-TD 8816)
Cable modem router
(NETGEAR N600)
Modulation type: DMT (Discrete Multi Tone) QPSK (Quadrature Phase
Shift Keying)
Modulation bit rate: 8Mbps 10Mbps
Error control strategy: Forward error correction
method is used.
Cable modem termination
system is used.
Cable and connector
required:
RJ-45 RJ-45

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Comparison of ADSL2+ router and cable modem router for host interfacing:
ADSL2+ router
(TP LINK-TD 8816)
Cable modem router
(NETGEAR N600)
Supported bit rates 24Mbps(downlink) 30Mbps(downlink)
Provided ports 4 LAN ports, 1 Ethernet port 4 LAN ports,1 Ethernet port
Is DHCP provided? Yes Yes
ADSL2+ runs on DMT (Discrete Multi Tone) modulation. DMT uses the Fast Fourier
Transform (FFT) algorithm for modulation and demodulation (Cho and Lee 2013). Other
modulation technologies which are used by ADSL2 are Multiple Virtual Line (MVL) and
Carrierless Amplitude Modulation (CAP). The most commonly used modulation for ADSL2
router is DMT (Lafata 2013). On the other hand cable modem router uses QPSK (Quadrature
Phase Shift Keying) with speed of 10mbps and QAM64 (Quadrature Amplitude Modulation)
whose speed is up to 64 mbps. Though the speed for QAM64 is more than that of QPSK
modulation for cable modem router but then also QPSK is preferred as it is robust when
compared to QAM64 (Lazar 2015). Modulation and demodulation of the data is the main task of
modem. The DMT is the type of modulation which is used over MVL and CAP type of

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modulation because DMT uses FFT algorithm making the ADSL2+ router faster. QPSK is lower
than that of QAM64 but QPSK is the preferred over QAM64 modulation technique in the cable
modem router as it is more robust.
The preferred wireless router would be ADSL2+ router (TP LINK-TD8816) because it
provides a full rate of ADSL2+ standard which is highly reliable and very cost effective when
compared to cable modem router. Cable modem router runs at speed of 30 Mbps compared to
download speed 24 Mbps in ADSL2+ routers but the speed can decrease at very fast rate when
compared to ADSL2+ routers. The upload speed of cable modem router is also slower than that
of ADSL2+ routers. The price of ADSL2+ routers is cheaper than that of the cable modem
routers, thus ADSL2+ router is always preferred over the cable modem router.
References
Cho, T. and Lee, H., 2013. A High-Speed Low-Complexity Modified ${\rm Radix}-2^{5} $
FFT Processor for High Rate WPAN Applications. IEEE Transactions on Very Large
Scale Integration (VLSI) Systems, 21(1), pp.187-191.
Lafata, P., 2013. Examination of multiplexing VDSL2 over ADSL2+ line. Elektronika ir
Elektrotechnika, 19(8), pp.123-127.
Lazar, P., Netgear Inc, 2015. System and method for remotely updating cable modem software.
U.S. Patent 9,146,730.