=Paper=
{{Paper
|id=Vol-2544/paper7
|storemode=property
|title=Cost Effective Tri-Band Mobile Phone Jammer for Hospitals Applications
|pdfUrl=https://ceur-ws.org/Vol-2544/paper7.pdf
|volume=Vol-2544
|authors=Abdulkarim A. Oloyede,Adeniyi Shamsudeen,Nasir Faruk,Lukman A. Olawoyin,Segun I. Popoola,Abubakar Abdulkarim
|dblpUrl=https://dblp.org/rec/conf/irehi/OloyedeSFOPA18
}}
==Cost Effective Tri-Band Mobile Phone Jammer for Hospitals Applications==
https://ceur-ws.org/Vol-2544/paper7.pdf
Cost Effective Tri-Band Mobile Phone
Jammer for Hospitals Applications
Abdulkareem. A. Oloyede, A. Shamsudeen, Nasir Faruk,
Lukaman. A. Olawoyin, S.I. Popool, Abubakar. Abdulkarim
aao500@york.ac.uk
Abstract—Wireless Telecommunication services are becoming a part of
our everyday life because they support a lot of services. However, they are
often misused in environments such as hospitals where some patients would
require quietness or sometimes they distract medical practitioners from
carrying out their duties of saving lives. Therefore, there is a need to use a
jammer that prevents mobile phone from working in such an environment.
Hence, this paper proposes a cost-effective tri-band mobile phone jammer
for hospitals applications. The jammer is designed, constructed, test and
found very effective in terms of jamming signal within the bands.
Keywords—Cell Phone, Jammer, Mobile Phone, Hospital
1. INTRODUCTION
In the last decade, wireless phones has achieved significant global
penetration in both developed and developing countries [1]. They are now
becoming an important and essential tool in our day-to-day activities because
of their use in communication, entertainment, education, e-commerce, e-
banking etc. They are used; to watch videos and play music for entertainment
purpose, to access documents and watch online tutorial for learning, to
perform online financial transaction and to exchange and disseminate
information among others. However, the widespread use of these mobile
phones or mobile stations (MSs) presents some problems and could also pose
a threat in certain scenarios especially in hospital environments. A number
of such cases are when the sound of ringing cell-phones becomes distractive,
annoying or disruptive to health workers who are saving lives [2]. A possible
preventive measure is to setup and install a device in a place that will
regulate or inhibit the using of a cell-phones and render them inactive. Such a
device can be a mobile-phone jammer. It can also be called a “GSM
jammer”. This can categorize as some electronic devices/system that hinder
communication between mobile device and base station [2].
Generally, a cell phone-jammer is a device that block signal from mobile
by creating interference such that it prevents transmission and reception
power at the certain frequency [3]. They can concurrently jam services in a
number of frequency bands, so they could be a dual, tri or quad-bands
Jammer which are very effective against intelligent phones that can
automatically switch between different frequencies bands when interfered
with in a bid to get service connection. Mobile Jammer works by either
blocking the uplink transmission of mobiles or by blocking the downlink
transmission of Base transceiver stations (BTSs). Either one has same effect
of hindering both since the phone would assume a “no service”. This is
because it can only receive from one of the frequencies [4]. Less amount of
energy is needed to interfere with the signals from the BTS to MSs than the
signals from MSs to the BTS, since the BTS is located at a farther distance
from where the jammer is than the cell-phone and as such would have a
weaker signal compared to that of the cell-phone [1]. Although, power
control is possible when weak signal is being received by the MS, however,
Copyright © 2019 for this paper by its authors. Use permitted under Creative
Commons License Attribution 4.0 International (CC BY 4.0) IREHI 2018 : 2nd
IEEE International Rural and Elderly Health Informatics Conference
the Jammer must on the other hand be matches its power to commensurate
the increase in the transmitting power of the MS [5]. The jamming cancels
out the communication when all the mobiles located in close proximity to
where the Jammer device is deployed are effectively blocked and denied
access to the cellular network [6]. Early Jammers were initially developed
and used by the military in wartimes to disrupt an enemy’s communication or
send false information in an attempt to mislead an enemy [5]. It is important
to note that in most countries of the world, mobile Jammers are unlawful
devices and their usage are prohibited, with the exception of law enforcement
agencies such as the military and security use. This work therefore, provides
a detailed insight into the Design, Construction and Operational analysis of a
device that would effectively jam the signal transmitted from MS providing
the GSM and WCDA services.
2. RELATED WORKS
Jammers are classified into different types. In this work, we would be
focusing on type “A” jammers. This uses the Denial of Service technique.
therefore, this section provide an executive summary of the related works in
table 1.
Table 1: Related Works
PUBLICATION LOCATION COMMENT
P. Naresh, P. R Hyderabad, This design implemented a pre-
Babu and K. India. scheduled timer with a mobile Jammer.
Satyaswathi When the ON time reaches, the Jammer
(2013) [1] is activated through a relay and blocks
all GSM and CDMA services within a 5
– 7 m range. The device was
successfully able to jam cell-phones
using these services.
S.K. Mahato and Tamil Nadu, The designed Jammer was able to block
C.Vimala (2014) India. 2G and 3G services. However, the
[3] challenge faced in this work was that
the amplification process did not
achieve proper output gain to jam the
target services due to issues with the
power amplifiers. Because of this, their
project is partially designed till date.
D.S Madara, E. Moi The mobile Jammer was able to block
Ataro, and S. University, cell-phones using 2G and 3G networks.
Sitati (2016) [5] Kenya. But the jamming device had a poor
frequency selectivity and the jamming
range was smaller than expected. Also
the tuner circuit had poor calibration,
this makes difficult to block all
frequencies in the applicable
bandwidth.
Ahmed Jiswari Jordan The designed Jammer was able to block
(2014) [6] GSM 900 services. However in this
design, the right amount of current was
not provided to the VCO and the Power
amplifier which consequently prevented
tuning to the desired frequency range
for the VCO and also limiting the
output power of the Jammer. This
limited the jamming range to 10 meters
instead of the intended 20 meters.
J.G. Martins et al Abuja, The designed dual band GSM Jammer
(2016) [8] Nigeria. used a directional Yagi-uda antenna
PUBLICATION LOCATION COMMENT
instead of the conventional monopole
antenna. The Jammer was able to
achieve a maximum jamming distance
of 16.72 meters when the antenna is at
an angle of 10 degrees and a minimum
distance of 3.12 meters at an angle of
120 degrees
A. Mahmoud et Egypt. Their cell-phone Jammer works in both
al (2015) [9] the GSM 900/1800 bands and tested
Egypt. After full testing, a heat sink was
later implemented with the RF power
amplifiers in this design to reduce
overheating during operation.
A.O. Oke, A.S. Oyo, Nigeria. The designed Jammer used a different
Falohun and jamming technique by first detecting
A.A. Adigun mobile phones operating in the
(2016) [10] GSM900 band, and upon detection
transmits a jamming signal to block the
service within a 2.5 m range. At GSM
900 it was capable of detecting and
blocking all the services.
3. METHODOLOGY
The proposed jamming device consists of three (3) major sections
that makes up the Jammer circuit. These include the Power supply, the
Intermediate Frequency (IF) and the Radio Frequency (RF). Fig. 1 illustrates
the general overview diagram of the Jamming system.
Fig 1. Block diagram of the Jamming device
The circuit schematic for each of these sections and the various electronic
components that makes up these sections are critically chosen and selected.
Also detailed calculations and measurements is carried out before assembling
these different electronic components (resistors, capacitor, transistors, diodes,
voltage controlled oscillators, amplifiers, antennas etc.) that forms the
Jammer circuit. The range of frequencies that are jammed in this work is
provided in table 2: The Network providers considered were: Airtel, MTN.
Globacom and 9mobile networks.
Table 2: UP-link and Down-link frequencies for GSM 900/ 1800 & UMTS
2100.
UPLINK DOWNLINK
SERVICES FREQUENCY FREQUENCY
RANGE RANGE
(MHz) (MHz)
GSM 900 890 – 915 935 – 960
GSM 1800 1710 – 1785 1805 – 1880
UMTS 1920 – 1980 2110–2170
2100
4. DESIGN SPECIFICATION
4.1 Path Loss
In this paper, we employ the free space path loss model (FSPL). Generally,
path loss can be determined using the mathematical model defined in
equation (1), that is.
𝐹𝑆𝑃𝐿 (𝑑𝐵) = 32.45 + 20𝑙𝑜𝑔 𝑑 + 20𝑙𝑜𝑔 𝑓 (1)
where 𝑑 is the jamming distance in 𝑘𝑚 and 𝑓 is the operating frequency in
𝑀𝐻𝑧.
4.2 Jamming to Signal Ratio (J/S)
The Jamming-to-Signal ratio (J/S) of a target system is another important
parameter in mobile jamming. It is the ratio of the jamming signal power at a
specific receiver to the strength of the target signal at that same receiver [11].
This ratio is an indicator that shows the degree of vulnerability of a system to
interference. The larger the J/S ratio of a system, the greater it’s jamming
rejection capability [12]. The J/S ratio can be calculated by the use of Friis
equation for free space transmission.
𝑃𝐽 𝐺𝐽 𝐺𝑅 2
𝐽 (4𝜋𝑑𝐽 )2
= 𝑃𝑇 𝐺𝑇 𝐺𝑅 2
(2)
𝑆
(4𝜋𝑑𝑆 )2
𝐽 𝑃𝐽 𝐺𝐽 𝑑𝑆 2
= (3)
𝑆 𝑃𝑇 𝐺𝑇 𝑑𝐽 2
𝐽⁄
𝑆 (𝑑𝐵) = 𝑃𝐽 + 𝐺𝐽 − 𝑃𝑇 − 𝐺𝑇 + 20 𝑙𝑜𝑔(𝑑𝑆 ) − 20 𝑙𝑜𝑔(𝑑𝐽 ) (4)
where; PJ, PT, GJ, GT, dJ,and dS are the Jammer output power (dBW),
Transmitter power (dBW), antenna gains (in dBi) of Jammer and transmitter,
distance (in meters) of jammer to receiver and then transmitter to receiver
respectively. Applying some mathematical rearrangements, J/S can also be
obtain using the equation (5).
𝐽 𝑃𝐽 𝐺𝐽𝑅 𝐺𝑅𝐽 𝑅 2 𝑇𝑅 𝐿𝑅 𝐵𝑅
(𝑑𝐵) = (5)
𝑆 𝑃𝑇 𝐺𝑇𝑅 𝐺𝑅𝑇 𝑅 2 𝐽𝑅 𝐿𝐽 𝐵𝐽
where; RTR and RJR is the distance between the transmitter and receiver, and
Jammer and receiver, LR and LJ is the signal loss in of the communicating
device and signal Loss by the Jammer. BR is the bandwidth of the Receiver
and BJ is the bandwidth of the Jamming.
4.3 Signal to Noise Ratio (SNR)
Every radio device has a limit to which they can accommodate noise present
in any signal. This is known as the SNR handling capability of the device. It
is the wanted signal divided by that of noise [13]. The received signal power
is considered along with noise power to determine the SNR at the receiver
input [14].
4.4 Maximum Receive Signal Power
The maximum receive signal power refers to the best or strongest level of
signal a mobile station can possibly receive from another radio device in the
cellular network e.g. the Base station. Table 3 show the maximum power for
each band [15].
Table 3: Bands and Maximum RSSI
SERVICES MAXIMUM RSSI
GSM 900 -15 dBm
GSM 1800 -23 dBm
EDGE -26 dBm
GPRS -26 dBm
WCDMA -25 dBm
4.5 Power Calculation
The mathematical models to determine the receiver jamming power and the
Jammer output power is given in the equations (6) to (7).
Jamming power at mobile receiver,
𝐽𝑟 ≥ 𝑅𝑆𝑆𝐼𝑚𝑎𝑥 − 𝑆𝑁𝑅𝑚𝑖𝑛 (6)
Maximum Jammer output power, 𝐽𝑂 = 𝐽𝑟 + 𝐹𝑆𝑃 (7)
For GSM 900
Maximum RSSI, RSSImax = -15dBm
Minimum SNR, SNRmin = 9dB
Jamming power at mobile receiver , 𝐽𝑟 ≥ −15𝑑𝐵𝑚 – 9𝑑𝐵
For GSM 1800
Maximum RSSI, RSSImax = -23dBm
Minimum SNR, SNRmin = 9dB
Jamming power at mobile receiver, 𝐽𝑟 ≥ −23𝑑𝐵𝑚 – 9𝑑𝐵
𝐽𝑟 ≥ −32𝑑𝐵𝑚
5. SYSTEM IMPLEMENTATION
This section presents implementation of the Tri-band cell-phone Jammer.
The figure 2 depicts the different parts of the Jammer which are developed
individually and assembled to form the whole jamming system.
Fig. 2: Block diagram of the Tri-band cell phone Jammer.
6. TESTING, RESULTS AND ANALYSIS
After the successful design and simulation of the Jammer circuit, the design
was shifted to a Vero-board to connect all the electronic components. The
constructed Jammer device is shown in figure 3.
Fig. 3. Complete Tri-band cell-phone Jammer.
7. TESTING OF THE JAMMER
The testing of the cell-phone Jammer was a full successful as developed
device was able to block the four major Mobile operators in Nigeria namely
MTN, Globacom, Airtel and 9mobile as shown in Figures 4-6. Although the
average jamming range of the system was approximately 10 meters, which is
less than the design specification. This limitation can be attributed to the use
of telescopic antennas by the jamming system instead of duck antennas that
have a good gain. Also the RF power amplifiers that increase the strength of
the jamming signal were not able to get the precise voltage supply as
specified in their data sheet, as 3.3 volts was provided to them instead of the
required 3.5 volts.
During testing, the Jammer was able to block the target services on an
average of two (2) minutes after being turned “ON”. Further testing
confirmed that, the relationship between the distance between the Jammer
and the base station increases proportionally thus blocking more numbers of
cell-phones. This is due to the fact that the signal strength at cell-phones are
at their strongest when close to the base station, and the farther these cell-
phones are from the base station, the lesser the amount of power reaching
them, thus having a weak signal strength.
The figures 4-6 show the effect of testing the Jammer on different mobile
networks. It can be clearly seen that when the Jammer is “OFF”, network
services on the different cell-phones were available, but after turning the
Jammer “ON”, these services disappears or becomes unavailable.
Fig. 4. 9mobile and MTN services before and after the Jammer was “ON”.
Fig. 5. Airtel service before and after the Jammer was “ON”.
Fig. 6. Globacom service before and after the Jammer was “ON”.
8. CONCLUSION
This project work presents a detailed insight into the implementation of a tri-
band cell-phone Jammer that uses the denial of service jamming technique to
inhibit the operation of cell-phones. The aim and objectives initially set out
for this work has been achieved as the designed Jammer was relatively able
to block GSM 900/1800 and UMTS 2100 services within its jamming range.
Further testing of this device shows that its effective jamming distance
reduces when tested close to a base station and as we move farther from the
base station, this distance increases.
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