Mobile Signal Jammer Device

  A mobile phone jammer or blocker is a Basically an RF transmitter

device which deliberately transmits signals on the same radio frequencies as mobile phone, thus,disrupting the communication between the phone and the cell-phone base station, effectively disabling mobile phones within the range of the jammer, preventing them from receiving signals and from transmitting them. Mobile signal frequency is different for different countries ranging from 800MHz to 1900MHz

Because they disrupt the operations of legitimate mobile phone services, the use of such blocking devices is illegal in many jurisdictions, especially without a licence. When operational, such devices also block access to emergency services.

 

The actual range of the jammer depends on its power and the local environment, which may include hills or walls of a building that block the jamming signal. Low-powered jammers block calls in a range of about 30 feet (9 m). Higher-powered units create a cell-free zone as large as a football field. Units used by law enforcement can shut down service up to 1 mile (1.6 km) from the device.

Internet of Things : Wireless Communication Protocols

  NB- IoT

NB-IoT is a low power,low data rate service at 250kbps

SigFox

It's a proprietary standard operated by a company with the same name.

It uses ultra narrow band modulation which requires only 100hz of bandwidth per message with low rate of 100600bps 

Currently deployed more in western Europe than in the United States.

LoRaWAN and LoRa

Open standards for low power WWAN.

LoRaWAN specifies the MAC 

LoRa specifies the physical layer

LoRa has a built-in resistance to interference and multipath fading as it uses spread spectrum modulation

LoRa has a very low data rate

MQTT

Message queue telemetry transport is targetted for device to server communication

It is used for collecting data from a large number of devices and transferring that onto the server

The telemetry name indicates its use in remote monitoring and control

Since latency of several seconds is tolerable over the reliability of data transfers,TCP is used instead of UDP in its transport layer.

MQTT is not suitable for device to device communication.

XMPP

Extensible messaging and presence protocol is designed for connecting devices to humans

It uses XML text and name@domain.com acdressing.

It is used in consumer IoT applications such as connecting home appliances to the web server which a user can access using a smart phone.

AMQP

Advanced message queuing protocol is a queuing system designed to connect servers

Transactional messages are exchanged between servers which are buffered by using queues.

Since reliability is of great importance here TCP is used.

CoAP

Constrainted application protocol uses HTTP commands like PUT and GET for device to device communication.

It is a web transfer protocol designed for constrainted nodes and constrainted networks that are low power but lossy.

The end nodes are typically constrained of computing power and memory.

DDS

Data distribution service is used for device device communication which can deliver millions of messages per second to many devices

Offers ways to filter data and select multiple destinations thus implementing multicast operation.

It requires very low latency that can vary depending on the device and hence instead of TCP ,DDS uses quality of service (QoS) control scheme.

This protocol finds use in hospital environments and millitary.

What is 2.4GHz ISM frequency band

   ISM stands for Industrial, Scientific,Medical 

These are 2.4GHz bands reserved internationally for the use of unlicensed low-power devices

Example: 

Cordless Phones

Bluetooth Devices

Near Field Commuication (NFC)

Drop-in Compatibility

   Devices which operate at the same voltage and are pin-to-pin compatible

Example : 

nRF24L01+ is drop-in compatible with nRF24L01 

Sensor materials used for wireless wearables in healthcare

Polymeric sensors are used for biomedical sensors

Biomedical sensors signals have low frequency and hence require a low data rate

Mostly powered up by tiny lithium polymer batteries.

For an energy harvested sensor application,the energy is often less than 100uW.thus a duty cycled radio is best to be used in such energy constrained applications 

The sensing elements can be furtherclassfied as:

Solids : polymers, carbon semiconductors, carbon nanotube, nanowires,nanofibers and nanoparticles.

Liquids : ionic fluids and mettalic fluids.

Flexible substrates for mimicking skin include thermoplastic polymers such as polyurethane and polythylene 

Other class of flexible substrates used are soft silicone elastoners such as polydimethylsiloxane which are chemically inert and biocompatible.

Transducers used in such applications are piezoelectric, capacitive or resistive.

Wireless Communication in Biomedical IoT devices

Impulse radio ultra wideband(IR-UWB) architectures are adopted for the implementation of duty cycled radios 

They demonstrate excellant energy efficiency for high data rate applications however the energy efficiency is not equally Perfect for low data rate applications.

In low data rate applications the power leakage is much higher and can even degrade the energy efficiency at 100kbps data rate.

The IR-UWB transmitter does not require any mixer or phase lock loop,which minimises the power consumption of the system.

For wireless transmission of the data on-off keying(OOK) based transmitter scheme -  in which bit 1 is represented by a short pulse and bit 0 is represented by the absence of a pulse signal needs to be analysed to reduce the complexity of the transmitter architecture.

The above system level block diagram of the IR-UWB transmitter which is designed using a standard180nm complementary metal oxide semiconductor(CMOS)  includes

An impulse generator designed with digital gates

Its core building blocks are

1.Tunable delay block

2. An inverter

3. A NAND logic gate

4. Another inverter to generate the desired signal

Below block diagram puts all these blocks together

A tunable cross coupled inductor-capacitor based LC oscillator for uoconverting the baseband impulse signal to UWB frequency range.

A buffer to drive the 50ohm antenna.