Specifications

LIST OF TABLES
FIFO First In, First Out. Term used to describe a buffering technique
whereby the data which was first buffered is also the first to be replaced
by fresh data.
GPRS General Packet Radio Service. 2.5G GSM mobile phone technology
allowing packet-based data communication.
GSM Global System for Mobile Communications. International standard
for mobile telecommunications. This is the standard for cell-phones in
South Africa.
Interrogator Term used interchangeably with “reader” to describe a device
which is able to read/write to an RFID transponder.
ISR Interrupt Service Routine. Refers to a piece of software which is de signed
to be executed when an interrupt is generated.
LCD Liquid Crystal Display. Display technology relying on the physical
properties of crystals under the influence of an electric field. Popular
in digital wrist-watches and pocket calculators.
LOS Line of Sight. Term used in radio-frequency communication to refer to
an unobstructed signal path between transmitter and receiver.
Non-volatile memory Memory technology which does not lose its contents
upon loss of power.
PIN Personal Identification Number. Numerical code used to identify the
user.
PSU Power Supply Unit. Short-hand term used to refer to the power supply
module of a device.
PWM Pulse Width Modulation. Scheme used to control the amount of
power in a waveform by varying the ratio of the “on” time to the “off”
time.
RAM Random Access Memory. Term used to describe memory in a computer
which can be accessed randomly (rather than sequentially). Typically
xiii