FLEX (protocol)
Encyclopedia
FLEX is a communications protocol
developed by Motorola
and used in many pager
s. FLEX provides one-way communication only (from the provider to the pager device), but a related protocol called ReFLEX
provides two-way messaging.
Transmission
of message data occurs in one of four modes: 1600/2, 3200/2, 3200/4, or 6400/4. All modes use FSK
modulation
. At 1600/2 this is on a 2 level FSK
signal transmitted at 1600 bits per second. At 3200/2, this is a 2 level FSK
signal transmitted at 3200 bits per second. At 3200/4, this is a 4 level FSK
signal transmitted at 1600 symbols per second. Each 4 level symbol represents two bits for a bit rate of 3200 bits per second. At 6400/4, this is a 4 level FSK
signal transmitted at 3200 symbols per second or 6400 bits per second.
Data is transmitted in a set of 128 frames that takes 4 minutes to complete. Each frame contains a sync followed by 10 data blocks. The data blocks contain 256, 512 or 1024 bit
s for 1600, 3200 or 6400 bits per second respectively.
A BCH
type ECC is used to improve the integrity of the data. The standard has been designed to allow the pager's receiver to be turned off for a high percentage of the time and therefore save on battery
usage.
In The Netherlands the emergency services use the Flex-protocol in the nationwide P2000 network
for pagers. The traffic on this network can be monitored via several websites.
In South Australia the State's SAGRN network for the Emergency Services paging system (CFS, SES, MFS and SAAS) is run on the FLEX 1600 protocol, and can be monitored through several websites.
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
developed by Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
and used in many pager
Pager
A pager is a simple personal telecommunications device for short messages. A one-way numeric pager can only receive a message consisting of a few digits, typically a phone number that the user is then requested to call...
s. FLEX provides one-way communication only (from the provider to the pager device), but a related protocol called ReFLEX
ReFLEX
ReFLEX is a wireless protocol developed by Motorola which is used for two-way paging.The Motorola PageWriter released in 1996 was one of the first devices to use the ReFLEX network protocol.-Versions:...
provides two-way messaging.
Transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
of message data occurs in one of four modes: 1600/2, 3200/2, 3200/4, or 6400/4. All modes use FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
modulation
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
. At 1600/2 this is on a 2 level FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
signal transmitted at 1600 bits per second. At 3200/2, this is a 2 level FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
signal transmitted at 3200 bits per second. At 3200/4, this is a 4 level FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
signal transmitted at 1600 symbols per second. Each 4 level symbol represents two bits for a bit rate of 3200 bits per second. At 6400/4, this is a 4 level FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
signal transmitted at 3200 symbols per second or 6400 bits per second.
Data is transmitted in a set of 128 frames that takes 4 minutes to complete. Each frame contains a sync followed by 10 data blocks. The data blocks contain 256, 512 or 1024 bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
s for 1600, 3200 or 6400 bits per second respectively.
A BCH
BCH code
In coding theory the BCH codes form a class of parameterised error-correcting codes which have been the subject of much academic attention in the last fifty years. BCH codes were invented in 1959 by Hocquenghem, and independently in 1960 by Bose and Ray-Chaudhuri...
type ECC is used to improve the integrity of the data. The standard has been designed to allow the pager's receiver to be turned off for a high percentage of the time and therefore save on battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
usage.
Security
Since data transmission over FLEX is unencrypted and insecure, transmitting private information over it should be done with caution. There have been reported instances of individuals actively listening to pager traffic (private investigators, news organizations, etc.).In The Netherlands the emergency services use the Flex-protocol in the nationwide P2000 network
P2000 (network)
P2000 is a one-way communications network for pagers based on Motorola's FLEX-protocol in the Netherlands. The network is used by all emergency services and provides nationwide coverage...
for pagers. The traffic on this network can be monitored via several websites.
In South Australia the State's SAGRN network for the Emergency Services paging system (CFS, SES, MFS and SAAS) is run on the FLEX 1600 protocol, and can be monitored through several websites.