ISO/IEC 24730-2:2006
(Main)Information technology — Real-time locating systems (RTLS) — Part 2: 2,4 GHz air interface protocol
Information technology — Real-time locating systems (RTLS) — Part 2: 2,4 GHz air interface protocol
ISO/IEC 24730 defines two air interface protocols and a single application program interface (API) for real-time locating systems (RTLS) for use in asset management and is intended to allow for compatibility and to encourage interoperability of products for the growing RTLS market. ISO/IEC 24730-2:2006, the 2,4 GHz air interface protocol, establishes a technical standard for real-time locating systems that operate at an internationally available 2,4 GHz frequency band and that are intended to provide approximate location with frequent updates (for example, several times a minute). In order to be compliant with this standard, compliance with ISO/IEC 24730-2:2006 and ISO/IEC 24730-1 is required. Real time locating systems are wireless systems with the ability to locate the position of an item anywhere in a defined space (local/campus, wide area/regional, global) at a point in time that is, or is close to, real time. Position is derived by measurements of the physical properties of the radio link. ISO/IEC 24730-2:2006 specifies the air interface for a system that locates an asset in a controlled area, e.g. warehouse, campus, airport (area of interest is instrumented) - accuracy to 3 m. There are a further two methods of locating an object which are really RFID rather than RTLS: Locating an asset by virtue of the fact that the asset has passed point A at a certain time and has not passed point B. Locating an asset by virtue of providing a homing beacon whereby a person with a handheld can find an asset. The method of location is through identification and location, generally through multi-lateration. The different types are Time of Flight Ranging Systems, Amplitude Triangulation, Time Difference of Arrival (TDOA), Angle of Arrival. ISO/IEC 24730-2:2006 defines the air interface protocol needed for the creation of an RTLS system. There are many types of location algorithms that could be used. An example of a location algorithm is given in Annex A. ISO/IEC 24730-2:2006 defines a networked location system that provides X-Y coordinates and data telemetry. The system utilizes RTLS transmitters that autonomously generate a direct-sequence spread spectrum radio frequency beacon. These devices may be field programmable and support an optional exciter mode that allows modification of the rate of location update and location of the RTLS device. ISO/IEC 24730 also defines these modes, but does not define the means by which they are accomplished.
Technologies de l'information — Systèmes de localisation en temps réel — Partie 2: Protocole d'interface d'air à 2,4 GHz
General Information
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Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 24730-2
First edition
2006-12-15
Information technology — Real-time
locating systems (RTLS) —
Part 2:
2,4 GHz air interface protocol
Technologies de l'information — Systèmes de localisation en temps
réel —
Partie 2: Protocole d'interface d'air à 2.4 GHz
Reference number
ISO/IEC 24730-2:2006(E)
©
ISO/IEC 2006
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ISO/IEC 24730-2:2006(E)
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ISO/IEC 24730-2:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Symbols and abbreviated terms . 3
5 Requirements . 3
5.1 Frequency range. 3
5.2 2,4 GHz spread spectrum air interface attributes. 3
5.3 Compliance requirements. 4
5.4 Manufacturer tag ID . 4
5.5 Physical layer parameters . 4
6 Mandatory air interface protocol specification.7
6.1 Introduction . 7
6.2 RTLS transmitter radiated power. 10
6.3 DSSS message specifications. 10
7 Optional air interfaces. 13
7.1 RTLS transmitter OOK/FSK message specifications. 13
7.2 Programmer magnetic FSK message specifications. 15
7.3 Exciter air interface. 27
Annex A (informative) Locating an object through trilateration. 29
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ISO/IEC 24730-2:2006(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 24730-2 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 31, Automatic identification and data capture techniques.
ISO/IEC 24730 consists of the following parts, under the general title Information technology — Real-time
locating systems (RTLS):
⎯ Part 1: Application program interface (API)
⎯ Part 2: 2,4 GHz air interface protocol
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ISO/IEC 24730-2:2006(E)
Introduction
ISO/IEC 24730 defines two air interface protocols and a single application program interface (API) for
real-time locating systems (RTLS) for use in asset management and is intended to allow for compatibility and
to encourage interoperability of products for the growing RTLS market.
This part of ISO/IEC 24730, the 2,4 GHz air interface protocol, establishes a technical standard for real-time
locating systems that operate at an internationally available 2,4 GHz frequency band and that are intended to
provide approximate location with frequent updates (for example, several times a minute). In order to be
compliant with this standard, compliance with this part of ISO/IEC 24730 and ISO/IEC 24730-1 is required.
Real time locating systems are wireless systems with the ability to locate the position of an item anywhere in a
defined space (local/campus, wide area/regional, global) at a point in time that is, or is close to, real time.
Position is derived by measurements of the physical properties of the radio link.
This part of ISO/IEC 24730 specifies the air interface for a system that locates an asset in a controlled area,
e.g. warehouse, campus, airport (area of interest is instrumented) - accuracy to 3 m.
There are a further two methods of locating an object which are really RFID rather than RTLS:
⎯ Locating an asset by virtue of the fact that the asset has passed point A at a certain time and has not
passed point B.
⎯ Locating an asset by virtue of providing a homing beacon whereby a person with a handheld can find an
asset.
The method of location is through identification and location, generally through multi-lateration. The different
types are
⎯ Time of Flight Ranging Systems,
⎯ Amplitude Triangulation,
⎯ Time Difference of Arrival (TDOA),
⎯ Angle of Arrival.
This part of ISO/IEC 24730 defines the air interface protocol needed for the creation of an RTLS system.
There are many types of location algorithms that could be used. An example of a location algorithm is given in
Annex A.
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INTERNATIONAL STANDARD ISO/IEC 24730-2:2006(E)
Information technology — Real-time locating systems (RTLS) —
Part 2:
2,4 GHz air interface protocol
1 Scope
This part of ISO/IEC 24730 defines a networked location system that provides X-Y coordinates and data
telemetry. The system utilizes RTLS transmitters that autonomously generate a direct-sequence spread
spectrum radio frequency beacon. These devices may be field programmable and support an optional exciter
mode that allows modification of the rate of location update and location of the RTLS device. ISO/IEC 24730
also defines these modes, but does not define the means by which they are accomplished.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 24730-1, Information technology — Real-time locating systems (RTLS) — Part 1: Application
program interface (API)
ISO/IEC 18000-4, Information technology — Radio frequency identification for item management — Part 4:
Parameters for air interface communications at 2,45 GHz
ISO/IEC 19762-1, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 1: General terms relating to AIDC
ISO/IEC 19762-3, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 3: Radio frequency identification (RFID)
ISO/IEC 15963, Information technology — Radio frequency identification for item management — Unique
identification for RF tags
ISO/IEC 8802-11:2005, Information technology — Telecommunications and information exchange between
systems — Local and metropolitan area networks — Specific requirements — Part 11: Wireless LAN Medium
Access Control (MAC) and Physical Layer (PHY) specifications
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19762-1, ISO/IEC 19762-3 and
the following apply.
3.1
air interface
wireless communications protocol and signal structure used to communicate data between RTLS transmitters
and other RTLS devices
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ISO/IEC 24730-2:2006(E)
3.2
corporate LAN
customer-provided network such as Ethernet or wireless LAN
3.3
host applications
customer’s management information systems
3.4
RTLS infrastructure
system components existing between the air interface protocol and the RTLS server API
3.5
real-time locating system
set of radio frequency receivers and associated computing equipment used to determine the position of a
transmitting device relative to the placement of the aforementioned receivers that is capable of reporting that
position within several minutes of the transmission used for determining the position of the transmission
Note: Refer to Figure 1 for clarity regarding elements of RTLS infrastructure.
RTLS
transmitters
RTLS RTLS RTLS host
transmitters infrastructure server applications
exciter
RTLS
transmitters
optional mandatory Application
air air Program
interface interface Interface
Figure 1 — Elements of RTLS infrastructure
3.6
RTLS server
computing device that aggregates data from the readers and determines location of transmitters
3.7
RTLS transmitter
battery powered radio devices that utilize the protocols specified in ISO/IEC 24730
3.8
RTLS reader
device that receives signals from an RTLS transmitter
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ISO/IEC 24730-2:2006(E)
3.9
open field
path from transmitter to receiver is LOS (line of sight)
[ANS T1.523-2001]
3.10
exciter
device that transmits a signal that alters the behaviour of an RTLS transmitter
3.11
upconvert
change a baseband signal to a higher frequency signal
3.12
tag blink
radio frequency transmission(s) from an RTLS transmitter that may consist of one or multiple duplicate
messages
3.13
sub-blink
message that is transmitted one or multiple times in a “blink”
4 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in ISO/IEC 19762-1,
ISO/IEC 19762-3 and the following apply.
DSSS Direct Sequence Spread Spectrum
EB Event Blink
EXB EXciter Blink
RTLS Real Time Locating System
TIB Timed Interval Blink
5 Requirements
5.1 Frequency range
This part of ISO/IEC 24730 addresses real-time locating systems (RTLS) operating in the 2,400 GHz to
2,4835 GHz frequencies.
5.2 2,4 GHz spread spectrum air interface attributes
The minimum feature set shall include the following.
⎯ RTLS transmitters shall autonomously generate a direct sequence spread spectrum radio frequency
beacon.
⎯ Transmission shall be at a power level that can facilitate reception at ranges of 300 m open-field
separation between the transmitter and receiver when operating within the parameters described in
Table 1.
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ISO/IEC 24730-2:2006(E)
⎯ RTLS transmitters shall be fully compliant with local regulatory requirements.
⎯ Class 1 RF transmissions are low power and electro-magnetically compatible with and shall not interfere
(not cause any measurable difference in throughput) and co-exist with existing standardized
ISO/IEC 8802-11 wireless communication networks. They are also systems that co-exist with
ISO/IEC 18000-4, and shall not exceed the maximum power requirements of the local regulatory
agencies.
⎯ Class II RF transmissions shall not exceed the maximum power requirements of the local regulatory
agencies.
5.3 Compliance requirements
The beacon transmitters specified in this part of ISO/IEC 24730 shall transmit at a power level that can
facilitate reception at ranges of at least 300 m LOS separation between the transmitter and receiver. Such
RTLS transmitters shall be fully compliant with local radio frequency regulatory requirements. Each receiver
shall be capable of receiving and processing data from a minimum of 120 beacon transmissions per second.
The nominal location data provided by the RTLS shall be within a 3 m radius of the actual location of the
RTLS transmitter. The RF transmissions are low power, compatible with, and shall not interfere with existing
standardized ISO/IEC 8802-11 wireless communication networks, and systems compliant with
ISO/IEC 18000-4.
To be fully compliant with this part of ISO/IEC 24730, RTLS shall also comply with ISO/IEC 24730-1.
5.4 Manufacturer tag ID
The manufacturer’s tag identification number identifies a particular manufacturer and consists of 16 bits. A
manufacturer may have more than one ID number. As reported from the RTLS Server to the API, the first 16
bits are designated for the manufacturer’s identification number. As reported from the Data Link Layer to the
API, the remaining 16 bits establish a numbering system made unique by the initial manufacturer ID number.
The manufacturer’s identification number is a registration in accordance with ISO/IEC 15963. The 16-bit
manufacturer’s identification number shall be assigned in accordance with ISO/IEC 15963, under Allocation
Class 16h.
5.5 Physical layer parameters
The parameter definitions given in Table 1 apply. These parameters are referenced by parameter name.
These operating parameters are to be defined for the temperature range of –30 degrees Celsius to 50
degrees Celsius.
Table 2 and Table 3 specify the parameters for the optional air interfaces that may be implemented.
Table 1 — RTLS transmitter DSSS link parameters
Parameter name Description
Operating frequency range 2400 MHz – 2483,50 MHz
Operating frequency accuracy ± 25 ppm maximum
Centre frequency 2441,750 MHz
Occupied channel bandwidth 60 MHz
Transmit power Class 1: 10 dBm EIRP max.
Class 2: Maximum in accordance with local regulations.
Spurious emission, out of band The device shall transmit in conformance with spurious
emissions requirements defined by the country’s regulatory
authority within which the system is operated.
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ISO/IEC 24730-2:2006(E)
Parameter name Description
Modulation BPSK Direct Sequence Spread Spectrum (DSSS)
Data encoding Differentially encoded
Data bit rate 59,7 kb/s
Bit error rate 0,001%
PN chip rate 30,521875 MHz ± 25 ppm
PN code length 511
PN spread code 0x1CB
Data packet lengths Option 1: 56 bits
Option 2: 72 bits
Option 3: 88 bits
Option 4: 152 bits
12 11 3 2
Message CRC polynomial G(x)=X + X + X + X + X + 1
CRC polynomial initialized value 0x001
Blink interval Programmable, 5 s minimum
Blink interval randomization ± 638 ms maximum
Number of sub-blinks Programmable, 1 - 8
Sub-blink interval randomization 125 ms ± 16 ms maximum
Maximum Frequency Drift < ± 2 ppm over the duration of the entire message
Phase Accuracy < 0,50 radians within any 33 µs period
Phase Noise < 15 degrees when the noise is integrated from 100 Hz to
100 kHz
Table 2 — RTLS transmitter OOK link parameters
Parameter
Parameter Name Description
Number
O 1a Carrier frequency 2400 MHz – 2483,5 MHz
O 1b Operating frequency accuracy ± 25 ppm maximum
O 1c Centre frequency 2441,750 MHz
O 2a Data encoding Differentially encoded
O 2b Data packet lengths Option 1: 88 bits
Option 2: 184 bits
16 12 5
O 2c Message CRC polynomial G(x) = X + X + X + 1
O 2d CRC polynomial initialized value 0x0001
O 3 Transmit power Class 1: 10 dBm EIRP max.
Class 2: Max. per local radio regulations
O 4 Transmit spurious emissions, out of Within local radio regulations
band
O 5 Modulation OOK/FSK, using 2 tones @ 376,8 kHz /535,5 kHz
O 5a Logic “0” 19 cycles at a 377 kHz rate of 2,44652 GHz on/off
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ISO/IEC 24730-2:2006(E)
Parameter
Parameter Name Description
Number
O 5b Logic “1” 27 cycles at a 535 kHz rate of 2,44652 GHz on/off
O 6 Data rate 19,83 kb/s
O 7 Duty cycle 50%
O 8 Data error rate 0,001% max.
Table 3 — RTLS transmitter magnetic link parameters
Parameter
Parameter Name Description
Number
M 1 Signalling frequencies 114,688 kHz and 126,976 kHz
M 2 Field strength Regulatory/application dependent
M 3 Bit data rate 2,048 kb/s
M 4 Symbol period 244,14 ms
M 5 Data error rate 0,001%
M 6 Start sync 3 symbol periods @ 114,688 kHz followed by 3 symbol
periods @ 126,976 kHz
M 7 End sync 3 symbol periods @ 126,976 kHz followed by 3 symbol
periods @ 114,688 kHz
M 8 Data bit 0 1 symbol period @ 126,976 kHz followed by 1 symbol
period @ 114,688 kHz
M 9 Data bit 1 1 symbol period @ 114,688 kHz followed by 1 symbol
period @ 126,976 kHz
M 10a Programmer packet lengths Option 1: 10 bits
Option 2: 48 bits
Option 3: 64 bits
Option 4: 68 bits
Option 5: 144 bits
Option 6: 160 bits
M 10b Exciter packet lengths Option 1: 10 bits
Option 2: 28 bits
Option 3: 44 bits
Option 4: 144 bits
M 11 Data encoding Manchester encoding
12 11 3 2 1
M 12a Programmer message CRC G(X) = X + X + X + X + X + 1
polynomial
8 4 3 2
M 12b 28 bit exciter CRC polynomial G(X) = X + X + X + X + 1
12 11 3 2 1
M 12c 44 bit exciter CRC polynomial G(X) = X + X + X + X + X + 1
4 1
M 12d 10 bit programmer / exciter CRC G(X) = X + X + 1
polynomial
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ISO/IEC 24730-2:2006(E)
6 Mandatory air interface protocol specification
This part of ISO/IEC 24730 defines the 2,400 GHz to 2,4835 GHz RTLS spread-spectrum transmissions and
the command/data level air interface communication protocols. These protocols facilitate communication
between a compliant RTLS transmitter and a compliant infrastructure. The optional protocols in clause 7
facilitate communication between an RTLS transmitter and a programming device and also an exciter device
respectively. The timing parameters and signal characteristics for the protocols are defined in the physical link
specification in clause 5.
6.1 Introduction
Beacon type RTLS system architecture consists of RTLS transmitters that “blink” a Direct Sequence Spread
Spectrum (DSSS) signal, and fixed position RTLS readers that receive those signals. The system then
determines the x, y location of the RTLS transmitters. Location of tagged assets can be determined with better
than 3 m accuracy in most environments, indoors and out. Once the location of the RTLS transmitter is
determined, the location information and any other information are passed to the host application.
Additionally, an option that provides the ability to transmit telemetry data is defined.
Functional classification
The RTLS transmitter module is typically a compact internally powered radio frequency device that is a
component of the RTLS system. The RTLS system is designed to track and locate items with attached RTLS
transmitters. Each locatable transmission is a pulse of direct sequence spread spectrum radio signal. The
RTLS infrastructure receives these signals, or blinks. The blink is a short ID-only message or a longer
telemetry message also containing the RTLS transmitters ID. Each transmission also contains a status data
word that provides information on the RTLS transmitter configuration, battery status and other data. The RTLS
transmitter’s ID, status data word, and location are provided to the host by the RTLS Infrastructure. Multiple
RTLS transmitters may be present in typical installations allowing a large number of items to be tracked and
located in real time.
Anti-collision synchronization protocols are not required. Each “blink” is comprised of multiple sub-blinks. The
sub-blinks are part of a multiple level anti-interference system; time diversity, spatial diversity, processing gain.
The combination of these multiple sub-blinks, multiple receiving antennas and spread spectrum correlation
also allow multiple RTLS transmitters to blink simultaneously and still be received.
The RTLS transmitter data shall be binary encoded with the MSB (Most Significant Bit) transmitted first in all
messages. It is differentially encoded using the example circuit of Figure 2. The output of the encoder shall be
initialized to "1". It shall be exclusively OR’d with the output of the PN (Pseudo Noise) generator, modulated
using a BPSK (Bi-Phase Shift Keyed) format and upconverted using a single sideband upconverter. The
signal is then amplified and transmitted to the RTLS infrastructure.
SET
D Q
Data Out
Data In
Q
CLR
Clock
Figure 2 — Example of differential encoding circuit
An example of the RTLS transmitter PN Generator is shown in Figure 3.
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ISO/IEC 24730-2:2006(E)
PN-
code
1
B C
SE
T SE SE SE SE SE SE SE SE
T T T T T T T T
D Q
D Q D Q D Q D Q D Q D Q D Q D Q
Q
Q Q Q Q Q Q Q Q
CL
R CL CL CL CL CL CL CL CL
R R R R R R R R
D1 D2 D3 D4 D5 D6 D7 D8 D9
PN generator
output
Figure 3 — RTLS transmitter PN generator
Data encoding and transmission process is shown below in Figure 4.
Differentially encode data
Exclusive (XOR) differentially
encoded data with output of PN
generator
BPSK modulate
Frequency translate/upconvert
to 2.44175 GHz
Amplify signal and transmit to
system
Figure 4 — RTLS transmitter data encoding and transmission process
The format of the Direct Sequence Spread Spectrum (DSSS) transmission from the RTLS transmitter is
shown in Figure 5. Each DSSS transmission from the RTLS transmitter contains a “blink” packet containing N
sub-blinks. Each set of sub-blinks can be one of four message lengths. All sub-blinks within a “blink” shall be
identical to provide time diversity. Each sub-blink includes the RTLS transmitter’s 32-bit ID, 4-bits of status
data, CRC (Cyclical Redundancy Check) data and optional telemetry data depending on the type of message.
The “blink” packet occurs at the beginning of the blink interval. Sub-blinks shall be separated by an interval,
which is not user configurable. The number of sub-blinks per blink and the blink interval are configurable.
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ISO/IEC 24730-2:2006(E)
Blink containing N sub-blinks
Sub-blink
Blink interval
Figure 5 — DSSS air interface
Three classes of DSSS blinks are defined; Timed Interval Blink (TIB), exciter Blink (EXB), and Event Blink
(EB). A TIB shall transmit at a pre-programmed rate. An EB shall be caused by a switch event or external
stimulus. A state diagram showing the different operational states of the RTLS transmitter is shown below in
Figure 6.
Note: For Figure 6 and all future figures, solid lines denote required features and dotted lines denote optional features.
Set blink
rate=off.
Initial power-on
Program mode
Timed Interval
Programmer
Completion of
signal
Blink (TIB) mode
blink
Sec 6.4.3.4
Completion of
programming
Sec 6.4.3.1
Interval
Sleep mode
timer
Exciter
message
Completion of
blink
External
Exit exciter
input
mode
EXciter Blink
Event Blink (EB)
(EXB) mode
mode
Sec 6.4.3.3
Set blink
Sec 6.4.3.2
rate=off.
Figure 6 — RTLS transmitter state diagram
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ISO/IEC 24730-2:2006(E)
The DSSS carrier frequency is fixed at 2441,75 MHz and the chip rate shall be fixed at 30,521875 MHz.
6.2 RTLS transmitter radiated power
Two classes of RTLS transmitters exist with respect to the output power level they are capable of delivering.
The Equivalent Isotropically Radiated Power (EIRP) of a Class 1 RTLS transmitter is less than 10 mW
(10 dBm). Class 1 RTLS transmitters are intended for applications with moderate to dense infrastructures and
minimal obstructions.
The EIRP of a Class 2 RTLS transmitter is greater than 10 mW (10 dBm) and less than the maximum allowed
by local radio regulations. Class 2 RTLS transmitters are intended for sparse infrastructures where RTLS
readers may be located greater than 300 m from the RTLS transmitter or environments with major
obstructions.
The antenna of the RTLS transmitter should provide a pattern that is as omni-directional as possible within the
constraints of the RTLS transmitter packaging requirements. This will ensure near equivalence with regard to
orientation performance of individual transmitters within the system. The RF EIRP of a tag shall not vary more
than 10 dB peak to peak in a spherical pattern in free space. It shall not vary more than 10 dB in a semi-
spherical pattern around a tag mounted directly to a metallic plate of one square meter in order to achieve the
required system performance.
6.3 DSSS message specifications
6.3.1 DSSS message encoding
The PN Spreading Code shall be 0x1CB. The PN Generator is initialized with a “1” in register D9 and “0”’s in
all other registers.
The beginning of the blink interval shall be randomized by a maximum of ± 638 ms to avoid repeatedly
colliding with blinks from other RTLS transmitters. The beginning of each successive sub-blink shall also be
randomized. The interval between each sub-blink shall be 125 ms randomized by a maximum of ± 16 ms from
the beginning of the previous sub-blink.
6.3.2 DSSS message structures
There are four different message formats determined by the length of the message in bits: the 56-bit message,
the 72-bit message, the 88-bit message, and the 152-bit message. An RTLS transmitter shall be capable of
transmitting at least one of these message formats. The 56-bit and 72-bit message format is intended for
transmitting the RTLS transmitter ID, the 72- and 88-bit messages are intended for transmitting the RTLS
transmitter ID and exciter information and the 152-bit message format is intended for transmitting limited
amounts of telemetry information. The structure of each of these message formats is shown in more detail in
the following sections.
Each message type contains an 8-bit preamble of 0x01.
Each message type contains a 4-bit RTLS transmitter Status as defined in the message definitions.
72- and 88-bit messages may carry an exciter ID. An exciter ID is comprised of 16 bits. The MSB designates
whether the RTLS transmitter has entered or left an exciter field.
12 11 3 2
Each message ty
...
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