ISO/IEC 18000-62:2012

INTERNATIONAL ISO/IEC
STANDARD 18000-62
First edition
2012-07-15
Information technology — Radio
frequency identification for item
management —
Part 62:
Parameters for air interface
communications at 860 MHz to 960 MHz
Type B
Technologies de l'information — Identification par radiofréquence
(RFID) pour la gestion d'objets —
Partie 62: Paramètres de communications d'une interface radio entre
860 MHz et 960 MHz, Type B
Reference number
©
ISO/IEC 2012
©  ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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Published in Switzerland
ii © ISO/IEC 2012 – All rights reserved

Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Conformance . 1
2.1 Claiming conformance . 1
2.2 Interrogator conformance and obligations . 2
2.3 Tag conformance and obligations . 2
3 Normative references . 3
4 Terms, definitions, symbols and abbreviated terms . 3
4.1 Terms and definitions . 3
4.2 Symbols . 3
4.3 Abbreviated terms . 4
5 Overview . 5
5.1 Parameter tables . 5
6 Type B . 9
6.1 Physical layer and data coding . 9
6.1.1 Interrogator power-up waveform . 9
6.1.2 Interrogator power-down . 9
6.1.3 Frequency hopping carrier rise and fall times . 10
6.1.4 FM0 return link . 11
6.1.5 Manchester forward link . 14
6.1.6 Protocol concept . 17
6.1.7 Command format . 18
6.1.8 Response format . 20
6.1.9 WAIT . 20
6.1.10 Examples of a command packet . 20
6.1.11 Communication sequences at packet level . 21
6.2 Btree protocol and collision arbitration . 22
6.2.1 Definition of data elements, bit and byte ordering . 22
6.2.2 Tag memory organisation . 23
6.2.3 Block security status . 24
6.2.4 Overall protocol description, Btree protocol . 24
6.2.5 Collision arbitration . 29
6.2.6 Commands . 31
6.2.7 Command types . 31
6.2.8 Transmission errors . 58
Annex A (informative) Calculation of 16-bit cyclic redundancy checks . 59
A.1 Example CRC-16 encoder/decoder . 59
A.2 Example CRC-16 calculations . 60
Annex B (normative) Memory mapping . 62
B.1 Unique identifier (normative) . 62
B.1.1 Unique identifier general . 62
B.1.2 Unique identifier format . 62
B.1.3 Unique identifier according to ANSI 256 . 62
B.1.4 Remaining system memory . 63
Annex C (informative) Tag memory map . 67
C.1 Tag memory map . 67
Bibliography . 68

© ISO/IEC 2012 – All rights reserved iii

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.
ISO/IEC 18000-62 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 31, Automatic identification and data capture techniques.
ISO/IEC 18000 consists of the following parts, under the general title Information technology — Radio
frequency identification for item management:
 Part 1: Reference architecture and definition of parameters to be standardized
 Part 2: Parameters for air interface communications below 135 kHz
 Part 3: Parameters for air interface communications at 13,56 MHz
 Part 4: Parameters for air interface communications at 2,45 GHz
 Part 6: Parameters for air interface communications at 860 MHz to 960 MHz General
 Part 61: Parameters for air interface communications at 860 MHz to 960 MHz Type A
 Part 62: Parameters for air interface communications at 860 MHz to 960 MHz Type B
 Part 63: Parameters for air interface communications at 860 MHz to 960 MHz Type C
 Part 64: Parameters for air interface communications at 860 MHz to 960 MHz Type D
 Part 7: Parameters for active air interface communications at 433 MHz

iv © ISO/IEC 2012 – All rights reserved

Introduction
This part of ISO/IEC 18000 describes a passive backscatter radio frequency identification (RFID) system that
supports the following system capabilities:
 identification and communication with multiple tags in the field;
 selection of a subgroup of tags for identification or with which to communicate;
 reading from and writing to or rewriting data many times to individual tags;
 user-controlled permanently lockable memory;
 data integrity protection;
 Interrogator-to-tag communications link with error detection;
 tag-to-Interrogator communications link with error detection;
 support for both passive back-scatter tags with or without batteries.
This part of ISO/IEC 18000 specifies the physical and logical requirements for a passive-backscatter, RFID
system operating in the 860 MHz to 960 MHz frequency range. The system comprises Interrogators, also
known as readers, and tags, also known as labels.
An Interrogator transmits information to a tag by modulating an RF signal in the 860 MHz to 960 MHz
frequency range. The tag receives both information and operating energy from this RF signal. Passive tags
are those which receive all of their operating energy from the Interrogator's RF waveform. If tags maintain a
battery then they may operate using some passive principles; however, they do not necessarily get all their
operating energy from the Interrogator's RF waveform.
An Interrogator receives information from a tag by transmitting a continuous-wave (CW) RF signal to the tag;
the tag responds by modulating the reflection coefficient of its antenna, thereby backscattering an information
signal to the Interrogator. The system is Interrogator-Talks-First (ITF), meaning that a tag modulates its
antenna reflection coefficient with an information signal only after being directed to do so by an Interrogator.
Interrogators and tags are not required to talk simultaneously; rather, communications are half-duplex,
meaning that Interrogators talk and tags listen, or vice versa.
The International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC)
draw attention to the fact that it is claimed that compliance with this document may involve the use of patents
concerning radio frequency identification technology.
ISO and IEC take no position concerning the evidence, validity and scope of these patent rights.
The holders of these patent rights have assured ISO and IEC that they are willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect,
the statements of the holders of these patent rights are registered with ISO and IEC.
© ISO/IEC 2012 – All rights reserved v

Information on the declared patents may be obtained from:

Contact details
Patent Holder Contact for license application
Legal Name: Impinj, Inc.  Name & Department: Chris Diorio, CTO
Address: 701 N 34th St Suite 300, Seattle,
WA 98103, USA
Tel.: +1 206 834 1115
Fax: +1 206 517 5262
E-mail: diorio@impinj.com
URL (optional): www.impinj.com
Patent Holder Contact for license application
Legal Name: NXP B.V.  Name & Department: Aaron Waxler,
Intellectual Property & Licensing

Address: 411 East Plumeria, San José, CA
95134-1924, USA
Tel.: +1 914 860 4296
E-mail: Aaron.Waxler@nxp.com
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights other than those identified above. ISO and IEC shall not be held responsible for identifying any or all
such patent rights.
The latest information on IP that may be applicable to this part of ISO/IEC 18000 can be found at
www.iso.org/patents
vi © ISO/IEC 2012 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 18000-62:2012(E)

Information technology — Radio frequency identification for
item management —
Part 62:
Parameters for air interface communications at 860 MHz to
960 MHz Type B
1 Scope
This part of ISO/IEC 18000 defines the air interface for radio frequency identification (RFID) devices operating
in the 860 MHz to 960 MHz Industrial, Scientific, and Medical (ISM) band used in item management
applications. It provides a common technical specification for RFID devices that can be used by ISO committees
developing RFID application standards. This part of ISO/IEC 18000 is intended to allow for compatibility and
to encourage inter-operability of products for the growing RFID market in the international marketplace. It
defines the forward and return link parameters for technical attributes including, but not limited to, operating
frequency, operating channel accuracy, occupied channel bandwidth, maximum effective isotropic radiated
power (EIRP), spurious emissions, modulation, duty cycle, data coding, bit rate, bit rate accuracy, bit
transmission order, and, where appropriate, operating channels, frequency hop rate, hop sequence, spreading
sequence, and chip rate. It further defines the communications protocol used in the air interface.
This part of ISO/IEC 18000 specifies the physical and logical requirements for a passive-backscatter,
Interrogator-Talks-First (ITF) systems. The system comprises Interrogators, also known as readers, and tags,
also known as labels. An Interrogator receives information from a tag by transmitting a continuous-wave (CW)
RF signal to the tag; the tag responds by modulating the reflection coefficient of its antenna, thereby
backscattering an information signal to the Interrogator. The system is ITF, meaning that a tag modulates its
antenna reflection coefficient with an information signal only after being directed to do so by an Interrogator.
In detail, this part of ISO/IEC 18000 contains Type B.
Type B uses Manchester in the forward link and an adaptive binary-tree collision-arbitration algorithm.
This part of ISO/IEC 18000 specifies
 physical interactions (the signalling layer of the communication link) between Interrogators and tags,
 Interrogator and tag operating procedures and commands,
 the collision arbitration scheme used to identify a specific tag in a multiple-tag environment.
2 Conformance
2.1 Claiming conformance
To claim conformance with this part of ISO/IEC 18000, an Interrogator or tag shall comply with all relevant
clauses of this part of ISO/IEC 18000, except those marked as “optional”. The Interrogator or tag shall also
operate within local radio regulations, which can further restrict operation.
Relevant conformance test methods are provided in ISO/IEC TR 18047-6.
Conformance can also require a license from the owner of any intellectual property utilized by said device.
© ISO/IEC 2012 – All rights reserved 1

2.2 Interrogator conformance and obligations
To conform to this part of ISO/IEC 18000, an Interrogator shall
 support Type B
 implement the mandatory commands defined in this part of ISO/IEC 18000;
 modulate/transmit and receive/demodulate a sufficient set of the electrical signals defined in the signalling
layer of this part of ISO/IEC 18000 to communicate with conformant tags; and
 operate within the applicable local regulations.
To conform to this part of ISO/IEC 18000, an Interrogator may
 implement any subset of the optional commands defined in this part of ISO/IEC 18000, and
 implement any proprietary and/or custom commands in conformance with this part of ISO/IEC 18000.
To conform to this part of ISO/IEC 18000, the Interrogator shall not
 implement any command that conflicts with this part of ISO/IEC 18000 or any of the parts 61, 63 and 64, or
 require the use of an optional, proprietary, or custom command to meet the requirements of this part of
ISO/IEC 18000.
2.3 Tag conformance and obligations
To conform to this part of ISO/IEC 18000, a tag shall:
 support Type B;
 operate over the frequency range from 860 MHz to 960 MHz, inclusive;
 implement the mandatory commands defined in this part of ISO/IEC 18000 for the supported types;
 modulate a backscatter signal only after receiving the requisite command from an Interrogator; and
 conform to local radio regulations.
To conform to this part of ISO/IEC 18000, a tag may
 implement any subset of the optional commands defined in this part of ISO/IEC 18000; and
 implement any proprietary and/or custom commands as defined in 6.2.7.4 and 6.2.7.5.
To conform to this part of ISO/IEC 18000, a tag shall not:
 implement any command that conflicts with this part of ISO/IEC 18000 or any of the parts 61, 63 and 64;
 require the use of an optional, proprietary, or custom command to meet the requirements of this part of
ISO/IEC 18000; or
 modulate a backscatter signal unless commanded to do so by an Interrogator using the signalling layer
defined in this part of ISO/IEC 18000.
2 © ISO/IEC 2012 – All rights reserved

3 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 7816-6, ldentification cards — lntegrated circuit cards — Part 6: Interindustry data elements for
interchange
ISO/IEC 15961, Information technology — Radio frequency identification (RFID) for item management — Data
protocol: application interface
ISO/IEC 15962, Information technology — Radio frequency identification (RFID) for item management — Data
protocol: data encoding rules and logical memory functions
ISO/IEC 18000-1, Information technology — Radio frequency identification for item management — Part 1:
Reference architecture and definition of parameters to be standardized
ISO/IEC 19762 (all parts), Information technology — Automatic identification and data capture (AIDC)
techniques — Harmonized vocabulary
4 Terms, definitions, symbols and abbreviated terms
4.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19762 (all parts) and the
following apply.
4.1.1
collision arbitration loop
algorithm used to prepare for and handle a dialogue between an Interrogator and a tag
NOTE This is also known as collision arbitration.
4.1.2
physical layer
data coding and modulation waveforms used in Interrogator-to-tag and tag-to-Interrogator signalling
4.2 Symbols
Cht carrier high-level tolerance
Clt carrier low-level tolerance
D modulation depth of data coding pulse
f frequency of operating field (carrier frequency)
c
M number of subcarrier cycles per symbol
Mi modulation index
Mb modulation lower tolerance Type B
M RF signal envelope ripple (overshoot)
h
M RF signal envelope ripple (undershoot)
l
T or T RF signal envelope fall time
f f,10-90%
T FHSS signal envelope fall time
hf
© ISO/IEC 2012 – All rights reserved 3

T FHSS signal envelope rise time
hr
T time for an FHSS signal to settle to within a specified percentage of its final value
hs
T or T RF signal envelope rise time
r r,10-90%
Tbmf Manchester fall time
Tbmr Manchester rise time
Tcf carrier fall time
Tcr carrier rise time
Tcs carrier steady state time
Tf fall time
Tfhf carrier FHSS fall time
Tfhr carrier FHSS rise time
Tfhs carrier FHSS steady time
Tr rise time
Trlb return link bit time
xxxx binary notation
xxxx hexadecimal notation
h
4.3 Abbreviated terms
AFI application family identifier
ASIC application specific integrated circuit
ASK Amplitude Shit Keying
CRC cyclic redundancy check
CRC-16 sixteen bit CRC
DSSS direct sequence spread spectrum
FHSS frequency hopping spread spectrum
ITF Interrogator-talks-first
NOTE The common usage is RTF (Reader-talks-first) but the more precise term is ITF, which is
used throughout this part of ISO/IEC 18000.
LSB least significant bit
MSB most significant bit
NRZ non return to zero
ppm parts per million
RFU reserved for future use
SOF start of frame
Word 16 bits
4 © ISO/IEC 2012 – All rights reserved

5 Overview
5.1 Parameter tables
Table 1, Table 2, Table 3 and Table 4 contain the parameters for Type B in accordance with ISO/IEC 18000-1.
Detailed description of the operating modes and parameters are specified in the subsequent clauses.
Table 1 — Interrogator to tag link parameters
Ref. Parameter Name Description
860 MHz – 960 MHz, as required by the local
Int:1 Operating Frequency Range
regulations
In accordance with the local radio regulations.
Int:1a Default Operating Frequency
Operating Channels
In accordance with the local radio regulations.
Int:1b
(spread-spectrum systems)
Int:1c Operating Frequency Accuracy In accordance with the local radio regulations.
Frequency Hop Rate Where FHSS is permitted, the hop rate shall be
Int:1d
in accordance with the local radio regulations.
(frequency-hopping [FHSS] systems)
In accordance with the local radio regulations.
Where not specified by such regulations a
Frequency Hop Sequence
Int:1e pseudo-random hopping sequence shall be
(frequency-hopping [FHSS] systems)
used that ensures an even distribution of
transmissions over available channels.
Int:2 Occupied Channel Bandwidth In accordance with the local radio regulations.
In accordance with the local radio regulations.
Int:2a Minimum Receiver Bandwidth
Interrogator Transmit Maximum
Int:3 In accordance with the local radio regulations.
EIRP
Interrogator Transmit Spurious
Int:4
In accordance with the local radio regulations.
Emissions
Interrogator Transmit Spurious
In accordance with the local radio regulations.
Int:4a Emissions, In-Band (spread-
spectrum systems)
Interrogator Transmit Spurious
Int:4b In accordance with the local radio regulations.
Emissions, Out-of-Band
Interrogator Transmitter Spectrum
Int:5 In accordance with the local radio regulations.
Mask
Int:6 Timing See below Int: 6x.
Transmit-to-Receive Turn-Around The Interrogator transmit/receive settling time
Int:6a
Time shall not exceed 85 µs.
Receive-to-Transmit Turn-Around As determined by the communication protocol –
Int:6b
Time refer Tag: 6a.
Dwell Time or Interrogator Transmit
Int:6c 1500 µs, maximum settling time
Power-On Ramp
Decay Time or Interrogator Transmit
Int:6d Maximum 1 ms.
Power-Down Ramp
Int:7 Modulation Amplitude Modulation.
Spreading Sequence
Int:7a Not applicable.
(direct-sequence [DSSS] systems)
Chip Rate
Int:7b Not applicable.
(spread-spectrum systems)
© ISO/IEC 2012 – All rights reserved 5

Ref. Parameter Name Description
Chip Rate Accuracy
Int:7c Not applicable.
(spread-spectrum systems)
Int:7d Modulation Depth Nominal 18% or 100% .
Int:7e Duty Cycle In accordance with the local radio regulations.
Int:7f FM Deviation Not applicable.
Int:8 Data Coding Manchester bi-phase
10 kbit/s or 40 kbit/s as constrained by the local
Int:9 Bit Rate
radio regulations.
Int:9a Bit Rate Accuracy 100 ppm
Interrogator Transmit Modulation
Int:10 Not applicable.
Accuracy
Int:11 Preamble Yes, See clause 6.1.7.3
Int:11a Preamble Length 9 bits. See clause 6.1.7.3
Int:11b Preamble Waveform(s) See clause 6.1.7.3
Int:11c Bit Sync Sequence See clause 6.1.7.3
Int:11d Frame Sync Sequence Not Applicable.
Scrambling (spread-spectrum
Int:12 Not Applicable.
systems)
Int:13 Bit Transmission Order MSB is transmitted first
Presence of an appropriate RF signal at the tag
Int:14 Wake-up process followed by a wake-up command as required by
the tag type. See relevant clauses.
Interrogator dependent.
Int:15 Polarization
Not defined in this part of ISO/IEC 18000.

Table 2 — Tag to Interrogator link parameters
Ref. Parameter Name Description
Tag:1 Operating Frequency Range 860 MHz – 960 MHz, inclusive
The tag shall respond to an Interrogator signal
Tag:1a Default Operating Frequency
within the frequency range specified in Tag: 1.
Operating Channels The tag shall respond to an Interrogator signal
Tag:1b
within the frequency range specified in Tag: 1.
(spread-spectrum systems)
The tag shall respond to an Interrogator signal
Tag:1c Operating Frequency Accuracy
within the frequency range specified in Tag: 1.
Frequency Hop Rate
Not applicable.
Tag:1d
(frequency-hopping [FHSS] systems)
Frequency Hop Sequence
Tag:1e Not applicable.
(frequency-hopping [FHSS] systems)
Tag:2 Occupied Channel Bandwidth In accordance with the local regulations
Tag:3 Transmit Maximum EIRP In accordance with the local regulations
Tag:4 Transmit Spurious Emissions In accordance with the local regulations
Transmit Spurious Emissions, In-
Tag:4a Band In accordance with the local regulations
(spread spectrum systems)
Transmit Spurious Emissions, Out-
Tag:4b In accordance with the local regulations
of-Band
Tag:5 Transmit Spectrum Mask In accordance with the local regulations
6 © ISO/IEC 2012 – All rights reserved

Ref. Parameter Name Description
Transmit-to-Receive Turn-Around
Tag:6a 400 µs
Time
Receive-to-Transmit Turn-Around
Tag:6b Range 85 to 460 µs (see clause 6.1.8.2)
Time
Dwell Time or Transmit Power-On
Tag:6c Not applicable.
Ramp
Decay Time or Transmit Power-
Tag:6d Not applicable.
Down Ramp
Bi-state amplitude modulated backscatter.
Tag:7 Modulation
Spreading Sequence
Tag:7a Not applicable.
(direct sequence [DSSS] systems)
Chip Rate
Tag:7b Not applicable.
(spread spectrum systems)
Chip Rate Accuracy
Tag:7c Not applicable.
(spread spectrum systems)
The tag Delta RCS (Varying Radar Cross
Tag:7d On-Off Ratio Sectional area) affects system performance. A
typical value is greater than 0.005 m .
Tag:7e Subcarrier Frequency Not applicable.
Tag:7f Subcarrier Frequency Accuracy Not applicable.
Tag:7g Subcarrier Modulation Not applicable.
The tag shall transmit its response when
Tag:7h Duty Cycle
commanded to do so by the Interrogator.
Tag:7i FM Deviation Not applicable.
Bi-phase space (FM0)
Tag:8 Data Coding
Typical 40 kbit/s or 160 kbit/s (subject to tag
clock tolerance see Table 8), The return bit rate
Tag:9 Bit Rate
selection for 160 kbit/s is defined in
clause 6.1.7.4.5
Tag:9a Bit Rate Accuracy +/- 15% (refer to Table 8)
Tag Transmit Modulation Accuracy
Tag:10 Not applicable.
(frequency-hopping [FHSS] systems
Tag:11 Preamble The preamble is defined in clause 6.1.4.6
16 bits made up of a quiet period, followed by
Tag:11a Preamble Length sync, followed by a code violation followed by
an orthogonal code.
Tag:11b Preamble Waveform Bi-phase encoded data ‘1’.
Included in the preamble.
Tag:11c Bit-Sync Sequence
Tag:11d Frame-Sync Sequence Included in the preamble.
Scrambling
Tag:12 Not applicable.
(spread-spectrum systems)
Tag:13 Bit Transmission Order MSB is transmitted first
Tag:14 Reserved Deliberately left blank.
Product design feature.
Tag:15 Polarization
Not defined in this part of ISO/IEC 18000.
Tag:16 Minimum Tag Receiver Bandwidth
860 – 960 MHz
© ISO/IEC 2012 – All rights reserved 7

Table 3 — Protocol parameters
Ref. Parameter Name Description
P:1 Who talks first Interrogator
P:2 Tag addressing capability See clause 6.2.2
Contained in tag memory and accessible by
P:3 Tag ID
means of a command.
P:3a Tag ID Length 64 bits.
P:3b Tag ID Format See clause B.1.2
P:4 Read size Addressable in byte blocks.
Addressable in byte blocks. Writing in blocks of
P:5 Write Size 1, 2, 3 or 4 bytes. See details in relevant
clauses.
A single tag can typically be identified and have
its first 128 bits of user memory read in less
than 10 ms. This time may vary depending on
P:6 Read Transaction Time
the data rate used as constrained by the local
radio regulations.
Once a tag has been identified and selected, a
32-bit data block can typically be written in less
P:7 Write Transaction Time than 20 ms. This time may vary depending on
the data rate used as constrained by the local
radio regulations.
Interrogator to tag: CRC-16
P:8 Error detection
Tag to Interrogator: CRC-16
No forward error correction code used. Errors
are handled by signalling an error to the
P:9 Error correction
Interrogator that then repeats its last
transmission.
No minimum user memory size is specified, but
if user memory is provided it shall be an integer
P:10 Memory size
multiples of 4 bytes.
Several command codes are reserved for future
P:11 Command structure and extensibility
use.
Table 4 — Anti-collision parameters
Ref. Parameter Name Description
A:1 Type (Probabilistic or Deterministic) Probabilistic
Essentially linear up to 2 tags depending
A:2 Linearity
on size of data content.
The algorithm permits the reading of not
A:3 Tag inventory capacity less than 250 tags in the reading zone of
the Interrogator.
8 © ISO/IEC 2012 – All rights reserved

6 Type B
6.1 Physical layer and data coding
6.1.1 Interrogator power-up waveform
The Interrogator power-up waveform shall comply with the mask specified in Figure 1 and Table 5.

Figure 1 — Interrogator power-up waveform
Table 5 — Interrogator power-up waveform parameter values
Parameter Min Max
Tcs 1500µs
Tcr 1 µs 500 µs
Cht 10%
Clt 1%
6.1.2 Interrogator power-down
Once the carrier level has dropped below the ripple limit Cht, power down shall be monotonic and of duration
Tcf, as specified in Figure 2 and Table 6.
© ISO/IEC 2012 – All rights reserved 9

Figure 2 — Interrogator power-down waveform
Table 6 — Interrogator power-down timings
Parameter Min Max
Tcf 1 µs 500 µs
Cht  5% of steady state
(100 %) level
Clt 1 %
6.1.3 Frequency hopping carrier rise and fall times
When the Interrogator operates in the frequency operating hopping spread spectrum mode (FHSS), the carrier
rise and fall times shall conform to the characteristics specified in Figure 3 and Table 7. The Interrogator shall
complete a frequency hop in a time not exceeding 30 µs (to ensure that the tag is not reset by the frequency
hop). The frequency hop is measured from the beginning of Tfhf to the end of Tfhr.

NOTE Ripple is  5 % of 100 % of steady state level
Figure 3 — FHSS carrier rise and fall characteristics
10 © ISO/IEC 2012 – All rights reserved

Table 7 — FHSS carrier rise and fall parameters
Parameter Min Max
Tfhr 30 µs
Tfhs 400 µs
Tfhf 30 µs
6.1.4 FM0 return link
6.1.4.1 FM0 return link general
The tag transmits information to the Interrogator by modulating the incident energy and reflecting it back to the
Interrogator (backscatter).
6.1.4.2 Modulation
The tag switches its reflectivity between two states. The “space” state is the normal condition in which the tag
is powered by the Interrogator and able to receive and decode the forward link. The “mark” state” is the
alternative condition created by changing the antenna configuration or termination.
6.1.4.3 Data rate
The return link datarate shall be 40 or 160 kbit/s, which may be selected at the time of tag configuration. The
Interrogator shall be able to read and decode the tag reply at either datarate without the need to have prior
knowledge of the tag configuration in order to handle mixed populations.
6.1.4.4 Data coding
Data is coded using the FM0 technique, also known as Bi-Phase Space.
One symbol period Trlb, as specified in Table 8, is allocated to each bit to be sent. In FM0 encoding, data
transitions occur at all bit boundaries. In addition, data transitions occur at the mid-bit of logic 0 being sent.
Table 8 — Return link parameters
Data rate Trlb Tolerance Note
40kbit/s 25 µs +/-15% Chip set to 40kbit/s Return Link Data Rate
160kbit/s 6.25 µs +/-15% Chip set to 160kbit/s Return Link Data Rate

Coding of data is MSB first. Figure 4 illustrates the coding for the 8 bits of 'B1'.

© ISO/IEC 2012 – All rights reserved 11

Figure 4 — Tag to Interrogator data coding
6.1.4.5 Message format
A return Link Message consists of n data bits preceded by the Preamble. The data bits are sent MSB first.
The Preamble enables the Interrogator to lock to the tag data clock and begin decoding of the message. It
consists of 16 bits as shown in Figure 5. There are multiple code violations (sequences not conforming to FM0
rules) that act as a frame marker for the transition from Preamble to Data.
6.1.4.6 Return preamble
The return preamble is a sequence of backscatter modulation specified in Figure 5.

NOTE The high state represents high reflectivity and the low state represents low reflectivity.
Figure 5 — Preamble waveform
Changing the tag’s modulator switch from the high impedance state to the low impedance state causes a
change in the incident energy to be back-scattered, see Figure 6.
12 © ISO/IEC 2012 – All rights reserved

The tag shall execute backscatter, a half-low and half-high sent by the tag defined as follows:

Figure 6 — Return link bit coding
6.1.4.7 Cyclic redundancy check (CRC)
6.1.4.7.1 CRC General
On receiving a command from the Interrogator, the tag shall verify that the checksum or the CRC value is
valid. If it is invalid, it shall discard the frame, shall not respond and shall not take any other action.
6.1.4.7.2 Interrogator to tag 16-bit CRC-16
6.1.4.7.2.1 Interrogator to tag CRC-16 general
The 16-bit CRC shall be calculated on all the command bits after the SOF up to but not including the first CRC
bit.
16 12 5
The polynomial used to calculate the CRC is x + x + x + 1. The 16-bit register shall be preloaded with
'FFFF’. The resulting CRC value shall be inverted, attached to the end of the packet and transmitted.
The most significant byte shall be transmitted first. The most significant bit of each byte shall be transmitted
first.
NOTE A schematic of a possible implementation is provided in Annex A.
The CRC may be implemented in one of two ways:
6.1.4.7.2.2 Inversion of incoming CRC bits by the tag
At the tag, the incoming CRC bits are inverted and then clocked into the register. After the LSB CRC bit is
clocked into the register the 16-bit CRC register should contain all zero’s.
6.1.4.7.2.3 Non-inversion of incoming CRC bits by the tag
If the received CRC bits are not inverted before clocking into the register, then after the LSB CRC bit is
clocked into the register the 16-bit CRC register will have the value 1D0F
h
6.1.4.7.3 Tag to Interrogator 16-bit CRC-16
6.1.4.7.3.1 Tag to Interrogator CRC-16 general
The 16-bit CRC shall be calculated on all data bits up to, but not including, the first CRC bit.
© ISO/IEC 2012 – All rights reserved 13

16 12 5
The polynomial used to calculate the CRC is x + x + x + 1. The 16-bit register shall be preloaded with
FFFF . The resulting CRC value shall be inverted, attached to the end of the packet and transmitted.
h
The most significant byte shall be transmitted first, see Table 9. The most significant bit of each byte shall be
transmitted first.
On receiving of a response from the tag, it is recommended that the Interrogator verifies that the CRC value is
valid. If it is invalid, appropriate remedial action is the responsibility of the Interrogator designer.
NOTE A schematic of a possible implementation is provided in Annex A.
Table 9 — CRC-16 bits and bytes transmission rules
MSByte LSByte
MSB LSB MSB LSB
CRC-16 (8 bits) CRC-16 (8 bits)
 first transmitted bit of the inverted CRC

The CRC may be implemented in one of two ways.
6.1.4.7.3.2 Inversion of incoming CRC bits by the Interrogator
At the Interrogator receiver, the incoming CRC bits are inverted and then clocked into the register. After the
LSB CRC bit is clocked into the register the 16-bit CRC register should contain all zero’s.
6.1.4.7.3.3 Non-inversion of incoming CRC bits by the Interrogator
If the received CRC bits are not inverted before clocking, the CRC register will have the value 1D0F .
h
6.1.5 Manchester forward link
6.1.5.1 Carrier modulation
The data transmission from the Interrogator to the tag is achieved by modulation of the carrier (ASK). The
data coding is performed by generating pulses that create a Manchester coding, as shown in
Figure 7, Figure 8, Table 10 and Table 11.
14 © ISO/IEC 2012 – All rights reserved

Figure 7 — 100 % modulation (example of 40 kbit/s signal)

Table 10 —
Parameter for 100% modulation
Parameter Minimum Nominal Maximum
Mi = (A-B)/(A+B) 90 100 100
Ma 0 0.03 (A-B)
Mb 0 0.03 (A-B)
Tr 0 µs 1.8 µs 0.1 / f
Datarate
Tf 0 µs 1.8 µs 0.1 / f
Datarate
NOTE Tr and Tf measured from 10% (A-B) to 90% (A-B)
© ISO/IEC 2012 – All rights reserved 15

Figure 8 — 18% modulation (example of 8 kbit/s signal)
Table 11 — Parameter for 18% modulation
Parameter Minimum Nominal Maximum
Mi = (A-B)/(A+B) 15% 18% 20%
Ma 0 0.05 (A-B)
Mb 0 0.05 (A-B)
Tr 0 µs 0.17 / f
Datarate
Tf 0 µs 0.17 / f
Datarate
NOTE Tr and Tf measured from 10% (A-B) to 90% (A-B)
6.1.5.2 Bit coding of forward link fields
Data is Manchester encoded as per Figure 9.
16 © ISO/IEC 2012 – All rights reserved

Figure 9 — Forward link bit coding
6.1.6 Protocol concept
Data is encoded and presented in slightly different ways in the constituent fields. For Interrogator-to-tag
communication (forward link), data is sent using an on-off key format. The radio frequency field being on
corresponds to 1, while the radio frequency field being off corresponds to 0. The modulation index
specification is defined in 6.1.5.1. In the case of Manchester coding a Manchester 1 is a 1 to 0 transition, while
a Manchester 0 is a 0 to 1 transition.
For tag-to-Interrogator communication (return link), data is sent using backscatter techniques. This requires
that the Interrogator provide steady power to the tag during the return link. While the Interrogator powers the
tag, the tag shall change alternately the effective impedance of the tag front end and thus changing the overall
radio frequency reflectivity of the tag as seen by the Interrogator. During this time, the Interrogator shall not
modulate the carrier. During the WAIT field (when tags write data into their memory), the Interrogator shall
also provide steady power to the tag, and shall not modulate the carrier. The transmission protocol defines the
mechanism to exchange instructions and data between the Interrogator and the tag, in both directions.
It is based on the concept of “Interrogator-Talks-First”.
This means that any tag shall not start transmitting (modulating) unless it has received and properly decoded
an instruction sent by the Interrogator.
The protocol is based on an exchange of a command from the Interrogator to the tag and a response from the
tag(s) to the Interrogator.
The conditions under which the tag sends a response are defined in 6.2.7
Each command and each response are contained in a frame. The respective frames are specified in 6.1.7
and 6.1.8. Each command consists of the following fields:
 Preamble Detect (no modulation of the RF carrier),
 Preamble,
 Delimiter,
 Command code,
© ISO/IEC 2012 – All rights reserved 17

 Parameter fields (depending on the command),
 Application data fields (depending on the command), and
 CRC-16.
Each response consists of the following fields:
 Quiet (no modulation of the RF carrier),
 Return Preamble,
 Application data fields, and
 CRC-16.
The protocol is bit-oriented. The number of bits transmitted in a frame is a multiple of eight (8), i.e. an integer
number of bytes. However, the frame itself is not based on an integer number of bytes, to support the frame
detection.
In all byte fields, the MSB shall be transmitted first, proceeding to the LSB. In all word (8-byte) data fields, the
MSByte shall be transmitted first.
The MSByte shall be the byte at the specified address. The LSByte shall be the byte at the specified address
plus 7 (i.e., bytes are transmitted in incrementing address order).
The byte significance is relevant to data transmission and to the GROUP_SELECT and GROUP_UNSELECT
greater than and less than comparisons.
The MSByte of the byte mask shall correspond to the most significant data byte, the byte at the specified
address.
Word (8-byte) addresses are not required to be on an 8-word boundary and may be on any byte boundary.
RFU bits and bytes shall be set to zero (0).
6.1.7 Command format
6.1.7.1 Command format general
The command frame, as shown in Figure 10, consist of the following fields:
 Preamble Detect,
 Preamble,

...