VAC TagMaster Training Module T2, Page 1 TagMaster AB Обучающий семинар TagMaster 2013 Система GEN4 2.45 ГГц

VAC

TagMaster Training

Module T2, Page 1TagMaster AB

Обучающий семинар TagMaster 2013Система GEN4 2.45 ГГц

TagMaster Training


Содержание1. Технический обзор RFID-системы TagMaster

2. Reader TagID and User-data acquisition techniques

3. Tag products, Tag operating modes and timing

4. Read-range definitions and data-acquisition probability

5. Reader frequency options and spectral environment

6. Impact of the physical Tag and Reader installation

7. About multiple reader installations

8. Battery Assisted Passive (BAP) ID-tag endurance

TagMaster Training


1. Технический обзор RFID-системы TagMaster

RFID-система TagMaster работает в диапазоне частот 2450 МГц ISM, не требующем специальной лицензии. RFID-система обеспечивает стабильное считывание на расстоянии до 14 м, а в идеальных условиях пиковое расстояние может достигать 20 м.

Выходная радиоволновая мощность разных моделей считывателей составляет 1 - 75 мВт (EIRP). Стандартные 10 мВт (EIRP) являются крайне низкой и безвредной величиной, в сравнении с системами 900 МГц, использующими несколько единиц Вт.

Все компоненты считывателя – антенны, радио-компоненты и контроллер – заключены в едином корпусе с классом зашиты IP65.Для считывания меток под любым углом используются антенны с круговой поляризацией.

Непрерывный сигнал от считывателя

Модулированный по фазе отраженный сигнал от ID-метки

TagMaster Training


2. Reader TagID and User-data acquisition techniques (a) ID-метка передаст свою информацию любому запрашивающему

считывателю TagMaster, работающему в определенном диапазоне частот. Если разные считыватели работают на разных каналах и одновременно обращаются к метке, то данные с метки будут без помех считаны каждым устройством.

Блок обработки сигналов считывателя интерпретирует оцифрованный фазомодулированный сигнал от ID-метки.

Доступны два типа меток: ID-метки только для чтения ID-метки для чтения и записи

Данные метки могут быть запрограммированы считывателем для работы в различных режимах, путем изменения следующих параметров: емкость памяти, тип интервала (фиксированный или случайный), длина интервала (молчания), высокая или низкая скорость.

The Mark is the unique ID-tag identity defining the TagID. The TagID is set at the semiconductor manufacturing level.The TagID is unique and never repeated.

TagMaster Training


2. Reader TagID and User-data acquisition techniques (b)

Mark Status

ID frame

IntervalMessage time

CRC

The ReadOnly ID-tag message

Mark Status

ID frame

IntervalMessage time

CRC User-Data CRC

The Read/Write ID-tag message

32 bit CRC checksumThe ID-frame (see fig above) includes a 32 bit CRC programmed checksum to support the TagID acquisition process. The User-data is also protected by a separate 32 bit CRC checksum to make sure that only correct TagID (Mark) and User-data is delivered by the Reader processing block to the interrogating system.

Status bits The status bits include the actual battery status and the application software can initiate a low battery alarm.

TagMaster Training


3. Tag products, Tag operating modes and timing (a)

Different ID-tag modelsTagMaster offers various ID-tag models to fit the actual application requirement. Differences in the basic electric design, including the RF antennas, may give different read-range properties (see section 4).

Some applications require programmable ID-tags providing distributed information storage whereas on-line systems only requires a unique TagID to associate information stored in a host computer.

MarkTag and ScriptTag familiesThe TagID frame for the MarkTag is only 10ms long. If a ScriptTag (ReadWrite) is used the time required for a complete reading (i.e. ID-frame) will increase to 17 – 56 ms.

TagMaster Training


3. Tag products, Tag operating modes and timing (b)

Interval LengthThere are different Interval Length settings available. During the Interval the ID-tag is silent. The Interval Length can vary from 0 (continuous) to 4, 8 and 16 times the ID frame time-length. One ID-frame includes all necessary information to read the ID-tag if acquired correctly. In case the ID-tag passes very fast through the firm read-range the advice is to allow enough time for three consecutive ID-frames and the use of an ID-tag with Interval Length = 0 (continuous).

A 400km/h ≈ 83.3m/s passage through a 4m wide Read-lobe allows for 4.8 complete 10ms MarkTag ID-frames

TagMaster Training


3. Tag products, Tag operating modes and timing (c)

Single or multiple tag readingsStandard ReadOnly MarkTag products are hard-programmed for either Interval Length 0 (continuous) or 8. The Interval Length = 8 standard product is programmed for Random Interval Length (R8H) causing the ID-tag to be silent for a randomly varying interval between 0 and 16 ID-frames. The silent interval allows other ID-tags of the same type, present within the read-range-lobe, to talk and to be registered by the Reader.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

14.0

15.0

16.0

1 2 3 4 5 6 7 8 9 10

Number of tags

Tim

e t

o r

ea

d a

ll ta

gs

(s

) 99.90%

99%

95%

90%

80%

70%

60%

50%

Multiple readingsIf the application requires that several ID-tags (R4/R8/R16) are identified simultaneously, the time required for identifying all tags will vary vs. the number of tags present.

The graph valid for Random Interval length 8 (R8H-mode)

TagMaster Training


4. Read-range definitions & data-acquisition probability (a)

FundamentalsA strong received RF-signal from an ID-tag provides a high data-acquisition probability and a weak received RF-signal from an ID-tag provides low probability. The RF-signal strength will depend on several factors including:

● Reader output power level● Reader- and Tag-model● Distance between Reader and Tag● Frequency setting ● Physical environment for the Reader and the Tag

Read-range definitionsFirm Read-range: Wherethe acquisition probabilityis almost 100%.Max Read-range: Wherethe ID-tag no longer canbe read.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

[meter]

Max read-range

Firm read-range

Different output power

TagMaster Training


4. Read-range definitions & data-acquisition probability (b)

Read-rangeThe read-range graphs represent the average performance over the available frequency range (ideal environment). A graph can be plotted for each Tag-model and Reader model, at a certain power level (EIRP)

The diagram below shows the read-ranges for two different ID-tags at different positions (Reader and ID-tags in parallel.)

-5

-4

-3

-2

-1

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

[meter]

[met

er]

Max (B)

Max (A)Firm (A)

Firm (B)

Reader

ID-tag A

ID-tag B

TagMaster Training


5. Reader frequency options and spectral environment (a)

Basic frequency rangeThe allowed frequency range for the 2450 MHz ISM band is usually 2400 – 2483.5 MHz. Some countries apply special frequency and/or RF output power restrictions. Special options for “Motion-detection” within this frequency range may also apply. If necessary, a TagMaster Reader can be classified as a field-disturbance sensor since the Doppler-shift motion and speed detection is a built-in feature. The default frequency range setting for the TagMaster readers is 2435MHz – 2465 MHz. The minimum frequency step interval is 100kHz.

Read-range vs. frequencyRead-range properties for ID-tags may be slightly different for different frequencies. The longest read-range is usually obtained in the middle of the frequency range 2435 – 2465 MHz. Some ID-tag models support the entire 2400-2483.5 MHz range. Some individual performance variation can be observed for ID-tags and Readers, this is a natural variation due to component and manufacturing tolerances

TagMaster Training


5. Reader frequency options and spectral environment (b)

Fixed frequency Reader settingsIf the Reader is set for a fixed frequency the system may become sensitive for the physical Reader installation at the actual site. Direct reflections, multi-path superimposed signals and jamming originating from other installations using the same frequency can affect system performance. The actual environment may also vary from one day to another.

FHSS frequency hopping Reader settingsFHSS is a preferred frequency setting option. The 2400 – 2483.5 frequency range is divided into 16 sub-bands each providing 50 channels. One or several of these sub-bands can be activated and the frequency will hop between channels, in a random sequence, using 300ms dwell time at each frequency.

The FHSS frequency setting option is the best alternative for most applications since every part of the system will always provide its best performance and possible impact from the RFID installation site and jamming is reduced to a minimum

TagMaster Training


5. Reader frequency options and spectral environment (c)

TagMaster Training


6. Impact of the physical Tag and Reader installation (a)

Tag vs. Reader geometriesRead-Range properties are usually specified for a Reader and an ID-tag positioned in parallel (ID-tag angle 0°).

See Read-Range characteristics below for ID-tags MarkTag Classic (green) and MarkTag MeM (red) for different ID-tag angels 0º/45º/60º.

Firm Read-Range ID-tag angle=0deg

-5

-4

-3

-2

-1

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 10[meter]

[me

ter]


-5

-4

-3

-2

-1

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 10[meter]

[me

ter]


-5

-4

-3

-2

-1

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 10[meter]

[me

ter]

TagMaster Training


6. Impact of the physical Tag and Reader installation (b)

Radio reflections in front of the ReaderThe Reader transmits the RF signal continuously. If the RF transmit signal is reflected back to the Reader by metal surfaces (just like a mirror), close to the reader, the sensitivity of the receiving part of the Reader will be degraded causing a reduced Read-Range. Also reflecting sheets of glass or plastic material etc. in parallel with the reader within 1 meter can reduce the reader sensitivity. FHSS, frequency hopping, may reduce or eliminate such problems.

2.4 2.41 2.42 2.43 2.44 2.45 2.46 2.47 2.48 2.49 2.5 (GHz)

Tx Rx Iso la tion [dB ]

-65

-60

-55

-50

-45

-40

-35

-30

-25

Isolation measurement

figures showing impact of

sheets of glass and metal

in front of the reader.

TagMaster Training


6. Impact of the physical Tag and Reader installation (c)

Multiple path interferenceIf a Reader is set for fixed frequency operation certain ID-tag positions can appear to be very bad. The reason can be caused by multiple reflections for the RF signal via different surfaces between the ID-tag and the Reader. Multiple reflections will be added at the receiver and/or at the ID-tag. For some positions (phase) or frequencies the result can worst case cause cancellation causing a no-read. FHSS, frequency hopping, always eliminates such problems.

ReaderTag

TagMaster Training


6. Impact of the physical Tag and Reader installation (d)

Material between the ID-tag and the ReaderThe RF signal can not pass through metal or metalized glass or metalized plastic (like solar films). Even if the RF-signal is not completely reflected the metallization will attenuate the RF signal to an extent that ID-tags can not be read. The same problem applies for all radio devices like mobile phones, GPS and 900 MHz RFID systems. Most non-lossy dielectric materials can be placed between the ID-tag and the Reader without problems. Some non-metallic materials can cause small reflections that can be observed as a slight read-range reduction

TagMaster Training


6. Impact of the physical Tag and Reader installation (e)

Material in front of and behind the ID-tagMetal behind the TagMaster ID-tags is no problem except for MarkTag MeM where there is a restriction for the distance between the ID-tag and the metal surface. Dielectric material in front of the tag is usually no problem but consult the ID-tag Data Sheet to be sure. Water and snow can sometimes be a problem, in particular if the ID-tag is completely drowned in water since the dielectric properties of water will detune the ID-tag antennas and cause RF attenuation.

TagMaster Training


7. About multiple reader installations (a)

Multiple reader installation examples● Entrance and exit gates sharing the same lane● Multiple lane entrances (and exits)● Multiple lane toll-gates● Readers for different purposes installed at the same site● Readers installed in truck and train depots

TagMaster Training


7. About multiple reader installations (b)

Frequency interference between readersThere is a basic rule not to use the same frequency for more than one reader in a multiple reader installation. This rule also include frequencies and channels within ±500 kHz from that frequency. The reason is that the jamming Reader continuously emits RF signals that make the other Reader almost “blind” for the information provided by the ID-tag. (If the jamming Reader is far from the Reader, ±300 kHz offset is sufficient.)

FHSS, frequency hopping is usually recommended and since the random frequency hopping scheme is individual for each Reader, interference is usually no problem. In case of interference, the duration will be short.At least 10 Readers can be used set for FHSS within 2435-2465 MHz.It is also possible to use different sub-bands for a limited number of readers to avoid interference.

If necessary the Reader can also be set for Carrier off (RF turned off) at any time by the application software.

TagMaster Training


7. About multiple reader installations (c)

Identifying the right ID-tag in the right positionChoice of ID-tag and Reader model for a particular application is very important. The placement of Reader and the ID-tag vs. the Reader is also very important.

The Readlevel function can be set to provide a very accurate read-range-lobe employing a threshold function that reduces the read-range and also equalizes the difference between the Firm and Max read-range. The Readlevel can be set in 100 steps (0...100).

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

75mW

75mW RL90

75mW RL80

75mW RL70

TagMaster Training


8. Battery Assisted Passive (BAP) ID-tag endurance (a)

The ID-tag batteryThe ID-tag is basically passive since the RF-signal is reflected back to the Reader (i.e. backscatter). The battery only keeps the digital circuit (ASIC) running. The TagMaster proprietary ID-tag ASICs are designed to consume an absolute minimum of power. It allows the ID-tag to operate continuously and provide an immediate response without any wake-up delay, RF-energy conversion or initial Reader/ID-tag conversation.

TagMaster Training


8. Battery Assisted Passive (BAP) ID-tag endurance (b)

Different ID-tag models and modes of operationID-tags set for longer Interval Length (see Section 4) have a lower power-consumption. The power-consumption is low during the “silent” Interval and higher when the ID-tag “talks”. MarkTag models have a slightly lower power-consumption than ScriptTag models. MarkTag models for continuous operation (Interval Length=0) and ScriptTag models are equipped with an extra battery to compensate for the slightly higher power consumption.

ID-tag and battery temperatureLithium Manganese Dioxide Batteries have a very low self-discharge rate. Even if the self-discharge is low the rate is temperature dependent. The internal self-discharge increases with the temperature. At lower temperature the self-discharge is almost negligible. To predict the ID-tag life (battery life) accurately the ambient temperatures for the ID-tag has to be known. A thorough analysis must include different time-periods for different temperatures - an average temperature model is not sufficient. (See ID-tag Data Sheets for detailed information.) Note that batteries are not specified by battery manufacturers beyond 10 years of operation.

TagMaster Training


8. Battery Assisted Passive (BAP) ID-tag endurance (c)

A predictable ID-tag lifeSince the ID-tag has a fairly constant power-consumption throughout its entire life the ID-tag life is predictable.

Low battery indicationWhen the long life Lithium Manganese Dioxide Battery voltage reaches a certain level after several years of operation the ASIC will set the Status-bits to “Low Battery”. The “Low Battery” indication can be registered by the Application software in the Reader and provide a user-alarm. The ID-tag will continue to operate for about 6 months after the first “Low Battery” indication.

Theoretical battery-life vs. temperature for ScriptTag Classic 125100

-30

-20

-10

0

10

20

30

40

50

60

70

80

2 4 6 8 10 12 14 16

Year

Te

mp

C

Int 0

Int 4

Int 8

Int 16

TagMaster Training


1-8. Further Reading

”TagMaster RFID read reliability” white paper can be downloaded from www.tagmaster.com.

VAC

TagMaster Training


End

Documents

VAC TagMaster Training Module T2, Page 1 TagMaster AB Обучающий семинар TagMaster 2013 Система GEN4 2.45 ГГц