Lyngsoe Systems PT30 Postal Tag, PT30 User Manual PT30 UserManualV3

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PT30 Postal Tag RFID-LSCAN

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PT30 Postal Tag

User Manual

Version 3 – Dec 2008

PT30 Postal Tag RFID-LSCAN

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TABLE OF CONTENTS

1 INTRODUCTION 3

1.1

Purpose 3

1.2

Definitions 3

2 BLOCK DIAGRAM 3

3 PT30 OPERATION DESCRIPTION 3

3.1

Modes of operation 4

3.2

Valid Excitation Fields 4

3.3

Commands and Parameters 4

3.4

PT23 / PT30 vs. PT21 4

3.4.1

ExId range 4

3.4.2

Black-out 4

4 REGULATORY COMPLIANCE 5

4.1.1

Maximum Transmission Time 5

4.1.2

Maximum Duty Cycle 5

PT30 Postal Tag RFID-LSCAN

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1 INTRODUCTION

1.1 Purpose

The purpose of this document is to describe the functionality and operation of the PT30 tag intended for use in a RFID system

custom designed for International Post Corporation. The tag features reflect the application requirements. You can find more

details into “PT30 Functional Specifications”.

1.2 Definitions

Valid LF Field – A 125 kHz carrier signal modulated OOK with a signal carrying the exciting device identification number

(ExID).

Excitation Mode – tag transmits its ID together with the exciter ID when it is woken up by a valid LF field.

Transmission – When is excited by a valid LF field, the tag transmits its ID over a 433.92 MHz FSK modulated carrier.

2 BLOCK DIAGRAM

Block diagram for Postag PT30 is presented in Figure 2-1 below:

3 PT30 OPERATION DESCRIPTION

Postag PT30 is a transponder (RF Tag) that receives an excitation signal and responds by transmitting back a message. It is

custom designed for low cost and reliability in the postal environment. It is a direct replacement of previous models PT21 and

PT23 tags and can be used with any of the Lyngsoe RFID systems – S96, S21 and S23.

Postag PT30 provides the following main functions:

- Identifies a valid excitation field and reads the excitation identifier (ExId);

- Following a valid excitation, it transmits on 433.92MHz several identical messages that include (among others) the tag user

data, the ExId and a battery flag.

- Its user data and operating parameters are programmed wirelessly using a special programming device

UHF Antenna

Figure 2-1

PT30 Postal Tag RFID-LSCAN

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3.1 Modes of operation

Postag PT30 has several main modes of operation: sleep, LF excitation recognition, UHF transmission and programming. The

sleep mode is the normal mode of operation.

In the sleep mode, only the LF receiver is powered up and the total current consumption is less than 5uA. When a LF signal is

detected by the LF receiver, it wakes-up the microcontroller to check if this signal has a valid modulation pattern. The LF field

validation is done by the microcontroller using an RC internal 90 kHz clock at a low current consumption. If a valid excitation

field is recognized, then the microcontroller wakes-up its UHF Transmitter and transmits on the UHF the pre-programmed

messages. When PT30 recognizes a valid S21 / S23 excitation it transmits on UHF messages using S21 format. The PT30

operation and the message content can be programmed using dedicated devices.

The tag transmits a number of messages each time it enters a valid S21 or S23 fields. First transmission is delayed a few ms

depending of the parameter WID that programmed randomly for each tag within the 10 -30 range during the manufacturing

process. Subsequent transmissions are each randomly delayed compared with the preceding one based on a calculation that

involves several random numbers generated internally function of another parameter WSD. This WSD parameter is also

programmed randomly for each tag within the 10 -30 range during the manufacturing process. Repeating the same message a

number of times ensures that, even if multiple tags are excited in the same time, many messages will not collide and at least one

from each tag will be successfully received.

3.2 Valid Excitation Fields

For a field to be valid, it has to have a special pattern called exciter ID. If fields with different exciter ID overlap and a tag moves

from one to another it will transmit WEP number of messages each time it “sees” a new exciter ID.

3.3 Commands and Parameters

The commands and parameters accepted by Postag PT30 are the same as for the Postag PT21 / PT23 and are listed in the RFID

System S21 – Reference Guide, document 950061 rev. 1.

The most used programmable parameters for PT30 are WIP, WRC and WUD. Examples of default parameters’ values that will

fit most applications are:

WUD = “xxxxx” 5 characters of user data

WIP, WRC= their sum represents the number of identical messages to transmit following an excitation. WIP

parameter range is 1 to 20, WRC parameter range is 0 to 10, and default values for each are 10.

WID = randomly assigned initial delay after excitation, multiples of 4 ms, range 1-200, default 1. This

ensures a randomization of the first transmissions following an (almost) simultaneously excitation of multiple tags.

WSD = inter-message random delay, range 7 – 15, default 10 (no direct physical interpretation of this value)

3.4 PT23 / PT30 vs. PT21

The main functional differences between tags model PT23 / PT30 and PT21 are related to the ExId range of identifiers and the

black-out time.

3.4.1 ExId range

Postags PT21 recognize and report received ExId with S21 format in the range 0 to 31.

Postags PT23 / PT30 recognize and report received ExId with S21 format in the range 0 to 31, and with S23 format in the range

0 to 127.

3.4.2 Black-out

Black-out is the minimum time interval between two consecutive excitations which the tag can recognize. Postag PT21 has a

black-out time 10.0 s. For PT23 and PT30 this blackout time was reduced to less than 2.0 s. In situations where we want to re-

register a tag that leaves and re-enters a field with the same exciter ID, the tag has to be out of the field for more than the black

out time duration. This happens for example when you try to excite a tag multiple times using the same exciter, like a Universal

PT30 Postal Tag RFID-LSCAN

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Programmer UP23 box. If a tag enters LF field but the valid excitation pattern can not be recognized (i.e. overlapping fields or

interference), the tag does not transmits anything.

4 REGULATORY COMPLIANCE

This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may

not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause

undesired operation.

This equipment has been tested and found to comply with the limits for Class B digital devices, pursuant to Part 15 of the FCC

Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This

equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the

instruction manual, may cause harmful interference to radio communications. However, there is no guarantee that interference

will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which

can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one of more of

the following measures:

• Reorient or relocate the receiving antenna

• Increase the separation between the equipment and receiver

• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.

• Consult the dealer or an experienced radio/TV technician for help.

Warning: Changes or modifications not expressly approved by the party responsible for compliance could void the user’s

authority to operate the equipment.

4.1.1 Maximum Transmission Time

To comply with 15.231(a) of FCC regulations, the maximum transmission time of PT30 in Excitation mode must not exceed 5

seconds.

To minimize collisions in an application, PT30 tags are programmed with random values for the WSD parameter, which ensures

that inter-message durations are randomized differently for individual tags. To ensure sufficient transmission redundancy in an

application a certain optimum number of transmitted messages is selected and programmed into the WIP+WRC parameters. The

sum of both parameters represents the number of messages transmitted in a burst and this affects the overall transmission

duration.

In our typical application WIP + WRC = 20 and WSD = 7 and the resulting average transmission time is around 2s. If we set

maximum values for these parameters WIP + WRC = 30 and WSD = 30 the resulting transmission time is 4.3s so PT30 still

complies with the FCC requirements for maximum transmission time.

4.1.2 Maximum Duty Cycle

To comply with 15.231(a) of FCC regulations from average transmitted power point of view, the maximum transmission Duty

Cycle for PT30 must not exceed 24% in any 100ms time window.

The maximum value of duty cycle in PT30 is achieved when 100ms window falls on the Excitation transmission bursts. The table

below shows the best estimate of the duty cycle in 100ms for different combinations of WEP = WIP+WRC and WSD. As we

can see as long as WEP = WIP+WRC > 3 and WSD ≥ 7 the duty cycle in any 100ms window varies between 8% and 16% so

there is margin compared with the maximum value of 24%.

PT30 Postal Tag RFID-LSCAN

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Max Duty Cycle: 20 %Annex 3

WSD

WEP 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

8888888888888888888888888888888888888888

12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

16 16 16 16 16 16 16 16 16 16 12 12 12 12 12 12 12 12 12 12 12 12 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

20 20 20 20 20 20 16 16 16 16 12 12 12 12 12 12 12 12 12 12 12 12 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

24 24 24 24 20 20 16 16 16 16 12 12 12 12 12 12 12 12 12 12 12 12 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

29 29 29 24 20 20 16 16 16 16 12 12 12 12 12 12 12 12 12 12 12 12 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

33 29 29 24 20 20 16 16 16 16 12 12 12 12 12 12 12 12 12 12 12 12 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

Maximum possible Duty Cycle in any 100ms time window during a transmission of one packet of MsgNo messages

(set by WBP, WEP, WEB tag parameters).

This graph also depends on values of CC and EN parameters set in TagParms form.

Lyngsoe Systems PT30 Postal Tag, PT30 User Manual PT30 UserManualV3

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