PCD5008 datasheet(59/64 Pages) PHILIPS

59 / 64 page

1998 Jun 17

Philips Semiconductors

Product speciﬁcation

FLEX

™ Pager Decoder

PCD5008

15.3

FLEX

™ encoding and decoding rules

The encoding and decoding rules identify the minimum

requirements which must be met by the paging device,

paging terminal or other encoding equipment to properly

format a FLEX

™ data stream for RF transmission and to

successfully decode it.

15.3.1

FLEX

™ ENCODING RULES

The FLEX

™ encoding rules are as follows:

• The stability of the encoder clock used to establish time

positions of FLEX

™ frames must be no worse than

±25 ppm (including worst case temperature and aging

effects).

• A maximum of 2 occurrences of an identical individual or

radio group address is allowed in any frame for

unfragmented messages. This rule applies across all

phases in a multi-phase frame. For example, for

decoding devices that support any-phase addressing,

an any-phase address may appear at once in two

different phases in a single multi-phase frame.

• Once an individual or radio group address is used to

begin transmitting a fragmented message, that same

address must not be used to start a new fragmented

transmission until the first fragmented transmission has

been completed.

• For the duration of time that an individual or radio group

address is being used to send a fragmented message,

that same address must not appear more than once in

any frame to send an unfragmented message.

• Once a specific dynamic group address (temporary

address) is assigned to a group, it must not be reused

until its associated message has been transmitted in its

entirety. Given this constraint, the same dynamic group

address can only appear once in any frame.

• A dynamic group address cannot be used to set up a

second dynamic group.

• Messages using any of the three defined numeric

vectors (V2V1V0 = 011, 100 and 111) cannot be

fragmented, and thus must be completely contained in a

single frame.

• Fragments of the same message must be sent at a

frequency of at least 1 every 32 frames (i.e. at least

once a minute) or 1 every 128 frames (i.e. at least once

every 4 minutes) as specified by the service provider.

• Enhanced message fragmenting for symbolic character

transmission requires that the encoder track character

boundaries within each fragment in order to avoid

character splitting.

• Message numbering as an optional feature is offered by

some carriers and available on an individual subscriber

basis.

• Message numbers must be assigned sequentially in

ascending order.

• Message number sequences must be separately

maintained for each individual and radio group address.

• Message numbers are not used (retrieval message

number disabled) in conjunction with a dynamic group

address.

• When a missed message is re-transmitted from

message retrieval storage, the message must have

R = 0 to avoid creating an out of sequence message

which may cause the pager to indicate a missed

message.

15.3.2

FLEX

™ DECODING RULES

The FLEX

™ decoding rules are as follows:

• FLEX™ decoding devices may implement either

single-phase addressing or any-phase addressing.

• FLEX™ decoding devices that support the numeric

vector type (V2V1V0 = 011) must also support the short

message vector (V2V1V0 = 010) with the message

type (t1t0) set to 00.

• FLEX™ decoding devices that support the alphanumeric

vector type (V2V1V0 = 101) must support the numeric

vector type (V2V1V0 = 011) and the short message

vector (V2V1V0 = 010) with the message type (t1t0)

set to 00, FLEX

™ paging devices that implement

any-phase and support the alphanumeric vector type

(V2V1V0 = 101) must also support the short instruction

vector (V2V1V0 = 001) with the instruction type (i2i1i0)

set to 000.

• FLEX™ decoding devices must be capable of decoding

frames at all of the following combinations of data rate

and modulation mode. They are: 1600 bps 2 level;

3200 bps 2 level; 3200 4 level and 6400 bps 4 level.

• FLEX™ decoding devices must be designed to tolerate

4 minute fragment separation times.

PCD5008 Datasheet(PDF) 59 Page - NXP Semiconductors

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