PCD5008 datasheet(46/64 Pages) PHILIPS

46 / 64 page

1998 Jun 17

Philips Semiconductors

Product speciﬁcation

FLEX

™ Pager Decoder

PCD5008

8.8

Message reception

8.8.1

FLEX

™ SIGNAL STRUCTURE

The FLEX

™ signal transmitted on the radio channel (see

Fig.17) consists of a series of four minute cycles, each

cycle having 128 frames at 1.875 seconds per frame.

A pager may be assigned to process any number of the

frames. Battery saving is performed for frames which are

not assigned. The FLEX

™ signal can assign additional

frames to the pager using collapse, fragmentation,

temporary addressing or carry-on information within the

FLEX

™ signal.

Each FLEX

™ frame has a synchronization portion followed

by an eleven block data portion, each block lasting

160 milliseconds. The synchronization portion indicates

the rate at which the data portion is transmitted,

1600, 3200 or 6400 bits per second (bps). The 1600 bps

rate is transmitted at 1600 symbols per second (sps)

using 2 level FSK modulation and consists of a single

phase of information at 1600 bps, phase-A. The 3200 bps

rate is transmitted at either 1600 sps using 4 level FSK

modulation or 3200 sps using 2 level FSK modulation and

consists of two concurrent phases of information at

1600 bps, phase-A and phase-C. The 6400 bps rate is

transmitted at 3200 sps using 4 level FSK modulation and

consists of four concurrent phases of information at

1600 bps (phase-A, -B, -C and -D).

Each block has eight interleaved words per phase, thus

there are 88 codewords (numbered 0 to 87) per phase in

every frame. Each word has information contained within

an error correcting code which allows for bit error

correction and detection. The 88 words in each phase are

organized into a block information field, an address field, a

vector field, a message field, and an idle field.

The boundaries between the fields are independent of the

block boundaries. Furthermore, at 3200 and 6400 bps,

the information in one phase is independent of the

information in a concurrent phase, and the boundaries

between the fields of one phase are unrelated to the

boundaries between the fields in a concurrent phase.

The synchronization portion consists of: a first sync signal

at 1600 bps; a frame information word having the frame

number 0 to 127 (7 bits) and the cycle number

0 to 14 (4 bits); and a second sync signal at the data rate

of the interleaved portion.

The block information field contains BIWs. These can be

used for determining time and date information and certain

paging system information.

The address field contains addresses assigned to paging

devices. Addresses are used to identify information sent to

individual paging devices and/or groups of paging devices.

Information in the FLEX

™ signal may indicate that an

address is a priority address. An address may be either a

short (one word) address or a long (two word) address.

An address may be a tone-only address in which case

there is no additional information associated with the

address. If an address is not a tone-only address, then

there is an associated vector word in the vector field.

Information in the FLEX

™ signal indicates the location of

the vector word in the vector field associated with the

address. A pager may perform battery saving at the end of

the address field when its address(es) is not detected.

The vector field consists of a series of vector words.

Depending upon the type of message, a vector word (or

words in the case of a long address) may either contain all

of the information necessary for the message, or indicate

the location of message words in the message field

comprising the message information. Short addresses

have one associated vector word in the vector field. Long

addresses have one associated vector word in the vector

field directly followed by the first message codeword of the

call.

The message field consists of a series of information

words containing message information. The message

information may be formatted in ASCII, BCD or binary

depending upon the message type.

PCD5008 Datasheet(PDF) 46 Page - NXP Semiconductors

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