MT9075B datasheet(11/78 Pages) MITEL

11 / 78 page

Preliminary Information

MT9075B

Depending

the

mode

selected,

the

Jitter

Attenuator (JA) can attenuate either transmit clock

jitter or receive clock jitter, or be disconnected.

Control bits JAS, JAT/JAR (address 18H of page

02H) determine the JA selection under certain

modes. Table 2 shows the conﬁguration of related

control pins and control bits required to place the

MT9075B in the appropriate jitter attenuation mode.

Referring to the mode names given in Table 2, the

basic operation of the jitter attenuation modes is

summarized as follows:

•In

SysBusSync (1-3) modes, pins C4b and

F0b are always configured as inputs, while in

the Line Synchronous and Free-Run modes

C4b and F0b are configured as outputs.

•In

SysBusSync1 mode, an external clock is

applied to C4b. The applied clock is

dejittered by the internal PLL before being

used to transmit data. The clock extracted

(with no jitter attenuation performed) from

the receive data can be monitored on pin

E2o.

•In

SysBusSync2 mode, the clock applied to

pin C4b is assumed to be jitter-free and is

directly used to transmit data. The internal

PLL is used to dejitter the extracted receive

clock. The dejittered receive clock is output

on pin E2o.

•In

SysBusSync3 mode, no jitter attenuation

is applied to either the transmit or receive

clocks. The transmit data is synchronized to

clock applied to pin C4b. The extracted

receive clock is not dejittered and is supplied

directly to the E2o output.

•In

Line Synchronous mode, the clock

extracted from the receive data is dejittered

using the internal PLL and then output on pin

C4b. Pin E2o provides the extracted receive

clock before it has been dejittered. The

transmit data is synchronous to the clean

receive clock.

•In

Free-Run mode the transmit data is

synchronized to the internally generated

clock. The internal clock is output on pin

C4b. The clock signal extracted from the

receive data is not dejittered and is output

directly on pin E2o.

The PCM 30 Interface

PCM 30 (E1) basic frames are 256 bits long and are

transmitted at a frame repetition rate of 8000 Hz,

which results in an aggregate bit rate of 256 bits x

8000/sec = 2.048 Mbits/sec. The actual bit rate is

2.048 Mbits/sec +/-50 ppm encoded in HDB3 format.

The HDB3 control bit (page 01H, address 15H, bit 5)

selects either HDB3 encoding or alternate mark

inversion (AMI) encoding. Basic frames are divided

into 32 time slots numbered 0 to 31, see Figure 31.

Each time slot is 8 bits in length and is transmitted

most signiﬁcant bit ﬁrst (numbered bit 1). This results

in a single time slot data rate of 8 bits x 8000/sec. =

64 kbits/sec.

It should be noted that the Mitel ST-BUS also has 32

channels numbered 0 to 31, but the most signiﬁcant

bit of an eight bit channel is numbered bit 7 (see

Mitel Application Note MSAN-126). Therefore, ST-

BUS bit 7 is synonymous with PCM 30 bit 1; bit 6

with bit 2: and so on (Figure 31).

PCM 30 time slot 0 is reserved for basic frame

alignment, CRC-4 multiframe alignment and the

communication of maintenance information. In most

conﬁgurations time slot 16 is reserved for either

Channel Associated Signalling (CAS or ABCD bit

signalling) or Common Channel Signalling (CCS).

The remaining 30 time slots are called channels and

carry either PCM encoded voice signals or digital

Table 2 - Selection of Clock Jitter Attenuation Modes

Mode Name

BS/LS

BL/FR

JAS

JAT/JAR

Note

SysBusSync1

JA on Tx side; No JA on Rx side

SysBusSync2

JA on Rx side; No JA on Tx side

SysBusSync3

No JA on Tx or Rx side

Line

Synchronous

By default, JA is on the receive side.

Controls bits need not be selected.

Free-Run

In free-run mode JA will be automatically

disconnected

MT9075B bảng dữ liệu(PDF) 11 Page - Mitel Networks Corporation

MT9075B bảng dữ liệu(HTML) 11 Page - Mitel Networks Corporation

Html Pages

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 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78

bảng dữ liệu tải về

Link URL