DS26521 datasheet(74/258 Pages) MAXIM

74 / 258 page

DS26521 Single T1/E1/J1 Transceiver

74 of 258

Figure 8-20. Typical Monitor Application

PRIMARY

T1/E1 TERMINATING

DEVICE

MONITOR

PORT JACK

T1/E1 LINE

DS26521

SECONDARY T1/E1

TERMINATING

DEVICE

8.11.3.4

Loss of Signal (LOS)

The DS26521 uses both the digital and analog loss-detection method in compliance with the latest ANSI T1.231 for

T1/J1 and ITU-T G.775, or ETS 300 233 for E1 mode of operation.

Loss of signal (LOS) is detected if the receiver level falls below a threshold analog voltage for certain duration.

Alternatively, this can be termed as having received “0s” for a certain duration. The signal level and timing duration

are defined in accordance with the ANSI T1.231, ITU-T G.775, or ETS 300 233 specifications.

For short-haul mode, the loss-detection thresholds are based on cable loss of 12dB to 18dB for both T1/J1 and E1

modes. The loss thresholds are selectable based on Table 9-19. For long-haul mode, the LOS detection threshold

is based on cable loss of 30dB to 38dB for T1/J1 and 30dB to 45dB for E1 mode. Note there is no explicit bit called

short-haul mode selection. Loss declaration level is set at 3dB lower that the maximum sensitivity setting

programmed in Table 9-19.

The loss state is exited when the receiver detects a certain ones density at the maximum sensitivity level or higher,

which is 3dB higher than the loss-detection level. The loss-detection signal level and loss-reset signal level are

defined with hysteresis to prevent the receiver from bouncing between “LOS” and “no LOS” states. Table 8-33

outlines the specifications governing the loss function.

Table 8-33. ANSI T1.231, ITU-T G.775, and ETS 300 233 Loss Criteria Specifications

STANDARD

CRITERIA

ANSI T1.231

ITU-T G.775

ETS 300 233

Loss

Detection

No pulses are detected for 175

±75 bits.

No pulses are detected for

duration of 10 to 255-bit

periods.

No pulses are detected for a

duration of 2048-bit periods or

1ms.

Loss Reset

Loss is terminated if a duration

of 12.5% ones are detected

over duration of 175 ±75 bits.

Loss is not terminated if 8

consecutive zeros are found if

B8ZS encoding is used. If

B8ZS is not used, loss is not

terminated if 100 consecutive

pulses are zero.

The incoming signal has

transitions for duration of 10 to

255-bit periods.

Loss reset criteria are not

defined.

DS26521 Datasheet(PDF) 74 Page - Maxim Integrated Products

DS26521 Datasheet(HTML) 74 Page - Maxim Integrated Products

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 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL