MT89761 Ver la hoja de datos (PDF) - Mitel Networks
Número de pieza
componentes Descripción
Fabricante
MT89761 Datasheet PDF : 6 Pages
| |||
MH89761
Applications
The MH89761 can be connected to the MH89760B
as illustrated in Figure 1. All pins on the MH89761
not shown connected in Figure 1 should be left open.
The internal circuit of the equalizer is shown in
Figure 2. The MH89761 has two separate circuits; a
6dB pad and an equalizer.
Ti and Ri are inputs to the 6dB pad on the device.
The outputs of the pad are brought out on TL and
RL. The 6dB pad is provided to loopback the
transmit signal back to the receive without altering
the equalizer settings. The 4 pole double throw relay
shown in Figure 1 permits connection of the output of
the transformer TR1 to either the equalizer or the
fixed 6dB pad. For normal operation and
transmission out to the line, the transformer should
be connected to the equalizer inputs EIT and EIR.
Enabling the relay will switch the connection through
the 6dB pad for loopback diagnostics.
The MH89761 is designed to accept output from the
secondary of the T1 transmit transformer and
condition it for transmission over twisted pair. The
seven switches (S1 to S7) permit configuration of the
equalizer for different line lengths. The pulse
amplitude at the secondary of TR1 is approximately
6V. Passing this signal through the equalizer with
zero line length setting on the switches will result in
attenuation of the pulse by 6dB. This will ensure that
the pulse fits in the template shown in Figure 3 and
meets DSX-1 requirements. By switching in
different C and L components, the frequency and
phase response of the equalizer can be altered as
shown in Figures 4 and 5. Note that the circuit
attenuates lower frequencies more than higher
frequencies. Consequently, when a pulse is passed
through the equalizer, lower frequency components in
the signal are attenuated more than higher frequency
components. The intention is to compensate for the
attenuation properties of twisted pair cable, which
tends to attenuate higher frequencies more than
lower frequencies. The net result is that a pre-
equalized pulse will meet DSX pulse requirements
after traversing a specific length of cable.
The cable length indicated along withthe equalizer
switch settings in Figure 4 are specific to 22 awg
ABAM cable interfaced to an MH89760B equipped
with a Filtran TFS2573 transformer. Different
equalizer settings may be more appropriate for other
cable and transformer types. Figure 6 shows the
generic switch settings for different levels of
equalization.
Reference:
Manufacturer:
ANSI T1.102 - 1987, Section 2.2
Filtran Ltd.
(613) 226-1626
4-94
Advance Information
Ti
•
50Ω
•
TL
50Ω
50Ω
6dB Pad
•
100Ω
•
50Ω
Ri
•
50Ω
50Ω
•
RL
•S5 200Ω
4870pF
•
S4
•
• 390Ω •
2150pF
•
EiT
•
50Ω
50Ω
•
TxT
50Ω
•
100Ω
EQUALIZER
••
12Ω
27Ω
S1
•
10µH
• S2
22µH
S3
50Ω
50Ω
EiR
50Ω
•
TxR
2150pF
•
S6 •
S7 •
•
4870pF
•
200Ω
Figure 2 - 6dB Pad and Equalizer Pin
Share Link: 