The following information is
provided to answer some of the
most common questions about
the use of these parts.
Transceiver Optical Power
Budget versus Link Length
Optical Power Budget (OPB) is
the available optical power for a
fiber optic link to accommodate
fiber cable losses plus losses due
to in-line connectors, splices,
optical switches, and to provide
margin for link aging and
unplanned losses due to cable
plant reconfiguration or repair.
Figure 4 illustrates the predicted
OPB associated with the three
transceivers series specified in
this data sheet at the Beginning of
Life (BOL). These curves repre-
sent the attenuation and chromatic
plus modal dispersion losses
associated with the 62.5/125
µm
and 50/125
µm
fiber cables only.
The area under the curves
represents the remaining OPB at
any link length, which is available
for overcoming non-fiber cable
losses.
Hewlett-Packard LED technology
has produced 800 nm LED and
1300 nm LED devices with lower
aging characteristics than
normally associated with these
technologies in the industry. The
industry convention is 3 dB aging
for 800 nm and 1.5 dB aging for
1300 nm LEDs. The 1300 nm HP
LEDs are specified to experience
less than 1 dB of aging over
normal commercial equipment
mission life periods. Contact your
Hewlett-Packard sales represen-
tative for additional details.
Figure 4 was generated for the
1300 nm transceivers with a
Hewlett-Packard fiber optic link
model containing the current
industry conventions for fiber
cable specifications and the draft
ANSI T1E1.2. These optical
parameters are reflected in the
guaranteed performance of the
transceiver specifications in this
data sheet. This same model has
been used extensively in the ANSI
and IEEE committees, including
the ANSI T1E1.2 committee, to
establish the optical performance
requirements for various fiber
optic interface standards. The
cable parameters used come from
the ISO/IEC JTC1/SC 25/WG3
Generic Cabling for Customer
Premises per DIS 11801 docu-
ment and the EIA/TIA-568-A
Commercial Building
Telecommunications Cabling
Standard per SP-2840.
The HFBR-5203 series 800 nm
transceiver curve in Figure 4 was
generated based on extensive
empirical test data of the 800 nm
transceiver performance. The
curve includes the effect of typical
fiber attenuation, plus receiver
sensitivity loss due to chromatic
and metal dispersion losses
through the fiber.
Transceiver Signaling
Operating Rate Range and BER
Performance
For purposes of definition, the
symbol (Baud) rate, also called
signaling rate, is the reciprocal of
the symbol time. Data rate (bits/
sec) is the symbol rate divided by
the encoding factor used to
encode the data (symbols/bit).
When used in 155 Mbps SONET
OC-3 applications the perform-
ance of the 1300 nm transceivers,
HFBR-5204/5205 is guaranteed
to the full conditions listed in
individual product specification
tables.
The transceivers may be used for
other applications at signaling
rates different than 155 Mbps
with some variation in the link
optical power budget. Figure 5
gives an indication of the typical
performance of these products at
different rates.
12
HFBR-5205, 62.5/125 µm
OPTICAL POWER BUDGET (dB)
10
HFBR-5203,
62.5/125 µm
8
HFBR-5205,
50/125 µm
6
HFBR-5203,
50/125 µm
4
HFBR-5204,
62.5/125 µm
2
HFBR-5204,
50/125 µm
0
0.3 0.5
1.0
1.5
2.0
2.5
FIBER OPTIC CABLE LENGTH (km)
Figure 4. Optical Power Budget vs. Fiber Optic Cable Length.
These transceivers can also be
used for applications which
require different Bit Error Rate
(BER) performance. Figure 6
111
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