The digital test functionality of the Model
404e allows a wide range of testing on framed or
unframed 1.544 & 2.048Mbps T1/E1 circuits and Datacom circuits like V.35 etc.
Two TX/RX ports are provided in order to allow bidirectional drop and
insert testing. The unit can terminate the line (simultaneous
pattern generation and pattern measurement) or
monitor the line for BERT patterns, ABCD bit status,
and TS16 frame synchronization and CRC errors. The
Model 404e is compatible with unframed PCM as well
as PCM24/30 and PCM31 framing with HDB3 encoding.
Enhanced Digital (optional)
With the Enhanced Digital option, an T1/E1 telephone is
added with dial, talk & listen capability on any user
selected T1/E1 voice channel. The Enhanced Digital option
provides VF testing of any user selected channel including
voiceband level, frequency, noise and return loss.
Real-time error counters are augmented by histograms
so that the distribution of errors during a test can be
The Enhanced Digital option augments the standard
patterns with 5 user programmed long patterns
which can be as short as 1 byte or as long as 128
Finally, the Enhanced Digital option provides a
graphical display of pulse shape with the G.703 or a
user set table Mask.
T1/E1 Physical Layer Testing
The Model 404-4 measures the actual T1/E1
frequency and level to verify basic signaling integrity.
Real time error counters of framing, code,
logical and CRC errors are kept for the duration of the
test. Individual error type displays can be accessed
each showing errored seconds, error free seconds,
degraded minutes and other
pertinent G.821 data.
Extensive pattern generation and detection with
G.821 bit error rate reporting are provided.
V.35, RS232, RS449 and EIA530 interfaces are provided
in the Model 404-4. Errors can be injected into the
data one bit at time or in bursts. The Model 404e also
reports the presence of both Transit and Receive clocks
to make troubleshooting fast and easy.
AutoTesting with AM440
Model 404-4 test analog measurements automatically
with AM440 Remote Test Partner placed at the other
end of the wire. LVL/FREQ/NOISE are examples of
auto tests performed with the Model 404-4 and the
In analog mode the unit provides a wide variety of
industry standard measurements to accomplish transmission
impairment testing on 2 or 4-Wire dedicated
or dial-up analog circuits.
The 400kHz bandwidth of the instrument makes it
ideal for qualifying metallic digital circuits which use
an analog carrier such as ISDN BRI (“U” interface)
and 4-Wire HDSL circuits.
A Full Functional Analog Transmission Impairment Tester
Full Duplex Operation
The internal measurement functionality and signal
generator functionality may be used separately at
each end of a transmission line or simultaneously as
would be the case when doing a loopback test from
one end of the line.
The display provides both a digital and analog readout
of the measurement, or the results may be printed on
the optional printer.