73k224bl ETC-unknow, 73k224bl Datasheet - Page 30

• Manufacturer Part Number: 73k224bl
• Description: Single-chip Modem Integrated Hybrid
• Manufacturer: ETC-unknow

73K224BL
V.22bis/V.22/V.21/Bell 212A/103
Single-Chip Modem w/ Integrated Hybrid
close to each other near the area of the board
where the phone line connection is accessed. To
avoid problems, power supply and ground traces
should be routed separately to the analog and
digital functions on the board, and digital signals
should not be routed near low level or high
impedance analog traces. The analog and digital
grounds should only connect at one point near the
K-Series device ground pin to avoid ground loops.
The K-Series modem ICs should have both high
frequency and low frequency bypassing as close
to the package as possible.
MODEM PERFORMANCE
CHARACTERISTICS
The curves presented here define modem IC
performance under a variety of line conditions
while inducing disturbances that are typical of
those encountered during data transmission on
public service telephone lines. Test data was
taken using an AEA Electronics’ “Autotest I”
modem test set and line simulator, operating
under computer control. All tests were run full-
duplex, using a Concord Data Systems 224 as the
reference modem. A 511 pseudo-random-bit
pattern was used for each data point. Noise was
C-message weighted and all signal-to-noise (S/N)
ratios reflect total power measurements similar to
the CCITT V.56 measurement specification. The
individual tests are defined as follows.
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BER VS. S/N
This test measures the ability of the modem to
operate over noisy lines with a minimum of data-
transfer errors. Since some noise is generated in
the best of dial-up lines, the modem must operate
with the lowest S/N ratio possible. Better modem
performance is indicated by test curves that are
closest to the BER axis. A narrow spread between
curves representing the four line parameters
indicates minimal variation in performance while
operating over a range of operating conditions.
Typically, a DPSK modem will exhibit better BER
performance test curves receiving in the low band
than in the high band.
BER VS. RECEIVE LEVEL
This test measures the dynamic range of the
modem. Because signal levels vary widely over
dial-up lines, the widest possible dynamic range is
desirable. The minimum Bell specification calls for
36 dB of dynamic range. S/N ratios are held
constant at the indicated values while the receive
level is lowered from a very high to very low signal
levels. The width of the “bowl” of these curves,
taken at the BER point, is the measure of dynamic
range.