73k222al ETC-unknow, 73k222al Datasheet - Page 24

• Manufacturer Part Number: 73k222al
• Description: V.22, V.21, Bell 212a, Single-chip Modem
• Manufacturer: ETC-unknow

73K222AL
V.22, V.21, Bell 212A, 103
Single-Chip
pattern was used for each data point.
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.
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 aberrant
Noise was
24
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.