Noise-With-Tone (Notched Noise); 50 Kbit Filter; Signal-To Noise Measurement - HP 4935A Operating And Service Manual

Operation
3-40. NOISE
3-42. NOISE-WITH-TONE
The noise-with-tone measurement technique is used to condition compandors and/or quantizers
the transmission
received which duplicate levels present under operating conditions.
At the receiving 4935A,
frequencies between 995 Hz and 1025 Hz are attenuated by 50 dR). The remaining received signal (noise) is
illustrates the combination of the
combines th(s notch with any of the five filters.
3-45. SIGNAL-TO-NOISE
1004 Hz signal is selectively attenuated by
The remaining received
computed signal-to-noise ratio is displayed in units of dB.
one or the most important parameters for determining the quality of a line.
- 8
- 2 0
1 0 100
Figure 3-10. 50 kBit Filter
MEASUREMENTS
noise levels are displayed in units ofdlirn, or dH with respect to reference noise (1000 Hz
is displayed in dRm.
(Notched
system to their normal operating
the 1004 Hz holding tone is selectively attenuated by
MEASUREMENT
mode allows measurement of the ratio of received signal-plus-noise power to
signal (noise) is then
F R E Q U E N C Y (Hz)
Noise)
levels for continuous
weighting and notch filter characteristics. The 4935A
compared with the original
Figure :<-I 2 illustrates this measurement. This is
5 0 K
power of -70 dHm (20 - 90 = -70).
data signals. Therefore,
signal-plus-noise signal.
Model 4935A
in
noise
1
The