Measurements (18-0015) AM-48 Test Set
0015-S088-4
8.3 Level (Loss or Gain) and Frequency
Level or frequency measurements are made by applying a tone of a
known frequency and amplitude (normally 1004Hz @ 0.0 dBm) to
the distant end of the transmission line being tested, and then
measuring the received level and frequency at the near end. The
difference between sent level and received level is the loss (or gain)
introduced by the line. The difference in sent frequency and received
frequency is the frequency offset introduced by the line.
8.4 Idle Channel Noise
These noise measurements are made through an internal noise-
weighting (shaping) filter on a line under test
without tone present.
One (1) of four (4) standard noise-weighting filters is selected for this
test:
C-Message,
C-MSG (Psophometric, PSHO , for AM-48E)
3-kHz,
3K
15-kHz,
15K
Program,
PROG (Sound-weighted, SWTD , for AM-48E)
The distant end of the line being measured is normally “Quiet
Terminated”, i.e., disconnected from the distant modem or terminal
and connected to a resistive termination.
8.5 Notched Noise (Noise with Tone)
Far End . A notched noise measurement is made with a holding tone
of a specific frequency (normally 1004Hz in North America) applied
to the distant end of the line under test.
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