Figure 2-3.
Frequency response test, block diagram.
(2) Output levels from the line are taken relative to the received
level at 1.0-kHz reference frequency. A separate level reading is taken for
each of the frequencies listed on the frequency response data sheet (figure
2-4).
(3) Establish a standard level at the transmitting end of the circuit
by placing the MEAS-CAL switch of the patch panel to the CAL position and by
adjusting the AMPLITUDE control for the oscillator for an output of 0 dBm at
1,000 Hz. (In the CAL position the oscillator is connected directly to the
voltmeter so that the level of the oscillator can be calibrated.) After the
level is set, return the MEAS-CAL switch back to the MEAS position. Do not
make any adjustments to the signal level. If the level varies, it can be
attributed to impedance mismatch between the 600-ohm oscillator output and
the line under test. Adjust the FREQ control of the oscillator to the first
frequency indicated on the frequency response data sheet (figure 2-4)
without making any adjustments to the signal level.
If at any selected
frequency the oscillator output level varies from the level observed at
1,000 Hz, set the MEAS-CAL switch on the patch panel to CAL and adjust the
AMPLITUDE control of
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