The calculations of relative levels start with finding the difference

between absolute levels.

Maximum permitted relative levels in dBm0 are

obtained from the appropriate parameter.

Example:

Assume that the normal level at the TLP is -10 dBm. If the

level of the second harmonic is -38 dBm, what is the

relative level of the second harmonic?

The difference in decibels between the TLP normal level (-

10 dBm) and the second harmonic level (-38 dBm) is 28 dB.

Since -10 dBm is equivalent to 0 dBm0, the relative

harmonic level is -28 dBm0.

Example:

If the parameter requirement of harmonic level is at least

-35 dBm0, is the parameter satisfied?

No, because -28 dBm0 is a higher relative level than -35

dBm0.

In other words, the harmonic level is 7 dB higher

than can be tolerated under the specified parameter.

(1) Using the voltmeter, calibrate the level of the oscillator to be

10 dB below the normal signal level at TLP of the circuit, at a frequency of

700 Hz. Then connect the oscillator to the sending end of the line in place

of the normal line signal.