For now, we discuss the first four concerns. Most of today s digital signals are generally flat across the channel bandwidth. This digital traffic is always on and will be time division multiplexed. This allows it to be multiplexed with other MPEG-2 digital streams and sends filler packets when needed. Upstream data signals from the subscribers equipment are bursty as in Figure 2 .
Measurements are easier to make on a continuous data carrier than on upstream, bursty signals.
Making accurate measurements Measurements should be made with the proper test equipment, such as a thermocouple power meter or test equipment made for an average power measurement. This is critical for set-up to prohibit laser clipping or extreme intermodulation noise. One approach to average power measurements takes small slices of the integrated RF energy, summing them together to one total power reading as displayed in Figure 3 . Sometimes a quick mode, which measures signals based on bandwidth estimation technique, is warranted for quick verification or for very narrow carriers. User-selectable bandwidth is needed for accurate power measurements when doing these tests.