SDA-5500/SDA-5510 Sweep Configuration: Sweep History and Theory
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A sweep transmitter injects a signal of a known level and frequency at the
input of the network. At the output of the network, a receiver measures the
level at the transmitter’s frequency and saves it in a table. Plotting the level
at each frequency makes it possible to calculate the frequency response of
the network. This is the most basic definition of sweep. However, in practice
this testing becomes more complex, as the following sections explain.
Remote Operation and Channel Plans
The first condition that must be satisfied to perform a forward sweep is that
the transmitter and receiver must be in different, or remote, locations. Prior
to the sweep, you must create a channel plan to coordinate the operation of
the transmitter and receiver. This channel plan must define exactly how the
network will be measured by establishing the frequencies to be measured,
how they will be measured, and for how long. A channel plan common to
both receiver and transmitter allows for the exact timing and frequency of
each pulse at both places. The receiver and transmitter move through each
frequency in unison, measuring the frequency response one point at a time.
See Also
½ "Creating Channel Plans" covers channel plans in more
detail (page 274).
½ Chapter 3, "Channel Plans," covers channel plan
configuration and creation with the SDA field units.
Telemetry Channel
Because it is important to minimize manpower requirements, the Stealth
sweep system allows the transmitter to work automatically and continuously
at the headend without an attending operator. This is possible because of a
telemetry channel that is set up to synchronize the transmitter and receiver.
Before beginning to sweep, the transmitter sends a synchronizing pulse,
which initiates a single sweep of the network. After this synchronizing pulse,
the transmitter and receiver both step, one frequency at a time, through the
channel plan. At each frequency the transmitter generates a pulse of a
known level, and the receiver measures the received level. Because the
channel plans are identical in receiver and transmitter, no human
intervention is required to keep the units synchronized, and the
measurements can be made far more quickly than if they were performed
manually.
Additionally, to be certain that the channel plan used by the receiver and
transmitter match, channel plan data are also sent over the telemetry
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