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SDA-5500/SDA-5510 Sweep Configuration: Sweep History and Theory

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relative readings among several system test points and to allow referencing

to cancel some errors. For this reason, sweep systems usually do not

display absolute levels.

Acterna’s Stealth sweep, however, has adapted the reverse sweep system

to provide the right information for quick alignment of reverse gain and tilt.

The screen displays absolute values for injection levels and headend

receiver levels at high and low frequency tilt markers. A chart below the

sweep response curve displays absolute levels, system gain (delta) and tilt

between the tilt markers.

Reverse Noise Broadcast

When you are troubleshooting reverse path problems in the field (including a

sweep system that is not working), it can be very helpful to see a spectrum

display from the headend. You can set up the SDA-5510 and SDA-5500 to

record a spectrum display of their reverse path input. The spectrum data can

then be sent out into the field over the Stealth telemetry channel for viewing

by field units. The SDA-5510 automatically performs this task; the SDA-5500

allows it as an option.

NOTE: Activating the feature in an SDA-5500 slows down

forward sweep response by roughly 0.5 seconds per

refresh.

Because this display is sent in the forward telemetry channel, it is available

even if reverse sweep is not working from the current location. The most

important use for this information is reverse path ingress troubleshooting.

You can compare the reverse path spectrum at the current location with what

the headend sees. If the noise causing reverse path problems at the

headend matches what is seen locally, then the noise source is probably

downstream from the current test point. This can be confirmed by reducing

the gain on the leg in question, or by momentarily disconnecting it.

CAUTION ! Disconnecting the leg will cause an

interruption in service.

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Wavetek 147 Spezifikationen Seite 328