User's Manual

Initial Prism System Setup

Page 166 FlexWave Prism Host, Remote and EMS 5.1 System Reference

400 In the

DART Forward Delay

box, set in microseconds the actual delay that will be

applied to the RF forward path signal. The minimum delay required is calculated.

The acceptable range of delays is 88us. If you attempt to set the delay to a value

outside the allowed range, the DART uses either the minimum or maximum,

dependant on whether the DART is exceeding the set delay (too high or low).

Be aware of simulcast links. Observe the minimum delay required for the longest

link, and set the delay to the same value for all simulcast nodes in the same

connection based on this value.

Here is an example:

•• Fiber has 8 usec per mile of fiber.

•• Remote 1 has 5 miles of fiber (40 usec of fiber delay).

•• Remote 2 has 10 miles of fiber (80 usec of fiber delay).

•• Remotes are set to Cellular A"/A Band which has 8 usec of system delay. The

delay ranges will therefore be:

– Remote 1 delay (48-136)

– Remote 2 delay (88-176)

The system calculates these delay values—this is a typical example based on the fiber

lengths provided. You select a delay value that’s within the range calculated by the

system.

Set the delays to the same values for all nodes in the network in order to:

•• Optimize simulcast

•• Make BTS datafill changes simple (same delay offsets for all nodes)

•• Simplify E-911 integration (same delay offsets for all nodes)

Delays cannot be shortened; they can only be lengthened. The recommended

approach is to normalize all Remotes to the longer minimum delay. In this

example the delay would therefore have to be 88 usec.

411 In the

DART Reverse Delay

box, set in microseconds the actual delay that will be

applied to the RF reverse path signal. The actual delay of the RF path will be within

1 usec. For E-911 TDOA applications, the reverse path delay must be measured to

achieve the +/- 50 nsec delay accuracy specified for DAS networks. The FWD and

REV delay values are usually the same because the fiber path between the two is

typically the same.

422 Click

Apply