Additional Gains & Losses

During communications and radar analyses, it is often necessary to model gains and losses that affect performance but are not defined using built-in analytical models. STK allows you to model these by specifying miscellaneous gains and losses to add to the equation. For communications receivers, these can be accounted for in two places: effects that occur before reaching the receiver antenna (pre-receive values) and those that occur after the output of the receiver antenna but before demodulating the data(pre-demodulation values). For communications and radar transmitters, post-transmit gains and losses are modeled.

Pre-Receive and Pre-Demodulation Gains & Losses

To specify pre-receive gains and losses, or to record pre-demodulation values for the receiver, select the Additional Gains and Losses tab on the Receiver's Definition page.

The first table allows you to record and track all gains and losses for the receiver by entering a brief description (up to 80 characters) and an associated value for the gain or loss. Gains are entered as positive values and Losses as negative values. A typical example of a pre-receive loss is a pointing loss of -1 dB.

To define a Gain or Loss, click Add. In the spaces provided in the grid, enter a brief description of the Gain or Loss and its value. Remember to make it negative if a Loss is being entered. Once the values are entered, you can click Remove to delete an entry from the table. To modify an existing entry, simply edit the fields in the grid. When you finish entering all values in the table, click OK. The value in the Pre-Receive field will reflect the net value of all gains and losses recorded in the table. To leave the Gains & Losses dialog without recording the additions or changes you have made, click Close.

You can record pre-demodulation values in the second table by adding, removing, and modifying entries in the same manner as for pre-receive gains and losses, described above.

Post-Transmit Gains & Losses

You can record post-transmit gains and losses for a communications transmitter or a radar transmitter by selecting the Additional Gains and Losses tab of the Transmitter Definition page or the Radar Definition->Transmitter tab and then adding, removing, and modifying entries in the same manner as for pre-receive gains and losses, described above.