Talk-Back Losses
Q: When I computed my field strength study I included body and building losses for the mobile receiver. How do I include these losses in the Talk-Back study?
A: Including these losses is an important part of evaluating the coverage of your base station or repeater. You can also include the losses in the talk-back calculations based on that study.
Note that all values shown in this article are for illustration purposes only. It is important that you use good engineering judgment to determine the values that are appropriate for your equipment and specific application.
As explained in the article about setting values for body or building losses when computing required field, the Mobile Facility database is used, first clicking the Required Field Lookup button:
Then on the Required Field Strength Lookup form, click the Gain/Loss Lookup button:
The loss values you want to use for the receiver portion of the mobile unit (for the Talk-Out study) are entered on the Miscellaneous Losses\Gains Lookup form:
Likewise, when you are setting up the transmitter portion of the mobile record (for the Talk-Back study) you can include loss values, such as body, building, or vehicle losses.
On the Mobile Facility Lookup form, click the ERP/ANTENNA Lookup button:
On the Effective Radiated Power Lookup form, click the Loss Lookup button:
Then enter the desired loss values for the mobile transmitter on the Miscellaneous Losses\Gains Lookup form:
The loss values you enter for the transmit and receive functions of the mobile unit may be the same, but TAP also gives you the flexibility to use different values to represent different configurations. For example, you may want to assume worse conditions for the Talk-Out study (higher loss values for the mobile receiver). This would represent the situation where a handheld radio was lying on the seat of a vehicle. However, when the user picks up the unit, holding the antenna vertically, near the window of the vehicle, you may want to represent the Talk-Back situation (mobile transmitter) with lower loss values. As always, you need to determine the best way to represent your particular circumstances.
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Copyright 2004 by SoftWright LLC