Talk-Out and Talk-Back Comparisons

TalkOut and TalkBack Comparisons

Q: I am looking at 100Watt Base Stations and 3-15W Portables/Mobiles. I understand that TalkOut is from the Base to the portable and the TalkBack (or TalkIn) is from the portable to the base. Why is my Talk Back coverage bigger? Shouldn't the base station, which is 100 Watts, be able to "talk out" further than a portable or mobile can "talk back"?

A: Your assumption (that a 100W base coverage should be better than a 15W mobile talkback) is generally true, but there are a number of factors that can produce legitimate (if counter-intuitive) results where the talkback coverage is better than the talkout.

Note that all values in this example are for demonstration purposes only. You should determine appropriate settings for your application.

For example, if the receiver specs at the base station are significantly better than the mobiles (higher gain base station receiver antenna, more sensitive receiver input), the talkback coverage will be improved.

Likewise, since our TAP software enables the user to include additional losses for the mobile receiver (to account for body losses, etc.) if those losses are not accounted for in the mobile transmit specifications, the talkback coverage will again be improved. This can be a realistic situation if the talkout study is designed for "worst case" conditions, such as when a mobile user has the radio in a jacket pocket or other conditions that restrict the mobile receiver for talkout coverage. But when the mobile user takes out the radio to transmit back to the base the losses are not as severe. Naturally, in that scenario, the mobile receiver also works a lot better, but that would be another situation where the computed talkback would be better than the talkout calculations.