ed in the desired direction. The unit of measure is dBW or dBm, because we are talking about power. EIRPdBW = Pt(dBW) + LL(dB) + antenna (dBi)' where Pt is the output power of the transmitter either in dBm or dBW. LL is the line loss in dB. That is the transmission line connecting the transmitter to the antenna. The third factor is the antenna gain in dB. Warning! Most transmitters give the output power in watts. This value must be con- verted to dBm or dBW. Example 1. A transmitter has an output of 20 W, the line loss is 2.5 dB, and the antenna has 27-dB gain. What is the EIRP in dBW? Convert the 20 W to dBW = +13 dBW. Now we simply algebraically add: EIRP = +13 dBW - 2.5 dB + 27 dB = +37.5 dBW. Example 2. A transmitter has an output of 500 mW, the line losses are 5.5 dB, and the antenna gain is 39 dB. What is the EIRP in dBm? Convert the transmitter output to dBm, which = +27 dBm. Now simply algebraically add (Ref. 3): EIRP = +27 dBm - 5.5 dB + 39 dB = 60.5 dBm. LEARNING DECIBELS AND THEIR APPLICATIONS REFERENCES 1. Transmission Systems for Communications, 5th ed., Bell Telephone Laboratories, Holmdel, NJ, 1982. 2. Transmission Systems for Communications, revised 4th ed., Bell Telephone Laboratories, Merrimack Valley, MA, 1971. 3. R.L. Freeman, Telecommunications Transmission Handbook, 4th ed., Wiley, New York, 1998. APPENDIX ACRONYMS AND ABBREVIATIONS 0 TLP zero test level point 2 binary to 1 quaternary ATM adaptation layer automatic alternative routing asynchronous balanced mode ABSBH average busy season busy hour ac, AC alternating current acknowledge, acknowledgment analog-to-digital add-drop multiplex ADPCM adaptive differential pulse code modulation asymmetric digital subscriber line automatic gain control alarm indication signal automatic line build-out amplitude modulation alternate mark inversion advanced mobile phone system American National Standards Institute avalanche photodiode average picture level asynchronous response mode Advanced Research Projects Agency automatic repeat request address resol