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73.840: Difference between revisions
→The difference between transmitter power output and effective radiated power
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Broadcast stations, including LPFM stations are authorized to operate a specific [[effective radiated power]] (ERP). The effective radiated power is the actual power of the station as the signal leaves the antenna. Between the transmitter and antenna, there are several factors that diminish the signal from the transmitter, this includes the type and length of the feedline (wire) from the transmitter to the antenna. The antenna itself may also play a factor. Some antenna configurations, such as the popular circular polarized antennas like the [[Nicom BKG-77]], [[Nicom BKG-88]] and [[Shively 6812]] in a single antenna configuration will cause a loss in the transmitter power as it reaches the antenna while some antennas, such as the vertical-only [[Norwalk Dominator]] will exhibit a gain at the antenna. | Broadcast stations, including LPFM stations are authorized to operate a specific [[effective radiated power]] (ERP). The effective radiated power is the actual power of the station as the signal leaves the antenna. Between the transmitter and antenna, there are several factors that diminish the signal from the transmitter, this includes the type and length of the feedline (wire) from the transmitter to the antenna. The antenna itself may also play a factor. Some antenna configurations, such as the popular circular polarized antennas like the [[Nicom BKG-77]], [[Nicom BKG-88]] and [[Shively 6812]] in a single antenna configuration will cause a loss in the transmitter power as it reaches the antenna while some antennas, such as the vertical-only [[Norwalk Dominator]] will exhibit a gain at the antenna. | ||
To compensate for this, the LPFM station actually needs to operate at a power level that exceeds and in some cases, well exceeds the 100 watts (or whatever power level) ERP they are authorized. This is done through a calculation that looks at the "insertion loss" of these items in the transmission system. Based on this calculation, it will determine how much power needs to run from the transmitter in order to be able to generate the authorized ERP at the antenna. This is referred to as the "transmitter power output" or TPO. When the construction is completed, this TPO will be placed on the license application and when granted, will show on the station license in addition to the ERP. | To compensate for this, the LPFM station actually needs to operate at a power level that exceeds and in some cases, well exceeds the 100 watts (or whatever power level) ERP they are authorized. This is done through a calculation that looks at the "insertion loss" of these items in the transmission system. Based on this calculation, it will determine how much power needs to run from the transmitter in order to be able to generate the authorized ERP at the antenna. This is referred to as the "[[transmitter power output]]" or TPO. When the construction is completed, this TPO will be placed on the license application and when granted, will show on the station license in addition to the ERP. | ||
== The TPO tolerance for LPFM stations == | == The TPO tolerance for LPFM stations == | ||