Use of “all- in-view” stations by a receiver is made possible due to the synchronization of LORAN stations signals to UTC. However, a new generation of receivers has been developed that use pulses from all stations that can be received at the pilot’s location. Acquisition involves the time synchronization of the receiver with the chain GRI, identification of the Master station signals from among those checked, identification of secondary station signals, and the proper selection of the tracking point on each signal at which measurements are made. For a currently certified LORAN aviation receiver to provide navigation information for a pilot, it must successfully receive, or “acquire,” signals from three or more stations in a chain. Similar coverage area charts are available for all chains.ġ. In a signal coverage area the signal strength relative to the normal ambient radio noise must be adequate to assure successful reception. The chain Master station is at Fallon, Nevada, and secondary stations are at George, Washington Middletown, California, and Searchlight, Nevada. Each individual LORAN chain provides navigation-quality signal coverage over an identified area as shown in FIG 1-1-15 for the West Coast chain, GRI 9940. These situations when detected cause signal transmissions from a station to be halted.Ĩ. Out-of-tolerance situations which only the local station can detect are also monitored. Blink is a distinctive change in the group of eight pulses that can be recognized automatically by a receiver so the user is notified instantly that the LORAN system should not be used for navigation. If an out-of-tolerance situation that could affect navigation accuracy is detected, an alert signal called “Blink” is activated. The System Area Monitor (SAM) is a single site used to observe the transmitted signal (signal strength, time difference, and pulse shape). The transmitted signal is also monitored in the service areas (i.e., area of published LORAN coverage) and its status provided to NAVCEN and NAVCEN Det. If both NACEN and NAVCEN Det are down or if there is an equipment problem at a specific station, local station personnel are available to operate and perform repairs at each LORAN station.ħ. In the event of a problem at one of these two 24 hour-a-day staffed sites, monitoring and control of the entire LORAN system can be done at either location. By the NAVCEN Detachment (Det), located in Petaluma, California.
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