Multi-Station POFA Procedures

Figure 3-2.—Link-11 multi-station POFA data flow. Multi-Station POFA Procedures The procedures for running a multi-station POFA require coordination of all participating units. For this to be a good test, all units must be positioned within 25 miles of each other. This is usually coordinated by the Link-11 manager in conjunction with the battle group commander. Just before the time the multi-station POFA is to be conducted, NCS should end the operational link and direct all stations to run a single station POFA. The picket station reports back to NCS when the single station POFA has been completed. The picket station will also report the status of the single station error printout. Any errors noted during single station POFA should be corrected before the multi-station POFA, or the station experiencing errors should not be included in the multi-station POFA. The multi-station POFA should be run using the same frequency as the current operational frequency. After running the single station POFA, NCS should direct all participants to go to Radio Silence. During this time, all stations should monitor the assigned frequency for noise. The frequency can be monitored through the headphones or by using a frequency analyzer. A noisy frequency can cause errors in the multi-station POFA. If the frequency is too noisy, consider using an alternate frequency. Once the frequency has been checked, NCS will tell all participants to prepare to receive POFA. After all stations report that they are ready, NCS initiates the POFA. All stations monitor the POFA, and check the control panel of the DTS for errors. After a minimum of 5 minutes, NCS terminates the POFA. When the POFA is terminated, a printout is generated. The final step in running a multi-station POFA is the analysis of the printout. Analyzing Multi-Station POFA Results Running a multi-station POFA closely approximates actual link operating conditions. To analyze the printout fully, the technician needs to be aware of some of the factors that can affect link operations. When the printout is completed, the analysis is easier to complete if the technician records the following information on the printout: Which station is NCS Distance and relative bearing of all participating units Frequency used Frequency quality Equipment used (radio, trunk line, computer, crypto, etc.) Start and stop time of the POFA The printout will contain a summary of the activity that includes the time, in minutes and seconds, that the station was on the air, the total number of words transmitted, the total number of words received, and the total number of words with errors. This information can be used to calculate the link quality factor. To calculate the link quality factor, divide the number of words received by the number of words transmitted. When the quotient is greater than 95 percent but less than 100 percent, consider the POFA successful. Next, compute the receive error factor. Ideally, the POFA should run with zero errors. Since the 3-5