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
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
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
Equipment used (radio, trunk line, computer,
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