Myth: Changing the NCS Will Always Solve Net Problems!

on to junior link techs and the mythology developed a life of its own. In the following paragraphs, we examine some of these myths and seek to clarify the real problems that led to the evolution of the myths. Myth: Changing the NCS Will Always Solve Net Problems! Changing the NCS may solve net problems, but only if the current NCS is causing the problem. What is the problem? If data is not being received from a unit because the current NCS has entered the PU number incorrectly, shifting NCS functions to a station with the PU data entered correctly will solve the problem. However, it would be easier if the current NCS were simply to enter the correct PU numbers. When the current NCS is using a radio set with poor receiver sensitivity and is polling on top of picket responses, effectively jamming the entire net, changing NCS is imperative. Also, if several units are not recognizing their interrogations because the NCS is out of range or in an RF propagation shadow, changing to a unit in a better location should improve net communications. Myth: Changing Frequency Always Solves Net Problems! Here again is a myth that has some basis of fact. Changing frequency is a time- consuming process. When all the procedures are not carefully followed, changing the frequency induces additional problems into the net. This myth developed because improperly set switch positions and patch panel configurations were often set to the proper position during the frequency changing process. When the problem is connectivity on the current frequency, the proper action is to find a better frequency. Myth: More Power Improves Link Performance! This is a myth. On the transmit side, the idea behind the myth is that keeping the link HF transmitter tuned to maximum output power will result in maximum area coverage. In fact, constantly outputting maximum power can lead to serious RFI/EMI problems (on the ship doing so) and will not significantly increase the signal propagation range. The idea behind the myth on the receive side is that by keeping the HF receiver audio output control maximized, receive quality improves. In fact, maximizing the audio output saturates most data terminal sets. Saturation generally occurs in the DTS at around 3 dBm. Signal inputs above this level actually increase receive data errors. Myth: Dummy PUS Improve Link Quality! A dummy PU is an address insert into the polling sequence by the NCS for which there is no live unit. Dummy PUS cause the net cycle time to increase and net efficiency to decrease. The idea that the NCS must use dummy PUS for the link to 3-2