Naval Electronics AB manufactures extremely efficient Tap-Offs that are expressly for the shipboard environment. They represent the most up-to-date technology for cable signal distribution with very low
distribution losses compared to the old fashioned "daisy chain" method.The advantages of using these Tap-Offs are several:
More cost efficient to install:
Because a cable only goes into a stateroom once and does
not come out again, means that you install about ½ as much cable for lower material and installation labor costs.
More equal signal levels throughout the distribution system:
Since less cable is installed, the
lengths are shorter and that gives you lower signal attenuation due to cable length. Naval Electronics AB has now come out with Tap-Offs with tap values of 21, 17 and 12 dB to level the outlet levels throughout the
distribution system. This eliminates the stair stepping of outlet signal levels seen in older "daisy chain" systems. This stair-stepping is caused in part by the daisy chain type of outlet. The signal going into the
outlet box is significantly reduced when it comes out to go on to the next outlet. So, because the Tap-Off is located equal distant from each of the outlets it serves (if it is mounted properly), each of the outlets
have the same signal level.
Lower after installation maintenance:
Because the tap isolation is in the Tap-Off, and it is located in the overhead in the passageway (ideally), the distribution system is
more "sailor proof" because it is mounted away from the sailor's space. The outlet in the room is just a feed-through and no matter what the sailor does to "modify" his outlet box, he cannot damage the distribution
system and affect any other outlet besides his own. The Tap-Off protects against that. If the sailor complains about signal in his room and everyone else around him is OK, you can be relatively sure that he had
something to do with it. One of the chief complaints with the old "daisy chain" systems is the "weakest link in the chain" syndrome. If a sailor fiddles with his outlet and he is one of the first in the chain, he
likely will cause the rest to be disconnected or greatly attenuated. This happens all the time. In short, the "daisy chain" has no socially redeeming values.
Example of system using Tap-Offs to minimize signal losses.
