LED "Emulated " Strobe Tuners Are Not Strobe Tuners. Typical imitation "strobe pattern" tuners attempt to emulate the image produced by an authentic rotating strobe disc by using an array of LEDs (Light Emitting Diodes) which are simply turned ON or OFF in sequence so as to "appear" that the light image is drifting left or right. Unlike our Virtual Strobe™ tuners, these emulation schemes necessarily have one thing in common: a digital decision must be made to interpret when to indicate an "in tune" signal either by lighting a green LED or creating a non- sequencing pattern on the LEDs.
This "digital decision" is referred to as the "dead band" problem. The circuitry to form an " in tune/out of tune" decision, by its very nature, demands that some amount of "out-of-tuneness" must be accepted when making an "in tune" indication. This is because a frequency that is EXACTLY in tune is an infinitely narrow point. If a circuit could be made to react to only this point (which is impossible by the way), getting a "green LED" to turn on would be impossible. In fact, given the normal pitch fluctuations in a real instrument, the light would simply never be on (or at best be turned on for such short periods that you would never see it).
As the manufacturers of such tuners widen the band of "out of tuneness" around that ideal frequency to allow for an indicator of an "in tune" state to be triggered,—the deviation from perfect tuning that they decide is "in tune" is what you are left with. This "dead band" typically gives up at about ±1 cent deviation and usually allows several times this degree of inaccuracy before the "in tune" signal reverts to an "out-of-tune" indication. | 
