longer flow over current lead into the next time division and perhaps reverses a 02 01 so even if you're automating the detection abuse current levels there is a fundamental limit to how far we can squeeze two pulses together and this is the same problem Alice and Bob ran into with their string communication system which we called the maximum pluck speed if they plucked any faster than two plugs for second the notice they started to bleed together and they got confused so this is called the symbol or e remember a symbol can be broadly defined as the current state some observable signal which persists for a fixed period of time the new whether you are using fire sound electrical current anything a signaling a vent is simply a change from one state to another so the symbol rate is the number of signaling events which can be squeezed together in one second it also became clear that there was one other way to increase the capacity of a communication system we can increase the number different signaling events for example with cows and bobs string communication system they soon found that varying the typeof blocks allowed them to send their messages faster for example hard medium versus softbox or high pitch verses low pitch bugs bite tightening the cable different amounts and this was an idea implemented by Thomas addis in which she applied to the Morse code system it was based on the idea that you could use a week and strong batteries to produce signals have different strengths he also used two directions as go said Weber dead forward verses reverse current and two intensities so he had plus three balls plus one vol 