2. Creating the Transition Response

Figure 2 defines this pulse in the AWG 2041's equation editor. The first line defines the pulse to be 256 ns long. The next two lines introduce the two constants k0 and k1 to represent T and PW50/T. This provides a simple way to change these parameters later. The fourth line duplicates Equation 2 with the t0 timing offset of 128 ns.

 

 

Figure 2. The pulse is defined in the AWG's equation editor.

The AWG's compiler converts the equation into a series of points and displays the result (Figure 3). In this case, the 256 ns pulse duration is converted to a 256 point record. We could generate this pulse as an AWG output signal, but the transition pulse is only a building component. The next step is to define the data patterns which created modulated waveforms. Note that we are modeling the transition response for longitudinal recording. We could also create a transition response for perpendicular recording systems, which has the approximate shape of the derivative of the Lorentzian pulse--in that a write transition yields a positive-negative pulse pair.

 

Figure 3. The AWG 2041 equation compiler calculates and plots the series of 256 points corresponding to the selected pulse parameters. Since the AWG clock rate was set to 1 GS/s, each point is separated by 1 ns.