Normal Wave vs. Forced Clock Generation
well not much saying here. as i'm not the expert in hardware design of analog and digital function/wave/arbitrary generator. you can find a lot of writing in the internet regarding the difference between the two (analog vs. digital). some of the random links that's not so good as example here are:
The Principle of DDS (radiolocman)
DDS technology (papay)
Arduino DDS Sine wave Generator (Lab III)
Function Generators - An Explanation of Technologies and Terms - Analogue and Digital (Aim & Thurlby Thandar Instruments)
Signal generator (WIKI)
Function generator (WIKI)
Arbitrary waveform generator (WIKI)
what i want to emphasize, is that digital synthesized signal (DDS) generators use clocking (sampling) method and data (wave) points to generate wave. The general formulation relating sample clock, wave frequency and number of data points can be expressed as...
Clock = (Number of
Points) * Frequency, or...
Frequency = Clock / (Number of Points)
what this formula got to do with Goltek software is, in the Tektronix ArbExpress CSV format file, there's clock and number of points information in the file, followed by the actual data points as can be seen in the following figure.
Goltek Controller will use this clock (#CLOCK) and data points (#SIZE) value to calculate the signal's "natural" or "original" frequency and set the frequency parameter with that value (using above formula) unless the Lock Parm feature is enabled. This information also will be used in Force Clock Mode (feature) to ensure originality of the source wave data (csv file). more information can be found in Goltek Controller's Utility Mode. In another way of saying, when we deal with DDS Technology, we cannot think in term of the signal and its frequency alone (along with the common property such as amplitude offset, phase etc) like when we are using analog signal generator, but we have to think digitally, ie the wave signal is constituted by many points of data that is sampled (generated) at predefined step of time, which reciprocal of it is the device clock or sampling frequency. With any 2 parameters from the above formula is given, we can calculate the 3rd parameter to get it into balance, like V = IR formula. So some of the terms and concepts in DDS may differ, new or unfamiliar to the person who spent most of his time with analog generator. But behold, i believe the DDS is the future to Signal Generation Technology, and i believe its pretty common now by the time of this writing (year of 2011), and i also believe that those of you reading this text will be already familiar with it. So, as said... not much of saying here.
any comment, improvement
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