Tegam 2711A, Руководство по эксплуатации

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Chapter 2 About arbitrary waveforms
Waveform Generation
In an arbitrary waveform generator, you will define a waveform, using either the
standard functions or custom profile data files to load waveform memory. A set
of start and stop addresses which correspond to a waveform memory location is
assigned with a waveform number. An address generator sequentially presents
data values from the specified memory location to the digital-to-analog
converter (DAC). The precision DAC converts the data into analog voltage
values. This series of sequential voltage levels describes the output waveform
with the frequency determined by the sample clock rate divided by the number
of samples in the waveform. Changing the sample clock rate causes the address
generator to change the speed at which the data is presented to the DAC,
thereby changing the output frequency.
The waveforms you create are a series of data points consisting of X- and
Y-axis values. For 16-bit generators, such as the TEGAM 2711A, the Y values
b32767 and -32768 are used. In describing the first point, 0, is given a
Y value. The next point has another Y value, and so on up to the last address in
your waveform. This series of points make up the waveshape.
All the data points in the specified waveform memory location make up one
waveform cycle. The waveform generator will output all the points in the
waveform at the sample clock rate specified. The resulting frequency is equal to
the sample clock rate divided by the number of data points in the waveform. If
more than one cycle of the waveshape is entered into a waveform, the output
frequency will be a multiple of one waveform generator cycle. For example, if
you create a waveform with 3 triangle wave cycles using the same number of
data points and the sample clock rate, the frequency will be 3 times higher.
Waveform Generation
Sample
Clock
Generator
Address
Generator
Waveform
Memory
(RAM) 16-bit
Digital-to-Analog
Converter
Output
Amplifier
Waveform Cycle
1000 points
1000 points
Frequency=1X to 3X