How To Use Zone Plate Signals On The Hd3G7 Module - Tektronix TG8000 User Manual

HD3G7 HD 3 Gb/s SDI Video Generator module

How to use zone plate signals on the HD3G7 module

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Here is an example of how you can use zone plate signals to simplify a common
task.
One common task is measuring the horizontal frequency response of a system.
With a typical swept-frequency generator you would apply a signal such as a
1 MHz to 30 MHz sweep with markers every 5 MHz. Then you try to estimate the
frequency of the 3 dB roll-off point by interpolating the position of the 3 dB point
between the markers.
The HD3G7 generator module's adjustable zone plate signal provides a better way:
The H Sweep Zoneplate pattern control parameter is the H Sweep Frequency,
which controls the upper frequency limit of the sweep (the swept-to
frequency).
Simply adjust the H Sweep Frequency until the system roll-off is at –3 dB.
Read the frequency directly from the instrument display.
The H Sine Zoneplate, which provides a constant frequency horizontal sine
signal instead of a swept signal, can be used to reduce error in measuring
attenuation at a given frequency.
Set the Horz. Frequency parameter to a low value and measure the
amplitude of the entire line.
Next, calculate the –3 dB point (0.707 × the low frequency amplitude).
Finally, increase the Horz. Frequency parameter until the system response
for the whole line is at the calculated –3 dB level, and read the –3 dB
frequency directly from the instrument display.
Since the ZP Amplitude parameter is adjustable for each of these signals, you
can measure the response at 100%, 60%, or any other level as needed.
These same techniques can be used to measure vertical or diagonal response, by
selecting the appropriate zoneplate signal.
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