Description:
This demonstration project
built on a 16 MHz DDS source and a A and B detectors to make
a full stimulus - response network analyzer that can be
built by nearly anyone at a fraction of the cost of a
commercial unit. This was a very popular project that showed
just how much could be done by a determined homebrewer! The
DDS synthesizer, built in source has 1 Hz resolution over
the full 10 Hz to 16 MHz MHz output range. Excellent phase
noise and spurious response performance is also achieved.
Also included in the design is a novel output leveling
circuit which provides four output levels over the entire
frequency range. The analyzer is really a virtual instrument
with all it's functions being controlled by a PIC
Microcontroller via a PC control program that was written in
Visual Basic. Communications to the PC is via a low cost 4.8
k Baud RS232 link.
- Built with only 15
IC's!
- True stimulus response
scalar network analyzer.
- 60 dB plus dynamic
range, better than 0.25 dB resolution.
- 10 Hz to 16 MHz output
range with 1 Hz resolution.
- Four output levels at up
to 5 volts p-p maximum..
- PC Control via virtual
front panel application program.
- RS232 communication (or
USB) link to the PC.
- On board PIC
Microcontroller.
- Spurious responses below
-50 dBc.
- Harmonics below -20
dBc.
- Phase noise = -120
dBc/Hz at 10 kHz offset.
- Wide band signal path,
no switching from 10 Hz to 16 MHz (9 octaves).
- Shielded, modular
design.
This is a screen
shot of the analyzer measuring a 455 kHz ceramic filter. The
excellent dynamic range and low noise of the traces can be
seen. The application programmed was written in Visual Basic
and can run on any version of windows from 3.1 on up.
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