Hi,
I just did some trials to use the SMA Spectrum Analyzer as a reflectometer using my software (see previous post).
You need:
- 1x SMA Spectrum Analyzer 138MHz-4.4GHz
- 1x Noise Generator – I used the cheap BG7TBL one (20 Euro at eBay)
- Cables and adapters
The setup is shown in this picture:
Using my software, the reflected patterns can be shown in the spectrum:
The patterns are characteristic to the location of the cable fault (i.e. a not properly terminated cable).
Measuring the distance between the “valeys”, you can determine the location of the cable fault, if you know the cable propagation speed. The above pictures shows a non-terminated cable with 600mm length.
This picture shows the pattern of a non-terminated cable with 2300mm length.
This resulted in the following measurements:
57 MHz > fault at 2300 mm
200 MHz > fault at 600 mm
Using simple math, we can calculate the location of a cable fault at unknown distance, measuring the frequency-width of the “valley”. Note that this requires that the cable to be measured has the same cable propagation speed as the cables used for determination of the calculation factor.
I am considering a calculation button on my software… Does this interest anyone?
Cheers,
vma