Not necessarily. For example, an HP8970 Noise Figure Meter reads to 0.01 dB,
yet uncertainty (for just instrument error) is +/- 0.1 dB. In the days of yore,
LNAs were typically highly mismatched at the input and this added further
uncertainty. I once measured a friend's homebrew 1296 MHz preamp NF at 0.7 dB.
I calculated the uncertainty at +/- 0.7 dB!
I got a chuckle when HP gave an '8970 to the ARRL lab and they did a test on a
preamp (ARR if memory serves) and gave the NF to two decimal places.
Wes N7WS
On 6/6/2016 4:11 AM, brian wrote:
There are some exceptions to this rule. HP equipment (at least the older
stuff) would only digitally display the number of truly believable significant
digits. For example, their counters would not display all available digits
but just those one can real. So there are exceptions to all rules of thumb.
One has to know their measuring gear characteristics to know what to believe.
73 de Brian/K3KO
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