How low can you go?Follow article
What’s the smallest signal we can measure with a PicoScope 5000D Flexible Resolution Oscilloscope?
At Pico we consider ourselves to be evangelists, spreading the good news about PicoScopes and finding new converts wherever we can.
We were at a trade show recently, proudly displaying Pico’s wide range of USB-connected test equipment, when a visitor came to the stand and asked if we did a low-cost audio analyser. I said no but would an oscilloscope do the job?
“No,” he laughed, “I need to see signals as low as 1 µV, and you can’t do that with a scope.”
Well I wasn’t sure if we could or we couldn’t, but we were both interested to find out what was the lowest level that could be measured.
So I invited the visitor to take a seat and I connected a PicoScope 5000D Series Flexible Resolution Oscilloscope with a setting for 16-bit vertical resolution and a handy built-in signal generator to provide us with a signal.
First I set the signal generator to output a 10 kHz sinewave and connect to the input of the scope through several 20 dB attenuators in order reduce the amplitude until the signal could hardly be seen even on the lowest range.
I set the Vertical Resolution to 16 bits and turned on the Lowpass Filter setting to 100 kHz to reduce noise.
Then I drew a zoom box along the length of the trace and zoomed in vertically:
The amplitude was measured with rulers at 103.7 µV, and the automatic measurements showed the value for AC RMS as 37.04 µV.
I reduced the signal down to about 30 µV pk-pk before the signal started to lose its clear sine shape.
“That’s good” said the visitor “but I would normally view the signal in the frequency domain.”
So I selected Spectrum Mode, first with 8-bit resolution but the signal was lost in the noise as would be expected with an 8-bit digitiser.
Then I selected 16-bit mode and the noise floor fell away to clearly reveal the 10 kHz signal.
I set the display to Average and the noise floor settled at below -130 dBV. Then I set a ruler at -120 dBV, which equates to 1 µV rms, and with the addition of another 20 dB attenuator the signal fell to this level.
Now the visitor was getting enthusisatic and asked what measurements were available in Spectrum Mode. I opened the measurement menu.
The enthusiasm continued as these seemed to match the visitor’s needs.
“And just how much would one of these PicoScopes cost me?”
When I said the starting price was €979, the reaction was very favourable to say the least.
Hallelujah! Another convert to PicoScopes.
The new PicoScope 5000D Series Flexible Resolution Oscilloscopes
PicoScope 5242D 60 MHz 2 channel
PicoScope 5243D 100 MHz 2 channel
PicoScope 5244D 200 MHz 2 channel
PicoScope 5442D 60 MHz 4 channel
PicoScope 5443D 100 MHz 4 channel
PicoScope 5444D 200 MHz 4 channel
PicoScope 5242D MSO 60 MHz 2 channel
PicoScope 5243D MSO 100 MHz 2 channel
PicoScope 5244D MSO 200 MHz 2 channel
PicoScope 5442D MSO 60 MHz 4 channel
PicoScope 5443D MSO 100 MHz 4 channel
PicoScope 5444D MSO 200 MHz 4 channel