Johnson Noise Thermometry - Page 13

The main problem is that the signal levels involved are extremely small, approaching the limits of measurement.

Prior art Johnson Noise Thermometers use 100 ohm sense resistance and 100 kilo hertz bandwidth.

At 20°C, the noise signal = 1.27 micro volts RMS.

Measuring to ¬plus or minus 0.3 K means measuring this noise to ¬plus or minus 1.27 nano volts, which is at the limits of measurement.