The Autorange Function; Spurious - Aaronia NF-5030S Manual

8.0 Correct measurement
When measuring magnetic fields by using the internal sensor, the attenuator
should be configured as follows:
>=200nT: 10dB, >=700nT: 20dB, >=2µT: 30dB, 7µT and above: 40dB.

8.11 The Autorange function

Magnetic fields are measured in Tesla or Gauss, electric fields in V/m. However,
as these fields can quickly vary in lots of factors and SPECTRAN additionally
provides an extremely wide dynamic range, display of all possible levels would
require a huge display with DOZENS of digits. To allow an usable readout with
just 4 digits, SPECTRAN provides the "Autorange" function which is popular in
professional measurement technology. SPECTRAN simply prepends an inter-
nationally standardized prefix to the actual value:
k = 1000 (Kilo=thousandfold)
m = 1/1000 (one thousandth)
µ = 1/1.000.000 (one millionth)
n = 1/1.000.000.000 (one billionth)
p = 1/1.000.000.000.000
Let's use 0.000,000,797 T as an example. This huge row of zeroes can simply
be replaced by one of the prefixes above, which simplifies the display enor-
mously. One possible illustration would be 0.797µT (0.7 millionth of a Tesla),
another 797nT (797 billionth of a Tesla). As this example clearly shows, the rea-
dout would literally drown in a huge pile of "zeroes" without the autorange func-
tion. However, using the "µ" or "n" prefixes, display is still accurately possible
even with just 4 digits.
This of course also works with very large values, like 20,000 V/m. Here, the dis-
play would just show 20kV/m (20 kiloVolts/meter).
SPECTRAN automatically changes the prefix used, you do not need to make
any manual adjustments.

8.12 Spurious

Because of the very high sensitivity of the SPECTRAN, the internal probes can
even measure the very low emissions of its own circuits. Typical are multiply sig-
nals of 1,6MHz (3,2MHz, 4,8MHz etc.), which is the frequency of the onboard
switching power supply, and multiply signals of about 128kHz (256kHz, 378kHz
etc.), which is the LCD clock. With the E-Field sensor you can also measure mul-
tiply 65Hz signals which is the refreshrate of the LCD.
Usually all those signals are very small and should not disturb any mea-
surement. Anyway we will add a function in one of the next software revi-
sions to remove them automatically.
Firmware V 1.0 / © 2005-2013 by Aaronia AG, D-54597 Euscheid, www.aaronia.com 40