DOC: Recorder Out Operation – V3.0 May 2021
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into a 1,000 ohm load (see image at right) for the output scaling to be accurate. The output
voltage will not be correct without the load. Once the settings are established, the output will
be a linear representation of the power between the two levels, the levels are set with dBm
values. The output voltage within these ranges is a calibrated DC measurement value.
To set up Recorder Out, identify the minimum and maximum power levels (in dBm) that you
require. Place these values in the RecorderOutLowerLimit and RecorderOutUpperLimit in the
left hand pane as shown in Figure 1. Once the values are established, the formula below can be
used to determine the output voltage (Vout) for any given dBm power level.
Vout= (10^(PMEAS/10)-10^(ZeroVoltSet/10))/(10^(OneVoltSet/10)-10^(ZeroVoltSet/10))
The same formula (shown below) can be copied and pasted into excel at cell B4. When pasted
into cell B4, the cells listed below will establish the inputs values. All power units are in dBm.
Out of range data is not accounted for.
B1 is the dBm power setting to deliver for 1 Volt
B2 is the dBm power setting to deliver 0 Volts
B3 is the actual input power.
=(10^(B3/10)-10^(B2/10))/(10^(B1/10)-10^(B2/10))
Grounding Note
LB5900 Sensors have solid grounding between the USB shield, USB Common and SMB
(Recorder Out) Common connections. It is important to take ground current into consideration
between all connected equipment. LadyBug Recorder Out resolution specifications are
generally (see specification sheet for exact specification and sensor accuracy data) in the range
of 25 micro volts. Small ground currents caused by power across cables can affect the measured
output voltage if care is not utilized.
Using Recorder Out in Unattended Mode
Analog Recorder Out can be used with no computer attached. The sensor can be set to retain
the Analog Recorder Out settings and start with the output activated by activating the
Unattended Mode (UOP) and Analog Recorder Output.
Note: The analog out features of Unattended Operation (Option UOP) are included with the
purchase of the Analog Recorder Out (Option 001), however the unattended internal digital
measurement storage is not implemented.
During the power up cycle when UOP is active, Analog Recorder Output will exhibit voltage
transitions from 0 volts to 5 volts until the sensor’s processor is running. After stability; and
prior to measurement, the output will be at 1 volt (into its specified 1000 ohm load); after the
sensor begins normal operation, the output will be stable and is updated 1000 times per
second. Depending on the sensor model, firmware version and the number stored
measurements, time to stability can be up to 20 seconds.
