12
MeasureReady™ M81 Synchronous Source Measure System Quick Start Guide
Remote operation
If desired, attach the the MeasureReady™ M81-SSM to
your PC using Ethernet, USB-Type B, or GPIB.
USB-Type B:
implemented as a virtual serial
com port connection. The USB driver is available
through Windows® Update or from the web.
USB-Type B Serial port settings
Baud rate
921,600
Data bits
8
Parity
None
Stop bits
1
Flow control
RTS/CTS
Time constant
The time constant setting determines the bandwidth of
the PSD output filter. Longer time constants will result in
lower Equivalent Noise Bandwidth (ENBW) at the cost of
longer settle times. See the table below.
Rolloff
The rolloff setting determines the slope of the PSD
output filter in the stop band. Steeper rolloff will result in
lower ENBW at the cost of longer settle times. Steeper
rolloff will also provide better rejection of interfering
signals that are near the frequency of interest.
For time constant
T
, the ENBW and time to settle to 1%
are approximately:
Rolloff
Equivalent noise
bandwidth
1% settle time
6 dB/oct
5
T
12 dB/oct
7
T
18 dB/oct
9
T
24 dB/oct
10
T
