Keysight x-series Instruction Manual

3 Short-Range Comms & IoT Mode
3.8 SEM Measurement
Option MPB or pre-selector bypass provides an unpreselected input mixer path for
certain X-Series signal analyzers with frequency ranges above 3.6GHz. This signal
path allows a wider bandwidth and less amplitude variability, which is an advantage
when doing modulation analysis and broadband signal analysis. The disadvantage is
that, without the preselector, image signals will be displayed. Another disadvantage
of bypassing the preselector is increased LO emission levels at the front panel input
port.
Image responses are separated from the real signal by twice the 1st IF. For IF Paths
of 10MHz and 25MHz, the 1st IF is 322.5MHz, so the image response and the real
signal will be separated by 645MHz. The 1
st
IF will be different for other IF Path
settings. When viewing a real signal and its corresponding image response in
internal mixing, the image response will be to the left of the real signal.
Also, the image response and the real signal typically have the same amplitude and
exhibit the same shape factor.
However, if Option FS1 (Fast Sweep Capability) is enabled, the image response in
the Swept SA measurement appears lower in amplitude and has a much wider
shape factor compared to the real signal.
Full Bypass Enable
With Full Bypass Enable selected, the microwave preselector is bypassed. In
addition, the low band/high band switch and microwave preamp are bypassed
whenever all the following are true:
–
The instrument is not in the Low Band, meaning:
–
the start frequency is above 3.5 GHz and
–
the stop frequency is above 3.6 GHz.
–
the internal preamp is not installed or if installed, is set to Off or Low Band
Note that this means that, when any part of a sweep is done in Low Band, the Low
Noise Path is not used, whether or not the Full Bypass Enable is selected in the user
interface. Also, if the preamp is turned on, the Low Noise Path is not used, whether
or not the Full Bypass Enable is selected in the user interface. The only time the Low
Noise Path is used is when Full Bypass Enable is selected, the sweep is completely in
High Band (> 3.6GHz) and no preamp is in use.
CAUTION
When Full Bypass Enable is selected, and "Y Scale" on page 1633 is set to
0dB, there will be a direct AC connection between the input and the first
converter when the Low Noise Path switches in (when Start Freq >3.6GHz and
the Preamp is either not licensed, set to Low Band, or Off). This puts the first
converter at considerable risk to be damaged by high AC power. Consequently,
1072 Short Range Comms & IoT Mode User's &Programmer's Reference

Keysight x-series Specifications

General

Analysis Bandwidth	Up to 1 GHz (depending on model)
Real-Time Bandwidth	Up to 1 GHz (depending on model)
Form Factor	Benchtop
Connectivity	LAN, USB, GPIB
Resolution Bandwidth	1 Hz to 10 MHz (depending on model)