GW Instek GSP-827 User Manual - Manual (Page 58)

2.7GHz Spectrum Analyzer Operation Manual
⎯ ⎯
57
8.2.3 Trace
There are three traces Live, Tr. A and Tr. B. Live trace is always the one measuring the
signal. Trace A and Trace B are the traces for memory access. The Clear function is to clear the
Trace A and Trace B.
Live Trace has Peak Hold, Average and Freeze functions. Peak hold function is to hold the
peak signal until the next higher level signal is appeared. When the next higher signal is coming,
it will update the signal. Average function will average the specific number of traces and
present the result of average on the display. Freeze function will stop sweeping and present the
last trace.
The Trace Math directly uses the trace data to perform the math operation. In other words,
when trace A plus trace B in dB, the result is dB number pulsing other than transferring into
linear scale.
There are also several detection modes are provided. Basically the data of every point is
taken from several samples. How many samples are taken for one data will depend on the setting
of RBW and SPAN. There are several ways to pick one to present the all taken samples. Normal
mode takes average, Sample mode will pick randomly, and Peak + mode will pick the maximum
one. It is so-called positive peak sometimes.
There are also two detection modes implemented by hardware. Average is done by low pass
filter. There are three time constants of Quasi Peak detection, TC1, TC2 and TC3 for 600ms,
550ms and 160ms respectively.
F1
F2
F3
F4
F5
F6
Center
Start
stop
Step
Peak-
>Center
Trace
A B No
PkHold
ON OFF
Clear
AVG
ON OFF
Freeze
ON OFF 0
1 2 3
7
6 5 4
8 9
. -
Trace
More
Center
Step
Trace
Math
Detect
Return
Center
Start
stop
Step
Peak-
>Center
A ↔B
A-B->A
A+B->A
A+Const
->A
A*Const
->A
Return
Center
Start
stop
Step
Peak-
>Center
Normal
Detect
Peak+
Sample
Detect
AVG
1 2 3
QPeak
TC1
Return