Hi,
I am performing the following test on E4448A
Objective: measure a CW test signal at 14GHz with various span settings and with RBW set to 3.9KHz
Test Steps:
1. set centre frequency to 14.906 GHz, span 1MHz
2. detector RMS, RBW=3.9 KHz sweep time such that uncal does not appear on screen
3. set test signal (generator) level to -10 dBm @ 14.906 GHz, wait for complete sweep
4. press "marker"--> peak search
5. record marker position (y axis) obtained in step 4
6. repeat steps 1-5 with spans 5MHz, 12.5MHz, 20MHz, ,25MHz, 50MHz, 100MHz, and increase sweep time such that uncal does not appear on screen (40 Sec)
Expected Result:
marker position does not depend on span
Actual Result:
I got the following table, as you can see, the marker position seemed to be related to what span I used
RBW=3.9KHz
SPAN Marker1 Position
1MHz -13.64 dBm
5MHz -16.37 dBm
12.5MHz -20.28 dBm
20MHz -22.32 dBm
25MHz -23.28 dBm
50MHz -26 dBm
100MHz -29 dBm
why did the marker peak move when I changed the span ?
thanks
Joe
I am performing the following test on E4448A
Objective: measure a CW test signal at 14GHz with various span settings and with RBW set to 3.9KHz
Test Steps:
1. set centre frequency to 14.906 GHz, span 1MHz
2. detector RMS, RBW=3.9 KHz sweep time such that uncal does not appear on screen
3. set test signal (generator) level to -10 dBm @ 14.906 GHz, wait for complete sweep
4. press "marker"--> peak search
5. record marker position (y axis) obtained in step 4
6. repeat steps 1-5 with spans 5MHz, 12.5MHz, 20MHz, ,25MHz, 50MHz, 100MHz, and increase sweep time such that uncal does not appear on screen (40 Sec)
Expected Result:
marker position does not depend on span
Actual Result:
I got the following table, as you can see, the marker position seemed to be related to what span I used
RBW=3.9KHz
SPAN Marker1 Position
1MHz -13.64 dBm
5MHz -16.37 dBm
12.5MHz -20.28 dBm
20MHz -22.32 dBm
25MHz -23.28 dBm
50MHz -26 dBm
100MHz -29 dBm
why did the marker peak move when I changed the span ?
thanks
Joe
Most likely the Yig Tuned Filter (YTF) is off in frequency by half its bandwidth and you are seeing the effect of the signal move up and down on the skirt of the preselector filter. Connect up your input signal and put a marker on the signal, then center the preselector by press [Amplitude]
Regards -