Specifications

32
Determining measurement speed
Table 1 shows the measurement speed (for data taking only) of the analyzer. The actual
measurement speed also includes frequency stepping time, settling time, bandcross-
ing time, retrace time and handshake time (if two PNAs are used). If external sources
are used, the measurement speed is often determined by the remote source which is
usually the slowest resource in the system. All measurement times in this section are
nominal values.
1. Measure the speed
Calculating the measurement speed of your antenna test system is not straightforward.
Two methods can be used to determine the speed of the PNA, either measure it directly
or use the following equation to calculate the approximate speed.
To measure the speed, either use a program to time when the PNA completes the mea-
surement, or use an oscilloscope and monitor the “ready for trigger” line out the rear
panel BNC labeled I/O 2 (Trig Out). Put the PNA in external trigger mode, set it to the
default of “hi level” trigger (If there is no trigger in, you do not have to enable Trigger
Out). A pull up on the “trig in” line will cause the PNA to run at max speed. The total
measurement time is the spacing between “trig outs”.
2. Calculate the speed
To calculate the approximate measurement speed use the following equation:
Total Measurement time = data taking + pre-sweep time + band crossing + retrace
Data taking: Measurement time per point is determined by the larger of 1/BW or the
maximum sweep rate. For wide spans with fewer points, sweep rate is more likely to
dominate. Sweep rate is approximately 600 GHz/ms for the PNA and approximately
900GHz/msforthePNA-L.
Pre-sweep time: In swept mode, pre-sweep time is 222 uS for the PNA and 56 uS for
thePNA-L.Instepmode,calculatethesweeptimefromthefollowinginformation:PNA
fastest step speed at 1 Hz/pt, max IF BW is 170 us, and at 10 MHz/pt, max IF BW is
278us;PNA-Lfasteststepspeedat1Hz/pt,maxIFBWis80us,andat10MHz/pt,
max IF BW is 160 us.
Band crossings take on the order of 4 – 8 ms per crossing for the PNA and 2 ms for the
PNA-L.However,thenumberofbandcrossesincreaseswheninfrequencyoffsetmode.
In that mode, band crossings of source and receiver may not coincide. Exact band cross-
ing locations can be found in the Microwave PNA Service Manual on Table 5.2.
Retrace takes 10-15 mSec with the display on, or 5-8 mSec with the display off. Retrace
will take the system back to the start frequency of the previous sweep.
Upgrade note
In general, the PNA will provide significant
speed improvements over the 8510 or 8530
analyzers. However, some measurement set-
ups will require additional external component
speed improvements in order to fully capture
the PNA speed benefits.