NF FRA5087, Instruction Manual

Page: 89 / 194

4.6 Display setting
FRA5087
4-15
！
CAUTION
When grid style is selected for X-Y1-Y2, two types of grid are displayed on the
Y axis. If preferred for clarity, the grids can be overlapped as described below.
1)
Set the [AUTO SCALING] in the Graph at “OFF”.
2) Calculate the difference between the upper and lower limits of the phase
scale that you want to display and divide the difference by six (6).
Express the divided value as  . The phase grid interval is obtained
according to the following:
Phase grid interval
For 15.0
≦
  22.5: 15.0
For 22.5
≦
  37.5: 30.0
For 37.5
≦
  67.5: 45.0
For 67.5
≦
  135.0: 90.0
3)
Multiply by arbitrary integers the phase grid interval that has been obtained
above. Find two values from among the phase grid interval multiplied by
integers so that the two values individually are the closest to the upper and
lower limits of the phase grid interval which you want to display. Set
these two values individually for the [  MAX] and [  MIN] in the
[SCALE]. Then, phase grids will be drawn and displayed so that the
number of the phase grids is the quotient of the difference between the
values set for [  MAX] and [  MIN] divided by the phase grid interval.
The afore-mentioned quotient is called the “phase grid division
number” hereunder.
4) Next, calculate the difference between the upper and lower limits of the
gain scale that you want to display, and then divide the difference by the
phase grid division number. Express the divided value as  R. The gain
grid interval is obtained according to the following:
Gain grid interval
For 0.75E  n
≦
 R  1.5E  n: 1.0E  n
For 1.5E  n
≦
 R  3.5E  n: 2.0E  n
For 3.5E  n
≦
 R  7.5E  n: 5.0E  n
For 7.5E  n
≦
 R  15.0E  n: 10.0E  n
5) Multiply by arbitrary integers the gain grid interval that has been obtained
above. Find two values from among the gain grid interval multiplied by
integers so that the two values individually are the closest to the upper and
lower limits of the gain grid interval which you want to display. The
difference between these two values must be equal to the “phase grid
division number”. Set these two values individually for the [dBR MAX]
and [dBR MIN] in the [SCALE].
6) Lastly, set [X-Y1] or [F-Y2] for the [GRID STYLE].
(EXAMPLE:) The following describes an example of the procedure of finding
setting values for the display scale according to the above-mentioned principle,
assuming the maximum gain of 110 dB, the minimum gain of -10 dB, the
maximum phase of 170  and the minimum phase of -170  :
 First, obtain the phase grid interval, and then, set the [  MAX] and [  MIN]
in the [SCALE]:
Since {170-(-170)}  6=56.7, the phase grid interval is determined to be 45.
The two values closest to 170 and -170, individually, which are selected from
among {45 multiplied by integers}, are found to be 180 and -180. Set 180
and -180 for [  MAX] and [  MIN], respectively, in the [SCALE].
The phase grid division number is calculated to be 8.
 Next, Calculate the gain grid interval, and set the [dBR MAX] and [dBR
MIN] in the [SCALE]:
From {110-(-10)}  8(=phase grid division number)=15, the gain grid interval
can be obtained as 20. Set either 120 and -40, or 140 and -20 for [dBR
MAX] and [dBR MIN], respectively, in the [SCALE].