Bristol 428 - Page 13

Model 428 User’s Manual OPERATION
Bristol Instruments, Inc. 13
List Mode Display Screen – Main
Displays wavelength, power, and optical signal-to-noise-ratio (OSNR) for up to 5
channels simultaneously. This data can be sorted by wavelength (Wav) or power
(Pow).
1 1 3 1 0 . 6 1 0 7
1 1 . 8 5 3 7 . 2
1 : 0 0 : 0 0
2 1 3 1 0 . 6 2 0 3
1 1 . 0 5 3 1 . 2
3 1 3 1 2 . 1 5 7 0
1 2 . 6 3 3 4 . 7
A v g : O f f
4 1 3 1 3 . 1 6 3 1
1 2 . 0 2 2 8 . 4
P o f f s : O f f
5 1 3 1 4 . 7 0 6 3
9 . 4 4 3 5 . 5
S N R : U s e r
nm- v a c
uW
dB
W a v
L i s t
M o d e


C h a n g e
S e l e c t
Figure 3.4: List Mode Display Screen – Main
 Wavelength List – Displays the current wavelength, wavenumber, or
frequency value for up to 5 channels. If the optical signal has more than 5
channels, the Arrow buttons can be used to scroll to any of the up to 1000
computed wavelengths. The scrolling may be done either by line (Smooth) or
by page (Page). The scrolling method is selectable in Config Screen 1.
 Wavelength Units and Medium – Identifies the units chosen for the
measurement of wavelength (nm), wavenumber (cm
-1
), or frequency (THz).
Also identifies the medium to which the measurement is referenced. The
options are vacuum (-vac) or standard air (Std Air) at 20°C, 760 mm Hg, and
0% relative humidity. The Wavelength Units and Medium can be changed
from Config Screen 1.
 Power Values List – Displays the measured optical power, in the user
selected units, directly to the right of its corresponding wavelength or
frequency value.
 Power Units – Identifies the units chosen for the measurement of power.
The options are mW or μW (scaled automatically) or dBm. This parameter
can be changed from Config Screen 1.
 Signal-to-Noise Ratio (SNR) – The OSNR for each channel, expressed in
dB, is displayed directly to the right of its corresponding power value. The
OSNR is calculated as the ratio of the power in the optical channel relative to
either a user selected noise location (User) or relative to the interpolated
noise at the channel location (Auto).The noise at the channel location is
interpolated by calculating the average of the noise measured 100 GHz to
the left and to the right of the peak location. If another channel is less than
200 GHz from the peak, then the noise is calculated midway between the two
channels.
 Measurement Timer – Displays the time in hours, minutes, and seconds
that the instrument has been tracking channel values. The timer is reset
when the instrument is restarted, or can be manually restarted with the Reset
option on List Mode Display Screen – Drift.