Fluke 54200 - Definitions; Operating

54200
Users Manual
5-50
Definitions
The following explanations will help to define the level specifications of the various
BTSC signals that are delivered by the 54200.
•
100% modulation of the L+R signal corresponds to a peak deviation of the sound
carrier of
∆
fmax = 25 kHz. 100% modulation of the SAP signal corresponds to a peak
deviation of the SAP carrier of
∆
f = 10 kHz.
•
The maximum allowed audio input level of 100% modulation (100%
$ =
0 dB) is fre-
quency dependent due to the 75 µs pre-emphasis; see Figure 5-34.
Example:
For a signal component of 15 kHz, the maximum allowed input level is
14%, about -17 dB, for L (if R = 0) or R (if L = 0). Due to the 75 µs pre-emphasis this
leads to the maximum allowed peak deviation of
∆
f = 25 kHz for L+R.
On the other hand, at 300 Hz the maximum allowed input level is approximately
100% neglecting the small gain factor of the pre-emphasis at 300 Hz.
•
Another often used level definition is called '75 µs EIM' of a certain value in percent-
age, for example 100%.
This is used as a reference and determines the modulation level that would occur for
the equivalent Mono signal processed using a 75 µs pre-emphasis, see Figure 5-34.
Example:
An audio input level of 14% at 15 kHz leads to '75 µs EIM*' of 100%. At 300 Hz the
same input level leads about to '75 µs EIM' of 14.1%.
* EIM = Equivalent Input Modulation
Operating
Fluke 54200 offers different BTSC sound modes for TV systems NTSC M and PAL M.
For details, see table below.
Table 5-16. 54200 BTSC Sound Systems
Menu
Indication
Sound Modes TV / Sound System Sound Carrier
Frequency
BTSC
BTSC
Mono/Stereo/SAP
Mono/Stereo/SAP
NTSC M
PAL M
4.5 MHz
4.5 MHz