7700 MultiFrame Manual
7736CEM Composite Encoder with Monitoring
Page - 62
Revision 1.5
*Grey background indicates un-implemented or un-tested features
PPM with peak hold:
The peak hold feature allows the user to keep track of the audio peak. A
floating mark is pushed up by audio peaks and is reset with menu command (see the “Clear
Faults” menu).
VU:
Volume Unit meter follows, approximately, the perceived loudness of human hearing.
VU with peak hold:
The peak hold feature allows the user to keep track of the peak VU reading.
A floating mark is pushed up by audio VU peaks and is reset with a menu command (see the
“Clear Faults” menu).
VU with floating PPM:
This mode displays both VU levels and PPM levels on the same
bar graph. The VU level is indicated by the solid bar going up and down, while the PPM reading is
indicated by a floating white bar. The scale displayed is a decibel scale with 0 corresponding to
program reference level (for all modes except AES/EBU).
8.3.4.4. PPM Mode
This parameter selects one of four industry standard of Peak Program Meter (PPM) display modes.
When one of these modes is selected, a number of items are set to adhere with predefined industry
standards. The items affected include; meter attack time, meter decay time, min level displayed, max level
displayed, analog reference (100%) level and, in some instances, region colouring and phase graph
representation. Table 8-1 illustrates the values set by the standards.
Mode
Attack
Time
Decay
Time
Ref.
Level
Min
Level
Max
Level
Peak
Output
Level
Notes
DIN 45 406
(IRT Rec. 3/6)
10 ms
1.5 sec
for
20 dB
6 dBu
-50 dB
5 dB
6 +
headroom
1 dB per div until –10 dB,
logarithmic to bottom -50dB.
Associated DIN phase
correlation scale:
•
both the same => 1 r,
•
only 1 signal => 0 r,
•
both out of phase => -1r.
BBC
"IEC 128-10, type
IIa, fast mode
10 ms
2.8 sec
for 7 to 1
8 dBu
1
-12 dB
7
+12 dB
8 +
headroom
# 6 on the scale is the
reference level
Nordic N9
5 ms
1.7 sec
for
20 dB
6 dBu
-42 dB
+12 dB
6 +
headroom
AES/EBU
1
sample
period
1.5 sec
for
20 dB
User
defined
-60 dB
0 dB
User
defined
100% reading is user
definable.
0 dB corresponds to 0 dB
FS.
Table 8-1: PPM Bar Graph Characteristics
Please Note: The phase correlation scale on the DIN type is different from our other
phase indicators (Sum + Difference and phase bar graphs).
