LM 128P
Loudness and Peak Program Meter according to EBU R 128
15
SSB AUDIO GmbH * Sonnenweg 25 * 30827 Garbsen, Germany
Tel.: +49 5131 464272 * www.ssb-audio.com * [email protected]
7
USB Functions
The loudness meter is equipped with a USB port in order to read out the measured loudness values as well as to
enable the control of the most important functions of the LM 128P.
When connected to a PC it logs on with a virtual COM port. This virtual COM port requires a driver originating from
the company FTDI. The download can be found on the website of FTDI (ftdichip.com) under Drivers
→
VCP Drivers
for different operating systems. At the time of writing this manual the driver for Windows has the version no.
2.12.28 and can be reached via this link:
http://www.ftdichip.com/Drivers/CDM/CDM%20v2.12.28%20WHQL%20Certified.zip
On request, SSB AUDIO GmbH provides a Windows software for test and demonstration purposes only. A
screenshot illustrates the USB functions:
As soon as the COM-port is opened, the LM continuously sends 40 cr/lf-terminated strings per second as visible on
the screenshot above, in this case:
VER=P4.00;MOM=-021.350;STL=-022.300;INT=-022.500;LRA=002.4;LUR=-23;HRL=RUN;SRT=044.1;INP=AES3;Rx: !MDL
VER=P4.00
the firmware version
MOM=-021.350
the Momentary Level (MOM) in LUFS (can also be MOD=, see below)
STL=-022.300
the Short Term Level (STL) in LUFS (can also be STD=, see below)
INT=-022.500
the Integrated Loudness in (INT) LUFS
LRA=002.4
the Loudness Range (LRA) in LU
LUR=-23
the relative numeric LU/LUFS setting
HRL=RUN
the state of the Integrated and the Range measurement
SRT=044.1
the current sample rate
INP=AES3
the input state and selection
RX: !MDL
the last received command
Note: All transmitted values are always absolute LUFS-values and not relative LU values.
Remarks on the transmitted values:
MOD=
instead of
MOM=
resp.
STD=
instead of
STL=
indicates that this value is also displayed on the numerical display of the LM so that
inconsistencies between numerical PC- and numerical LM-display can be avoided (the
LM's numerical display is only updated a couple of times per second while these values
are sent 40 times per second).
????.???
resp.
????.?
for a measured values indicates that there is currently no valid value available
LUR=
LUR=+00
: Numeric LM display in LUFS,
LUR=+23
: Numeric LM display in LU with 23 LUs added to the LUFS value (transmitted values are
always LUFS values).
HRL= HRL=RUN:
Normal measurement,
HRL=HLT
: Halted (paused),
HRL=LOW
: The 400 ms (STL) as well as the 3000 ms (MOM) value is momentarily too low to contribute
to the Loudness Integrated resp. Loudness Range value,
HRL=LO4
: The 400 ms (STL) is momentarily too low to contribute to the Loudness Integrated (INT)
value,
HRL=LO3
: The 3000 ms (MOM) value is momentarily too low to contribute to the Loudness Range
(LRA) value.
INP= INP=AES3
: The AES input is selected
INP=ADC
: The analog input is selected (if available)
INP=SDI1
to
SDI4
: The SDI channel pairs 1 to 4 are selected (if available)
