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AM-55 / Sep 2015
A M - 5 5 G U I
Output Bandwidth
A drop down menu that selects one of EIGHT bandwidth options for
the AM‑55.
Full
: No bandwidth restriction.
10kHz NRSC
: Restricts the audio to the NRSC‑1 10kHz standard
6kHz CCIR
: Restricts the audio to the 6kHz CCIR standard.
There are also options to set the AM‑55 bandwidth to 7.5kHz, 6.5kHz,
5.5kHz, 5kHz and 4.5kHz.
Digital Output
Assigns one of the following options to the AES output:
TX1/TX2
: Assigns the TX1 to the left channel of the AES output stream,
and TX2 to the right channel of the AES stream.
TX1
: Assigns TX1 to both the left and right channels
TX2
: Assigns TX2 to both the left and right channels.
AES Sample Rate
: Sets the output sample rate. Options are 44.1kHz and 48kHz. The
input sample rate is displayed below the dropdown menu. In the example above, the input
is at 44.1kHz and the user has selected a change to 48kHz on the output.
TX Outputs
Many AM transmitters require an
output drive of +10dBu to achieve
100% modulation. When driven to
0dB, the output of the AM‑55 produces
+24dBu output.
Both the TX1 and TX2 outputs
can be driven between ‑79.95dB (or
‑59.95dBu) to 0dB (or +24dBu). Care
should be taken to properly monitor
the negative peaks when adjusting
these controls. The proper procedure
is as follows.
With the Pos. Peak Threshold set
for 100%, advance the correspond
‑
ing TX output control so the modulation monitor indicates approximately 95% negative
peaks. Then, increase the
Pos. Peak Threshold
so that the modulation monitor indicates
120% on positive peaks. You now have the proper ratio of positive to negative peaks set
up, along with 5% headroom to adjust for loudness.
Polarity Invert
Polarity Invert
check box switches output’s absolute polarity.
