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FM-531HD / May 2013
F M - 5 3 1 H D G U R U G U I
Composite Clipper – Emulates analog
composite clippers but uses a very high
sample rate and special algorithms to drasti‑
cally reduce the artifacts caused by analog
composite clippers.
Look Ahead Limiter – This is a true
look ahead limiter which utilizes a 0.5 mil‑
lisecond look ahead and extremely high
sample rates to precisely control composite
waveform peaks on a cycle by cycle basis.
It works similarly to the oversampled look
ahead peak limiters found in the FM and
HD Limiter screens, but because of the
much higher bandwidth required by the composite signal, it operates at a much higher
sample rate.
MPX Process Control
The amount of MPX processing being applied to the composite signal is controlled
by the MPX Process control. This control is calibrated in 0.05dB steps and allows the
amount of MPX processing to be precisely set. Unlike other processors the control
may be set to values below 0dB for test purposes. Note also that unlike conventional
composite processors the amount of multiplex signal processing can be set quite ag‑
gressively without encountering the usual artifacts.
BS412 MPX Power Controller
In certain European countries the control of maximum Multiplex Power is required
by broadcast regulatory agencies. The regulation governing this is commonly referred
to as ITU‑R BS.412‑7, and the primary aim of controlling maximum MPX power is
to reduce adjacent channel interference by lowering the average modulation level.
FM‑531HD is equipped with a sophisticated MPX Power Controller which enables
it to operate within these regulatory guidelines. On the left side of the Stereo Encoder
screen are the two controls associated with its BS412 MPX Power Controller.
Note that the MPX Power Controller is always measuring multiplex power, even if
the Enable check box is not checked. Therefore if the MPX Power Controller setting
is set to any value except off, when the Enable check box is checked MPX Power will
immediately fall to the value set by the MPX Power Controller control.
Enable – When the Enable check box is checked the BS412 algorithm is control‑
ling the multiplex power. Likewise, when the check box is not checked, multiplex
power is not being controlled, regardless of the setting of the MPX Power Controller
control. As mentioned previously, when the Enable check box is checked the MPX
Power Controller will immediately set the processing output’s MPX Power to the
level set by the MPX Power Controller’s value.
MPX Power Controller – This control sets the maximum permitted multiplex
power according to the BS.412 measurement algorithm. The control has 15 possible
settings, plus an OFF position: +8db, +7dB, +6db, +5dB, +4dB, +3dB, +2dB, +1.5dB,
+1.0dB, +0.5dB, 0, ‑0.5dB, ‑1.0dB, ‑1.5dB, and ‑2.0dB.
Summary of Contents for FM-531 HD
Page 2: ...Technical Manual Wheatstone Corporation May 2013 FM HD Digital Audio Processor FM 531hd...
Page 122: ...page A 2 FM 531HD May 2013 A P P E N D I C E S Appendix A General Specifications A 3 Contents...
Page 128: ...page A 8 FM 531HD May 2013 A P P E N D I C E S Appendix B FM 531HD GPI Interface A 9 Contents...
