— —
17
subcarrier level control) for the proper injection. This is normally
about 5% for an RDS subcarrier, 10% for an SCA.
7. Put the Mod-Monitor back into its “Total Peak Modulation”
measurement mode and, if necessary, trim the
OUTPUT LEVEL
control so that the peak flasher(s) indicate only
occasional
100%
peaks.
NOTE:
Depending on current operating rules and practices, when
either an SCA or an RDS subcarrier is broadcast, total peak carrier
deviation
may be permitted
to exceed the customary 100%-modulation
figure. The station (or consulting) engineer should be aware of legal
guidelines in effect and assume responsibility for any adjustment which
deviates from this procedure.
AVERAGE COMPRESSION ADJUSTMENT
Once the
OUTPUT LEVEL
has been set for proper carrier peak deviation,
the user may determine a setting for the
AVERAGE COMPRESSION
control based on listening tests. A guideline already expressed has
stated that “hard rock” formats may use any
AVERAGE COMPRESSION
setting up to
10dB
, probably
without ill effect. More conservative
practice, particularly on “mellower” formats, would dictate a
6dB
to
8dB
maximum setting.
COMPOSITE PROCESSING
This control will have a definite effect on program “loudness,” but not
without some tradeoff for distortion or probable interference between
the main program and any auxiliary subcarriers. Please see the
discussion under
COMPOSITE PROCESSING
on Page 14.
