The present invention involves a transmitter for transmitting two levels
of data in a hierarchical transmission system. The transmitter has
encoders, a modulator, an adjuster, and an up converter. The first
encoder has a first output and capable of providing digital information
based on a first level of data on the first output. The second encoder
has a second output and is capable of providing digital information based
on a second level of data on the second output. The modulator is coupled
to the first encoder and has I and Q outputs. The adjuster is coupled to
the modulator and second encoder and modifies signals on the I and Q
outputs of the modulator to produce transmission I and transmission Q
outputs. The up converter is coupled to the adjuster and is capable of
transmitting broadcast radio signals based on the transmission I and
transmission Q outputs. The modulator may include a root raised cosine
filter and/or a QPSK modulator. The I and Q outputs of the modulator
include analog I and analog Q signals. The adjuster includes an inverter,
a phase rotator circuit, a combiner, and/or a limiter. The transmission I
and transmission Q outputs of the adjuster include analog I and analog Q
signals.