The Bessel filter could not yet solve overshoot issue

The Bessel pulse shaping filter is patched to the 27MHz, AD9851 DDS remote control transmitter.

The pulse shape looks OK when after shaping filter, but the modulating waveform envelop rise time not matched with shaping filter output. The rise time of envelop is a lot faster than fall time, it contribute to the overshoot in receiving waveform.

The ASK demodulator in receiver also have an old issue of envelop rise time faster than fall time. This makes the issue getting even more serious.

Demodulated waveform in receiver, sadly it has ~10% overshoot, it is highly suspected that this is caused by nonlinear phase response in 455kHz ceramic IF filter, the issue still not yet improved by adding transmit pulse shaping filter. The problem looks like from the AD9851 current reference input having asymmetry in rise time and fall time. Or power amplifier stage amplitude nonlinearity. This overshoot issue must be resolved.