The transmitter was run at average power of 100 Watts, with an Icom 706 receiver in the truck connected via IF converter where necessary to the appropriate software demodulators. Most tests were done with the in-vehicle audio, some shorter tests recorded audio directly in software.
Reception of 100 watt DRM30 10kHz 64QUAM transmission 10 km local route.
Reception of 100 watt AM stereo CQUAM NRSC-1 transmission, 10km local route with SoDiRa, AGC in peak, fast mode, 7.5k baseband audio and de-emphasis added in Audacity
The worst part of AM broadcast is the poor receivers.
In the late '80s the AMAX standard was suggested to allow better fidelity when conditions allow but with rollback to narrowband in poor reception areas.
Ironically, most medium / high power transmitters are now supplied with CQUAM already in the modulator. For long range coverage of sparsely populated areas, this is the best choice available today.
It ain't broken, so nothing to fix. Someone needs to tell the radio makers though. Not convinced? here is a better example
AM stereo ROCKS
Reception audio tracks of Roadtrip, 100 watt DRM30 transmission then 100 watt AM transmission over the same 20 km route, 2 channel comparison, L ch = DRM, R ch = AM, start of each track approx. same part of journey, stationary at same location for last 8 mins of recording. May be easier to listen to the tracks separately.
Reception of Roadtrip, 100 watt AM stereo transmission same 20 km route.
Reception audio tracks of Roadtrip, 100 watt P25 digital transmission then 100 watt SSB transmission over the same 20 km route, 2 channel comparison, L ch = P25, R ch = SSB, start of each track approx. same part of journey, stationary at same location for last 8 mins of recording. May be easier to listen to the tracks separately.