Omnia Audio’s Frank Foti was the last speaker of the day at the National Radio Conference, but his presentation packed a punch, especially for the ears. He played audio of radio stations that were processing too much and suffering from distortion because of it (on air anabolic steroids he calls it), then played audio to show that these problems can be fixed. He also suggested that a more efficient way of transmitting FM signals can decrease multi-path distortion.
Being loud is not the problem. “If it’s too loud, you’re too old” does apply,” Foti told the audience. The problem is the unfriendly annoying artefacts generated by current processing practices employed by broadcasters and the music industry. The combination of hyper-compressed content and “I gotta be louder than the other guy” on-air processing, results in audio lacking definition, and quality, while containing many annoyances. It would be easy to say, just back down the processing and all will be OK, except, in reality, and the psychology of broadcasters believe differently.
He says we will always have loud radio stations, as long as programming philosophy remains, as it has, since Mike Dorrough fathered multiband processing. The challenge now is how do we put quality back into on-air audio; yet retain the competitive loudness level broadcasters demand. He says this is not just about more bands or filters in the processors to try and eliminate that ‘frying’ sound, although many think it is. The answer is in how all distortion products are dealt with interactively on an instantaneous basis.
The solution is not in the number of bands. Anyone who thinks adding more bands of clipping and filtering to the system is wasting DSP cycles, or computer MIPS, along with a lot of marketing rhetoric! The answer lies in understanding the range of frequencies that generate both harmonic and intermodulation distortion, then applying various masking means to suppress both simultaneously, as they are generated.
It is a combination of breaking down the audio spectrum by octaves and interaction with the Gibbs Phenomenon. This, along with SENSUS technology enables a clipping system that suppresses BOTH harmonic and IMD distortion components, when aggressive processing levels are required. Additionally, and more importantly, this new clipping method does not employ the use of dynamic compressors or limiters to control depth of clipping, in order to minimize clipping induced IMD.
Omnia is using these ideas to develop the next generation of processors. The company is embarking on means where audio processors autoadjust themselves based upon content, density – or lack there of – in signal content. It’s a wide open spaces, Foti says.
Tackling the problem of multi-path distortion, Foti says it is possible to transmit Fm differently by reducing the upper sideband and reducing bandwidth from 53kHz to 38 kHz. There is also a 4dB signal to noise improvement with this method. He illustrated it in the diagrams below.
Testing done by Foti and his team has resulted in interest from America’s FCC to help get better signals in the overcrowded, interference prone American market.
JVC/Kenwood are currently testing his method and considering decoder redesign if the results are successful, and field tests should begin very soon.