Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now


As Goes Your FM Processing, So Should Your HD1

Jurison emphasizes the need to process those two identically

Alan Jurison is senior operations engineer for iHeartMedia. Much of his focus has been on advancing its transmission of digital HD Radio data services, RDS and other metadata services. This is an excerpt from the ebook “Trends in Audio Processing 2022,” available at

Alan Jurison

Radio World: How would you describe your approach to radio processing?

Alan Jurison: There are a lot of opinions on signature sounds. In my position, I offer advice but allow some of our engineers with audio processing backgrounds to help shape those opinions for our use. A key philosophy to take away is to process your FM and HD1 signals identically.

As we’ve learned in the past few years, as goes FM processing, so should HD1. FM+HD1 processing should be done in the same appliance and processing core for the best blending transition. Separate audio processors for FM vs HD1 and different sound profiles between the two are now strongly discouraged, and that advice has been acknowledged by the industry as a best practice; see Section 5.1 of NRSC-G203. 

For channels that are all-digital, or pure-play digital — HD2, HD3, HD4 or internet streams or other applications well ahead of a transmitter site — I see the general trend into moving those into software or cloud-based processing services. The industry has already started shifting in this direction.

RW: What features or capabilities would you like manufacturers to add to their offerings?

Jurison: Making the FM+HD1 audio processing identical, easy for the end-user in a single-box processor. There are scores of firmware updates, tech notes, settings changes and tweaks needed in a lot of common modern signal-box processors to get the FM and HD1 to be processed identically.

It’s hard for the engineers out in the field to know all this information. These should be the default settings with the latest firmware update and not left up to the user to find out how to update the product to fix some misconceptions in earlier processor design. Any new products leaving the factory need to be set this way, and careful review and analysis in a lab should be done for any future firmware updates or product redesigns to focus in this area. HD is no longer an afterthought.

RW: What tools are available to mitigate issues involving synchronization of HD Radio and analog signals?

Jurison: Single-box, common processing for both FM+HD1. Do not employ multiple devices to process FM and HD1 signals separately. With overall automotive HD penetration in some markets exceeding 40%, this is becoming more important every day. In some markets we are arriving at the point where we have just as many listeners to the HD1 as we do the analog FM. 

Using an automated alignment processor is important too. There are various ways to achieve this either in the properly equipped Gen4 Exporters, external alignment processors, audio processors with integrated time alignment features, or external monitors that direct an older Exporter or audio processor to change the delay.

RW welcomes your Tech Tips, email us at [email protected].

[Check Out More of Radio World’s Tech Tips]