I’ve found several sites on the Internet claiming that the AAR is recommending that all new radios purchased by the railroads be compatible with the digital NXDN, 6.25 kHz , format. I read that CSX just received 500 Kenwood NXDN type radios. I also saw and held a Kenwood NXDN portable radio supposedly destined to BNSF. So, it appears, the railroads are focusing on NXDN, 6.25 kHz radios, thus skipping the conversion to 12.5 kHz, either analog or digital. Currently Icom and Kenwood manufacture the NXDN radios and hold the license for the technology. I have some Kenwood NXDN (called NexEdge by Kenwood) radios and based on subjective testing, the performance is excellent, as is the audio quality.
Since the NXDN radios are capable of digital and analog, the conversion is eased, and the radios can be programmed to respond to either a digital or analog signal, and respond in the same mode as received, thus easing the conversion, though not eliminating all operational issues. The downside is that I’m not aware of any scanners that will receive NXDN format.
AAR asserts a need for more frequencies for rail operations as the reason for the conversion to NXDN 6.25 kHz bandwidth, and the reason for skipping the intermediate conversion to 12.5 kHz as mandated by the FCC.
All the above information is gleaned form various sources, perhaps not all reliable. Any clarification or verification of the information would be appreciated. Some of this information conflicts with the statement that UPRR is installing new narrowband (12.5 kHz) analog equipment so from my perspective, the future is kind of fuzzy.