Drive Time in the 2010s (Part 2)

As listeners to mountainchill.com are probably aware, the digital age has redefined the radio medium in many ways. Here is a list of many of the current US delivery methods that are considered mobile/automobile "radio" and some of their advantages and disadvantages. There are a plethora of non-US options as well, and maybe we'll cover those at a later date.

*AM/FM analog radio. Now often referred to as "terrestrial radio." These stations broadcast with a power of hundreds to hundreds of thousands of watts and generally cover a metro region. FM sound quality within the local broadcast area is generally excellent, often comparable or better than 256 kb/s digital audio in my opinion. Since the audio is analog, it does not suffer from digital compression artifacts. Advertising and news can be targeted toward a local audience.

* Satellite radio - In the US, this service is known as SDARS and is delivered by XM and Sirius Satellite Radio. These services offer hundreds of specialty channels and rebroadcasts of some major market AM/FM stations as well. Signals are delivered from satellites at about about 22,223 miles (35,764 km) above Earth to special portable and in-car receivers. Satellite radio receivers are included in many US vehicles, including many rental fleets. Satellite radio is subscriber supported and, unfortunately, has suffered from low subscriber numbers.

Due to the limited bandwidth/throughput of the satellite and the large number of channels, satellite radio channels are highly compressed with bit rates as low as as 32-48 kbps whereas Internet radio bit rates are typically 128 kbps.

Listen carefully to satellite radio and you will soon become annoyed with the low quality and high level of compression artifacts. Most critical listeners will agree that a clear FM radio signal offers much higher fidelity.

* HD radio - HD radio is iBiquity's trademark for it's in-band-on channel method which allows AM/FM stations to broadcast multiple channels of digital audio, literally on-top of their analog signal.

HD radio supports one channel at 300 kbps or that channel may be subdivided into several lower bit rate channels. Since the FCC requires that the analog signal be rebroadcast in digital form, subsidiary channels are left which a much lower sub-divided bit rate, as low as 12 or 5 kbps.

HD radio is delivered free to the listener, however a special HD radio is required and consumer uptake has been low. Also, the broadcast radius of HD radio is often significantly less than conventional AM/FM radio. Nonetheless many broadcasters have developed an array of specialty programming for their HD channels including NPR stations, Clear Channel and CBS Radio.


* Internet Radio - With the widespread rollout of third generation (3G) wireless service in the US and Long Term Evolution (LTE) on the horizon, the real revolution in the Internet today is wireless access through smartphones such as the iPhone and those running the Android operating system.

3G networks have finally reached a level where it is possible to reliably stream audio at 128 kbp/s and, in many cases, higher rates. Smartphone listeners now have acces to not hundreds, but tens of thousands of streaming radio stations, including many AM, FM, HD, and satellite stations that provide a secondary Internet stream.

Another upside is that as smartphones become ubiquitous, no additional receiving equipment is required. One downside is that an adapter of some sort is usually required to listen over car speakers. Another downside is that there are a gazillion different listening applications. In the next installments, we'll cover those details and simplify the whole process of listening in the car.