Is All Rosy in HD Land?
Before you conclude after reading all the above description that HD radio is the cure for all ills related to radio transmission and is of the best quality ever made available to mankind, think again.
Let's look at the flaws of HD, or rather I would prefer to call it the hype associated with HD, which tends to cloud the main issues related to its performance.
Firstly the IBOC or "In-Band On-Channel" technology which is used to transmit digital and analog signals at same frequency, causes interference with adjacent channels, so much so that new acronyms have been coined (in pun) like In-Band Adjacent-Channel (IBAC) or even IBUZ due to the buzzing or humming noise it generates. The effect on FM is reduced or absent distant adjacent channel rejection if more local stations are running HD radio, which is particularly bothersome if the receiver locks onto a distant digital station's signal instead of the desired local analog FM signal.
Yet supporters of HD argue that even though this "capture effect" is indeed applicable in case of FM channels, it is very unlikely that IBOC signals would cause interference in adjacent channels unless they were much weaker. Yet not only distance from the FM station is involved; characteristics like terrain and even time of the day act as spoilsports and cause the problem.
Many AM stations have switched off IBOC because of the objectionable buzz or buzz-saw-like noise heard in adjacent channels in crowded urban areas.
In the end it could be stated that though HD radio is an innovative idea, and practically seems to provide a much better audio quality for radio transmission, it is not yet so in practice. The practical limitations which have plagued the actual implementation of the HD systems have added a quantity of problems as great as the number of meager benefits of this so-called improved quality.
It is high time that we perceive this technological development in light of the actual circumstances. Scientists, researchers, and broadcast engineers should try to find less expensive cures for the noise and interference so as to aid large scale adoption and implementation of this technology.