Obnoxious, fatiguing artifact-laden codec. High costs. Self-interference and analog noise. Adjacent-channel interference. Encoding delay. Limited digital coverage. Necessitates drastically reduced analog bandwidth. Won't work with a large percentage of existing directional arrays. Engineers hate it; listeners couldn't care less.
To these well-known HD-AM features we can now add: IBOC-AM can damage power modules in the latest generation Harris 50kw transmitter, the 3DX-50.
There have now surfaced an increasing number of accounts - of course, in typical HD fashion, being forcibly hushed by IBOC powers-that-be - that the HD encoding and COFDM system can cause transient drive failure to MOSFETS in the PA modules of the popular high-power Harris AM transmitter being used by a large number of HD-equipped stations. Result: PAs shut down, forcing reduced-power operation until an engineer can make repairs.
There is at least one account of a 50kw midwest station that operates its older-generation transmitter - that's right, a BACKUP - because it's less susceptible to PA damage from HD encoding. Which of course means that the shiny new 3DX-50 is relegated to the status of being an expensive standby TX!
An unnamed source in the tech-support department at Broadcast Electronics stated that he was truly thankful for HD Radio. Without HD, the number of employees required to deal with technical problems and issues would likely be halved.
------------------------ Cameron Smith - CSRE®
Senior Member - SBE 68 Birmingham
Senior Digital Product Manager - Hibbett Sports|City Gear
Well, think about it. Ever try doing a proof on a plate modulated transmitter? How did it like 10 KC at full modulation? HD goes out to 19 kc (the 1000 demonic cicadas sound on the second adjacent channel).
Sure, the more modern rigs have the bandwidth to pass information that high in frequency. But I bet they don't like it!
Tom Taggart wrote:Well, think about it. Ever try doing a proof on a plate modulated transmitter? How did it like 10 KC at full modulation? HD goes out to 19 kc (the 1000 demonic cicadas sound on the second adjacent channel).
Sure, the more modern rigs have the bandwidth to pass information that high in frequency. But I bet they don't like it!
That being the case, subtile antenna changes could be disastourous on so many levels.
------------------------ Cameron Smith - CSRE®
Senior Member - SBE 68 Birmingham
Senior Digital Product Manager - Hibbett Sports|City Gear