1) Marcus’ NCE DCC for Everyone
Marcus's DCC Website is full of good technical information gathered by himself from many sources. Although it is NCE oriented, many of the topics apply to all DCC systems. Marcus has multiple pages and I often will reference them on this site as needed. Although he is a NCE user, the information about problems can often be applied to any DCC system.
This is the DCC site for novices:
http://www.members.optusnet.com.au/nswmn2/DCC.htm
DCC articles talk about investigation into specific topics:
http://www.members.optusnet.com.au/nswmn/dcc_articles.htm
2) Mark’s Schutzer's Web Site
Mark is also a NCE user. However his loves to rebuild brass engines and install decoders makes the information useful for any brand of decoder.
Mark Shutzer's website offers DCC Decoder installation clinic and how to rebuild Brass Engines.
http://www.markschutzer.com/Brass_Clinics/Clinics_page1.htm
He also has some articles regarding NCE radio upgrades.
http://www.markschutzer.com/DCC_Articles/DCC_Articles_page1.htm