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QUOTE (Gary @ 14 Jan 2007, 12:36) <{POST_SNAPBACK}>Hornby have said their decoder has been designed to be NMRA compliant. Hornby have said it has yet to receive a conformance warrant.

Do you have to submit your decoder to the NMRA to be NMRA compliant?

You need to submit the decoder if you want a conformance warrant. The DCC specification is in two parts, (a) the standard, and (
recommended practices (RP). To get the warrant you have to comply with the standard AND meet all applicable RPs. The standard covers only the very minimum functionality required to have something work. Practical interworking will usually require that many of the RPs are followed as well.

From the information available at the moment it appears that the Hornby decoder may satisfy the standard, but does not conform to the relevant RPs.

All that is in the 'standard' are speed and direction packets, idle packet, reset and emergency stop. All methods of programming are part of RPs.

I don't think the Guagemaster/Prodigy product has a conformance warrant either. So perhaps they too have implemented some subset of the RPs.
 

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QUOTE (darobi @ 13 Jan 2007, 21:55) <{POST_SNAPBACK}>Apparently the Hornby decoder frequency is out of the range of the prodigy and they are having to change a chip in the controllers to expand the frequency range of the dcc signal they use to enable it to work with the hornby chips.
That sounds like pure bull****.
 

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The choice of programmimg methods may be due to two reasons:
1) evolution of the standard. As more CVs became desireable, better methods of programming were required.
2) documenting existing practice by manufacturers.

See for example the issue with 21 pin decoders. The NMRA haven't yet got around to issuing a standard for high pin count decoders, but there is already product out there.
 
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