Summary: A DCC Sniffer is an interface between the track and another device, often used for DCC Packet Analysis.
A DCC Sniffer has several applications. Its main purpose is to connect to the track or power bus and extract the DCC data from it.
Data Packet Analysis
In this application, the sniffer's output goes to another device, such as a computer or a handheld analyser. Software then processes the DCC data stream to extract information which is presented in a human readable form.
For example, it could extract a multifunction decoder packet and display details such as Address, Functions, Direction and Speed. It could be used to troubleshoot issues such as poor decoder response or determine that the signal is of poor quality resulting in excessive errors being generated.
A more recent application is to bridge between DCC systems with incompatible throttle networks. The sniffer will provide the DCC data (at logic levels) to the input of a command station or booster via its Sniffer Input. This avoids using a throttle network, which may be proprietary or subject to licence fees. A number of European DCC suppliers feature this, such as Roco's Z21 and the ESU ECoS.