A digital mode used on HF which has a high reliability of getting through under adverse conditions. The TNC used in a digital system has various setting which must be programmed by the operator to obtain the best performance for its particular function. These setting are called parameters and are different for each use, e.g. user station, node, etc. A path is a complete circuit between two packet radio stations. A path may cover several routes and nodes to bridge two stations.
All nodes have one or more ports.
A port in this discussion is a physical interface between the TNC and a radio such as a cable connection. A typical TNC will have at least one radio port and one cable port usually an RS-232 connection to a computer running some type of communications software. A set of rules used for communication. This can include the speed used, the number of bits, the mark and space frequencies. In packet radio, AX.25 is the form of protocol.