Driver to decode NMEA '$GPGGA' sentences (or '$PTNL,GGK' sentences) from a TCP/IP network connection.
Driver does not handle NMEA sentences from UDP/IP connections, see remarks below.
If PPS is connected, then the time field from the input data string is used. Otherwise, the timetag will be set when the last byte of the NMEA sentence is recieved. Since data transfer over TCP/IP network connections can vary considerably, there is no correction for string length and latency applied. Therefore, only use this driver when PPS is connected, or when exact timing of positions is not an issue.
The NMEA WinSocket driver only supports TCP/IP network connections, not UDP/IP communications.
TCP/IP (Transmission Control Protocol / Internet Protocol) is based on a connection between 2 computers. UDP (User Datagram Protocol) is based on connectionless communication. The primary difference between TCP and UDP lies in their respective implementations of reliable messaging. TCP includes support for guaranteed delivery, meaning that the recipient automatically acknowledges the sender when a message is received, and the sender waits and retries in cases where the receiver does not respond in a timely way. UDP, on the other hand, does not implement guaranteed message delivery. A UDP datagram can get 'lost' on the way from sender to receiver, and the protocol itself does nothing to detect or report this condition. However, UDP messaging will be faster, since UDP packets are limited in size and no connection setup is required. TCP is used for normal Internet traffic and applications such as web servers and FTP, whereas UDP is ideal for applications like video streaming and online gaming, where speed takes precedence over lost packets.
Drivers IO Notes
Command line parameter 'N' indicates the type of NMEA sentence that will be decoded. Currently only '1' (GPGGA) and '1024' (GGK, e.g. Trimble TNL) are supported. The 'NOCS' parameter will make the driver ignore the checksum field. 'MSL' gets the altitude from the message and adds the geoidal separation before storing it. 'ELL' will only decode the altitude field and store it as height on the ellipsoid.
Enter port number and IP adress from the sending computer on the TCP/IP network.