M8N资料整理+参考电路

NEO-M8N-0-01、NEO-M8N-0-10官方详细资料整理打包，外加U-center测试软件，以及关于GPS模块的电路参考图

1 Introduction

This document provides important software-related information for customers when migrating from u-blox 7 to u-blox 8 or u-blox M8 FW SPG3.01 based products. Although most of the receiver features remain unchanged， some new ones have been added and some older ones revised or altered. These changes are reflected in alteration or addition to the u-blox message protocol and an extended range of NMEA sentences. Note that all the features described below are applicable to the u-blox 8 and u-blox-M8 devices except in the satellite constellations allowed. The M8 is a concurrent multi-GNSS receiver that can be configured to receive combinations of GPS， SBAS， QZSS， Galileo， GLONASS and BeiDou. The u-blox 8 is similar to the u-blox 7 in that it can be configured to receive GPS plus SBAS and QZSS or GLONASS signals only.

For the u-blox 8 / M8 devices the assistance messages for AssistNow Offline and Online service have been overhauled to work effectively with all supported constellations. Also， the AssistNow Autonomous function adds support for all the major GNSS constellations. The major software and operational changes are summarized as follows：

· NMEA default version is now 4.0; 4.1， 2.3， and 2.1 can be enabled

· Multiple GNSS assistance with the MGA AssistNow services

· GeoFence capability added

· UBX message integrity mechanism

· A new wrist mounted platform dynamical model for arm-swing mitigation

· New Power Save Modes

· Anti spoofing measures provided

· Odometer function for trip and total distance plus a Low Speed COG filter （intended for marine use）

· Reference for time pulse and time mark switched to UTC instead of GPS

· Operation with the Japanese Indoor MEssaging System （IMES）

As a quick reference， this document lists the basic message changes and then expands on these to provide some background information on the features that have been introduced or changed with this generation of Firmware. For a fuller explanation and description of the u-blox 8 / M8 capabilities， customers are directed to the u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification ［1］。