(1) Module working voltage: the working voltage of the terminal comes from the on-board battery, which is usually 12V or 24V, and the module voltage should be less than the power supply voltage;

（2）通訊方式：可采用無線網(wǎng)絡(luò)和短信息方式通訊；（3）終端在線率：為了確保終端與監(jiān)控?cái)?shù)據(jù)交流的實(shí)時(shí)性，終端應(yīng)保持高在線率；

(2) Communication mode: wireless network and short message communication can be used; (3) terminal online rate: in order to ensure the real-time data exchange between the terminal and the monitoring center, the terminal should maintain a high online rate;

（4）丟包率：丟包率是指測(cè)試中，所丟失數(shù)據(jù)包數(shù)量占所發(fā)送數(shù)據(jù)包的比率，為了降低數(shù)據(jù)丟包率，在設(shè)計(jì)中可以考慮，發(fā)生無線傳輸模塊不能連接網(wǎng)絡(luò)，導(dǎo)致終端不能登錄系統(tǒng)的情況時(shí)，待無線傳輸模塊脫離盲區(qū)后，將數(shù)據(jù)補(bǔ)傳服務(wù)器；

(4) Packet loss rate: the packet loss rate refers to the ratio of the number of lost packets to the transmitted packets in the test. In order to reduce the packet loss rate, it can be considered in the design that when the wireless transmission module cannot connect to the network and the terminal cannot log in to the system, the data will be transmitted to the server after the wireless transmission module is out of the blind zone;

（5）定位精確度：車輛監(jiān)控調(diào)度系統(tǒng)的電子地圖精度數(shù)量級(jí)是米，我國(guó)二級(jí)道路的標(biāo)準(zhǔn)寬度為 30~60m，如果要對(duì)車輛進(jìn)行準(zhǔn)確的監(jiān)控，定位精度需控制在30m 以內(nèi)，否則，當(dāng)兩條道路的距離過近時(shí)，就可能出現(xiàn)定位錯(cuò)誤，即正在某條公路上行駛的車輛被定為在道路外或其它道路上。

(5) Positioning accuracy: the order of magnitude of the electronic map accuracy of the vehicle monitoring and dispatching system is meters. The standard width of the secondary road in China is 30 ~ 60m. If the vehicle is to be accurately monitored, the positioning accuracy should be controlled within 30m Otherwise, when the distance between the two roads is too close, positioning error may occur, that is, the vehicle driving on a certain road is determined to be outside the road or on other roads.