Kenwood_PG-4W_APRS_user.pdf

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1、1 APRS Return to Contents APRS ABOUT APRS The Automatic Packet/ Position Reporting System (APRS) was created by Bob Bruninga, WB4APR, of Maryland, U.S.A. Bob Bruninga is the president of APRS Engineering LLC, which owns the trademark for APRS. Bob created the APRS protocol and developed a program ca

2、lled “APRSdos”, which is the official name of “APRS”. This program runs on the MS-DOS platform. The idea of APRS came about in the late 1970s, and it has been constantly updated since its initial release in 1992. Today, many licensed versions have been released for many platforms (refer to page 4, “

3、The APRS Program”). Versions include MacAPRS for the Macintosh, WinAPRS and APRSplus for Windows, javAPRS written in Java, and PocketAPRS which runs on the Palm III. One of the latest creations for APRS is the TH-D7. The TH-D7 is an APRS data communicator radio. The APRS protocol uses packet communi

4、cations which are Unnumbered Information (UI) frames. The packet contains the position, station data, status, and messages. The position contains the latitude and longitude, the station data contains the stations information (call sign, output power, etc.), weather information (temperature, wind spe

5、ed and direction, etc.), etc., the status is like your comment, and the message is like e-mail. To enjoy APRS, you require a transceiver with a Terminal Node Controller (TNC), and an APRS program that runs on a personal computer. The TH-D7 has an internal TNC and also contains the APRS functions tha

6、t are considered indispensable in a portable transceiver. For information on how to operate APRS on the TH-D7, refer to page 12, “USING THE TH-D7 AS A SIMPLE APRS STATION”. The following section describes general usage of APRS on transceivers, TNCs, and personal computers. 2 APRS Return to Contents

7、APRS STATION CONFIGURATION A basic APRS station configuration is as follows. The transceiver connects to a TNC and the TNC connects to the serial port of a personal computer which must have the APRS program installed. Return to Contents MIC PC SP ESC OK GPS KENWOODFM DUAL BANDER TM-V7 Dual PC Radio

8、TH-D7 TNC APRS Software KENWOODFM DUAL BANDER TM-V7 Dual PC APRS Software TNC Radio Weather Instrument The configuration of a weather station consists of a weather observation instrument connected to one serial port on the personal computer, and the TNC connected to another serial port. 3 APRS Retur

9、n to Contents Mobile stations require a GPS receiver. The GPS receiver should be connected to one serial port on the personal computer and the TNC to another serial port. If the computer has only one serial port, the TNC should have GPS input. APRS Mobile S t a t i o n Configuration (Desktop PC) APR

10、S Mobile S t a t i o n Configuration (Laptop PC) KENWOODFM DUAL BANDER TM-V7 Dual PC Radio TNC APRS Software GPS KENWOODFM DUAL BANDER TM-V7 Dual MIC PC SP ESC OK GPS PC Radio TNC APRS Software GPS GPS TH-D7 4 APRS Return to Contents IThe APRS Program The APRS program currently runs on a number of p

11、latforms. These programs are constantly being updated and can be downloaded from the Internet. Most programs are shareware and the latest versions are available at the TAPR (Tucson Amateur Packet Radio) FTP site: ftp:/ftp.tapr.org/aprssig APRSdos (ftp:/ftp.tapr.org/aprssig/dosstuff/APRSdos) Written

12、by Bob Bruninga, WB4APR, the Father of APRS Runs on MS-DOS. MacAPRS (ftp:/ftp.tapr.org/aprssig/macstuff/MacAPRS) Written by Mark Sproul, KB2ICI and Keith Sproul, WU2Z Runs on Macintosh computers using Operating System 7 or higher. WinAPRS (ftp:/ftp.tapr.org/aprssig/winstuff/WinAPRS) Written by Mark

13、Sproul, KB2ICI and Keith Sproul, WU2Z Runs on Windows 95 or higher, or on Windows 3.1 + Win32s. javAPRS (ftp:/ftp.tapr.org/aprssig/javastuff) Written by Steve Dimse, K4HG Runs on JAVA. APRSplus (ftp:/ftp.tapr.org/aprssig/winstuff/APRSPLUS) Written by Brent Hildebrand, KH2Z Runs on Windows 95 or high

14、er, or on Windows 3.1 + Win32s. PocketAPRS (ftp:/ftp.tapr.org/aprssig/palmstuff/palmaprs) Written by Mike Musick, N0QBF Runs on Palm III. Displaying Received Data When APRS data including position data is received, the icon and call sign of the station that sent the data will appear on the map displ

15、ayed on your screen. The icon indicates the type of station, so you can see at a glance the type of APRS stations that are active in your area. 5 APRS Return to Contents Tracking Mobile stations frequently send their position data. By receiving their positions, the APRS programs can track their move

16、ment. Movement is in real time, including speed and direction. You can save the tracked data to a file and replay it at a later time. Two famous mobile stations in the past were the lead car of an Olympic marathon, and the Space Shuttle. Maps Maps are usually included with the APRS program, so you c

17、an select the map of your area. Map data is frequently updated and is available at the TAPR ftp site (ftp:/ftp.tapr.org/aprssig/maps/). Status APRS stations transmit status data packets and position data packets separately. These data packets have transmission interval times. Status data is the free

18、 text data called Status Text which is usually used for describing the station. Position data has a Position Comment. But some stations, such as a weather stations Position Packet, have meteorological data and cannot use a Position Comment. Objects APRS allows information on natural disasters, such

19、as hurricanes and tropical storms, to be transmitted as object data. This data includes location, direction of movement, and speed. When you receive such data, the object name appears on the map screen rather than the call sign of the transmitting station. Meteorological Data APRS supports many mete

20、orological instruments. You can connect them to your computer and send the real time data in APRS format with the location. By receiving real time data such as temperature and wind speed and direction, you can have beneficial information for surfing, hang gliding, mountain climbing, etc. 6 APRS Retu

21、rn to Contents Messages APRS has a powerful message function. Two types of messages can be used: Addressed messages and bulletins. Addressed messages allow you to use a call sign as an address, create a line message, and transmit it. The recipient returns the acknowledgment automatically. The messag

22、e is resent at set interval times until an acknowledgment is returned. Digipeater and gateways (refer to page 9, “Networks”) provide wide coverage area. A handheld transceiver like the TH-D7 can send messages from Los Angeles to New York with no troublesome setup procedure. APRS will also accept to

23、send the message to Internet e-mail. A bulletin is a message with no address. The purpose of a bulletin is to send multi-lined messages to all APRS stations. No acknowledgment is used because no recipient is specified. IGPS Receivers GPS receivers have become affordably priced. To use the GPS receiv

24、er, it must have NMEA-0183 format output (refer to page 7, “NMEA Format”). Most GPS receivers have this type of output. Mobile APRS stations with this type of GPS receiver can transmit their position in real time. If your PC has 2 serial ports, connect the GPS receiver to one port and the TNC to the

25、 other, then use the APRS software to set up these devices. If your PC has only one serial port, use a TNC that is equipped with a special input socket for a GPS receiver, such as the TH-D7. Alternatively, you can switch the serial port connection either automatically or manually between the TNC and

26、 the GPS receiver. To connect the GPS receiver to the serial port on the PC, simply connect the Ground terminal of the GPS receiver to the SG (Signal Ground) terminal on the PC, and the Data Output terminal of the GPS receiver to the RD terminal on the PC. Keep in mind that GPS receivers work in the

27、 1500 MHz frequency range. Spurious emissions of 440 MHz or 1200 MHz transceivers may affect GPS signal reception. To avoid this, keep the GPS receiver and the transceiver as far apart as possible. 7 APRS Return to Contents Latitude, Longitude, and Grid Square Locators APRS is designed to send and r

28、eceive position data. Position data is described by latitude and longitude, expressed as “ddmm.mm” (for example, 3231.82 minutes). The decimal places are not seconds, they are actual decimal places. You can establish your latitude and longitude using a GPS (Global Positioning System) receiver, or ch

29、eck it on a map which shows lines of latitude and longitude. When you operate in a fixed location, such as your home, a map is sufficient. When you operate as a mobile station, you need a GPS receiver to constantly identify your position. Ham operators normally use the “Grid Square Locator” notation

30、 to explain their location. APRS allows the use of the Grid Square Locator notation when you cannot specify your exact latitude and longitude. A special data format is used for the purpose. The Grid Square Locator divides the world into an 18 x 18 grid (324 areas), with each grid area assigned a nam

31、e from AA to RR. Specify the grid square you are in, then divide that square into another 10 x 10 grid (100 squares). These squares are labeled 00 to 99. Each of these squares is then further divided into a 24 x 24 grid (576 sub-squares), labeled AA to XX. You can then obtain your exact location as

32、a point between AA00AA and RR99XX (18,622,400 total grid squares). NMEA Format NMEA-0183 is a standard used by the National Marine Electronics Association concerning interface with marine electronics devices. This standard contains electrical signals, data protocol and timing, and management of the

33、serial signal bus. In the electrical signal level, +5 V/0 V TTL level output and EIA-422 compatible interfaces are used. The baud rate is 4800 bps, there are 8 bits for data bits, there is no parity, and there is 1 bit for the stop bit. All data starts with “$” and ends with “”. This data unit is ca

34、lled a sentence. A Talker identifier is represented by two characters which follow the “$”, then characters showing the sentence format follows that. The data field is separated by commas. “ * ” shows the check sum field. is at the end of the sentence. The Talker identifier for a GPS receiver is GP.

35、 For example, “$GPRMC” stands for an RMC sentence from a GPS (GP) device. $GPGGA = Global Positioning System Fix Data $GPRMC = Recommended Minimum Specific GPS/TRANSIT Data $GPGLL = Geographic Position - Latitude/Longitude. 8 APRS Return to Contents ITNC APRS requires a Terminal Node Controller (TNC

36、) that complies with the 1200 bps AX.25 protocol. The transfer speed between the PC and TNC can be set by the APRS software. Some TNCs have built-in functions for APRS, such as direct connection to a GPS receiver and the Trace function which embeds the call sign into the signal when it is passed thr

37、ough a digipeater (refer to page 9, “Digipeaters”). APRS packet data uses UI frames in converse mode. BTEXT is not used. ITransceivers You can use any FM transceiver to operate APRS in the VHF/UHF band. Plug the transceiver audio output into the TNC. Connect the TNC modulated output and PTT signals

38、to the transceiver. Connecting the transceiver and TNC ground terminals completes the connection. Finally, adjust the transceiver AF volume so the packet signals can be effectively decoded. Operating Frequencies APRS originally began operating in the U.S.A. on 145.790 MHz, but is now available in mo

39、st areas on 144.390 MHz. In southwestern Arizona, New Mexico, and Texas, APRS operates on 145.010 MHz. These regions are also preparing to shift to 144.390 MHz, however. The HF gateway frequency is 10.151 MHz Lower Side band (10.1492 MHz MARK tone) for all areas. 9 APRS Return to Contents INetworks

40、APRS is a network system which uses Packet communications. VHF transceivers are limited in range, but with the use of digipeaters, you have nationwide APRS coverage. With the use of HF and Internet Gateways, you can access nation wide APRS stations. Digipeaters Digipeaters are a function of TNCs and

41、 are an indespensable tool in packet communication. Using digipeaters, you can transfer packet data over longer distances. Unlike normal voice repeaters, which send and receive simultaneously on different frequencies, a digipeater sends and receives on the same frequency. Digipeaters do not send and

42、 receive at the same time, however. They store received packet data in the TNC memory until the end of reception, then they recall the data from memory and resend it. Packet data is rebuilt by the digipeaters TNC and it is transferred with no degradation. Digipeaters can relay the packet data from o

43、ne repeater to the next, making it possible to transmit packet data over distances that cannot be attained by voice communications. Generally, a digipeater relays (digipeats) data when the packet path includes the digipeaters own call sign (specified in the MYCALL command). APRS makes particularly g

44、ood use of the way digipeaters operate. In fact, the growth of APRS to its current level is due in large part to the use of digipeaters. How are digipeaters used in APRS? First, the digipeater uses either a WIDE or RELAY packet path. Most TNCs have a MYALIAS command which can assign a name other tha

45、n MYCALL. For example, you send APRS data with the packet path WIDE, an APRS digipeater around your area with MYALIAS WIDE digipeats your data. WIDE type digipeaters are digipeaters that cover long distances. All other digipeaters are classified as RELAY digipeaters. Also, using a combination of REL

46、AY and WIDE (the packet path will be RELAY,WIDE), your APRS data hops RELAY digipeaters first and then WIDE digipeaters. This means that a transceiver using APRS does not need to know the call sign of the digipeater. Simply by specifying “RELAY,WIDE” in its own packet path settings, it can send data

47、 over great distances. However, to reduce the APRS packet traffic, you should specify the digipeaters call sign in the packet path. Without doing so, all RELAY or WIDE type digipeaters in your area will digipeat your data, creating unnecessary traffic. 10 APRS Return to Contents HF Gateways A gatewa

48、y is a digipeater that can relay packets between different frequencies. In APRS, HF gateways have been established to allow the thousands of VHF users to see what is happening on the HF APRS band. Most packets on the very low data rate (300 Baud) HF channel are automatically relayed by HF gateways i

49、nto local VHF APRS networks everywhere. This is possible because the low data rate of HF does not significantly affect local VHF activity at higher baud rates. Other than for emergencies, APRS packets are not encouraged in the opposite direction where thousands of VHF users on VHF could instantly saturate the much slower HF channel and render it useless to everyone. The single HF channel can handle about 100 or so users nationwide whereas the hundreds of VHF nets can handle thousands of users independently. Yet, the thousands can still see what is happening on HF