Transcript
Email:
[email protected] Visit us at http://www.sunrom.com
Document: Datasheet
Date: 26-May-11
Model #: 1141
Product’s Page: www.sunrom.com/p-731.html
GPS Receiver with Active Antenna – RS232 Global Positioning System (GPS) satellites broadcast signals from space that GPS receivers, use to provide three-dimensional location (latitude, longitude, and altitude) plus precise time. GPS receivers provides reliable positioning, navigation, and timing services to worldwide users on a continuous basis in all weather, day and night, anywhere on or near the Earth. Sunrom’s ultra-sensitive GPS receiver can acquire GPS signals from 65 channels of satellites and output position data with high accuracy in extremely challenging environments and under poor signal conditions due to its active antenna and high sensitivity. The GPS receiver’s -160dBm tracking sensitivity allows continuous position coverage in nearly all application environments. The output is serial data of 9600 baud rate which is standard NMEA 0183 v3.0 protocol offering industry standard data messages and a command set for easy interface to mapping software and embedded devices.
Features • • • • • • • • •
High sensitivity -160dBm Searching up to 65 Channel of satellites LED indicating data output Low power consumption GPS L1 C/A Code Supports NMEA0183 V 3.01 data protocol Real time navigation for location based services Works from +12V DC signal and outputs 9600 bps serial data Magnetic base active antenna with 3 meter wire length for vehicle rooftop installation
Applications • • • • • • • • •
Car Navigation and Marine Navigation, Fleet Management Automotive Navigator Tracking, Vehicle Tracking AVL and Location-Based Services Auto Pilot, Personal Navigation or touring devices Tracking devices/systems and Mapping devices application Emergency Locator Geographic Surveying Personal Positioning Sporting and Recreation Embedded applications which needs to be aware of its location on earth
Package Includes • • •
2
GPS receiver board (Assembled/Tested with 1 year warranty) Active Antenna with 3 meter cable(Antenna has magnetic base for mounting on vehicle top) Serial Port Cable
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
Specification Parameter Operating Voltage Operating Current Sensitivity Channels
Value 9-12 V 150 -160 65
Protocol output baud rate Protocol format Output Voltage level Frequency C/A Code Accuracy in Position Accuracy in Velocity Accuracy in Time Datum Time to First Fix for first power on Time to Reacquisition Update Rate Acceleration Limit Altitude Limit Velocity Limit Jerk Limit Operating Temperature
9600 NMEA0183 V 3.01 RS232 level +12/-12 1,1575.42 1.023 5 0.1 0.1 WGS84(Default) 33 2 1 4 18,000 515 20 -40 to +85
Unit V AC/DC Power Supply mA dBm 65 parallel channels all in view searching L1 C/A code bps no handshaking(8-N-1) GGA,GLL,GSA,GSV,RMC,VTG Can connect directly to PC serial port Mhz Mhz chip rate Meters Meters/Second Microsecond. Sync GPS time total 219 datum’s Second approx. Second Hz G Meters Meters/Second Meters/Second3 Degree Celcius
GPS Introduction The Global Positioning System (GPS) is global navigation satellite system which uses a constellation of between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals, that enable GPS receivers to determine their location, speed, direction, and time. GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, tracking and surveillance, and hobbies such as geo-caching and way marking. Also, the precise time reference is used in many applications including the scientific study of earthquakes and as a time synchronization source for cellular network protocols. GPS has become a mainstay of transportation systems worldwide, providing navigation for aviation, ground, and maritime operations. Disaster relief and emergency services depend upon GPS for location and timing capabilities in their life-saving missions. The accurate timing that GPS provides facilitates everyday activities such as banking, mobile phone operations, and even the control of power grids. Farmers, surveyors, geologists and countless others perform their work more efficiently, safely, economically, and accurately using the free and open GPS signals.
GPS Method of Operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS satellites high above the Earth. Each satellite continually transmits messages containing the time the message was sent, a precise orbit for the satellite sending the message (the ephemeris), and the general system health and rough orbits of all GPS satellites (the almanac). These signals travel at the speed of light through outer space, and slightly slower through the atmosphere. The
3
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
receiver uses the arrival time of each message to measure the distance to each satellite thereby establishing that the GPS receiver is approximately on the surfaces of spheres centered at each satellite. The GPS receiver also uses, when appropriate, the knowledge that the GPS receiver is on (if vehicle altitude is known) or near the surface of a sphere centered at the earth center. This information is then used to estimate the position of the GPS receiver as the intersection of sphere surfaces. The resulting coordinates are converted to a more convenient form for the user such as latitude and longitude, or location on a map, then displayed. It might seem that three sphere surfaces would be enough to solve for position, since space has three dimensions. However a fourth condition is needed for two reasons. One has to do with position and the other is to correct the GPS receiver clock. It turns out that three sphere surfaces usually intersect in two points. Thus a fourth sphere surface is needed to determine which intersection is the GPS receiver position. For near earth vehicles, this knowledge that it is near earth is sufficient to determine the GPS receiver position since for this case there is only one intersection which is near earth. A fourth sphere surface is also needed to correct the GPS receiver clock. More precise information is needed for this task. An estimate of the radius of the sphere is required. Therefore an approximation of the earth altitude or radius of the sphere centered at the satellite must be known.
Block Diagram
Active Antenna
Low Noise Amp
SAW
GPS RF Front End
GPS Base Band
NMEA Serial Data TXCO
The GPS Receiver consist of two units, first is active antenna which receives RF signals and amplifies it. The antenna is active in the sense it takes power from the module and amplifies the signal for high sensitivity. The RF signal is filtered and processed to generate NMEA format serial data output.
4
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
Software for monitoring GPS data The NMEA data from GPS unit can be monitored by following. Download GPS monitoring software http://www.sunrom.com/files/TrimbleStudio_V1-01-21.exe
Select COM port to which GPS is connected and configure setting for 9600 Create “New Connection…”
It takes around 10-15 minutes for data to be shown after power up.
Click Monitor > RAW Data to see what GPS receiver is sending raw serial data.
5
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
Click Monitor > SKY Plot to see what satellites are located
Power Requirement of Receiver The unit needs around 200mA power to operate at 12V. You can use any readymade 12V 500mA DC Adapter or design a transformer plus rectifier based 12V DC power for the board. You can also use just the 12V transformer as the board has bridge and capacitor to convert to DC. We recommend SMPS based 12V 1A DC Adapter for 24 hours operation as it is efficient and does not generate heat as compared to transformer based adapters. Product page is here http://www.sunrom.com/power-supplies/dc-adapters/12v-1a-dc-smps-adapter There is not polarity for the DC pin as the board has diode bridge onboard.
6
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
Serial Cable connections for RS232 interfacing (Provided with product) To use with a PC serial port, use a serial cable of male-female type with pins 2,3,5 connected to 2,3,5 straight(no cross over cable).
General GPS Receiver User’s Tips •
• • • • •
If the satellite signals cannot be locked or experiencing receiving problem (while in urban area), following steps are suggested: o a) Please plug the external active antenna into GPS receiver and put the antenna outdoor or on the roof of the vehicle for better receiving performance. o b) Move to another open space or reposition GPS receiver toward the direction with least blockage. o c) Move the GPS receiver away from the interference sources. o d) Wait until the weather condition is improved. Some vehicles having heavy metallic sun protecting coating on windshields may affect signal receptions Driving in and around high buildings may affect signal reception. Driving under tunnels or in buildings may affect signal reception. In general, GPS receiver performs best in open space where it can see clean sky. Weather will affect GPS reception – rain & snow contribute to worsen sensitivity. When GPS receiver is moving, it will take longer time to get position fix. Wait for satellite signals to be locked at a fixed point when first power-on the GPS receiver to ensure quick GPS position fix.
Related links GPS Introduction http://en.wikipedia.org/wiki/Introduction_to_the_Global_Positioning_System GPS Working Details http://en.wikipedia.org/wiki/Global_Positioning_System http://en.wikipedia.org/wiki/GPS GPS - NMEA sentence information http://home.mira.net/~gnb/gps/nmea.html
7
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
AVR Library for parsing GPS Data http://www.mil.ufl.edu/~chrisarnold/components/microcontrollerBoard/AVR/avrlib/docs/html/nmea_8c.html
Interface to GPS - Article http://www.kronosrobotics.com/Projects/GPS.shtml AVR Project and Source code http://www.avrfreaks.net/index.php?module=Freaks%20Academy&func=viewItem&item_id=1062&item_type=project×tamp=2007-08-19%2015:46:24
NMEA Messages The serial interface protocol is based on the National Marine Electronics Association’s NMEA 0183 ASCII interface specification. This standard is fully define in “NMEA 0183, Version 3.01” The standard may be obtained from NMEA, www.nmea.org
NMEA Protocol This section provides a brief overview of the NMEA 0183 protocol, and describes both the standard and optional messages offered by the GPS Receiver. NMEA 0183 is a simple, yet comprehensive ASCII protocol which defines both the communication interface and the data format. The NMEA 0183 protocol was originally established to allow marine navigation equipment to share information. Since it is a well established industry standard, NMEA 0183 has also gained popularity for use in applications other than marine electronics. The GPS receiver supports the latest release of NMEA 0183, Version 3.0 (July 1, 2000). The primary change in release 3.0 is the addition of the mode indicators in the GLL, RMC, and VTG messages. For those applications requiring output only from the GPS receiver, the standard NMEA 0183 sentences are a popular choice. Many standard application packages support the standard NMEA output messages. The standard NMEA output only messages are: GGA, GLL, GSA, GSV, RMC, VTC, and ZDA. NMEA RECORD GGA GLL GSA GSV RMC VTG ZDA
8
Description GPS fix data Geographic GNSS DOP and active satellite GNSS Satellites in view Recommended minimum specific GNSS data Course Over Ground and Ground Speed Time&Data
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
NMEA 0183 Message Format The NMEA 0183 protocol covers a broad array of navigation data. The entire protocol encompasses over 50 messages, but only a sub-set of these messages apply to this GPS receiver. The NMEA message structure is described below. $IDMSG,D1,D2,D3,D4,.......,Dn*CS[CR][LF] “$” ID MSG “,” Dn “*” CS [CR][LF]
The “$” signifies the start of a message. The identification is a two letter mnemonic which describes the source of the navigation information. The GP identification signifies a GPS source. The message identification is a three letter mnemonic which describes the message content and the number and order of the data fields. Commas serve as delimiters for the data fields. Each message contains multiple data fields (Dn) which are delimited by commas. The length of the fields can be variable. The asterisk serves as a checksum delimiter. The checksum field contains two ASCII characters which indicate the hexadecimal value of the checksum. The carriage return [CR] and line feed [LF] combination terminate the message.
NMEA 0183 standard messages vary in length, but each message is limited to 79 characters or less. This length limitation excludes the “$” and the [CR][LF]. The standard message data field block, including delimiters, is limited to 74 characters or less.
9
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
GGA - Global Positioning System Fix Data Time, position and fix related data for a GPS receiver. Structure: $GPGGA,hhmmss.sss,ddmm.mmmm,a,dddmm.mmmm,a,x,xx,x.x,x.x,M,,,,xxxx*hh
Field 1 2 3 4 5 67 8 9 10 11 Example: $GPGGA,111636.932,2447.0949,N,12100.5223,E,1,11,0.8,118.2,M,,,,0000*02 Field 1 2 3 4 56 7 8 9 10 11 Field Name 1 UTC Time
Example 111636.932
2
Latitude
2447.0949
3 4
N/S Indicator Longitude
N 12100.5223
5 6
E/W Indicator GPS quality indicator
E 1
7 8 9 10
Satellites Used HDOP Altitude DGPS Station ID
11 0.8 108.2 0000
11
Checksum
02
Description UTC of position in hhmmss.sss format, (000000.000 ~ 235959.999) Latitude in ddmm.mmmm format Leading zeros transmitted Latitude hemisphere indicator, ‘N’ = North, ‘S’ = South Longitude in dddmm.mmmm format Leading zeros transmitted Longitude hemisphere indicator, 'E' = East, 'W' = West GPS quality indicator 0: position fix unavailable 1: valid position fix, SPS mode 2: valid position fix, differential GPS mode 3: GPS PPS Mode, fix valid 4: Real Time Kinematic. System used in RTK mode with fixed integers 5: Float RTK. Satellite system used in RTK mode. Floating integers 6: Estimated (dead reckoning) Mode 7: Manual Input Mode 8: Simulator Mode Number of satellites in use, (00 ~ 12) Horizontal dilution of precision, (00.0 ~ 99.9) mean sea level (geoid), (-9999.9 ~ 17999.9) Differential reference station ID, 0000 ~ 1023 NULL when DGPS not used
Note: The checksum field starts with a ‘*’ and consists of 2 characters representing a hex number. The checksum is the exclusive OR of all characters between ‘$’ and ‘*’.
10
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
GLL – Latitude/Longitude Latitude and longitude of current position, time, and status. Structure: $GPGLL,ddmm.mmmm,a,dddmm.mmmm,a,hhmmss.sss,A,a*hh Field 1 2 3 4 5 6 7 8 Example: $GPGLL,2447.0944,N,12100.5213,E,112609.932,A,A*57 Field 1 2 3 4 5 6 7 8 Field Name 1 Latitude
Example 2447.0944
2
N/S Indicator
N
3
Longitude
12100.5213
4
E/W Indicator
E
5 6 7
UTC Time Status Mode Indicator
112609.932 A A
8
Checksum
57
11
Sunrom Technologies
Description Latitude in ddmm.mmmm format Leading zeros transmitted Latitude hemisphere indicator ‘N’ = North ‘S’ = South Longitude in dddmm.mmmm format Leading zeros transmitted Longitude hemisphere indicator 'E' = East 'W' = West UTC time in hhmmss.sss format (000000.000 ~ 235959.999) Status, ‘A’ = Data valid, ‘V’ = Data not valid Mode indicator ‘N’ = Data not valid ‘A’ = Autonomous mode ‘D’ = Differential mode ‘E’ = Estimated (dead reckoning) mode ‘M’ = Manual input mode ‘S’ = Simulator mode
Your Source for Embedded Systems
Visit us at www.sunrom.com
Other NMEA Message output
12
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
13
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
14
Sunrom Technologies
Your Source for Embedded Systems
Visit us at www.sunrom.com
