Global Positioning System was developed by the United States' Department of Defense. It uses between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals. This enables GPS receivers to determine their current location, time and velocity. The GPS satellites are maintained by the United States Air Force.
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GPS is often used by civilians as a navigation system. On the ground, any GPS receiver contains a computer that "triangulates" its own position by getting bearings from at least three satellites. The result is provided in the form of a geographic position - longitude and latitude - to, for most receivers, within an accuracy of 10 to 100 meters. Software applications can then use those coordinates to provide driving or walking instructions.
Getting a lock on by the GPS receivers on the ground usually takes some time especially where the receiver is in a moving vehicle or in dense urban areas. The initial time needed for a GPS lock is usually dependent on how the GPS receiver starts. There are three types of start - hot, warm and cold.
The hot start is when the GPS device remembers its last calculated position and the satellites in view, the almanac used (information about all the satellites in the constellation), the UTC Time and makes an attempt to lock onto the same satellites and calculate a new position based upon the previous information. This is the quickest GPS lock but it only works if you are generally in the same location as you were when the GPS was last turned off.
The warm start is when the GPS device remembers its last calculated position, almanac used, and UTC Time, but not which satellites were in view. It then performs a reset and attempts to obtain the satellite signals and calculates a new position.
The receiver has a general idea of which satellites to look for because it knows its last position and the almanac data helps identify which satellites are visible in the sky. This takes longer than a hot start but not as long as a cold start.
And finally – the cold start is when the GPS device dumps all the information, attempts to locate satellites and then calculates a GPS lock. This takes the longest because there is no known information.
The GPS receiver has to attempt to lock onto a satellite signal from any available satellites, basically like polling, which takes a lot longer than knowing which satellites to look for. This GPS lock takes the longest.
In an attempt to improve lock times, cellphone manufacturers and operators have introduced the Assisted GPS technology, which downloads the current ephemeris for a few days ahead via the wireless networks and helps triangulate the general user’s position with the cell towers thus allowing the GPS receiver to get a faster lock at the expense of several (kilo)bytes.
TYPE OF GPS MODULE AND FEATURES:
GPS Module - EM-406A
New improved GPS Module with built-in antenna and memory back-up for OEM and hobbyists projects. This unit features low power consumption, high sensitivity. The unit is ideal for navigation systems, distance measurements, vehicle monitoring and recording, boating direction and location, together with hiking and cross country exploring.
This module includes high precision surface mount technology to provide both high accuracy and very compact size. The module can be easily installed on a main board, with all inputs using standard TTL signal levels. A series of standard NMEA format messages are provided to give position, satellite information, time, etc. The module can be easily connected directly to a microcontroller to display and record this information.
Develop your own GPS navigation system or connect to a pocket pc for a low cost navigation system. Use in the car or boat for trip recording and distance to destination information. The possibilities are endless with this easy to use GPS module.
This module includes high precision surface mount technology to provide both high accuracy and very compact size. The module can be easily installed on a main board, with all inputs using standard TTL signal levels. A series of standard NMEA format messages are provided to give position, satellite information, time, etc. The module can be easily connected directly to a microcontroller to display and record this information.
Develop your own GPS navigation system or connect to a pocket pc for a low cost navigation system. Use in the car or boat for trip recording and distance to destination information. The possibilities are endless with this easy to use GPS module.
Part Code: GPS_EM-406A
Features
- SiRF Star III high performance GPS Chipset
- Very high sensitivity (Tracking Sensitivity: -159dBm)
- Extremely fast TTFF (Tiem To First Fix) at low signal level
- Supports NMEA 0183 data protocol
- Built-in SuperCap to save system data for rapid satellite acquisition
- Built-in patch antenna
- Acquisition Time, cold start 42 seconds
- Includes Connecting Cable
- Power Supply - 5Vdc
- TTL Level Output Voltage 0 - 2.85V
- Dimensions: Length - 30mm , Width - 30mm, Height - 10mm
GPS Module - EM-411
New improved GPS Module with built-in antenna and memory back-up for OEM and hobbyists projects. This unit features low power consumption, high sensitivity. The unit is ideal for navigation systems, distance measurements, vehicle monitoring and recording, boating direction and location, together with hiking and cross country exploring.
This module includes high precision surface mount technology to provide both high accuracy and very compact size. The module can be easily installed on a main board, with all inputs using standard TTL signal levels. A series of standard NMEA format messages are provided to give position, satellite information, time, etc. The module can be easily connected directly to a microcontroller to display and record this information.
Develop your own GPS navigation system or connect to a pocket pc for a low cost navigation system. Use in the car or boat for trip recording and distance to destination information. The possibilities are endless with this easy to use GPS module.
This module includes high precision surface mount technology to provide both high accuracy and very compact size. The module can be easily installed on a main board, with all inputs using standard TTL signal levels. A series of standard NMEA format messages are provided to give position, satellite information, time, etc. The module can be easily connected directly to a microcontroller to display and record this information.
Develop your own GPS navigation system or connect to a pocket pc for a low cost navigation system. Use in the car or boat for trip recording and distance to destination information. The possibilities are endless with this easy to use GPS module.
Part Code: GPS_EM-411
Features
- SiRF Star III high performance GPS Chipset
- Very high sensitivity (Tracking Sensitivity: -159dBm)
- Extremely fast TTFF (Tiem To First Fix) at low signal level
- Supports NMEA 0183 data protocol
- Built-in SuperCap to save system data for rapid satellite acquisition
- Built-in patch antenna
- Acquisition Time, cold start 42 seconds
- Includes Connecting Cable
- Power Supply - 5Vdc
- TTL Level Output Voltage 0 - 2.85V
- Dimensions: Length - 30mm , Width - 30mm, Height - 10mm
GPS Module - EM-410
New improved GPS Module with external high-gain patch antenna and memory back-up for OEM and hobbyists projects. This unit features low power consumption, high sensitivity. The unit is ideal for navigation systems, distance measurements, vehicle monitoring and recording, boating direction and location, together with hiking and cross country exploring.
This module includes high precision surface mount technology to provide both high accuracy and very compact size. The module can be easily installed on a main board, with all inputs using standard TTL signal levels. A series of standard NMEA format messages are provided to give position, satellite information, time, etc. The module can be easily connected directly to a microcontroller to display and record this information.
Develop your own GPS navigation system or connect to a pocket pc for a low cost navigation system. Use in the car or boat for trip recording and distance to destination information. The possibilities are endless with this easy to use GPS module.
This module includes high precision surface mount technology to provide both high accuracy and very compact size. The module can be easily installed on a main board, with all inputs using standard TTL signal levels. A series of standard NMEA format messages are provided to give position, satellite information, time, etc. The module can be easily connected directly to a microcontroller to display and record this information.
Develop your own GPS navigation system or connect to a pocket pc for a low cost navigation system. Use in the car or boat for trip recording and distance to destination information. The possibilities are endless with this easy to use GPS module.
Part Code: GPS_EM-410
Features
- SiRF Star III high performance GPS Chipset
- Very high sensitivity (Tracking Sensitivity: -159dBm)
- Extremely fast TTFF (Tiem To First Fix) at low signal level
- Supports NMEA 0183 and SiRF binary data protocol
- Built-in SuperCap to save system data for rapid satellite acquisition
- External patch antenna with 27dB Gain
- Acquisition Time, cold start 42 seconds
- Includes Connecting Cable
- Power Supply - 3.3Vdc
- Dimensions - GPS: Length - 47mm , Width - 25mm, Height - 7.5mm
- Dimensions - Antenna: Length - 18mm , Width - 18mm, Height - 4mm
GPS Module - Active Antenna
GPS Active Antenna to suit above module, this unit has excellent technical performance with a gain of up to 28dB. This unit is compact and easy to mount, suitable for mounting outside and is built into a solid attractive plastic waterproof housing.
Part Code: GPSANTENNAFeatures
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