Most GPS devices have an accuracy of 10-15 meters. For most people, this kind of accuracy in their location and navigation systems is satisfactory. However, for people who require greater accuracy using GPS devices, especially those in the fields of engineering and science, need a more powerful kind of GPS device. A GPS control point locator device is what they usually seek. This type of device supports differential GPS devices, which allows for more accurate data to be presented to the user.
What is Differential GPS (DGPS)?
Differential GPS works like normal GPS systems with the exception of the augmentation of data that is collected from GPS satellites. This augmentation is done by taking into consideration local reference stations or control points. Normal GPS data usually contains errors due to factors like satellite geometry and the view from the sky. Errors can be categorized by Lonosphere, Clock, Ephemeris data, Troposphere, Receiver and Multipath. On average, these factors contribute approximately 10.4 meters of error. Differential GPS minimizes errors by constant correction of data via control points. These control points provide accuracy of three to five meters as opposed to normal GPS accuracy which is 10-15 meters. There are several GPS devices that support DGPS. Here are some recommended products.
i-Blue 737A+ Bluetooth GPS Receiver
This energy efficient device is very sensitive with a 66-channel MTK chipset, 165dB, tracking and 148dBm signal acquisition. It is DGPS capable and can locate a position with a 2.5-meter accuracy. Being a Bluetooth-enabled device, it goes well with Bluetooth-enabled laptops. It is designed to be easy to use and easily configurable. It goes for around $66 at Amazon.
12 Channel Lassen IQ GPS Receiver with DGPS
This device is designed to be compact and energy efficient. This GPS receiver features a hot start time of ten seconds, a warm start of 38 seconds, a cold start of 50 seconds, antenna detection, a serial output stream and an enhanced sensitivity mode. You can buy it from Sparkfun.com for around $50.
Qstarz BT-Q818X Bluetooth GPS Receiver
This super high sensitive GPS receiver has a 165dMb MTK II chipset, a three-level switch and an automatic on and off function. It has an accuracy of approximately 2.5 meters with DGPS. Its efficient use of battery life allows it to stay on for 42 hours of continuous operation. You can buy this product from Amazon for around $70.
Magellan SporTrak Pro Waterproof Hiking GPS
This GPS receiver is capable of using normal GPS, DGPS and WAAS position locating. In normal GPS mode, it has an accuracy of about 15 meters. In DGPS mode, it has an accuracy of three to five meters and less than three meters when using WAAS. It is designed to be used in rugged situations like hiking trips or sailing trips. You can buy one from Amazon for around $120.
These GPS control point locator devices are all designed to support both normal GPS and DGPS. Point locators and reference stations may not be available everywhere, so DGPS may not always be possible. So that’s why normal GPS is also available to give you more than one option to get GPS data. If you are near a point locator or a reference station, then your DGPS device can give you better accuracy than normal.