Feature: 1.12 parallel satellite-tracking channels for fast acquisition and reacquisition 2.Use the high-sensitive Xtrac software 3.Compatible with Bluetooth Serial Port Profile (SPP) completely 4.Built-in rechargeable Lithiumion battery without external power supply 5.Built-in rechargeable battery for memory and RTC backup and for fast Time To First Fix (TTFF) 6.Support NMEA0183 v2.2 data protocol or SiRF binary code 7.FLASH based program memory. New software revisions upgradeable through serial interface 8.Provide expand terminal and can contact to other system without Bluetooth device Specification: 1.Tracks up to 12 satellites 2.Receiver: L1, C/A code 3.Snap Start: <3 sec(at < 25 minutes off period) 4.Update rate: 1 HZ 5.Antenna Type: Built in Patch Antenna 6.Minimum signal tracked: -175dBW 7.Dimension: 77.9 ?56.9 ?22.8 mm 8.Weight : < 70g 9.Electronic Switch On/off push button: Push one second to power on / two second to power off, with automatic shut off system power after ten minutes non connecting to any Bluetooth device. 10.Lithium-ion battery lasts for more than 9 hours of use 11.Over-Temperature protection. Protection circuit on GR-231 should stop charging the cell when over-temperature condition occurs. 12.Operation Temperature: -10 ℃ to + 60 ℃ 13.Store Temperature: -20 ℃ to + 85 ℃ 14.Operation Humidity:5% to 95% No condensing