Below is a comparison table of the three Polstar GPS modules sold by Parallax. This chart also includes our breadboard friendly GPS Module (#28146), which features a co-processor for ask/receive making it particularly useful for BASIC Stamp projects. The modules below send out the entire NMEA0183 GPS string.
Choosing a GPS module is easy. If you need basic operation at a low consider the PMB-248. The highest performance modules are the PMB-648 and PMB-688, which track up to 20 satellites with quick signal acquisition. All of these are compatible with the BASIC Stamp and Propeller, too. You will find source code examples on each product page.
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Parallax GPS Module
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PMB-648 GPS SiRF Internal Antenna
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PMB-688 GPS SiRF Internal / External Antenna
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RXM-SG GPS Module w/Ext Antenna
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General
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Price:
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$79.99
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$34.99
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$39.99
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$79.99
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Stock #
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28146
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28500
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28501
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28505
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Antenna
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Built-in Patch
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Built-in Patch
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Built-in Patch or optional external (#28502)
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Included
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Connections
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Breadboard friendly 4-pin SIP
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Has cable to connect with stripped wires to breadboard or prototype
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Has cable to connect with stripped wires to breadboard or prototype
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3.3 V CMOS asynchronous serial @ 9600 baud default for microcontrollers, or USB for PC
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Special Features
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2 modes of operation:
RAW - Unformated data
Smart - Syntax Formatted data
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TTL, RS232 Outputs
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TTL outputs
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Four general purpose I/O pins provide expansion for pin intensive projects
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Specifications
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GPS Controller
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Custom ASIC
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SiRFstar III
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Receiver (L1 1575.42 MHz)
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Tracking up to 12 Satellites
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Tracking up to 20 Satellites
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Accuracy
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2DRMS approximately 2m, WAAS support
Velocity: 0.1 m/s
Time: +/- 1 us
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Position: 2DRMS appx. 5m, WAAS support
Velocity: 0.1 m/s
Time: +/- 1 us
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Acquisition Time
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Cold start: 40s (avg.)
Warm start: 33s (avg.)
Hot start: 2s (min.)
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Cold start: 42s (avg.)
Warm start: 38s (avg.)
Hot start: 1s (min.)
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Cold start: 35s (avg.)
Warm start: 15s (avg.)
Hot start: 2s (min.)
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Sensitivity
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Acquisition: -139 dBm
Tracking: -152dBm or less
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Acquisition: -148 dBm
Tracking: -159dBm
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Dynamics
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Altitude: 18000m (max)
Velocity: 515 m/s (max)
Acceleration: +/- 4g (max)
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Altitude: 18000m (max)
Velocity: 515 m/s (max)
Acceleration: +/- 4g (max)
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Navigation update rate
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Once per second
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Serial Port
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TTL / RS-232
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TTL only
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3.3 V CMOS asynchronous serial
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Baud Rate
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4800 bps
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4800 bps (Optional 9600, 19200, 38400)
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38,400 bps or higher recommended
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Output message
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NMEA0183 V 2.2 GGA, GSV, GSA, RMC (optional VTG, GLL)
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Datum
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WGS84
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Power Supply
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5VDC
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3.3V~5V
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Power consumption
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Typ 115 mA@5V
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Typ 65 mA@5V
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Typ 50 mA@5V
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LED function
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Always on: Valid Signal
Flashing: Not Valid Signal
Off: no power
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Operating Temperature
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+18C ~ +78C
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-28C ~ +78C
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-30C ~ +85C
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Humidity
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5%-95%
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