Connecting your GPS receiver
Connecting your GPS receiver to Esri software is an easy process that involves the following steps:
- Determine what cables, adapters, gender changers, or wireless technology if any, are needed to connect your GPS receiver to your mobile device.
- Connect the GPS receiver to the mobile device.
- Configure the GPS receiver.
- Set any GPS Preferences in your software.
There is no standard method for connecting a GPS receiver to mobile GIS software since most GPS receivers have unique configurations. However, by using this section and the documentation for your GPS receiver and mobile device, it is fairly easy to successfully connect your GPS receiver.
Determining what items are needed
The most common method for connecting GPS receivers to devices is via bluetooth. Compact Flash and SD GPS receivers insert into standard slots on windows devices and built-in GPS receivers require no connection. USB GPS receivers usually come with a USB cable permanently attached and connect to standard USB ports on Windows devices.
In some specific cases, you will need one or more of the following items to connect your external GPS receiver to your mobile device:
- A serial cable to connect to the GPS receiver
- A serial cable to connect to the mobile device
- A male-to-male gender changer
- A null modem adapter
You will not need any of the above items if you are connecting your GPS receiver to your mobile device via Bluetooth or USB.
Some GPS receivers and mobile devices have unique fittings for their serial ports and hence require their own proprietary serial cables. However, not all GPS receivers require all of the above items to connect to the mobile device. For example, some GPS receivers connect directly to the serial cable for the mobile device and do not require their own proprietary serial cable, null modem adapter, or gender changer. Other GPS receivers do not require any cables or adapters—for example, GPS receivers that support Bluetooth, Compact Flash GPS receivers, and built-in GPS receivers.
In the case of physical serial connectors, most serial cables that connect to the GPS receiver on one end are designed to connect directly to a PC serial port on the other end using a standard DB9 serial connector. This is not always the case when connecting to Windows devices and these can have nonstandard, proprietary serial ports. Consequently, a proprietary serial cable is usually also required when connecting a GPS receiver to a Windows Mobile device.
Most GPS serial cables and Windows Mobile device proprietary serial cables have 9-pin DB9 female connectors on the ends that need to be connected together. Consequently, a 9-pin male-to-male gender changer is required to connect the two female serial cables.
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Finally, a null modem adapter or cable is sometimes needed when connecting a GPS receiver to a Windows device, using the device’s sync cable.
Null modem adapters and cables
The following paragraph explains why you usually need a null modem adapter when using a synchronization cable to connect a GPS receiver to a Windows Mobile device.
PCs and Windows Mobile devices use the serial port’s pin 2 to receive data and pin 3 to transmit or send data. Devices that output data via serial ports, such as GPS receivers, use pin 2 to transmit or send data and pin 3 to receive data. This works since the GPS receiver sends data on pin 2, while the PC receives data on pin 2. However, a Windows Mobile device will not be able to communicate with a PC when connected using a standard serial cable since both the Windows Mobile device and PC will be trying to send data on the same pin 3. To solve this problem, most Windows Mobile devices have synchronization cables that reverse pins 2 and 3 so that the device can communicate with a PC. This synchronization cable works for communicating between a Windows Mobile device and a PC. It does not work, however, when communicating between a Windows Mobile device and a GPS receiver since both devices are now sending data on the same pin. Consequently, you need a null modem adapter, or cable, when using a synchronization cable to connect a Windows Mobile device to a GPS receiver. The null modem adapter also reverses pins 2 and 3 and, therefore, cancels the pin reversal in the synchronization cable.
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How do you know whether the Windows Mobile serial cable is a synchronization cable and, therefore, requires a null modem adapter? In most cases, if the Windows Mobile serial cable has a female DB9 connector on one end, it is likely to be a synchronization cable, and thus a null modem adapter will be required to connect to a GPS receiver.
Connecting your GPS receiver
Using the information in the preceding discussion you should now be able to determine which cables, null modem adapters, and gender changers you will need to connect your GPS receiver to the device that is running Esri software. Obviously, you will not need any cables or adapters if connecting via Bluetooth or when using an integrated GPS receiver, or a USB receiver. Assemble and connect the required items before moving to the next step of configuring your GPS receiver. Also, make sure that the batteries on your GPS receiver are fully charged!
Configuring your GPS receiver
By default, most handheld GPS receivers are configured to not output any GPS data. You need to configure your GPS receiver to output data, generally via the NMEA protocol. You may also need to verify the communication parameters that your GPS receiver is configured for, specifically the baud rate, parity, data bits, and stop bits.
If you are using Bluetooth, you will need to use the Bluetooth Manager on your mobile device to discover the GPS receiver, and possibly to pair your GPS receiver with your mobile device. Consult the documentation for your GPS receiver and mobile device for more information on connecting via Bluetooth.
When you connect your USB GPS receiver for the first time, ensure that you install the drivers for that device which allow NMEA messaging. It is not recommended to install the Microsoft Generic GPS driver for USB GPS receivers. Instead, ensure that you go to your GPS manufacturer's website and download the most appropriate driver for your device (if it was not supplied with your hardware). Some USB GPS receivers require additional software to translate proprietary formats to NMEA.
One example of this is Garmin's Spanner Software. Spanner creates a virtual serial port which allows you to send data to your mobile GIS software. Refer to Garmin's website for compatible devices.
Setting the GPS Preferences in ArcPad
Before you can activate your GPS, you need to set the GPS communication parameters in ArcPad to match the parameters set on your GPS receiver. The GPS protocol and communication parameters are set in the GPS page of the GPS Preferences dialog box. It is recommended to use the Find GPS tool on the GPS Preferences dialog to search for the parameters, but these can also be manually entered.