Iridium connection to GPS site using XP v2.0

Iridium connection to GPS site using XP v2.0
Establishing Iridium Communications from an XP Computer to a UNAVCO Polar
Remote GPS Station
Version 2.0, March 2011
This document contains instructions on how to establish an Iridium communications link
between an XP computer and a remote Trimble NetRS GPS receiver. An Iridium test call
must be performed before leaving newly-installed remote GPS site, or a site which has
had its communications hardware modified during a site visit.
You should configure your computer and Iridium modem before going to the field.
Various bugs have been observed with specific Iridium modems and XP computers, and
it is not guaranteed that the procedure below will hold for all cases. Also, these
instructions also assume a connection made using NSF-supplied DOD Iridium SIM cards,
which are not compatible with commercially-available SIM cards. In short, be sure you
know how to establish an Iridium comms link with your equipment before going to the
field; do not assume that you will simply figure it out once you get there.
Finally, although this procedure assumes the call is originated from an Iridium data
modem (e.g. NAL Research A3LA series), an Iridium telephone handset can also be
used, but requires the Data Kit accessories.
I. Configure the Iridium PPP Dialup Connection
A. Install the modem driver
1. Turn on your modem and connect its serial cable to your computer, either to the
computer’s serial port or through a USB-serial adapter.
Note: it has been found that certain USB-serial adapters can lock up
certain XP machines, and there is no assurance a USB-serial device will
work with a given PC until it is tested. However, no issues have been
found with Trendnet devices where as problems have been seen with those
from Belkin and Keyspan.
1. Choose Start > Control Panel.
2. Double click on Phone and Modem Options.
3. Select the Modems tab and click Add...
4. Check “Don’t detect my modem; I will select it from a list.” Then, click Next >.
5 .Click Standard 19200 bps Modem, and then click Next>.
6. Click the “Selected ports” button. Select the port to which your Iridium modem
is connected. A computer’s serial port is usually COM1, however a USB-serial
adapter will appear as some other COM port number, say COM3 or COM4. Click
Next >.
7. Click Finish.
8. Click the Standard 19200 bps Modem to highlight it and then click Properties.
9. Select the Advanced tab.
10. In the “Extra initialization commands” box, enter AT&F0&D0&K0
11. Click OK, OK.
B. Configure Dial-up Networking
1. Choose Start > All Programs > Accessories > Communications > Network
2. Click “Create a new connection” then Next>.
3. Select “Connect to the Internet” and click Next>.
4. Select “Set up my connection manually” and click Next>.
5. Select “Connect using a dial-up modem” and click Next>.
6. If a “Select a Device” window appears, check the box next to “Standard 19200
bps modem”, and uncheck all other devices. Click Next>.
7. Enter a connection name (e.g., “Iridium PPP”) and click Next>.
8. In the Phone Number box, enter 00881676300000 and click Next>. This is a
placeholder phone number for a US DOD Iridium SIM card. You can enter the
site’s unique phone number (last 5 digits) later, when dialing the site.
9. If using XP Professional Edition, a window may appear to select either
“Anyone’s use” or “My use only”. Choose either selection and click Next>.
10. A username and password are not necessary. Uncheck the “Use this account
name and password…” and “Make this the default internet connection” boxes.
Click Next> then Finish.
II. Place Iridium Phone Call and Verify Connectivity to GPS Receiver
A. Set up Iridium modem and antenna.
Connect the Iridium antenna to the modem. Iridium hardware is sensitive to sky view so
locate the antenna so it has an unobstructed view of the sky. Iridium modems are also
sensitive to cable loss so be sure the antenna cable plus any connectors do not add up to
more than 3 dB loss. For example, a 5-meter RG58 or 10-meter LMR400 cable will be
more than adequate. In general, shorter, thicker cable is better
B. Place an Iridium phone call.
1. Choose Start > Connect To, then select your Iridium dial-up connection, e.g.
Iridium PPP.
2. Do not enter a username or password and uncheck the “Save this username and
password…” box.
3. Enter 14-digit Iridium phone number and click Dial. Include leading zeros, e.g.
4. It may take several attempts to establish a connection. Once you receive a
message saying your computer is connected to the network, you can find the IP
address of the remote computer (e.g. the Trimble NetRS) under Start > Control
Panel > Network Connections. Click on the Iridium connection and look on the
left panel under Details. At present, all UNAVCO-configured Trimble NetRS
receivers will have an IP address of
5. At this point you can pull up any web browser to contact the GPS receiver.
There are two ways to query the receiver.
i. Enter the NetRS IP address in the navigation bar and hit Enter. This will
pull up the receiver’s web interface. The web interface loads very slowly
over Iridium, but you will be able to navigate through it and perform
normal system checks, such as verifying satellite tracking, data logging,
input voltage on its power ports, etc.
ii. Use the NetRS Programmatic Interface. The NetRS will respond to a set
of HTTP command entered directly into the browser’s navigation bar.
This is a much faster way to verify NetRS operation as compared to
loading the entire web interface. Programmatic Interface commands
typically used by UNAVCO to verify receiver operation are:
Note: when reading output of the show?trackingstatus command, the only
way to tell if the system is tracking satellites is to observe the signal-tonoise fields, e.g. L1snr, L2snr. Receivers with later firmware will also
have an L2Csnr column. All other columns will be populated with
almanac information regardless if the receiver is tracking satellites or not.
C. Dropped calls are a fact of life with Iridium, and it may take several dialing attempts
to establish successful communications with the GPS receiver. Also, if the Iridium
modem appears unresponsive during a call attempt, it may be necessary to reboot it.
Allow the modem to remain off for 20 seconds before powering it again.
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