GPS Overview
Satellite navigation is a system of satellites that provide autonomous geo-spatial positioning with global coverage and allow small electronic receivers to determine location (longitude, latitude, and altitude/elevation) using time signals transmitted from satellites. Often times the terms “GNSS” and “GPS” are used interchangeably but there are key differences between the two:
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The United States’ Global Positioning System (GPS) consists of up to 31 medium Earth orbit satellites in six different orbital planes, with the exact number of satellites varying as older satellites are retired and replaced. Operational since 1978 and globally available since 1994, GPS is currently the world’s most utilized satellite navigation system. A GPS receiver can only use signals from the 31 satellites in the Global Positioning System, and if too many of these signals are blocked, the receiver becomes useless until it can find a signal again.
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GNSS stands for Global Navigation Satellite System, and is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage. This term includes GPS, GLONASS, Galileo, Beidou and other regional systems. GNSS is a term used worldwide The advantage to having access to multiple satellites is accuracy, redundancy and availability at all times. Though satellite systems don’t often fail, if one fails GNSS receivers can pick up signals from other systems. Also, if line of sight is obstructed, having access to multiple satellites is also a benefit. Common GNSS Systems are GPS, GLONASS, Galileo, Beidou and other regional systems. A GNSS receiver can use signals from any positioning satellite, not just the ones in the GPS system. This means that even if all of the GPS signals are blocked, it can pick up signals from any of the other satellite systems worldwide. This flexibility makes GNSS receivers much more accurate and reliable than GPS technology alone. With GNSS, you can be confident that you are getting the best result possible, wherever and whenever you need it.
Note
A GNSS antenna is required for proper reception of GNSS constellation signal. Most Cisco antennas are GPS only, your antenna SKU must explicitly state it supports GNSS.
Note |
For the purposes of this document, we will be referring only to Cellular Modem based GPS. |
Cellular GPS Use Cases
The following are descriptions of some of the use cases for GPS:
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Geo-Fencing — Geo-fencing is the concept of controlling a device’s operation based on where it is located. One use may be to only allow a device to operate if it is located in an area it is authorized to be. For example, if a router inside a store, kiosk or ATM was taken to a location other than where it should be, the router could disable itself. Or if the device is programmed to send (or polled) for its location, and the cloud/host application finds it outside the authorized area, the application may stop allowing communications to the devices behind the router.
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Asset Tracking — Asset tracking is the concept of knowing where equipment or devices are currently, and their condition/operation. The condition/operation can be gleaned by cloud/host applications, or by network management tools. The location of the specific device/equipment however can be important to an organization’s operations. For example, a transportation enterprise may need to know the location of each of its trucks, train cars and ships in order to coordinate the on-time shipment and delivery of cargo. This may allow for the best selection of transport means and specific vehicles for a particular expedited shipment.
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Time Synchronization — Accurate time on a router can be important, for having exact time stamps of logs, or for accurate execution of tasks via automated/scheduled router functions. There may be times that the router requires synchronization of its internal clock with a highly accurate time source. Inability to sync the time may occur with deployments in vehicles or movable installations that are out of signal range for long periods, or where the deployment used a connection to an isolated private network with no NTP server.
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GPS streaming to Apps and IOx — When a modem has GPS enabled, the NMEA stream can be forwarded to IOx from the ngiolite module. This is accomplished by create a tunnel between Linux and IOx and then forward all NMEA messages over the tunnel to IOx.
Cellular GPS Parameters
Refer to the following table:
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Parameters |
Cellular Modem Based GPS |
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Type |
Cellular Modem based GPS |
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PIDs Supported |
See the Supported Modem Technology section for modules that support GPS. |
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Configuration Modes |
Standalone mode |
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Number of satellites needed for co-ordinates |
Standalone mode – 4 |
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Satellites Supported in show command |
Co-ordinates seen in show commands output is based only on GPS. |
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Initial Calibration Required |
No |
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Co-ordinates in Absence of Satellite |
No Co-ordinates will be acquired, and it stays in acquiring status. |
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Device Name of Controller to use for Configuration |
controller cellular <slot> |
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CLI to enable feature |
lte gps enable lte gps mode standalone
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CLI to configure nmea |
lte gps nmea |
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CLI to configure nmea udp socket |
lte gps nmea ip udp <source_ip> <destination_ip> <destination_port> |
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CLI to verify configuration under show running-config |
show run | sec controller cellular<slot> |
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Show commands to verify gps output |
show cellular <slot> gps show controller cellular <slot> | inc GPS |
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Access to GPS nmea traffic on IOx side |
Supported |
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Debug Command |
debug cellular<slot> messages gps debug cellular<slot> messages nmea |
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Yang Model Support |
Yes |
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