VR2000 Standard Applications

The VR2000 is supplied with standard programs (applications) that are part of the Debian Linux 3.1 operating system as well as standard applications provided by Thorcom for GPS based vehicle location and power management.

The operating system includes the PPP protocol stack, IP networking, the IPtables/Netfilter sub-system (including a simple stateful packet instecting firewall script provided by Thorcom), FTP server, DNS server, DHCP server and SSH server.

The majority of the operating system is documented here or on the Debian Website and is not repeated here.

The Automatic Vehicle Location Daemon ('avld') is a Thorcom provided application which is norrmally loaded at VR2000 boot time which interfaces with the on-board GPS receiver and provides an automatic vehicle location facility.

AVLD receives the once-per-second GPS updates from the receiver and processes them against a set of 'rules' and determines when a position update message should be sent to the centre. AVLS transmissions use UDP/IP data grams sent over GPRS/GSM, IP packet data on TETRA or some other IP based communuications bearer.

Thorcom's AVLS sub-system uses intelligent rules-based decision making to decide when to send AVLS updates, these rules include the following:

	First fix: first GPS position fix since power applied
	Timed update: time since last AVLS transmission
	Distance travelled: distance in Km travelled since last AVLS update
	Change of status
	Loss of GPS coverage: for example driving in to an underground car park
	Restoration of GPS coverage
	Fault/tamper conditions, for example disconnecting the GPS antenna

The Power Management Daemon ('powerd') is a Thorcom provided application which manages the power to the VR2000 and devices attached that are controlled by the VR2000's 10A power switching relay.

The VR2000 is normally configured to power on when either of the two special inputs IGN (ignition sense) or ALM (alarm input) are driven active - thses cause VR2000 to boot up and start. At start up the power anamagement daemon ('powerd') is loaded automatically and it reads its configuration from the file /etc/vr2000/powerd.conf.

The Power Management Daemon:

	Monitors the input voltage (once per second) and looks for out-of-range conditions (eg. low battery voltage), if this persists for a configirable period the VR2000 can start an orderly shutdown before it would other crash
	Monitors the IGN input and can arrange for an orderly shutdown to begin after a predetermined time after the IGN switches from on to off
	Controls the on-board 10A relay and can switch external equipment on/off at the appropriate time