How to Build an
AIS 140 Compliant VLTD

The single most important component decision is the GNSS module, because NavIC support is a hardware property that cannot be patched in later. The receiver and antenna front end must handle the NavIC L5 band at 1176.45 MHz alongside the GPS L1 band. A common choice is the Quectel L89 (which integrates an active antenna and supports IRNSS L5) or the Quectel LC86G in NavIC variant for designs that use a separate external antenna. Both give multi-constellation fixes across GPS, GLONASS, Galileo, and NavIC, which is what the standard and the better positioning robustness both call for.

The antenna is as important as the receiver. An L5 capable patch antenna with a clean ground plane and a low-noise amplifier sized for the combined L1 and L5 bands is required to actually acquire NavIC satellites. A frequent mistake is to specify a NavIC capable module but pair it with an L1-only antenna, after which the device never locks onto an IRNSS satellite during testing. The receiver, the antenna, and the RF path have to be designed as one. This is covered under NavIC and IRNSS tracker development, and the RF specifics live in antenna and RF design for trackers.

Checklist for this block: multi-GNSS receiver with confirmed NavIC L5 support, L1 plus L5 capable active antenna, LNA gain and noise figure budgeted for the cable run, and a tested time-to-first-fix under 35 seconds cold and a few seconds hot. Validate NavIC lock specifically, since a module can pass on GPS alone and still satisfy your bench test while failing the standard.

For the controller the STM32 family fits well, typically an STM32L4 for the low-power profile or an STM32F4 where more compute headroom is wanted. The STM32 gives enough UARTs for the modem and GNSS, SPI and I2C for sensors, ADC channels for the analog inputs, and the low-power modes needed to manage the backup battery budget. It also has a mature toolchain and long-term availability, which matters for a product that must stay in production through a multi-year certification and fleet lifecycle. The broader embedded scope is described under STM32 firmware development.

The device needs digital inputs for ignition sense and door status, analog inputs for sensor signals such as fuel level, and at least one panic button input. A three-axis accelerometer is required for motion and event detection, useful for both harsh-driving alerts and for confirming the vehicle is actually stationary before entering a low-power state. Tamper detection covers enclosure open detection and antenna disconnect detection, both of which must raise an alert to the backend. The panic button input must be debounced in hardware and firmware and routed so a press can preempt whatever the device is currently doing.

Checklist for this block: STM32L4 or STM32F4 class MCU with spare UART, SPI, I2C, and ADC, ignition and door digital inputs, analog sensor inputs, three-axis accelerometer, one or more panic button inputs, enclosure tamper switch, and antenna disconnect detection. This sensor and input layer is the part most often under-specified when a generic tracker is retrofitted for AIS 140. The full device build is covered under GPS tracking device development.

The device communicates with the state Backend Control Centre using a structured packet protocol derived from the AIS 140 data specification. The connection lifecycle starts with a login packet that identifies the device by its IMEI and unique vehicle identity, followed by periodic location packets and heartbeat packets, with emergency packets inserted at the front of the queue when triggered. Each packet carries a header, a packet type, the vehicle identity, a timestamp, latitude and longitude, speed, heading, the number of satellites, the GNSS fix status, ignition and input states, the network and signal information, and a checksum.

The exact field order, delimiters, and packet types vary by state because each state implemented its own variant of the base specification. This is the part that most often surprises teams: a device can be functionally certified and still need per-state packet handling. The protocol layer is built to be data-driven so a new state format is a configuration change rather than a firmware fork. The transport is usually a persistent TCP connection to the state-designated IP and port, with the device reconnecting and resuming store-and-forward on any drop. Designing this packet and transport layer cleanly is part of AIS 140 device work and the broader telematics and GPS tracking platform engineering behind it.

Checklist for this block: login packet with IMEI and vehicle identity, periodic location and heartbeat packets, priority emergency packet, correct field order and checksum per the target state format, persistent TCP transport with reconnect, and ordered store-and-forward replay after reconnection. Validate against the actual state BCC test endpoint, not just a local mock, before you submit for state approval.

Teams routinely underestimate how long the full path takes. Hardware design and the first prototype run typically take 8 to 12 weeks, including the GNSS and antenna RF validation that confirms NavIC lock. Firmware development, including the store-and-forward, OTA, dual-SIM failover, and the per-state packet layer, runs in parallel but usually needs 10 to 16 weeks to reach a stable build worth submitting. EMC pre-compliance and the fixes it surfaces add another few weeks.

The accredited certification window at ARAI or ICAT itself depends on lab scheduling and the number of non-conformances found, and commonly runs 6 to 12 weeks from submission to certificate. After that, each state Backend Control Centre integration test is a separate step, and the live feed validation for a given state can take an additional few weeks. Budgeting six to nine months from kickoff to a device that is certified and approved in at least one state is realistic for a fresh design. Compressing it usually means running hardware, firmware, and pre-compliance aggressively in parallel rather than skipping steps.

The way to protect the timeline is to validate the riskiest items first: confirm NavIC lock on real hardware early, test the emergency path under power loss early, and run the packet layer against a real state endpoint early. These are the three areas where late discovery forces a redesign. Everything else can usually be fixed without restarting the hardware.