Opening a Barrier Without a Fob or Code: How Licence Plate Recognition Works

The limitations of fobs and codes

Fob systems have been standard for gated car parks for years. They work well as long as everyone has their fob on them, nobody loses it and the admin stays current. Those are three "as long as" conditions that rarely all hold at the same time.

Codes are even more vulnerable. A barrier code is not tied to a person: anyone who knows it gets in. People pass codes on to visitors, contractors and delivery drivers and then forget they did.

Licence plate recognition solves this structurally: the access credential is the vehicle itself. It can't be shared, can't be lost and is unique to each person.

What's technically behind it

An ANPR camera (Automatic Number Plate Recognition) sits at the entry lane, aimed at plate height. As a car approaches, the camera takes a rapid burst of frames at a high shutter speed to prevent motion blur. Built-in OCR software (optical character recognition) converts the image directly to text, such as "AB-123-CD", without needing a separate server or computer on site.

That string goes over the network to the parking platform. The platform compares it against the plate whitelist in under half a second. On a match, it sends a signal to the barrier controller, through a dry relay contact or a standard protocol such as Wiegand or RS-485, and the barrier rises.

The whole sequence: under two seconds from arrival to open barrier.

What hardware do you need?

In most cases you need two cameras: one for entry and one for exit. The cameras that work best for private car parks are models from Axis, Hikvision, Bosch or Dahua with built-in ANPR functionality. Prices range from €400 to €900 per camera depending on brand and spec.

Many existing CCTV cameras from these brands are already ANPR-capable with a firmware update or licence, which can reduce the hardware investment considerably.

The barrier itself usually doesn't need replacing. Virtually all modern barriers, from CAME, BFT, FAAC, Nice and similar brands, have a relay input for external triggering. The ANPR integration connects to this directly.

What you manage through the dashboard

The plate whitelist is managed through a web dashboard. Adding or removing residents and staff takes a name and plate. The dashboard works in any browser without separate software.

Every entry, exit and denied access is logged with timestamp and plate. The log is searchable and exportable, which helps with complaints, incidents and the annual check on who still uses the site.

When does licence plate recognition beat a fob system?

Licence plate recognition wins as soon as there are more than twenty to thirty users, turnover in who has access is regular, or visitors play a significant role on site. In those situations a fob system takes far more admin than a plate list.

For office environments where staff change and visitors are regular, combining ANPR with an access control system like Paxton is particularly effective. More on that combination on the Paxton integration page. For residential complexes the specific approach is described on the residential complex page.