IrDA
Infrared & Optical · 6 specs
Direct Answer
IrDA is a point-to-point, line-of-sight optical data transmission standard developed by the Infrared Data Association. Operating at 850–900 nm over distances up to 1 meter, it evolved from 115.2 kbps Serial Infrared (SIR) to 4 Mbps Fast Infrared (FIR) and 16 Mbps Very Fast Infrared (VFIR) for wireless printing, laptop file exchange, and mobile synchronization.
Source: Infrared Data Association (IrDA) Physical Layer Specification v1.4 · Last reviewed Aug 28, 2026
Specs
| Optical Wavelength | 850 to 900 nm |
| Nominal Range | 0 to 1.0 m (at ±15° cone angle) |
| Standard Speed Tiers | SIR (up to 115.2 kbps), MIR (1.152 Mbps), FIR (4.0 Mbps), VFIR (16.0 Mbps), UFIR (96.0 Mbps) |
| Pulse Encoding (SIR) | Return-to-Zero (RZ) with 3/16th bit duration pulse |
| Pulse Encoding (FIR) | 4PPM (4-Pulse Position Modulation) |
| Software Protocol Stack | IrLAP (Link Access), IrLMP (Link Management), Tiny TP, IrOBEX (Object Exchange) |
Historical Role and OBEX Architecture
Throughout the late 1990s and early 2000s before Bluetooth ubiquity, IrDA was the universal standard for wireless data exchange on laptops, PDAs (Palm Pilot, Pocket PC), and mobile phones (Nokia, Sony Ericsson). The IrOBEX (Object Exchange) protocol allowed users to 'beam' business cards (vCards), calendar entries (vCal), and photos simply by pointing two infrared ports at each other.
Directional Line-of-Sight Security
Because IrDA requires direct optical line-of-sight within a narrow ±15-degree cone and optical signals cannot penetrate walls or opaque surfaces, it has natural electromagnetic immunity and high physical security, making it very difficult to sniff or intercept from an adjacent room (though not impossible -- a receiver placed in the direct line of sight, e.g. through an open door or window, can still pick up the signal).