Also known as: Z-Wave, ZWave
Z-Wave is a low-power wireless mesh protocol for home automation that operates in sub-GHz ISM bands and uses GFSK modulation.1 By running near 900 MHz rather than in the crowded 2.4 GHz band, it sidesteps Wi-Fi and Bluetooth congestion and gets better wall penetration and range, at the cost of lower data rates than Zigbee.
Overview
Z-Wave keeps things deliberately simple and robust. Nodes form a source-routed mesh: a controller learns the topology and can route a command through up to four hops of mains-powered repeater nodes to reach a distant device. Battery devices sleep most of the time and wake to poll. Crucially, every region uses a mandated frequency so all devices in a market interoperate — 908.4 MHz in North America, 868.4 MHz in Europe, and other assignments elsewhere. The radio is GFSK at 9.6, 40, or 100 kbit/s, with the long-range variant reaching farther on a star topology.
Technical characteristics
| Property | Value |
|---|---|
| Bands | Sub-GHz ISM, regional (~865–926 MHz) |
| Modulation | GFSK |
| Bit rate | 9.6 / 40 / 100 kbit/s |
| Topology | Source-routed mesh (≤4 hops) |
| PHY/MAC | ITU-T G.9959 |
| Max nodes | 232 per network (classic) |
Running below 1 GHz is Z-Wave’s main technical differentiator: less contention and longer indoor range than 2.4 GHz systems, but narrower channels and lower throughput. The regional frequency mandate is why a device bought in one region will not talk to a controller from another.
History
Z-Wave was created by the Danish firm Zensys in 2001, later acquired by Sigma Designs and then Silicon Labs. The lower layers were published as ITU-T recommendation G.9959, and much of the specification was opened to the public in the late 2010s under the Z-Wave Alliance.
Deployment
Z-Wave is common in smart locks, thermostats, lighting, and security sensors, and is a staple of professionally installed home-automation and alarm systems. It competes head to head with Zigbee; hubs frequently support both.
Decoding it with GopherTrunk
GopherTrunk does not decode Z-Wave. Although its sub-GHz GFSK signals fall within the tuning range of common SDRs, the protocol’s framing, mesh routing, and security are outside GopherTrunk’s scope — it targets land-mobile voice trunking and aeronautical data, not home-automation control. Hobbyists use dedicated Z-Wave sniffers or SDR flow graphs for this traffic instead.