An RFID reader (also called an interrogator) is the device that talks to RFID tags. It transmits a radio signal through one or more antennas, receives the tags' replies and outputs a stream of reads — each typically containing the tag ID (such as an EPC), the antenna that saw it, a timestamp and a signal-strength value (RSSI). The reader does not know what the tag is attached to; software does that.
Types of RFID readers
| Type | What it is | Best for |
|---|---|---|
| Handheld reader | Battery-powered unit, often Android-based or a "sled" paired with a phone | Audits, stock-takes, finding a specific item |
| Fixed reader | Mains/PoE-powered unit with external antennas, mounted in place | Doorways, gates, dock doors, storeroom monitoring |
| Integrated reader | Reader and antenna in one enclosure | Simple single-point installations |
| Desktop reader / encoder | Short-range reader on a desk | Commissioning and encoding tags |
| Phone (NFC) | The built-in NFC reader in a smartphone | Tap-to-identify with HF/NFC tags only |
Key specifications to compare
- Frequency and region — a UHF reader must be configured for the legal band where it operates (for example 902–928 MHz in the US, 865–868 MHz in Europe).
- Transmit power — higher power reads further but can also pick up unwanted tags; adjustable power is essential for tuning.
- Number of antenna ports — fixed readers often support 2, 4 or 8 antennas to cover a doorway from several angles.
- Read rate — how many tags per second it can singulate; matters for dense areas.
- Connectivity — Ethernet, Wi-Fi, Bluetooth, USB; PoE simplifies fixed installs.
- Protocols — many fixed readers speak LLRP (Low Level Reader Protocol), an industry standard for reader control and data.
- Ruggedness — drop and ingress (IP) ratings for handhelds used in the field.
Handheld vs fixed: which do you need?
Handheld readers bring the reader to the assets. They are the workhorse of RFID stock-takes: walk the room, sweep the shelves, and every tag in range is counted. Many also have a "find" or geiger mode that uses signal strength to guide you to a specific tag. Fixed readers stay where they are and watch assets come to them — at a doorway, gate or storeroom entrance. They are what make automatic movement detection and zone-exit alerts possible. Most programs start with handhelds for audits and add fixed readers at the few doors that matter most.
Installing fixed readers well
- Pick true choke points — doors and gates assets must pass through.
- Mount antennas to face the path of travel, typically on both sides of a doorway.
- Start at moderate power and adjust; the goal is reliable reads in the doorway without reading tags stored nearby.
- Test with real tagged assets carried the way people actually carry them — in bags, on trolleys, stacked.
- Use software filtering (read windows, direction logic, minimum RSSI) to turn raw reads into clean events.
How Asetavo works with RFID readers
Asetavo is bring-your-own-reader: you register your handheld and fixed readers rather than buying locked-in hardware. Each registered device sends HMAC-signed events with a timestamp window and nonce, so forged or replayed reads are rejected; an edge gateway can translate LLRP output into Asetavo's HTTP ingest. Reads from handhelds feed audits; reads from fixed readers update each asset's last-seen zone and trigger zone-exit alerts. Readers and zones are part of the Business plan.