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 — which is the job of RFID asset tracking software.
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 |
| Portal reader | A fixed reader whose antennas are mounted around a doorway, gate or dock door | Recording what passes through an opening, in or out |
| 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 |
A fixed reader with antennas around a doorway is usually called an RFID portal or portal reader. That page covers how direction of travel is worked out and how to tune dock doors that sit side by side.
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. Readers need to send signed HTTPS events, so check a reader's network output options before buying. 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. See how it fits together on the RFID asset tracking software page.
