Don't know your frequency? How to identify what you have

1. Read the label

FCC-certified radio equipment carries a label reading "FCC ID" followed by its identifier:^[1] a grantee code assigned by the FCC plus a product code from the maker.^[2] Look that ID up in the FCC's equipment authorization search, or send it to us and we will. In Mexico, approved equipment shows a certificate number beginning "IFT".^[4]

2. Check the license

Licensed systems (two-way radio, licensed SCADA, microwave) have a call sign.^[5] The license lists the frequencies; in the US you can look it up in the FCC's license search.

3. Read the datasheet's band list

A cellular modem or router lists its LTE or 5G bands, and each band number maps to fixed frequencies in the 3GPP tables.^{[7, 8]} "Bands 2/4/5/12/13/14/66/71" means PCS 1900, AWS, 850 cellular, lower and upper 700 MHz, FirstNet, extended AWS and 600 MHz.^[7]

4. Identify the connector

Look at the center contact (pin or socket) and the outside (threaded, bayonet or snap-on). SMA and RP-SMA share threads but swap the center contact;^[9] N is the larger threaded 50 Ω connector; TNC is a threaded BNC-size connector; BNC is bayonet; QMA is snap-on.^[10] Trust photos and drawings over listing text.^[9] Connectors and cable

Common clues

• A cellular router or modem: LTE/5G bands, see its band list.
• A gateway labeled "US915": LoRa, 902–928 MHz. "EU868" means 863–870 MHz, the wrong one for the Americas.^[11]
• A port labeled "GPS" or "GNSS": L1 at 1575.42 MHz, receive-only, right-hand circular polarization.^[12]
• A licensed radio on 150–174 or 450–470 MHz: Part 90 land mobile.^{[13, 14]}
• "MAS 928/952": licensed SCADA under Part 101.^[15]