Feature: 1. CLASSIC AND EXCELLENT: MMDVM Duplex hot board use excellent crystal, which is a classic motherboard 2. INTERFACE AND MODE: Hotspot board has two Organic Light Emitting Diode interface, serial interface, SMA antenna base, IPEX antenna base, STLink firmware upgrade and degradation interface, support online upgrade, support DMR, D Star, YSF(C4FM), P25, NXDN, POCSAG and other digital modes 3. APPLICABLE MODEL: Hotspot board with PCB antenna, take up small space, with stable signal, convenient for DIY. LED light double row design bring more clear display, support for Raspberry PI 1B 2B, 3B, 3B+, ZeroW 4. SUITABLE FOR HAM: Small board supports PCB antenna and two external antenna interfaces. The large duplex version supports two types of external antenna bases and supports online firmware upgrade. Suitable for radio enthusiasts who like DIY, and ham research use 5. POWERFUL FEATURES: Duplex hotspot module uses for DMR mode for simultaneous calls without interference. One box can monitor two groups at the same time, and the two groups can talk to each other at the same time without interfering. One duplex plate is equivalent to two simplex plates.(dual panels can also be set to single.) Specification: Item Type: MMDVM Hotspot Board Material: PCB Frequency: U band (420.000-434.900/438.100-470.00/) Supported Modes: DMR, D Star, YSF(C4FM), P25, NXDN, POCSAG Power: 20mW Product Size: Approx. 65 x 30mm / 2.56 x 1.18in Supported for Raspberry PI: 2B, 3B, 3B+, 4B, ZeroW(can be directly installed for Raspberry PI, pin head has been welded) For BlueDV with Type C interface can be used to connect to computers Difference Between Simplex And Duplex: Simplex works only on direct frequency, like direct frequency walkie talkies on cell phone walkie talkies. Only one cell phone radio can talk to each other at the same time. The duplex box can act like a relay station. Cell phone radios need to be set to different transmit and receive frequencies. The duplex box works like a multimodule digital relay station. Duplex box has the advantage of using for DMR mode to talk at the same time without interference. One box can monitor two groups at the same time, and the two groups can talk to each other at the same time without interfering. One duplex plate is equivalent to two simplex plates.(dual panels can also be set to single.). Package List: 1 x Duplex Hotspot Board2 x Antenna2 x Pin Header