This effectively doubles the spectrum efficiency compared to an analog FM system occupying a 12.5 kHz channel.
![fcc amateur radio scrambler fcc amateur radio scrambler](https://i.pinimg.com/originals/d6/2e/38/d62e3807ea510c6d5b3dd8d9f5c96598.jpg)
6.25 kHz dual-channel systems can be configured to fit within a 12.5 kHz channel. The basic NXDN channel is digital and can be either 12.5 kHz or 6.25 kHz wide. Time-Division, Multiple-Access (TDMA) systems combine the communications streams into a single stream in which information from the different streams is transmitted in interleaved time allocations or "slots." Code-Division, Multiple-Access (CDMA) systems allow many users to share a common spectrum allocation by using spread-spectrum techniques. NXDN uses Frequency-Division, Multiple-Access (FDMA) technology in which different communication streams are separated by frequency and run concurrently. Part 90 regulations specify a bandwidth of 12.5 kHz, but the FCC “strongly urges licensees to consider migrating directly to 6.25 kHz technology rather than first adopting 12.5 kHz technology and later migrating to 6.25 kHz technology.” The FCC “will expeditiously establish a schedule for transition to 6.25 kHz narrowband technology.” Technical characteristics
![fcc amateur radio scrambler fcc amateur radio scrambler](https://ae01.alicdn.com/kf/HTB1lUnyLVXXXXcmXVXXq6xXFXXX6/Newest-Version-Quad-Band-800-CHS-50W-Cross-Band-Detachable-Panel-TYT-TH-9800-Plus-with.jpg)
Federal Communications Commission (FCC) mandate requiring all communications systems covered by Part 90 regulations to use narrowband technology by January 1, 2013. The NXDN protocol and the communications products in which it is used are intended for commercial Private Land Mobile Radio (PLMR) and public safety communications systems.
![fcc amateur radio scrambler fcc amateur radio scrambler](https://p.globalsources.com/IMAGES/PDT/BIG/008/B1170479008.jpg)
The NXDN Common Air Interface (CAI) was accepted at the Study Group 5 (SG5) meeting of the International Telecommunication Union Radiocommunications Sector (ITU-R) held in November 2016 and in report M.2014-3 published in February 2017 as an international digital land mobile system. The NXDN protocol was announced in 2005, and NXDN-compatible products first appeared in 2006. Icom and Kenwood began their collaboration in 2003.