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Technical specifications of NXDN™

Access Method FDMA
Modulation 4-level FSK
Vocoder AMBE+2™
Channel Spacing 6.25 kHz 12.5 kHz
Transmission Rate 4800 bps 9600bps
Codec Rate 3600bps 7200bps
Conventional Yes
Trunking operation Yes
Type-C and Type-D Yes
Type-C
Digital Scrambling Yes (15-bit/32,000 keys)
Encryption Yes (AES/DES)

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NXDN™ Trunking:

NXDN™ contains two trunking protocols within the same standards suite. For the purpose of simplicity these two trunking protocols have been called NXDN™ Type-C and NXDN™ Type-D trunking.

Type-C trunking is a centralized, control channel based architecture where the trunking logic and allocation of traffic channels is done via a dedicated control channel.

Type-D trunking is a distributed logic based architecture where no control channel is used, and all channels available in the system can operate as traffic channels.

As the NXDN™ standard contains a broad spectrum of functions, the feature set of a system is determined by the manufacturer developing their system for the market needs they will serve. There are mandatory and optional features defined in the standard here, but the following could be considered to be common to most NXDN™ trunking systems of either variety.

Single and Multi-site capability
Individual and Group call capability
Data features (Short text, GPS and status messaging)
Automatic Roaming
Maximum of 60,000 ID's per system
Wide area networking capability via IP linking

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Introduction
The NXDN (Next Generation Digital Narrowband) common air interface protocol, which was developed jointly by ICOM and Kenwood, uses Frequency Division Multiple Access (FDMA), employing a 4-level FSK modulation scheme. These companies and others together form the NXDN Forum.

Kenwood's brand for NXDN equipment is "NEXEDGE", while Icom's brand for NXDN equipment is "IDAS", or Icom Digital Advanced System.


Who are the Users?
Click on the NXDN category at the bottom of this page, and select the various regions to see if there are listings in this wiki. More information might be found in the trunking tab of your state in the RR Database.
You can use the Digital Frequency NXDN Search webtool to search by county for frequencies authorized to use NXDN (information extracted from the FCC database)
The Digital Frequency Quick Import webtool can also be used to import frequencies into several modern scanners.
Can it be Decoded?
Apart from using an actual Kenwood or Icom radio, the following methods are possible:

The Uniden SDS100 and SDS200 can handle this mode with a paid upgrade.
The Uniden BCD436HP and BCD536HP can handle this mode with a paid upgrade.
The upgrade is discussed in the NXDN Now Available for the 436, 536 Thread
NXDN Tips for the BCDx36HP and SDS Scanners
The Uniden BCD325P2 and BCD996P2 support this via a paid upgrade (version 1.08.00)
See the NXDN comes to BCD325P2 and BCD996P2 Thread for a discussion on this topic
Programming the P2 Scanners for NXDN
The Whistler TRX-1 and TRX-2 can be programmed to monitor conventional NXDN systems. However, these scanners cannot trunktrack NXDN systems. Whistler never bought the licenses, which is why the upgrades are free. The best these scanners can do is to decode the audio. This may be sufficient on systems that aren't too busy, but for busier systems, this is a serious limitation. See the following threads for more information:
NXDN Update Now Available Thread
Clarification for NXDN Decoding Thread
How to improve NXDN Scanning Thread
See our Trunked Radio Decoders article for several applications that can handle NXDN. Note that some of them are best used with Software Defined Radios

Radios with no trunking support
AOR AR5700D
AOR DV1 Note: 6.25 kHz NXDN4800 only
AOR DV10
Icom IC-R30 Note: Can decode encrypted audio if the key is known
Icom IC-R8600 Note: Can decode encrypted audio if the key is known

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NXDN stands for Next Generation Digital Narrowband, and is an open standard for public land mobile radio systems; that is, systems of two-way radios (transceivers) for bidirectional person-to-person voice communication. It was developed jointly by Icom Incorporated and Kenwood Corporation as an advanced digital system using FSK modulation that supports encrypted transmission and data as well as voice transmission. Like other land mobile systems, NXDN systems use the VHF and UHF frequency bands. It is also used as a niche mode in amateur radio.

NXDN is implemented by Icom in their IDAS system [1] and by Kenwood as NEXEDGE;[2] both Kenwood and Icom now offer dual-standard equipment which supports the European dPMR standard

NXDN uses Frequency-Division Multiple Access (FDMA) technology in which different communication streams are separated by frequency and run concurrently. 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.

The basic NXDN channel is digital and can be either 12.5 kHz or 6.25 kHz wide. 6.25 kHz dual-channel systems can be configured to fit within a 12.5 kHz channel. This effectively doubles the spectrum efficiency compared to an analog FM system occupying a 12.5 kHz channel. The architecture of NXDN is such that two NXDN channels, within a 12.5 kHz channel for example, can be allocated as voice/voice, voice/data, or data/data. As of 2012, this capability cannot be implemented in commercially available hardware on simplex or "talkaround" frequencies, but only through repeaters.

Systems that use NXDN also support mixed analog FM and digital NXDN equipment, including direct radio-to-radio communications. This allows system owners to migrate to a narrowband, digital system without replacing the entire system at once. NXDN equipment is currently FCC type-accepted for use on VHF (137-174 MHz) and UHF (406-512 MHz) bands.

Data is transmitted using 4-level frequency-shift keying (FSK) modulation. NXDN uses the AMBE+2 vocoder (codec) for digital audio.[8] This combination provides better weak-signal voice quality than for analog FM. For an equivalent transmitter power, NXDN is represented as having a wider range and slightly better multi-path characteristics than analog FM in typical RF environments, specifically at the 12 dB SINAD threshold. The transmission bit rate is 4,800 bit/s.

The following FCC emission designators apply to NXDN transmissions:[9]

8K30F1E 12.5 kHz single channel digital voice
8K30F1D 12.5 kHz single channel digital data
8K30F1W 12.5 kHz single channel digital voice and data
4K00F1E 6.25 kHz single channel digital voice
4K00F1D 6.25 kHz single channel digital data
4K00F1W 6.25 kHz single channel digital voice and data
4K00F2D 6.25 kHz single channel analog CW ID

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_________________
" SILENCE IS CONSENT "

Jim N7UAP - Bellingham, WA / InterceptRadio.com