With the ever increasing pace of modern technology, amateur radio was certain to embrace the new methods of digital communication. Indeed, modern digital voice systems encode speech into a stream of data before transmission, while the receiver decodes this stream back into a normal audio signal.
In the past the only way amateur radio operators used to send data was using conventional analogue methods. This is often achieved by inserting the data stream as an audio signal in place of voice. It should be noted that this method of data transmission is far from dead, and is still thriving. Further information on data modes (digimodes) can be found on this page.
The three most common digital systems are
D-STAR (Digital Smart Technologies for Amateur Radio) is a digital voice and data protocol designed specifically for amateur radio. The system was developed in the late 1990s by the Japan Amateur Radio League and was the first that was used by amateur radio. D-STAR also allows for networking connectivity, enabling D-STAR radios to be connected to the Internet or other networks.
Around 2004 Icom became the first amateur radio manufacturer to release the hardware modules as an option for it’s handheld radios. It is a common misconception that Icom developed the D-STAR system. Currently, the D-STAR network has grown and uses repeaters and gateways to allow linking radios and systems both locally and across the globe via the internet.
DMR (Digital Mobile Radio) has been designed with three tiers. DMR tiers I and II were first brought into service around 2005, these two tiers are the standard used for most DMR systems. DMR is the only mode that can support more than one voice channel at a time. It can support 2 different voice channels in the same 12.5Khz bandwidth. DMR refers to these as Timeslot 1 and Timeslot 2.
DMR Tier I products are for licence-free use in the European PMR446 band. Tier I products are specified for operation without the use of repeaters.
DMR Tier II covers licensed conventional radio systems, mobiles and hand portables. The ETSI DMR Tier II standard is targeted at those users who need spectral efficiency, advanced voice features and integrated IP data services in licensed bands for high-power communications. A number of manufacturers have DMR Tier II compliant products on the market.
DMR Tier III (Trunked version) came along in 2012. The trunked version is designed for high end users where service sharing and routing of communications is required.
System Fusion is Yaesu’s implementation of Digital Amateur Radio, utilizing C4FM 4-level FSK Technology to transmit digital voice and data over the Amateur radio bands. In the early 2000’s GMSK emerged in the Amateur radio market as the dominant digital mode, however in 2013 Yaesu introduced “System Fusion” which quickly became the dominating digital format in Amateur radio because of quality, reliability and enhanced performance in a wide range of environments.
I personally don’t use any of these digital modes although I have registered a digital ID for my callsign.
If you want to dip your toes into the murky waters of digital radio, but are unsure where or how to go about it, or what system is best then you can do a lot worse than have a read of this page.