FDMA (Frequentcy Divided Multiple Access)
About FDMA Technology
In digital two-way radio systems, there are two main “channel access” methods used today. One is FDMA (Frequency Divided Multiple Access). This method is the oldest and most established method in the industry. The other method is TDMA (Time Divided Multiple Access).
The basic difference between FDMA and TDMA is the definition of a channel and how it is used (accessed). In FDMA a particular bandwidth (E.g. 6.25 kHz) at a particular frequency (E.g. 150.000 MHz) is used to define a channel.
In TDMA, the same principle applies regarding bandwidth and frequency, but the signal is divided into time slots that allow the channel to have ‘extra’ capacity in the same bandwidth E.g. Two 6.25 kHz ‘equivalent’ channels in a 12.5 kHz channel. See the diagram above for a graphical explanation.
Why 6.25 kHz FDMA Narrowband?
True Narrowband: Reliable Communications for Half the Spectrum!
Communications Reliability When You Most Need It
FDMA: Proven History Like No Other Radio Technology
For over 50 years, FDMA has been the backbone of two-way radio communication. Generational enhancements have culminated in the realization of 6.25 kHz FDMA digital protocols that are literally ahead of their time, while keeping backward compatibility with analog FM.