Introduction, and History
Back in early 2013, when FPV was still in its infancy, and mini-quads hadn’t been invented yet,
ImmersionRC introduced the EzUHF 433MHz remote control system.
In the early days, this system was used for some of the most iconic fixed-wing FPV flights, pushing
limits out past 10s of km.
Since then, FPV has evolved massively, and now, 7 years later (4 years after development started), it
is time to bring a new innovative R/C link to the market.
Ghost doesn’t run on 433MHz, nor does it run on 868/900MHz. Ghost uses an innovative new
chipset on the 2.4GHz band for some very good reasons.
Why 2.4GHz, Are We Nuts?
At first glance this seems to be a questionable design decision, after all, shouldn’t ‘UHF’ systems run
on 433MHz, or 868/915MHz?
In Europe, the 868MHz band, commonly used for controlling hobby-class drones, has a couple of
serious limitations. Firstly, the entire (legal) band is only 2MHz wide (vs. 76MHz for 2.4GHz). This is
just not enough bandwidth to run more than a small number of systems simultaneously, and is just
not suitable for racing.
Secondly, duty-cycle limitations which allow other potentially life-saving equipment (fire alarms,
home automation, medical systems) to co-exist on this band, make it a poor choice for low-latency,
high duty-cycle model control.
The chirp-spread-spectrum technology used by the Internet of Things (LoRa WAN, etc.) when run on
the 2.4GHz band has some serious advantages, including:
- Tiny antennas, 2.4GHz antennas are only 36% of the size of the equivalent on 868MHz
- Much wider band, 76MHz vs. 2MHz on 868MHz (or 26MHz on 915MHz)
- Much better sensitivity (= much longer range) than traditional 2.4GHz systems
- Much better selectivity (adjacent channel rejection) than traditional 2.4GHz systems
- Much smaller directional antennas for the really crazy long range missions
- More range than 99% of pilots need, and with a higher gain (but still small) Tx antenna,
comparable range with 868/915MHz systems.
- Enough bandwidth to run 150Hz+ modes using the advantages of LoRa modulation
- Lower power consumption than Sub-GHz systems for longer radio battery life
ImmersionRC Limited, Kwai Chung, NT, Hong Kong, www.immersionrc.com
