ImmersionRC Ghost is here. Should you ditch Crossfire?

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Ghost is the new long-distance, low-latency control system from ImmerisonRC. The big question everybody is asking is: why should I care? Hasn't TBS Crossfire pretty much "solved" the control link situation? Here's my take on who should choose Ghost and who might want to stick with Crossfire.

The biggest difference between Ghost and Crossfire is that Ghost uses 2.4 GHz while Crossfire uses 900 MHz. The 2.4 GHz band is much wider than the 900 MHz band, especially in Europe. This means that Ghost can have lots of pilots in the air at the same time without interference. Crossfire pilots may start to experience micro-failsafes with as few as 4 pilots flying at the same time, in extreme situations. This mostly affects races, where organizers try to include as many pilots as possible in each heat. (Some race organizers have even insinuated that Crossfire pilots may intentionally sabotague a competitor by powering up during their race.) Advantage: Ghost.

What about range? All else being equal, low frequencies travel farther and penetrate better. In the latest firmware, Crossfire can go up to 1 watt on the micro module and 2 watts on the full-size module, while Ghost caps out at 350 mW. So Crossfire's range is significantly longer than Ghost's. However, both Ghost and Crossfire have 2x or more the range of a typical 5.8 GHz video link, so the extra range of Crossfire is not going to matter to most pilots. I'm tempted to call this one a tie for 99% of people, but if you fly long-range video systems, then advantage: Crossfire.

For pilots seeking the absolute lowest latency, Ghost offers a 222 Hz "pure race" mode, while Crossfire tops out at 150 Hz. Crossfire's range is significantly reduced when in 150 Hz mode, but its higher 1W output power makes up for this. Advantage: Ghost. But only barely, since I suspect few people would notice the difference between 150 Hz (6.6 ms) and 222 Hz (4.5 ms). They're both pretty fast.

Ghost has no real solution right now for people wanting to drive servos with PWM outputs, although one is planned for the future. Even the smaller Crossfire receivers can output four PWM channels, and there are larger Crossfire receivers with 8 or more PWM outputs. Crossfire is also highly configurable, allowing re-arranging PWM outputs and re-configuring receiver outputs, such as having Crossfire output on two pins while servo channels are on other pins at the same time. Advantage: Crossfire.

Both Crossfire and Ghost have the ability to directly connect a vTX to the receiver and control the vTX channel and output power from the radio module. Crossfire connects to TBS Unfiy vTX while Ghost connects to ImmersinRC Tramp. Since there are so many different Unify vTX's, and even licensed 3rd party vTX's that support SmartAudio, advantage: Crossfire. However, many people are going to wire the vTX to the flight controller, in which case this category doesn't apply.

TBS has been aggressively marking down the retail price of Crossfire in order to compete with FrSky R9. The  Crossfire Micro Starter Set with a module, three receivers, and antennas, is $120. The comparable Ghost bundle is $150. The Ghost Atto receiver runs $30, the same price as the Crossfire Nano. Advantage: Crossfire, but that advantage narrows the more receivers you buy, since the difference is mainly in the price of the initial bundle.

2.4 GHz antennas are much smaller than 900 MHz antennas. Anybody who has ever chewed up a an Immortal T will understand why, when it comes to antenna size, ease of mounting, and durability, it's advantage: Ghost. You can even install a regular 2.4 GHz "whisker" antenna on a Ghost receiver if you want. ImmersionRC also emphasizes the ease of putting a high-gain directional antenna on the radio for longer-range use.

Points have to be awarded for the fact that Crossfire has been around for several years. It's extremely stable and reliable. Most of the bugs have been worked out. When you buy Crossfire, you know what you're going to get. Ghost, being a brand new product, probably still has a few surprises in store. Advantage: Crossfire.

So then, in conclusion, which one should you get? 

If you're a dedicated racer who wants the lowest latency possible, without having to worry about getting micro-failsafed during a race, I think Ghost is very compelling. Even if you're already heavily invested in Crossfire, Ghost may be worth a look.

For a more typical pilot, who seldom flies in large groups, and who doesn't care much about latency, Crossfire and Ghost seem more evenly matched. You're unlikely to push either of the systems to their limit, so the question is whether you want to go with the proven system or venture out into something new and different.

For true long-range pilots, there's no question that the lower frequency and higher output power of Crossfire, as well as the fact that it has better support for PWM servo outputs, gives it the win.