Analogue vs Digital FPV Drone Systems

Analogue vs Digital FPV

The release of the new DJI FPV combo means that pilots of all skill levels but particularly new pilots are being asked to choose between Analogue or Digital FPV Systems.

With off the shelf and ready to fly digital systems making it ever easier to get in the air will these new digital systems lead to a decline in custom built drones and the availability of the analogue video systems that were fundamental in making FPV possible? If my build habit is anything to go by…. at least not yet!

If we look at a similar question posed to music lovers, we see a resurgence of vinyl and DIY turn tables that records are played on. Purists say it has a warmer sound, a sentimental fuzziness lacking in the digital copy. If this tells us anything is it that there will always be audiophiles?

 

Digital VS Analogue FPV - www.customquads.com.au

So what does this have to do with FPV?

The real world implications of flying at speed in proximity situations and the reaction time between you and your drone being critical, many pilots reported that they can still notice this lag and will continue to race with their analogue setup. Its more than that though, analogue is not tied in to any proprietary system, it is modular and cameras and VTX for the most part are interchangeable. Digital Pilots might need to consider the longevity of closed proprietary systems as newer tech rapidly supersedes previous versions.

Analogue FPV

Mathematically analogue video provides the shortest path between you and your drone’s camera output. Measured in milliseconds the lag is still an observable phenomenon particularly in earlier systems. Later systems have narrowed this down to where it is barely noticeable.

The image data that is taken from the sensor in your camera, is sent to the VTX with On Screen Display (OSD) Information overlaid . This task is done by an OSD module and these are now onboard the Flight Controller (FC) rather than a seperate unit as earlier builds had..

This data stream while technically converted to ones and zero’s is transmitted by an antenna attached to your drone as an Analogue signal. A waveform of a particular frequency with the video signal being added to that radio wave.

It works great, its fast but it is prone to interference. This is where one becomes a student of the magic subject of antennas and antenna theory.

This signal, caught by the antenna on the receiver module (RTX) in your goggles and the signal converted to a standard definition picture which you then see.

Typically most pilots are using 5.8 GHz systems but there are other VTX available that transmit using frequencies in the 900 MHz, 1.2 & 1.3 GHz and 2.4GHz and other ranges.

It is a good idea to transmit your video signal on a frequency different to the one that your radio uses. For example the TBS Crossfire operates on 915 MHz so it makes good sense to transmit video on something other than 915 MHz if you are using Crossfire. The lower frequency bands are better at penetrating buildings, trees and other things that obstruct your video link.

Digital HD FPV

What has taken until recently to solve was the bandwidth issue for High Definition video.

The DJI digital system ignores the previous advice and transmits its radio commands in the same 5.8Ghz ranges that the video is being sent at and across multiple channels. The reason for using multiple channels is to expand the available bandwidth but even then an extra process of compression is required. This extra step in the form of H264 encoding is what makes digital HD possible. But it is an extra step and why analogue will always have less lag.

What is hard to ignore, are the many more pilots moving to and persisting with the. DJI digital platform Is there something worth checking out here?

Absolutely! Curiosity finally got the better of me and I made an impromptu purchase deciding it was time, shortly after commencing a new build. What was originally to be an analogue build was now to be digital. An ImpulseRC APEX was to be my platform of choice.

I had to order a different top and bottom plate and camera side plates which were needed to fit the DJI Air Unit This is a module that combines both a Video Transmitter and a Receiver for the remote controller. While there are flight controllers that come HD ready, that is they provide correct power for the AIR UNIT it was not a stretch to make the FC I already had into a clean build. I powered the Air unit with a Micro BEC which stepped the power down to 9V from my 6S input.

The 720p Image presented by the DJI Goggles at 120fps, brings a clarity to flying that is crisp and sharp and gorgeous. Details that one used to guess at because of the limitations of analogue resolution are now clear and sharp in glorious HD. Lag has been addressed and reduced for a big step up in resolution.

And even without antenna mods or power output hacks I was able to fly further and with more confidence than I had ever felt comfortable doing before with my analogue setup.

The HD build was straight forward and yet another great experience provided by DJI.

So having built and flown both digital and analogue rigs what are my thoughts and what would I recommend?

Analogue FPV Pros / Cons

PROS

CONS

•      Modular support for a wide variety of cameras and video transmitters.

•      Signal is prone to interference from objects / breakup multi pathing

•      A range of price points to suit different budgets

•      Video looks ordinary when compared to HD Digital.

•      Are customisable with wide range of goggles, lenses and foam face plates

•      Can be frustrating to set up

•      Other pilots can spectate your flights

 

•      Wide range of bandwidth for pilots to operate on.

 

•      Compatible with tiny whoops

 

•      The cool factor - analogue rebel in an otherwise digital world

 

 

Digital HD FPV Pros / Cons

PROS

CONS

•      Fantastic Flying Experience

•      Image compression -always an extra step behind analogue.

•      Stunning HD Image

•      Can interfere with Analogue Pilots

•      Improved Range

•      Constant software updates

•      HD Image recorded in Googles as well as on board

•      Possible Geo Fencing

 

•      Closed Operating Environment

 

•      Modification required to work with analogue

 

•      longevity / redundancy

 

So who wins the Analogue / Digital Shootout?

Well I do love flying with my DJI goggles but if you are serious about the hobby you will eventually own a range of gear and be trying different things out anyway.

If you need a budget option then the analogue path is still rewarding and one can gain great results but its an exciting time to try what the digital offerings bring to the table: Reduced lag, the extra resolution of High Definition and in the case of the DJI system all the different modes and features that have come from their aerial photography platforms combine to create a fantastic flight experience!

 

Author: David Iversen
AKA Kawika Kahuna 


I have a background in Graphic Design and Computer Graphics and have worked in Film and TV for more than 15 years. I have been building and flying drones since 2011. I am a drone pilot for Aerial Acuity and have filmed surfing and off road racing as well as advertising, real estate and industrial jobs too. In my spare time I enjoy building and flying as well as surfing regularly..