Discussions

A long standing issue flying RC/UAV models in so-called “commercial airspace” has been the issue of safety associated with “situational awareness” i.e the ability of an  RC/UAV model to unilaterally institute an “avoidance procedure”.

Till that issue is addressed. the potential threat models pose to other aircraft/microlights/gliders/para-gliders etc etc …. remains an obstacle to greater freedom in & usage of airspace.

Could resolving that issue perhaps be a little closer?

NAVICO recently launched broadband radar – a radar system potentially adaptable & usable in at least a large-ish sized RC/UAV model?

Traditional (read traditional as “magnetron” type) radar systems have been a no go for models for a number of reasons:

-         WEIGHT – to heavy for a model

-         MASS/SIZE – to big for a model

-         COST – beyond what even a dedicated amateur/semi pro flyer would be willing to layout.

-         POWER CONSUMPTION–  perhaps not as big a problem today with the kilowatt size LiPo packs that are available, as it has been in the past, but still, traditional consumer radar systems add substantially to power budgets.

-         SAFETY – potential health issues at close range to bystanders and operators with 2Kw – 4Kw pulse @ 9Ghz!

With the recent launch by NAVICO of so-called broadband radar, the above obstacles are largely overcome in one go. Broad band also offers performance advantages (like finer obstacle resolution and elimination of dead space radius that surrounds a traditional radar antenna).

WEIGHT - NAVICO’s system comes in at just over 7kg’s – of which a large slice is made up by the antenna, and antenna associated mechanics/electronics (which can be reduced in both size in mass – by my estimates by around half (see my comments towards the end of these notes).

COST – around $1700.  Pricy? Agreed, yes, but quite a lot less than traditional consumer radar systems. I see many modellers been willing to stomach $1700, if with DIY work the off-the-shelf product can be “hacked” & adapted to work/fit in a suitably sized model.

POWER CONSUMPTION – 17watts!! Yup I’ll say that again – NAVICO’s unit consumes just 17watts in operation, and that’s at 13.8volts (1.6watts on standby)! Out the box the PSU it comes with accepts from 9v to around 31v, at which the amperage required is now in the milliamp range! Well within what a large RC/UAV onboard PSU/battery system can be configured for both weight & size to accommodate. A traditional consumer type radar system of say around 2Kw – 4Kw for a small/medium yacht will consume two to three times just on standby, never mind operating.

SAFETY – lots of potential health issues getting zapped at close range by a 2Kw/ 9Ghz pulse every time you fire up models’ radar system. NAVICO’s radar output is less than a mobile phones’ – at around 100milliwatts!

Can’t be much of a radar system is its only putting out 1/10of a watt, now can it?

Nope -  in fact broadband radar at this power level offers not only weight/size/cost and safety advantages that commercial systems don’t offer, it also offers a bunch of performance characteristics potentially ideal for RC/UAV application  that high powered commercial systems don’t offer.

Traditional systems (like those used in the yachting/boating community) suffer, from a significant dead-space around the antenna, which depending on the actual design can range from any radius up to around 200feet or so around the antenna, so users are okay seeing what’s out at a couple miles, but don’t see a damn thing around them in thick mist/fog coming into port. Not so with NAVICO’s broadband system – not only doesn’t it suffer close-in dead space radius, it offers object resolution down to 2m (actually real world resolutions close to 1m are reported – NAVICO are erring on the side of caution).

This 1m – 2m resolution extends out to around 5-6miles radius – providing plenty time to take avoidance action from just about anything of any threatening size, to include most models and large birds, not to mention any aircraft except perhaps some fast jets – and even then so long as the software “app” developed to integrate the radar with the models’ command & control electronics is responsive enough, chances are fast jets can be accommodated as well with decent safety margin.

What’s made this all possible is NAVICO have done some pretty thorough research. To start with they have binned the magnetron that radars traditionally use for the microwave pulse, thereby reducing required power and weight.

This system doesn’t pulse, it is a constant FM modulated wave – all based on solid state electronics (further reducing required power and mass) – no magnetron required. Constant wave radar offers finer resolution, and while overall the radius is reduced compared to traditional radar, the +/-24nautical miles that is obtainable from the 100milliwatt output is plenty sufficient for RC/UAV model flying. The 1m - 2m resolution available for 5 – 6miles radius does however drop as distance increases over the initial 5 – 6miles.

Adaptation

The skill level required to “integrate” this broad-band radar into some usable format for onboard auto-pilot/nav systems to make use of I would thought is well within what some DIY DRONES forum members would be capable of tackling. One “problem” is going to be the standard antenna mechanics & dimensions. As it stands the standard out-the-box antenna is some 488mm x 280mm: accommodated in a flat sided circular dome. Then there are the mechanics to spin the antenna, which are included in the above dome dimensions (at least they are already designed and intergrated).

The original dome would need to be re-profiled (think sharpe sided oval shape (?)) – no ways around it. A look at the antenna doesn’t show it to be anything too sophisticated. Off the top of my head, I see little reason stopping  it from been “re-engineered” in size & dimension, all-be-it with some sacrifice to performance, but still keeping it good for purpose. Could the electronics (i.e. receiver, transmitter, signal processing & GUI) be repackaged to fit in a medium/large sized model fuselage? See no reason why not, its all up and running, the issue is repackaging and layout – well within the skill level of some forum members.

What remains are the skills needed to integrate the radar output (at the video/display level?) into onboard auto-pilot/navigation electronics so that what is “seen” by the radar can be used by the model to monitor its surroundings in the air and take avoidance action when it needs too. Alternatively – feed the display graphics to the ground station, and implement the flight planning changes through the ground station and transmit them up to the model(?).

Again, I would have thought that there are folk on the forum who could tackle this.

In any event, onboard radar for UAV models, for whatever purpose (and avoidance has to be high on the list, keeping in mind its one of the big concerns that the FAA/CAA has regards UAV models in commercial airspace) is perhaps not so distant as folk think.

If anything, the electronics are now certainly light enough, small enough and power power conservative enough to be placed on any medium – large sized RC/UAV model.

All comments and ideas welcome …….

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