Comment by gregmac | Hacker News Reader

Comment by gregmac | Hacker News Reader

> Two AS355s serve as the video-copters, [...] An AS350 serves as a relay helicopter, equipped with VHF antennas that receive and transmit live feeds from the AS355s, as well as ground cameras on motorcycles.

> Circling at 2,000 feet (600m), the relay helo takes camera feeds and sends them to a fixed-wing aircraft flying higher at 10,000 to 25,000 feet (3,000-7,600m), depending on weather.

> The airplane sends the combined feeds back down to two receive trucks located along the race course. The trucks act like signal repeaters, the first sending video to a satellite that sends it back to the second truck further along the course, which finally forwards the signal to the town where the finish line is located.

> With stages of varying terrain up to 140 miles (225km) long, this hop-skip method ensures the best video fidelity with the least time-lag.

Knowing next to nothing about production video transmission, this seems overly complicated to me with several points of failure. I wonder how much of this article is editorialized and mixing up backup/redundant methods vs actual implementation?

The part about relaying between trucks using satellites seems especially strange, if the goal is to reduce time lag. Why are trucks needed to relay a satellite signal at all? Why can't the video-copters send direct to the fixed wing aircraft, or to the satellites? Why can't the fixed wing aircraft be used as a single hop?

If this is accurate, it makes me wonder how much of this setup is "we've been doing it this way for x years, and it works, so don't we mess with it" vs how it would be done with a modern, best-practices design. Anyone that's done this kind of work care to weigh in?

$DAYJOB is about installing satellite equipment of all sorts.

It's very challenging to establish high-bandwidth satellite links from a helicopter due to the rotor blades. I'm guessing VHF is used to avoid line-of-sight transmission at an angle that can avoid the blades.

It's however quite possible to establish satellite links from fixed-wing aircraft. The speed is a direct function of available satellite bandwidth (ie. money).

BUT, high throughput satellite systems (HTS), are a relatively new marvel of technology and are very costly to retrofit on airplanes because no airplane maker will want to allow a new hole on the aircraft's body.

So I'm assuming the fixed-wing aircraft lacks the required satellite equipment (as well as broadcast-management equipment typically found in live-action-reporting trucks) hence the beaming back to trucks.

> ... hence the beaming back to trucks.

Almost all of the television/radio broadcasting stations have their own uplink trucks (and directing rooms for their own camera's) on site. My guess is they send it there to allow the stations to intermix their own signals before sending it out, as well as to give the live reporters (which are at the finish) to view the most recent image without going though satellite delays.

Probably a naive question, but would it be possible to use drones instead of helicopters for this?

My thinking is they are significantly cheaper to buy and fly, and presumably much safer for pedestrians too. Maybe they could also form a mesh network to avoid a single point of failure.

Depends how big the dish is. But at the size where it would become competitive for endurance and risk tolerance you might as well charter or buy an aircraft that'd do a better job.

If you want a drone that's safer than the average helicopter, you're going to be paying a lot of money.

Regarding safety, what I meant is that a helicopter coming down in a crowd is going to be absolute carnage - a drone could do serious damage, but the death and injury toll would surely be a rounding error by comparison.

But drones have a much greater chance of crashing I would think.

Curious... Do you have data to back up your claims?

* about more professional drones

The professional peloton is an incredibly noisy RF environment. Every rider is carrying a two-way radio and a telemetry transponder, every car in the caravan has multiple radio systems, the TV motos are transmitting back to relay trucks with satellite uplinks. Much of a grand tour takes place on mountain roads replete with canyons, cuttings and tunnels.

If you're flying a drone in proximity to the peloton, it's not a question of if you'll lose your control signal link, but how often. I don't know how anyone could operate a drone in that environment with any degree of confidence, even if it's capable of GPS position hold. What happens if you lose your control link just as your battery is running flat? What happens if your chase vehicle gets stuck in traffic and your drone is stuck loitering on the other side of a tunnel? How can a large, heavy drone autonomously find a safe landing place on a mountain stage that's littered with thousands of spectators? A drone big enough to carry the requisite broadcast equipment is undoubtedly heavy enough to kill a bystander.

Broadcasters and race organisers have been using helicopters for decades and know how to manage them safely. Drones simply present too many unknowns. To the best of my knowledge, no helicopter has ever crashed while covering a cycling race. There have been a few incidents where the downdraft from a helicopter caused riders to crash, but none of them were serious.

Semi-pro drones aren't reliable enough. DJI recently shipped batteries for the Matrice and Inspire 2 which failed mid-flight due to a firmware bug. Affected drones fell out of the sky. Most "pro" drones haven't had anywhere near the level of auditing that any commercial helicopter has gone through.

(Battery-powered) Drones have ridiculously short loiter times compared to helicopters

The lightest video-capable satellite terminal that I, a mere civilian, know of weighs around 3kg. Even as a satellite equipment, it's relatively expensive to buy and operate. Its power requirements are also non-trivial, both because of the need for highly compressed video and the high-power radio transmission.

I think you can do the math from there.

As much as I know about the Tour, the route is extremely challenging, not so much related to time-lag of the video, but to actually having a clear signal going through at all times. The production of this race is done by the most qualified outdoor video professionals in the world, it is highly scrutinized, and I doubt that this setup is a product of coincidence.

And the quality has got a lot better over the last 10 years. It used to be that picture drop out was very common, but I haven't noticed much over the last couple.

I do broadcast production for $JOB (as the other person put it) as well. While satellite transmission sounds a bit old, it is proven and widely understood in the industry, if you can get the signal 'on the bird', someone else can get it down. Meaning, the downlink facility at the broadcaster's operations center, other networks, etc.

[edit]Communication between aircraft is a mix of RF and microwave, likely.[/edit] With regards to the camera helo -> relay helo -> fixed wing -> truck workflow, it's likely based on the ability for the camera helos not being able to 'see' the fixed wing aircraft. For instance, since the tour goes into mountainous areas, the camera helos may go down into a valley or be occluded from the fixed wing air craft at various points in time. Using the relay helo allows the fixed wing to fly a less complex flight plan, reducing potential issues with its link to the trucks.

Finally, having all of this operated by professionals who have many years of experience is required for live production. You just can't tolerate any outages, so things like drones, etc, which require longer iteration cycles for updates in flight plan, etc become less of an option.

>> With regards to the camera helo -> relay helo -> fixed wing -> truck workflow, it's likely based on the ability for the camera helos not being able to 'see' the fixed wing aircraft. For instance, since the tour goes into mountainous areas, the camera helos may go down into a valley or be occluded from the fixed wing air craft at various points in time. Using the relay helo allows the fixed wing to fly a less complex flight plan, reducing potential issues with its link to the trucks.

The two camera helicopters do need to remain within range of a relay airplane at all times. This is often tricky in mountainous areas, as you’ve correctly identified. A camera helicopter losing sight of its airplane relay is the most frequent source of signal dropouts.

The relay helicopters are only used to relay the motorcyles’ signals, not the camera helicopters’ signals. The helicopter relays travel freely up and down the route, depending on where the motorcycles are located.

It goes something like this:

Moto cameras 1-5 -> Helicopter relay -> Plane relay -> Roadside HF/Sat relay -> Finish line compound

Heli cameras 1-2 -> Plane relay -> Roadside HF/Sat relay -> Finish line compound

>Why can't the video-copters send direct to the fixed wing aircraft, or to the satellites?

For context, this is the sort of satellite truck you see used for live video broadcast of most sporting events. It looks like it might be difficult to mount the same hardware on a helicopter.

https://www.instagram.com/p/BonJyZZBzBP/?igshid=16sn4ax1pq66...

Yeah seems a little baroque. Though if there’s anything I’ve learned is that whenever you see an overly-complicated solution to a seemingly simple problem, you probably just don’t understand the problem. Though, like you said, sometimes the problem used to be complicated and isn’t anymore and there’s not a big incentive to change a known complex solution to an unknown solution.

This seems a reasonable application of Chesterton's Fence.

https://wiki.lesswrong.com/wiki/Chesterton%27s_Fence

Thanks a lot for posting this. I think it’s the most profound thing I’ve come across today!

Satellite links are actually used rather sparingly, precisely due to the high latency they introduce. None of the planes, helicopters and motorcycles are equipped with satellite uplinks; they are all using RF links in the HF band.

While there are multiple HF relays, there is only one satellite relay truck per stage, located at a geographically convenient location at roughly mid-point through the route. Its role is to pick up all the HF signals, multiplex them, and uplink them to a satellite for downlink by the Euro Media¹ HF trucks back at the finish line. It also works the other way round, in order to relay signals originating at the finish line, such as the director’s orders, back to the crews covering the race.

This satellite relay stops being used as soon as the riders have passed the midway point; from that point on, the two planes and relay helicopters are linked to the finish line solely via HF and microwave. Shorter routes like the time-trial stages don’t require a satellite relay at all.

Another use of satellite uplinks is the midway sprint location, which is covered by a fixed camera on a crane. It is relayed back to the finish line independently of the HF relays, by a regular SNG truck.

¹ Euro Media is the outfit tasked with coordinating all the HF feeds, for delivery to the (adjacent) France Télévisions production trucks which are, in turn, responsible for producing the international and domestic TV broadcasts.

As an absolute amateur, the fixed wing aircraft/relay helo probably can't carry the equipment (big? satellite dish? that have to be aimed accurately?) to send it to the satellite. The relay helo probably can't have LOS with the first truck all the time so the fixed wing plane is used to relay to the truck. The producers, where the signal needs to go to, want to sit at the finish line because that's also where the ceremony is located.

I think most of complications come from the varying terrains blocking the signal path to the producers at the finish line.

I'm guessing heli or plane to satellite is hard because of the movement requiring tracking of satellites. The intermediate heli and plane are probably to ensure you keep LOS. With the trucks. The third heli I'm guessing is either for boosting the signal (putting the heavy equipment on a heli that does less extreme maneuvering) or perhaps for ensuring LOS between the cameras and plane.

Then the two trucks are simply relay points for the satellite.

I would pay good money to see Bob Roll (one of NBC’s main pair of English-speaking commentators) use his famous gesticulations to explain the various signal hops.

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