Ham Radio ATV (video) gear

[stopNgoBeau 0]

I see some rather old posts regarding the use of Ham Radio while under canopy. I've been a licensed Technician (No-Code!) since 1993, but haven't made a contact in years.

I'd really in interested (after lots of time accumulated, not anytime soon) of rigging a VHF/UHF transmitter with TV capabilities for use during free fall and under canopy. I know it wouldn't be a first by any far stretch, but it would be for me.

Anyone have any experience with this, or care to recommend equipment for it? I'm still in training, but I would imagine this equipment would be expensive and would need to save up to purchase it (just like equipment in any other hobby).

Also, any thoughts on getting the DZ operator to sign off on letting me use it?

Again, I wouldn't even begin to attempt to try this until well after achieving my A card.

Blue skies and 73's, KC5DXR

[Laszloimage 0]

I jump every week with a 900MHz 0.7W video transmitter providing air to ground (live video).
You can buy even more powerful wireless video systems (transmitter and receiver) on ebay for $150.
...now you just need to become an experinced jumper.
73's HA3TW

[dninness 4]

Quote

I jump every week with a 900MHz 0.7W video transmitter providing air to ground (live video).
You can buy even more powerful wireless video systems (transmitter and receiver) on ebay for $150.
...now you just need to become an experinced jumper.
73's HA3TW

Prior to 900Mhz being a viable alternative, Tom Sanders, Norm Kent & Ken Crabtree jumped out of my helicopter with microwave transmitters (fairly directional) attached to them during the Opening Ceremonies of the Olympics in 1988. Of course, it required folks on the ground with directional antennas pointed at each camera flyer..

It was kind of bulky and complex, never mind the microwave energy being generated really, really close to your body :)

NIN
D-19617, AFF-I '19

[stopNgoBeau 0]

Thanks for the replies. I'm looking forward to exploring the different aspects of this sport and finding out how to 'customize' it for my own experiences.

And, yes, now its time to gain some experience first.

[Laszloimage 0]

I have received a few emails and PMs regarding this subject.
It is lot of time to give an answer to everybody individually. So I try to post a super simple article here to give some basic ideas to what principals to follow in order to be able to run a ground to air skydiving video successfully.

Clearing some mysteries about wireless systems.
Transmitters can NOT be simply rated for range based on their power.
It’s possible to cover 100miles with only 0.7W if everything is right, or you can’t even cover a mile with 20W if everything is wrong.
There are many different factors to determinate the effective range of a radio transmitter.
Of course higher power normally means more coverage.
But other things to consider… The frequency it self, different wave lengths propagate differently. In this case 900 MHz (33cm wave length) pretty much travels in the “straight line with very little reflection (bouncing if you will) from other objects and easily “faded out” by obstacles (terrain, buildings, or in this case airplane fuselage)
In the other hand as long as the transmitter and receiver can “see” each other directly with their antennas on 900MHz a very small output power can have a very long range.
The antennas are the other important factor. There are antennas radiating (beaming) to all directions all at once (like those rubber antennas) and there are antennas more directional (YAGI, parabola dish, quad, and more...). The directional antennas can pick up a weaker signal better (more directional effect more gain) but that means they have to point to the right direction all the time. It can be difficult when someone freefalls with a transmitter…
In the skydiving case the best compromise is to have a 1or 2W output transmitter with a rubber antenna (that’s also small and snag free) and the receiver with a directional antenna with a not too “pointy” angle of beam width. A 5 to 7 element YAGI is a good choice because of the 30-50 degree with combined 10-12db of gain.
Another important thing is the SWR (standing wave ratio) 1:1 is the perfect 1:2 is still usable but I would keep it under 1:1.5. This “SWR” thing is coming how the antenna is tuned to the frequency is used on and how the impendency (Ohms are matched) between the antenna, feed line (mostly coax cable), and transmitter/receiver.
Further more the polarization of the antenna makes a different too. The orientation of the transmitter antenna (vertical or horizontal depends how it’s mounted let’s say on a helmet) better be matched with the receiver antenna in order to avoid about 3db of loss.
As an analogy for this “gain/ direction/SWR” of antennas I can maybe bring up lenses to make it easier to understand. A wide angle lens takes wide images with easy to focus but everything looks smaller in the frame. A telephoto lens can take images farther, but it has to be pointed more accurately to the direction of the subject. Bigger the zoon is farther the lens can see, but more difficult the pointing and focusing becomes (steady hands or tripod required).

Higher the frequency shorter the wave length is, which means physically smaller antennas. But above a certain frequency (microwave range) things start behaving differently, so the 900MHz or the 1.2GHz wireless video systems are the most optimal for skydiving “air to ground video” purposes.



These receiver antennas should be pointed half way between the expected exit point and deployment point for a good result. Of course the best would be if someone could point the antenna non stop towards the transmitter (in this case the fee falling camera guy).

Some antennas: http://www.ebay.com/itm/900Mhz-GSM-Yagi-antenna-12-dBi-N-female-connector-/280746140029?pt=LH_DefaultDomain_0&hash=item415dc6217d

http://www.ebay.com/itm/Wilson-Yagi-900MHz-Cellular-Antenna-301142-/130547166596?pt=PDA_Accessories&hash=item1e6537ad84

Some wireless video systems:
http://www.ebay.com/itm/0-9GHz-2-5W-Wireless-Video-Audio-Transmitter-Receiver-/230459336467?pt=Other_MP3_Player_Accessories&hash=item35a8726713


http://www.ebay.com/itm/0-9GHz-1-5W-Wireless-Video-Audio-Transmitter-Receiver-/330421632323?pt=Other_MP3_Player_Accessories&hash=item4ceea9fd43

Transmitting with this kind of power directly from the helmet (right next to the brain) I would consider use shielding against electromagnetic field inside my helmet! Thin foil or thin wire web lining connected to the transmitter’s metal housing can serve that purpose.

[stopNgoBeau 0]

In order to correct the issue of higher frequency fade out, I intended to use something lower, possibly in the 2m band or as high as 70cm (144Mhz and 440Mhz respectively, if you aren't a HAM and are not familiar with the wavelengths). This, at around 2 to 5 watts, on a leg strapped transmitter using a rubber "duck" should help with range issues and issues with transmitting through a fuselage or a leg.

I've see fade outs occur on videos as the jumped tumbles immediately after leaving the plane, which to me is particularly fascinating and telling of the problems associated with 900Mhz to 1.2 or 2.4 Ghz.

My main concern is finding the gear that can do this while maintaining a small size and finding a good place that I can strap it without interfering with the more important systems (i.e., the canopy, container, and, God forbid, the reserve).

Fitting most of it under the suit would help to keep snags from occurring. Camera placement also comes to mind. What would a person on the ground want to see? Me, as in a camera mounted on the wrist? Or the surrounding area or another jumper, as see through a helmet mounted camera?

[rtyd 0]

I'm part of a group here in California that have been using ham gear to make contacts (QSOs) for a couple of years now. We just recently have started experimenting with video and ATV. Go to Parachutemobile.org for more info.

[stopNgoBeau 0]

You're site was one of the first I came across. Really cool stuff. If I were closer to CA (in Baton Rouge, LA) I would meet up and see what its all about.