September 2000 R/C Modeler
Vol. 37 - No. 9
Name AVX900S7 Wireless Color, 900 MHz Video System
Mfg. By Supercircuits, One Supercircuits Plaza Leander, TX 78641, (800) 335-9777.
Mfg. Sug. Retail Price $450.00
Available From Direct from Mfg.
Size and Weight
Transmitter 2-1/4" x 1-3/4" x 5/8" - 2.8 Oz.
Camera 2-1/8" x 2-1/8" x 1-1/2" - 3.8 Oz.
Battery 8-Cell/AA Alkaline - 7.4 Oz.
Total Airborne Weight 14 Oz.
WE LIKED THE:
Small size, plug-and-play operation, terrific airborne video.
WE DIDN'T LIKE THE:
It seems like a long time ago when a few fellow fliers of the soaring club and I got together to equip a glider test bed with airborne video. The year was 1993. We purchased a miniature color camera, a transmitter, and a receiver kit from Supercircuits. Using a large, hand-held UHF television antenna, we pointed the antenna at the glider for best reception. The airborne system worked okay, although the range was somewhat limited. It took days of work soldering the transmitter and receiver kits, and then tuning both for proper operation and range. The transmitter/receiver operated on a range-limited, low frequency band.
Ground-based receiver and the author's portable TV.
Now, seven years later, Supercircuits provides a turnkey, miniature airborne video system that's 100 percent plug-and-play. The transmitter and receiver are ready-built and tested, and both are fitted with miniature, whip antennas. The color camera is mounted in a rugged plastic case, and it even includes a microphone for sound transmission. The camera readily plugs into the transmitter using the supplied RCA cables. The transmitter/receiver pair operate at 900 MHz, which is a relatively quiet frequency band.
There are three components that make up the airborne section. They are the transmitter, the camera with microphone, and the battery pack. Each component is plug-and-play, with color-coded video, sound, and power cables. This makes set-up and testing an easy task. On the ground is the receiver, which receives the video and sound from the airborne transmitter. A battery-powered television, or preferably, a camcorder with audio/visual inputs, plugs into the video and sound output jacks of the receiver. This is almost all it takes to obtain first-rate, live video from your radio controlled airplane, helicopter, car, or boat.
Let's take a look at the individual components that make up the wireless video system. First and primary is the transmitter. It is encased in a metal, radio-frequency-shielded housing. The transmitter measures 2-1/4" x 1-3/4" x 5/8". This measurement does not include the antenna mounting ear, which protrudes another 5/8" out of the top. The transmitter is pre-wired with two RCA-type input jacks - one for video and the other for sound - and a power jack for battery power. The supplied whip antenna screws onto the mounting ear of the transmitter. The antenna measures approximately 6-1/4" long. The combined transmitter/antenna and cabling weigh 2.8 oz. The transmitter is powered by 12 volts DC at 120 milliamperes, and provides an RF output power of 450 milliwatts at an operating frequency of 910.1 megahertz.
Next is the color camera. The camera is housed in a rugged plastic case. The video, sound, and power cables come out from the back of the case. On the front of the case is the video lens and a small microphone. The case measures approximately 2-1/8" x 2-1/8" x 1-1/2". The video lens protrudes another 3/8" out from the front of the case. The camera/case and cabling weigh 3.8 ounces. The camera is a Supercircuits PC67, with a 4mm, medium/wide angle 80 degrees field-of-view lens. The PC67 delivers a sharp 400 lines of resolution, which is sharper than standard VHS or 8mm recorders. Low light performance goes all the way down to 1.5 lux, which gives the PC67 passable night vision. The camera is fully automatic in its operation of gain, white balance, back light compensation, stepless shutter, and audio. All that is required for operation is 12 volts DC at 120 milliamperes. The camera's video and sound output jacks mate to the transmitter's matching plugs - yellow to yellow (video) and white to white (sound).
The airborne transmitter and camera share an 8-cell, 12-volt DC battery pack. The battery pack includes a Y-harness to connect to both the transmitter and camera. The empty battery pack and Y-harness weigh 1.3 oz. Add eight alkaline AA cells and the battery pack with cabling weighs 7.4 oz. The entire airborne system, including transmitter, camera and batteries, will add an additional 14 oz. to your airplane.
The last component of the AVX900S7 system is the ground-based receiver. The receiver measures 7-1/2" x 5-1/4" x 1-1/4". On the back of the case are the color coded plug-and-play connections that output video and sound to your supplied television or video tape recorder. A rubber whip antenna screws onto the receiver's antenna mounting jack. A supplied wall-mounted transformer attaches to the receiver's power jack. Most of us will not be using the wall transformer other than for indoor testing. The receiver is marked at the power connection "DC 15V, 350 milliampere." The included instructions say to "pay close attention to the fact that the receiver operates on 15 volts DC." This being a product review, I opened the case and found that the receiver will operate happily with the 12/13.5-volt DC power furnished from your automobile's 12-volt battery, or even your 12-volt field battery.
The AVX900S7 falls under the category of FCC licensing known to amateur radio operators as ATV, or Amateur Television. Thus, the FCC requires that the operator of the AVX900S7 hold, as a minimum, a Technician class license. I do not feel that this should hinder most modelers from obtaining the license for a couple of reasons. The first is that the FCC has just recently streamlined licensing requirements. Due in part to the Internet, many testing sites are available to study for the exam and even take random sampled tests on-line. Local amateur radio clubs are of great help and can provide you the study guides and licensing information. With a few weeks of study, I foresee that most of you will be able to pass the 35-question exam. While making the licensing easier for most to obtain, the FCC has also raised the bar for violators. If caught using ATV without the proper licensing, the FCC can fine the operator up to $10,000 per day of unlicensed operation and up to six months in jail! The remedy here is to have the proper license. Again, all that is required is a Technician - no code - license.
Due to the lightness of the airborne components, the camera and transmitter can be placed just about anywhere, provided the cabling can reach between the two. It is important to place the heavy airborne battery at or near the C.G. of the airplane. The camera and transmitter should be mounted in a foam bed to isolate them from vibration. Keep the video transmitter away from your airplane's radio equipment as much as possible to lesson the likelihood of radio interference. I mounted the video equipment into my well-used DuraStik 40. There is not much room in this airplane, so I wrapped the transmitter in foam and secured it to the fuselage side using rubber bands. In a similar fashion, I did the same for the camera, attaching it to the fuselage top. I shifted the camera to look ahead and slightly downward. Rather than add an additional 7.4 oz. of dead weight using eight AA batteries, I reduced this weight to only 2.5 oz. using four Tadiran rechargeable lithium cells. Each AA-sized cell provides 3 volts at 800 mAh, or more than a day's worth of airborne video. I mounted the cells inside the fuselage slightly aft of the C.G. For maximum performance and range, the antennas of both the transmitter and receiver must be placed so that they are in the vertical plane. The video transmitter antenna should be vertical, pointed downward. The video receiver antenna should point upward.
I tested the operation of the video link and it worked perfectly. Next, I powered up the JR 652 FM transmitter and JR NER-226X FM receiver and could detect no interference problems during range check. I would like to point out that Supercircuits offers a videotape that provides detailed installation instructions, as well as excellent demonstrations of the airborne video in action.
I placed the video receiver on the hood of my automobile, powering it through the auxiliary plug of the automobile. The receiver's video and sound outputs went directly into a 12-volt color monitor. I would have preferred to hook up the video receiver's audio/video outputs directly into a camcorder for later viewing at home, but I did not have a camcorder with audio/visual inputs. One other possibility is to use your home videotape recorder powered by an inverter. This method would also allow the capturing of video for at-home review.
On the flight line, I turned on the airborne video and the airplane's radio. I again performed a range check and could detect no interference. I powered up the O.S. 40 LA and performed a satisfactory range check. My assistant reported that all looked well, as she peered into the television. Down the runway and now airborne, the additional weight did not adversely affect flight performance, nor were any radio glitches detected. I wondered what the airborne video was sending. My assistant was locked into fascination, as she said "the view was one of a bird." I flew through several tanks of fuel, sending video the whole time without flaw.
My assistant reported that the best visual sensation is to fly the airplane with smooth, carefully controlled and coordinated maneuvering. The smallest of jerky movements resulted in a less than realistic visual experience, especially my landings!
While I had wanted to submit for this review actual airborne photographs, the process is not as simple as it sounds. For example, my assistant used a camera to photograph the television monitor. The pictures, as many of you may know, did not capture the image at all. Then I asked friends if they had a camcorder with both A/V inputs and outputs. This would allow a PC, through a digital capture device, to acquire the airborne camcorder video, and process a still image for output to a printer. However, it seems that camcorders these days are difficult to find with A/V inputs. Furthermore, the digital capture device I use has a limited resolution of 320 x 200 pixels. This size and picture resolution quality would not reproduce well enough to suit the requirements of publication. One final aspect to consider is the use of a home VCR. Most home VCRs do have A/V inputs. However, another piece of hardware would be required - a 12Vdc to 120Vac inverter. While inverters are plentiful and reasonably priced, I did not feel my investment of an inverter would warrant its one-time use.
The AVX900S7 opens up a whole new world for the modeling enthusiast. Best of all, the system is very user-friendly thanks to its plug-and-play colored connections. There are many avenues to pursue using live video. My favorite application is high-performance "war bird" slope soaring. I would like to produce a combat video using two ground-based video cameras, and two or more airplanes furnished with the Supercircuits system in the cockpit of the airplanes. Let the dogfights begin! I think the action would result in some spectacular footage.
All Contents Copyright © 2000. R/C Modeler Corporation. All Rights Reserved.
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