Wireless Video Useful tools? Or Smoke and Mirrors?
Part Three of Three
Good evening, and welcome to the show. The holidays have come and gone, and along with them probably most of our New Year's resolutions. My resolution this year is to remember, "Moderation in all things". But then, of course, even moderation should not be practiced to excess. . .
Saw a very profound question on Betty's coffee mug: How much shit could a dipshit dip, if a dipshit could dip shit? I may lay awake nights agonizing over this.
Welcome to part three on wireless video systems. If you missed parts one and two, call Al Menear at Days Communications (215-538-1240) for your copies. We discussed the concept of wireless video for surveillance applications, the various frequency ranges available for video transmission with the pros and cons of each, the story with 900 megacycle "license free" systems, legal aspects of video transmitters, licensing and FCC type acceptance requirements and what they mean to you. We also learned that many wireless video systems being offered to law enforcement are illegal, and claims for transmission ranges almost always are extremely exaggerated.
We also discussed why you do not want to use a system that transmits on broadcast television frequencies, and what happens if you do. We also revealed and disassembled some extremely deceptive advertising on the part of a dishonest vendor of video transmitters who advertises "90 mile range" widely in magazine ads. We also discussed antennas, how critical they are to good range and reliable operation of any wireless video system, mistakes many people make dealing with antennas, and how to do it properly.
All this behind us, there is a place for wireless video systems in the law enforcement arena. For covert surveillances of all types, for officer protection, remote eyes and ears for tactical or EOD teams, and many other applications, nothing else can suffice. Selected and set up properly, wireless video can be an indispensable tool for the modern investigator.
Since last issue, I've run across two manufacturers who offers legal, quality equipment. I've spoken at length with their marketing and technical people and they both know what they're doing technically plus have the right attitude to work with law enforcement. You may wish to contact Greg Rowley at SEMCO, Tel 619-438-8280 for information on their L band (1700 MHz) and S band (2200 MHz) video transmitters. I haven't personally used their equipment but it smells like good stuff.
Another excellent supplier is Microtek in California (call their marketing group at 714-855-0332 and ask about their Minilink 2.4 system). Microtek will be shipping an S band (2400 MHz) multi channel video and audio transmitter and receiver pair by the time you read this. The equipment is quite small, FCC type accepted for license free legal operation by anyone. Based on personal experience with their equipment and many years association with the owner, I can testify that Microtek equipment is extremely well designed, quality manufactured to the highest specifications, support is superb and in every case the equipment will work as well or better than they claim if you follow the guidelines for installation.
You know how I cynical I am (Steve cynical? No way.) about claims for operating range with video transmitters in general. Microtek is claiming a 500 foot line of sight range with rubber ducks, and 3000 feet with high gain antennas. I am certain you can design an operation around these figures sight unseen and know it will work once you purchase the equipment. I absolutely would not suggest this with anything else on the market. (You other manufacturers -- you're welcome to send information or an evaluation transmitter and receiver which will be returned after being reported on honestly in these pages. If your stuff works, here's a chance to get free publicity.)
There is a matter of using several transmitters simultaneously in the same area which needs to be discussed. Sometimes you will have a job where you may want more than one transmitter active or installed on the same job. In some cases this can be done, but remember video transmission is not audio transmission, and a whole different set of rules apply. With any transmitter, be it audio, video, data or Morse code, the signal takes up a certain amount of space, called bandwidth.
When you speak of a transmitter being on a certain frequency, actually the transmitter is only centered on that frequency. The signal occupies a certain amount of space above and below the center frequency. The wider the bandwidth, the wider the chunk of space a signal occupies. There is a significant amount of fancy math some of the gurus like to throw in, but that's not necessary for our discussion. The one concept you need to understand regarding bandwidth is that the more information being transmitted, the wider the bandwidth. A very simple analogy can be with a Morse Code signal (called CW, for Continuous Wave). This is about the simplest form of transmitting intelligence -- just by turning the transmitter on and off in a coded pattern.
A CW signal being sent at 10 words per minute (moderately slow) will occupy a certain bandwidth. Speed up the signal to 20 wpm and you double the bandwidth. Speed it up from 10 wpm to 100 wpm and you increase the bandwidth by an order of magnitude. This is a crude explanation and not precisely correct technically, but will suffice for this article. If you want a lot of math to back this up, I'd be glad to oblige. Or you can just trust me and Joe Isuzu.
The same is true in a crude way for voice. Speak slowly, and your signal will take up a certain amount of space. Talk twice as fast and you'll double the bandwidth.
Works for video too. The more information you transmit the wider your signal is. Send a 200 line resolution black and white signal over an ordinary AM link like broadcast television does and you might occupy approximately a megacycle of bandwidth. Double the resolution to 400 lines and your bandwidth doubles.
Why do we care? Well, if you're only transmitting one video signal you may not. But if you're doing more than one, you need to know something about how wide your signal is (ask the manufacturer of your equipment. If he's really the manufacturer he'll know), or see if the information is mentioned in any meaningful way in the spec sheets. For example, on the 900 megacycle band, the frequency assignments are 902 - 928 megacycles. You can't go right up to the edges (remember your signal is a few megacycles wide for video) so you lose some with "guard bands" (a safety factor). The video signals can't be right next to one another because the bandwidth is not an absolute, so you need to allow a certain amount of space between adjacent channels.
By the time you take all this into account (for both legal and operational purposes), only a few video signals can fit simultaneously into the band. The higher in frequency you go the wider the bands (allocations) tend to be and the more signals you can have sharing the same band and behaving like gentlemen.
Several ads for 900 megacycle video transmitters claim to have X number of frequencies available, with the clear implication being the user could have that many simultaneous transmitters operating in the same area. Simple math will show that these manufacturers are not telling the whole story, as there simply isn't enough space in the band to fit in as many channels of video as they claim. Be certain you understand all aspects of frequency management before beginning the design of a wireless video system.
Especially if you are running high resolution (for purposes of this discussion we would consider anything over maybe 250 lines or so as high resolution) or if you're running color or audio, know your bandwidth considerations. A color signal is wider because, of course, you're basically transmitting 3 times the information (red, green and blue images) compared to a simple black and white picture. Audio makes it wider because you need a space for the audio subcarrier (frequently 4.5 megacycles above the video information).
A typical voice signal such as is transmitted on a police-type two way radio might be 10 kilocycles wide (10,000 cycles). A typical video signal may be 4 megacycles (4,000,000 cycles) wide. This means that nearly 400 audio signals can fit in the space occupied by one video signal. This may give you a concept of how wide a video signal is. Because one video signal can displace so many audio signals, video generally is used only on the higher up frequencies where the bands are wider and there is plenty of room.
Another way of looking at it -- 5 video signals take up as much space as *all* the shortwave bands from zero up to 30 megacycles. This includes tens of thousands of shortwave broadcast stations, the entire AM broadcast band, most of the long range military and aeronautical systems, the CB frequencies, all the amateur (ham radio) HF bands, submarine communications, and much more. All these, and much more, fit into the space occupied by only a few video channels. And this is for a video-only signal. Add audio and you take up a lot more space than needed for video only.
Remember this the next time some ad talks about their transmitter being able to operate on a large number of frequencies. Maybe so, but they're not telling you the whole story.
Another factor to consider is if several transmitters on the same band are operating at the same time in the same area, even if they are far enough apart to where they're not overlapping, it is quite difficult for the receiver to separate adjacent channel signals. If the signals are strong you will have quite a trick on your hands. If they are weak the matter is easier to control, but then you have the additional albatross of weak signals to contend with.
The bottom line of all this is you need to work with a manufacturer you can trust (and I mean somebody who genuinely designs and makes this stuff, not an experimenter who repackages inexpensive hobby or consumer equipment and offers it to law enforcement, or a spy store selling video transmitters in the same catalog with long play tape recorders, metal detectors and night vision) who truly understands his product and can advise you on all the factors we have been covering in these articles. Contrary to the beliefs of the hobbyist, this stuff is *not* as simple as buying some black boxes, putting power and an antenna on them and selling them as surveillance systems.
Sooner or later it will have to be said that the majority of the wireless video equipment being offered to law enforcement and security is repackaged amateur (ham radio) equipment. The use of amateur equipment and frequencies for business applications is absolutely illegal. Amateur television (ATV) is a popular area of interest in ham radio, and a number of manufacturers offer inexpensive television transmitting equipment. In almost every case, the hobbyists offering this equipment to law enforcement don't really understand what it is all about, and in all cases claims made for transmit ranges are extremely exaggerated.
A good reference: if range is claimed in miles, substitute yards for miles and you'll be much closer to an accurate figure. In certain cases, by extremely talented hobbyists with a lot of time and money to spend, transmit ranges of many miles are possible.
Possible for enthusiasts does not mean probable for law enforcement. An indicator of hobby equipment is the receiver is tunable, and/or a broadcast television is used with a black box for a receiver. These are not absolutes, merely guidelines. Frequencies of 434 MHz, 439.25 MHz, or various frequencies in the 430, 900 or 1200 megacycle amateur bands are dead giveaways. These frequencies are set aside for licensed hobby operation only, although hundreds of transmitters on these frequencies have been sold to law enforcement for surveillance use.
A third giveaway, especially since these transmitters are illegal to use except for hobby purposes by persons with a valid ham radio license, is a disclaimer in 4 point type that the equipment is offered for "hobby use only", or for "federal agency use only", or "for export only", or that an amateur license "may" be required for legal operation. These thinly disguised escape clauses would be fine if they were honored, but in every case the suppliers using them will sell anything to anyone who has the money.
One supplier mentions in his catalog that a valid ham radio license is needed to legally operate the equipment he sells. This is true, but it destroys his witness when that disclaimer is on the same page as where he brags of all the police agencies and news media that allegedly use his products. In the unlikely event that he is telling the truth about who is using his product, I doubt that entire police departments or television production crews all learned Morse code and communication theory and stood in line to take a test and get a ham license. This same catalog mentions the original application for his transmitters as being used to link video down from model airplanes.
In case you're interested, currently to obtain a ham license requires a test of electronic theory, rules and regulations, and usually Morse Code of varying speeds depending on the class of license you are seeking. Ham radio is a fun hobby (I've been a ham since 1971). Equipment designed for hams is designed to a level of quality and performance an average teenager or retired ham on a fixed income can afford, and is designed for use by persons with a demonstrated knowledge of radio and electronics theory, and a proven interest in playing with electronics as a hobby.
None of this means ham radio equipment is appropriate stuff to use for professional applications. If you are doing it as a toy, get a ham license and use ham equipment. If you're doing it for real, stay away from hobby equipment and, especially, the clowns who sell it into the professional circles. The reputable manufacturer of much of the hobby equipment that is abused and used illegally makes every effort to restrict sales of his products only to licensed hams. But if a licensed ham buys the equipment legally but converts it to illegal non-hobby use, there's nothing that manufacturer can do. By the way, a transmitter he typically sells for $200 is resold to police for five to ten times that price, with absolutely no changes whatever.
There also are a number of suppliers of "kits" of video transmitters, where you assemble them from a bag of parts. Sometimes the "kit" is completely assembled except for one final solder connection. The "kit" suppliers think that selling an unassembled transmitter keeps them out of legal hot water. The FCC doesn't. Avoid kits.
I just learned that in the Los Angeles area two different businesses (presumably security operations) were illegally using amateur video transmitters for surveillance. Their illegal transmissions activated an amateur video repeater, thus broadcasting the video over much of LA to hundreds of hobbyists. The hams being interfered with easily tracked down the illegal transmitters and confronted the operators, who shut them down. But shortly after the hams left they turned them on again.
This time the FCC made the contact, and it took a fine of $10,000 per day to get the attention of the illegal operators. This is *extremely* typical of what very likely will happen if you use amateur stuff for business purposes. The surveillance transmissions were monitored by hundreds of hobbyists. And the clown who sold the illegal transmitters probably sold them as a "covert" system.
You could protect yourself by requiring a statement to be signed with the submission of a bid or prior to placing the order that all wireless video components offered were designed and manufactured for legal law enforcement applications as their primary use, and are not transmitters or receivers intended for amateur use or operating on amateur frequencies. Ask for a statement that the equipment does not require a license for business operation, or if it does request the details of licensing.
If the bidder is not the manufacturer, you should demand the disclosure of the actual manufacturer of the equipment together with the manufacturer's contact information for verification. A good idea would be to require a letter from the manufacturer stating that the dealer is authorized to sell the equipment for law enforcement applications, to be sure you can get the support you will need to get the most use out of the equipment. Require a certification of precisely which frequency(ies) the equipment is using. As there are extremely few genuine manufacturers of wireless video equipment, be suspicious if some spy store or mail order place or "security" firm claims to be the "manufacturer" of the equipment.
Feel free to call me (410-879-4035) if you have questions about a particular product or supplier. Wireless video is a specialty area, and unlikely to be in the realm of a department store supplier offering a wide variety of spy equipment.
As a side issue, it is good to avoid dealing with suppliers who sell countersurveillance equipment as well as surveillance gear. There are very few applications for countersurveillance equipment in the law enforcement circles. Countersurveillance equipment, especially the low end do it yourself stuff, is purchased largely by bad guys trying to stay ahead of law enforcement surveillance operations. A supplier who offers both is telling you he sells to both sides -- do you want to deal with scrotes like this who admit their dedication is to money rather than the law enforcement profession?
Countersurveillance equipment, if the operator is lucky, can sometimes detect things like body wires or other police transmitters. Not cool. Countersurveillance equipment can get cops killed. My advice is not to deal with any firm who sells countersurveillance equipment as well as surveillance equipment. Don't support the bad guys -- there are plenty of suppliers with integrity you can work with. If you need countersurveillance equipment, it also is a specialty area, and the equipment is available directly from the manufacturers. You do not need to purchase it from a spy store.
No more time this issue. In part 4 we will discuss body video transmitters and recorders (possible, but read the article before you buy), updates on new products, and some more guidelines for installing and operating wireless video equipment. Also, I've been getting a good bit of feedback about problems regarding antennas, and we need to work on this area a bit more. Please call me at 410-879-4035 if you have any questions about what's been presented so far, or have suggestions for things to cover in future articles. Feel free also to call for advice if you have a wireless video system that's not working up to snuff, or if you want to ask about a particular product or supplier before you buy.
Best wishes from all of us at SWS for a peaceful, healthy and happy 1995.
Copyright December 1994 by Steve Uhrig, SWS Security. All rights reserved.