Let's get back to the relationship between reel-to-reel and modern digital recording. The first step to recording a video image is to understand that each image takes up space. Think about one image as one gallon of water. How big of a container do you need to hold it? One quart? One gallon? Ten gallons? For a half-inch video tape on a reel, let's consider it to be a three quart jar. Unfortunately, we have to fit the gallon image onto the tape. So, we do a couple of things. First, we dehydrate the gallon a bit (we lose some resolution). Second, we put the recorded image on a slant across the tape so that instead of it being a half-inch wide, it's more like 2/3-inch wide. Next, we restrict the number of images per second (the final portion of our water volume) to 25 or 30. Bring this concept forward to digital storage and the same concepts hold true. We only have so much room to store our water. So the first point of dehydration is to restrict the number of images that we store per camera, per second. This "dehydration" will remain so as long as the cost of a 10-gallon jug far exceeds the cost of the 1-gallon jug.
I know some of this may seem pretty basic (and pretty historic), but it's a good overall start for our trek of going digital with video storage. I will see you in about three weeks with a very detailed column on digital storage systems. Who knows, there might even be room enough for a frank discussion on compression factors. Until then, I remain faithfully in your service.
About the Author: Richard R. "Charlie" Pierce has been an active member of the security industry since 1974. He is the founder and past president of LRC Electronics Company, a full service warranty/non-warranty repair center for CCTV equipment. In 1985, Charlie founded LeapFrog Training & Consulting (Formally LTC Training Center), a full service training center specializing in live seminars, video-format certification training programs, plain language technical manuals and educational support on CCTV. He has also recently become the director of integrated security technologies for IPC International, Corp. He is an active member of ASIS, ALAS, CANASA, NBFAA, NAAA and SIA. He is the recipient of numerous security industry awards, and is a regular contributor to Security Technology & Design magazine. Look for his columns to also appear regularly via SecurityInfoWatch.com and this website's e-newsletters. He can be contacted via email at email@example.com.