|
Here's another interesting chapter in the history of the Beta format, the time-lapse recorders. Used primarily for surveillance, record keeping and intelligence work, these were not your typical VCR. As their name implies the video they recorded was time compressed. In addition to recording real time video their main purpose was to record individual frames spaced out over preselected time intervals, usually 24, 48, 60, 96 or 180 hours. When the tapes were played back a large span of time could be reviewed in a matter of minutes. The video source would typically be a single camera, a video array system or a monitoring station. (Video arrays and monitoring stations either used split screen or cycled through different cameras in a rotational pattern.) The unit pictured above, the 2500, was the last and most sophisticated model produced by Navco Security Systems. They also made two earlier models, the 2412 and the 2412 SB. You can get a pretty good feel for the size of the unit above if you compare the cassette door to the top and front of the VCR. They were big, and heavy too. Navco designed the specialized electronics and time-lapse circuitry. The chassis manufacturing and basic video electronics was contracted from NEC, who purchased some sub-assemblies from Sony. Click on the picture and you will see the unit from a different angle. The first entry, the 2412, featured several innovated functions. Including a variable speed stepping capstan capable of recording frames from several per second to several per hour. The 2412 SB was same machine but incorporated improved SuperBeta circuitry for a sharper picture. The last model, the 2500, featured improved beltless tape handling with a super controlled speed system, this offered more time interval options and better tape travel. It also featured Super High Band recording (switchable) with digital video recall. Clicking on the picture shows a close up of the function buttons and switches on the front panel of the model 2500. The Field advance buttons are not found on typical Betas, they provide movement of the picture from frame to frame, backwards and forwards. Click the picture again and the switch panel array appears. Notice the head hours clock (looks like a fuse) intended to notify a technician when a service interval was needed. The next click is of the back of the VCR. Notice the flat cable connector that allows for external control and the large heat sink. These units were built for durability as well as flexibility. It was routine for these units to sit in a secluded location steadily recording frame after frame of images over many hours in banks, markets, stores, automated teller machines, hospitals, plants; the list is long and extensive. Many units were remotely controlled by a cable system. If a incident occurred the tape(s) could be withdrawn, examined and evaluated. A set of tapes typically were rotated over a predetermined weekly interval. To aid in locating selected scenes various types of time stamp and frame identification methods were incorporated into the units software, a time and date legend is what was usually recorded and inserted in the video at all times. Click on the picture and you can see that the tape path was shielded to prevent stray magnetic fields from disturbing the recording image. Also, special formula tape was used that could withstand the repeated strikes of the video heads as the tape moved slowly around the video drum (the heads were spinning during all recording time). To reduce friction and prolong head life a small ceramic heater produced a slight convection of air to help lift the tape away from head surface ever so slightly. Click again and you can see the drum area inside the unit. Notice the designation "NEC" on the top of the green video disk rotor board (center of the drum). This identifies that manufacturer of the drum assembly. The next, and the last picture of the series, shows the electronics and mechanics located in the bottom of the machine. The reel motors, bottom center, came from Sony and were of the direct drive type found in many of their high end models. The drum and capstan motors near the top incorporated specialized hardware and electronics used to maintain the delicate, yet firm balance of tape tension and reverse braking during the stepping actions. Something not found in a typical Beta VCR. A couple more things of interest. These time-lapse Betas were not able to play back conventional recordings because they lacked the standard playback speeds. And they only recorded a single field of the picture, or to say it another way, each head recorded an independent scene and every one of those was made up of the individual picture. Each picture was not as sharp as a recording using both scans, but is was good enough for a device that cover so much time. Both video heads were the same on each side, unlike home video recorders where each side is different and slanted the opposite way to lessen crosstalk (see azimuth recording). Sound quality was not much of a consideration and even though audio playback was possible, it wasn't practical since the sound would be greatly compressed or mostly garbled. Today, all the time-lapse units are VHS but at one time this Beta was the top of the line and a stellar performer. To go back to your question click here.
|