THE FORMAT WAR

UNDERSTANDING BETAMAX

In this section we are going to take a closer look at Betamax and the magic cassette (PLATE 1). Before Betamax video recording was reserved for TV stations, recording studios and other professional services. The first Sony recorders, the LV-1901A and SL-7200A, changed all that. They gave the public the power to record and playback broadcast TV. The shackles of network programming were finally thrown away and the audience could pick when they wanted to watch a program. As we have seen in the previous sections making it practical and economical took some time and some new innovations. Because it was so different from audio recording there was a technical learning curve for this new system. Sony tackled this problem by educating their distributors on servicing (and selling) Betamax. It was an exciting time and they threw the full force of their technological expertise into promoting their new product. For their distributor/service centers there were seminars, training sessions and teaching materials. This process was upgraded as new features were added and Betamax became better and smarter. Please click on the picture (PLATE 2). This is how Betamax service personnel kept current about the VCR. Sony produced large amounts of instruction manuals and training tapes. Early on they understood that to keep the Beta format reliable and current regular service updates were going to required. As Betamax matured they decided to take on full responsibility for all of their product service and repair. This gave them a tighter hold on quality control and added revenue. The Independent service centers began to lose interest and gave up on factory support. Many saw this as a slap in the face. They felt it was sending a message that Sony no longer felt they were capable of working on their products (especially betamax). Suffice to say this didn't win them any Betamax supporters from within the general repair industry. It also didn't help Beta that VHS was easier to work on, required less professional skill and the manufacturers didn't care who worked on them (and it was starting to outsell Beta by then anyway). The hard reality was that this made many technicians began to refuse to work on Betamax altogether. This denial-of-service attitude from the repair sector didn't help promote the Beta format, even if it was far superior to VHS. I doubt that you, the reader, are preparing to work on a Betamax. But you might be interested in the nuts and bolts of how sound and video is stored on video tape (and then played back). So in this section we are going to take the information contained in those training manuals and make it easy to understand. Trust me. It'll be simple and fun, so let's get started. Click on the picture (PLATE 3).

If you started at the beginning of this "Legendary Betamax" presentation (with the THE BASICS) you now how conversion is needed for recording. Here is a quick refresher. Examine the picture above. In the center we see the human brain. In the left corner is an ear and in the right an eye. Sight and sound, vision and hearing. Both of the receiving organs, the eye and ear, are designed by nature to take physical forces and convert them into electrical signals. As you know the brain is an electrical processor so everything depends on moving electrons over wires (nerves). In the ear the vibrations from sounds hit the drum and cause it to move. This mechanical movement is passed along to a special organ that has tiny hairs inside with nerves attached to each one. When they wiggle this sends an electrical signal to the brain that processes it and interprets it as sound. The eye is very similar. A photon particle of light enters it and strikes a special receptor in the back. This generates an electrical pulse, which goes to the brain that turns it into an image. So we are constantly converting information around us into electrical information that our brains can process. Conversion isn't new and without it most things simply wouldn't work.
Click the picture (PLATE 4). Here are some common ways conversion is used for recording and storing information. The one we are most interested in is the video tape that uses magnetic storage. If you waved a Beta cassette in front of your TV all that would happen is your arm would get tired. The tape itself would not have any effect on the TV nor would it be affected. To play or make a recording requires a device that changes the video and sound into something the tape is capable of storing. Playing it back in this device simply reverses the process. The Betamax is just such an instrument.

Click the picture (PLATE 5). Here is the video and sound conversion process in basic terms. Fear not, understanding it and the Betamax is easy, I assure you. Look at the illustration above. It has a picture of a common test pattern in the upper left. I have put the words "IMAGE DOWN CONVERSION" over it. Under the screen shot in white letters is the word RECORDING. Don't be concerned about the list of terms next to that screen for now. These are just the parts to this painless recording process. For this discussion that test pattern is what is going to be converted (down) and RECORDED to video tape in the Beta videocassette on the upper right. From here it can be played back and is converted (up) in the Betamax to produce a video signal from the copy. The result is the same video test pattern shown in the lower right taken from the recorded cassette. I have worded this one "IMAGE UP CONVERSION". The beauty of having this copy is that it can be played over and over again, and the whole recording process itself is repeatable.

Now look at the list of terms in black letters beside the left test pattern and the left cassette. First in both of the lists is AUDIO RECORDED and AUDIO PLAYBACK. Click on the picture (PLATE 6). Audio recording (highlighted in white) with a Betamax is very like the standard reel-to-reel audio, audio cassette and disk methods. It is laid down using a separate track on the tape reserved just for it. Playing it back just involves rewinding the tape and picking up the signal, it plays no part in video recording. There is are several exceptions to this like Betahi-fi but this doesn't apply to this discussion. Audio is simple but basic to the magnetic recording process so it will be covered first. Click the picture (PLATE 7). Look at this simple diagram of a public address system. Here is how sound is sent over wires from a sound source to a sound output. On the upper left in the picture is what is simply a mechanical ear, or microphone. A mechanical drawing of a microphone is shown below it lower left. It uses a flexible diaphragm made of a thin material, usually shaped like a disk as the driver when vibrations strike it. The sound hitting it is represented as radiating blue bars. Attached to the diaphragm is a coil of wire that is free to move back and forth whenever the diaphragm flexes. When sound vibrations bounce against the diaphragm the coil moves. More when the sound is loud, less when it is soft. This moving coil generates a small amount of electricity when it moves in relation to the stationary permanent magnet. It converts the mechanical movement into an electrical signal just like the human ear. The electricity generated is very weak, but we can make it stronger by using an amplifier. It is shown in the center of the picture. Now we can send the amplified (stronger) signal to another device that will reproduce the sound, called a speaker, shown on the upper right. It is very much like the microphone but in reverse. It has a moveable diaphragm with a coil of wire attached to it. Exciting a coil of wire wound around a permanent magnet with electricity will generate magnetism. Since the coil of wire can float the it will make the diaphragm move back and forth and generate sound by moving the molecules in the air and duplicate the input coming from the microphone. This sound is represented coming from the speaker in the upper right corner by ratting blue bars. A mechanical drawing is shown below. So what we end up with is sound in, amplified, and stronger sound coming out. Let's do one more thing to this sound. Let's find a way to keep it so we can repeat it over and over again. To do this we have to convert or change it once more so it can be recorded using a storage method.

Click the picture (PLATE 8). Iron and several other metals have the unique property of holding magnetism. You are familiar with the common bar magnet that has its north and south polls. Magnetism of the particles used in recording behave the same way but we are going to ignore the polarity and concern ourselves just with the pattern and strength of the information the particles can store. The strength and pattern can be varied directly by the inputted magnetic force. Stay with me now because once you get through this audio process you'll have this whole recording thing whipped. Now let's store that sound on something convenient like that ribbon of magnetic tape shown here. It has ultra fine microscopic iron particles attached to it using a binder layer. Now that same electricity that moves the coil in the speaker can also be used to create a magnetic field that will excite those particles. Once magnetized in this way they will remain imprinted unless something comes along to excite (change) them again. But as long as that doesn't happen they be read or interpreted by a passive pick up coil. In the picture above we see two audio heads (electromagnets greatly enlarged). When sound (electrically amplified) is passed through the coil of wire wound around the recording head on the left it creates a strong magnetic force across a gap called a field. The gap is represented here by the white radiating circles. During recording when the strip of tape travels along at a regulated speed next to this field the particles on the tape will become magnetized in a pattern. It is now a converted duplication of the electrical force that was energized the field. The sound has been stored as aligned iron particles (little magnets) with a varying arrangement and strength on the tape. To get the sound back from the tape is just as easy. Just rewind it and send it by the same electromagnet again, shown now on the right. This time it is passive and the magnetized particles will generate a field in the electromagnet that matches the recording. Or to say it another way, it will be used to pick up the stored magnetic pattern on the tape. Amplify this pattern and you get your sound back. This is exactly how the audio is recorded and played back on the audio track of a video recorder. And guess what? The video is done almost the same way so it will be smooth sailing from here on out. Now on to the video recording.

Click the picture (PLATE 9). This picture shows two of the most common ways to place a video recording on magnetic tape. Unlike audio recording video requires a lot of space because the signal is so large and the need to excite the particles at a high frequent is necessary. 50,000 cycles per second is good enough for audio and most tapes can handle this. Video requires up to 8,000,000 cycles. That is a big requirement. It isn't practical to try to run tape at a speed to store enough information for video using a stationary recording head. It can be done but the heads wear out quickly from heat and the tape doesn't last very long. The solution to the this problem is to spin the head (called scanning) rather than have it remain stationary. By doing this the big magnetic required imprint can be stored while using a relatively slow tape speed. Two scanning methods are shown above. The top one is called Quadruplex and it was the first practical and successful videotape format. It was primarily used by professionals because it used a two inch tape and required a lot of floor space to house the equipment. Below it is the longitudinal system employed in commercial and home video recording. This tape is only a half inch wide and much easier to handle. There were earlier versions of this that used three quarter inch tape but the method was the same.

Click the picture (PLATE 10). No we are back to the conversion illustration. Look at the list next to the recording of the test pattern in the upper left. Highlighted now is SEPARATION OF CHROMA © AND LUMINANCE (Y). To record video in color requires these to elements to be recorded differently. Why is it necessary to do this? A conventional NTSC color broadcast signal contain two wave elements. One makes the original black and white (monochrome) TV picture, it is called luminance. Technical term for it is the "Y" component. The other is called chrominance, or chroma for short. Technical term is the "C" component. For years all programs and TV were in black and white. When a color system was finally agreed upon it was one that piggybacks a separate signal along with the black and white one. This system still works today and it is called analog broadcasting. Keep in mind this not how todays digital broadcasting is done. The method here is the original system, the kind a Betamax uses and so does an older TV we used for years. When the analog signal (or wave) comes from the TV station to the antenna, or from a cable (or from a Betamax) to the television monitor it has to know whether to produce a black and white or color picture. Why does it need to do this? There is only so much real estate available in each channel. If your area is broadcasting on channel 3 and you get a little aggressive with your signal strength you might bleed over into 2 or 4. Because of the massive of amount of power it takes to send a TV signal this does happen. That is why the channels aren't right together and why there is a switch on a Betamax to choose between 3 or 4, (to choose whichever channel is not active in your area). So you have to keep the broadcast signal within a certain area and color uses up a little space and this requires that the TV adjust its screen resolution. The black and white (luminance Y) picture, when it owns the screen is slightly sharper than the color picture. It has more resolution. Color lowers this slightly but because of all the pretty colors we live with. These two signals (Y and C) are handled separately during recording and playback. Click the picture (PLATE 11). The Betamax must also separate and convert the two signal elements into something it can record. If you go down to the cassette on the bottom left you see highlighted in white that the Y and C are mixed again to send the picture to the TV. That simply means that the two signals will be combined again when played back so the TV can deal with it just like it was coming from the TV station. The Betamax is acting like the TV stations place when it sends the picture and audio to your monitor or television. So simply put Y and C are different. They must be converted to a magnetic code so it all can be spread across a tape as it goes by the spinning video head. Just like with the TV broadcast channel there is only so much space of the tape as the head spins around. Within this path the VCR must write all the necessary information to construct and duplicate signal. So in this path space is placed a converted combination of the two in a magnetic form. As the heads buzzes over the tape during recording it lays down one of these compiled signals for each frame of video. The frame rate is 30 per second and it is very like a movie. It is single frames that your brain constructs into motion. When the heads goes by that recorded signal during playback it sends the information to the circuits in the VCR that change it back into the signal the TV understands. In the picture above these methods are highlighter in white. To keep the picture regular and running at the 30 frames per second the beginning of each frame must be started. To do this the TV signal incorporates trigger and it is simple a short burst of that precedes the actual picture that tells the VCR or TV to begin filling in the picture. It is called the sync signal. Click the picture (PLATE 12). It comes from the TV station, is synchronized with the 60 cycles coming from the AC outlet and keeps everything running at the same rate. To record it the VCR has to recognize it and clamp onto it and record it. In playback it sends it to the monitor (TV) using the same 60 cycles as a reference. But that is not enough to keep the Betamax regulated so it works the same over time on every recorder. Click the picture. (PLATE 13). When recording the Betamax is using s spinning disk with heads on it to save that signal and it must be a regulated. The picture sync is within the recorded signal but the start of the track being recorded and played back is control by special separate signal altogether. At the start of each rotation of the recording head the VCR places a pulse along the bottom edge of the tape. Called the control track it tell the VCR during playback when to begin reading each recorded signal (which also has the sync for the TV). The control track is 30 pulses per second and it matches the picture frame rate and moves everything along. When the tracking knob is moved to accommodate minor differences in recorded tapes the control track location on the tape is being moved electronically slightly faster and slower. This change can be heard in the audio of a monaural VCR. This changes the picture slightly and clears up any mismatches in tapes. When all this comes together it is sent to the TV. Click the picture (PLATE 14). To do this it converts it to an RF signal and sends it over channel 3 or 4 along with the audio to be accepted by the TV. You can eliminate the this last step if the audio and video in and out jacks are being use. Click the picture one more time (PLATE 15). Here is how all this looks on the video tape. Audio recorder at the top and the control track along the bottom. Video is at an angle because the tape is moving when recorded. Two video tracks are used and they are named A and B. The head gaps are slanted differently by seven degrees to help prevent cross talk (magnetic noise) from affecting each other. This method is called azimuth recording and it was developed for Betamax. Click for the last picture. Nothing to see here but look below this copy and a diagram is shown of how one line of analog video is represented in a technical graph:

This ends the discussion on how Betamax recording works. For more on the analog video recording system check out this Wikipedia link by clicking here. Below the line are some internal links to more information. (You will be able to return to this panel.) To go to the next section that highlights the "INNOVATIVE BETAMAX" click here.

°	How does the Betamovie, with a video drum half the size of a standard Beta, manage to remain compatible? To find out click here.
°	Would you like to examine how electrical heads are able to operate when they are mounted on a rotating or spinning disk? If so, click here.
°	Maybe your asking yourself now what is the big deal about the video signal needing such a large recording area. What exactly is this frequency thing and why does it have to be so high or so big? Understanding radio and television signals (electromagnetic waves) seems like a perplexing question but it's really easy, so if you would like to know more click here.
°	Would you like to examine how electricity and magnetism work together to make recording possible. This link leaves this section and takes you back to the very first panel on the basics of electricity.) To go to THE BASICS, click here.

If you would you like to skip this section altogether and go forward on to the next subject panel "Innovative Betamax" click here.