Is This Recording Device Scientifically Possible?

A long time back I asked a few questions in a thread about whether or not to get TiVo. I decided against it, for this reason: you cannot watch one program and record another at the same time. I believe the reason was “it violates the laws of physics.”

Sincere there are nights when there are sometimes 3 or even 4 or 5 shows that I want to watch, all on at the same time, and there are only two VCRs in my house, this makes for some tough TV viewing decisions.

Anyway, I’m imagining something akin to a DVR³, where an internal device “splits” the signal coming from your cable wire into, say, ten different signals. (I know that splitting a cable signal is possible; I have one cable wire coming into my house, split into two, and running to two TVs). Anyway, each signal goes to its own hard drive. Then, you have a wire running to your TV.

So, you turn your TV to your DVR interface, and you have an interface that looks like this:

Drive 1: Record channel 3 7PM - 9PM Monday 9/27
Drive 2: Record channel 13 7PM - 830PM Monday 9/27
Drive 3: Record channel 24 7PM - 730PM Monday 9/27

…and so on.

So I ask, is this scientifically possible?

I think your premesis is wrong. First off, it’s plently possibly to watch one show and record another with a TiVo. You have three options: 1) while one show is recording, you can watch another that has already been recorded. 2) (This only works if the wiring is done correctly) While one show is recording on the TiVo, you change the channel directly on the TV. 3) Put the TiVo in standby. It will still record whatever it needs to, but any RF signal that comes in, goes out unaltered (this only works if you use the RF in/RF out for the signal). I’m not sure why it 'violates the laws of physics."

Your idea is compleatly 100% no question possible. You may need an amplifier to ramp up the signal before making that many splits. But your idea is no different then having 10 VCR’s or 10 TiVos, it’s just that they would all be inside one box (one really really hot box, but one box none the less.

It certainly is, you just need an additional tuner circuit for every channel you want to record simultaneously. You also need enough computer bandwidth to handle the multiple signals. Your standard TiVo has only one tuner (or, for a digital cable system, one input from the cable box.) The DirecTivo boxes have two tuners and can, in fact, record two programs simultaneously.

Note that you can watch a previously recorded program and record one at the same time.

Also, don’t forget, you can catch 3 shows at once with your current setup (2 VCRs). It’s just a matter of using the TV/VCR button. Are the two VCR’s on one TV or is each one on it’s own. Either way, all you have to do is record one channel on each VCR and then physically watch the third show.

Trouble is, two nights per week I’m not at home, so I can’t watch anything. So that means that if there are 3 shows, 2 get recorded and one I miss entirely.

I had to miss the season finale of Amish in the City for just this reason.

Yes, but I can’t watch the CBS feed and record the NBC feed, which is what I’d need to do (Fear Factor on NBC and Still Standing/Listen Up on CBS are both on Mondays at 7PM Central).

You can do it with just a VCR. Get the VCR set to NBC (for example) and set up the recording. The display you should be getting is the one from the VCR. Now, use the TV/VCR button, which’ll switch control to the TV without moving the VCR setting. Voila! And you’ve been able to do this for years. I’ve done it on a really old (I’d say mid-to-late 80s) Magnavox VCR. Of course, it was a pretty high-end VCR for the time, but still, it’s been possible for a long time.

Sure you can, you have two options for doing this. 1) Run Coax from wall, to tivo, then from TiVo to TV. Set it to record one show, put the TiVo in standby and change the channel on the TV to the other station. 2)Coax from wall to splitter, one side to TiVo one side to TV, then composite or SVideo to TV. Then you can record on Tivo (and watch TiVo stuff with TV set to ‘input’ and watch TV normally as if there were no TiVo there at all. Hopefully this all makes sense.

I used to fix VCRs as a teenager (when the cost, and my income, made them worth fixing), so I always had enough VCRs to record anything I wanted.

You might need an amplifier for an antenna signal, but a cable signal can often be split 4-5 ways into modern VCRs with little picture degradation. Tuners today are pretty sensitive. Use a single five-way splitter, because every single connection on the signal path causes significant signal loss. Also, use cables with screw-on F-connectors instead of the slide-ons often packaged with VCRs.

You could, in principle, “daisy chain” 2-3 VCRs in series between the source and the TV (i.e. connect the output of one into the input of the next), but sooner or later you’re going to forget to set all the VCRs to “TV” (the “TV/VCR” switch could more accurately be called “Tuner output/direct signal (bypass)” but that would confuse more people than it would help.

I’d recommend a 5-way splitter on the signal, splitting it to the VCRs in parallel, and a manual pushbutton 5-way switchbox between the outputs of the VCRs and the TV. you need a video amplifier, place it before the splitter. For casual viewing you can use one good VCR for playback, and several cheap $30-40 for recording additional channels. The TiVo can be treated as a VCR in this case.

This may sound extravagant, but total cost could be under $30 for cables, splitter and switch plus $30-40 per VCR. If you want an amp, I’d recommend a good distribution amp with a built-in splitter to 4-5 outputs. They can run as little as $30-$50 on eBay. (I’m afraid you’ll have to read up on the brands; neither cost nor brand familiarity are good guides. The familiar consumer brand names generally market terrible and overpriced amps for about $30 while the best and most cost-effective brands will seem like no-names to consumers because they don’t market to, and don’t pretty up their packaging and cases for, the end consumer.)

Personally, I think a $15 cable crimper, a pack of spare F-connectors, and 50’ of quad shielded RG-6 coax are essentials for any household, but I’m weird. Making and repairing your own cables is vastly better than buying/replacing commercial cables. It’s really easy, and you’ll get better cables than most consumer cables that people use. (there are some great prosumer cables out there, but they can be pricey: a single cable can cost more than the crimper, connectors and raw cable needed to make 10 cables at home, and your wiring will be far neater if you make you cables to length, instead of using 6’ cables when you only need 1’

A brief word on dB: this is the unit used to measure signal amplification or attenuation. Though the subject is more complicated than even many electronics technicians realize (because the formal definitions dB in signal voltage, power, etc. are NOT straightforward, and consumer spec sheets rarely tell you which standard is being used), I can crudely say this: the decibel is a logarithmic unit. a 10 dB gain or lost is a tenfold increase or decrease. a 3dB gain or loss is a doubling or halving of the signal. (This is not always strictly true - e.g. with video signal voltage, 10 dB is more like a factor of 40- but it gives you a general idea of how dB works: adding a few dB cuts your signal strength dramatically. When you add or subtract dB, you’re adding/subtracting an exponent!)

But be careful. You might just find yourself with a hobby that’s much more useful and engaging than watching TV.

I don’t have a TiVo, but I do have a DVR from my cable company. It has two tuners, so I can easily record two things at the same time. I can even watch a previously recorded show while recording two other things.

Here are my options:

  1. Record a show while watching it (or while it’s in standby, so I’m not watchin anything).
  2. Record a show while watching something else.
  3. Record two things at the same time while watching nothing, or something previously recorded.

Since my TV has a tuner that’s not really being used (only to recieve the Ch. 3 output of the DVR), I could probably set up a switcher of some sort to send coax to the DVR and record two things while watching a third thing on the TV. I don’t care to do that, but it’s certainly possible. I’d have to subsequently rewire the damned thing to get the DVR back into the TV. Or I could wire the thing up with one switch and one splitter, and be able to switch the DVR in or out of the loop.

Come to think of it, I may have to make this work.