Cable TV Engineering Question

[notalkallstatic]

Okay, so I don’t know where to actually post this question, as it really didn’t fit into the criteria for the television board, since this is an engineering question for television, so I decided to post it here, if the mods wish to move it to TV, go ahead…

There are a very few “cable only” local television stations out there in the US. (Meaning that they are not seen OTA, but on cable only.) My question is how do they get their transmission to the cable company? Do they need a special piece of equipment from their servers/automation/switcher to the cable line? Or what? How do they relay their broadcast to the cable company?

(note: I’m not talking about cable networks, like TBS, TNT, USA, etc, but local TV stations that do not broadcast from a transmitter.)

Thanks!

 

[radiorob2.0]

If it is within the cable company's service area it can be fed on the existing system back to the head end utilizing special equipment. Microwave is another option along with a dedicated data line and then there is option of an HD subchannel of a full power signal.

 

[nmoore6676]

Depends on the technology used by the cable operators. In my day, late 80's early 90's, if the originating station was located within the service area we set up a reverse feed (upstream) back to the headend where the signal was demodulated and retransmitted on a downstream channel. Otherwise a microwave could be established back to the headend.

Today most systems have replaced supertrunk and CARS systems with fiber optics so likely you would need to get a fiber link back to a cable system hub and then onto their main headend system. Of course you could use microwave but if you're in a major metro area there is already a lot of clutter and getting a permit might be difficult.

If you aren't doing live programming you could just send recorded programs and pay for someone to play them or find out if they have an automated playback system that could handle it. For non-live you could also use internet transfer to send your stuff to them to be recorded for playback. There is not many places where there is enough bandwidth that you can stream NTSC video, never mind HD so recording would be the only way for that route.

 

[LA_Guy]

Several ways-all expensive....

The first way is using a reverse upstream feed. Most cable systems are designed so frequencies below channel 2 (54 mHz) feed backwards towards the head end. Unfortunately, this is mostly used today for the upload bandwidth used by cable Internet, so its no longer available.

There are a few other ways: First, you can digitize your video and send it via microwave using either the licensed or unlicensed bands. This would work in both the 2.6 gHz and 5 gHz bands (Google: Motorola Canopy). You could also digitize the video and send it via a telco digital connection (the minimum you would probably need is 3 mb/sec). Telco video circuits are also a possibility, but are quite expensive.

Finally, there is the sneakernet possibility, where you locate your server at the cable head end and then bring (physically carry) your programming there. This is the most labor intensive but the cheapest in terms of upfront cost.

 

[fybush]

I worked for one (R News in Rochester NY) for a few years. We had it easy - we were in the same building as the cable company, which owned us, so we just fed right into the headend from our master control on the other side of the building.

 

[CW]

Re: Several ways-all expensive....

The first way is using a reverse upstream feed. Most cable systems are designed so frequencies below channel 2 (54 mHz) feed backwards towards the head end. Unfortunately, this is mostly used today for the upload bandwidth used by cable Internet, so its no longer available.

There are a few other ways: First, you can digitize your video and send it via microwave using either the licensed or unlicensed bands. This would work in both the 2.6 gHz and 5 gHz bands (Google: Motorola Canopy). You could also digitize the video and send it via a telco digital connection (the minimum you would probably need is 3 mb/sec). Telco video circuits are also a possibility, but are quite expensive.

Finally, there is the sneakernet possibility, where you locate your server at the cable head end and then bring (physically carry) your programming there. This is the most labor intensive but the cheapest in terms of upfront cost.

Cable modems use a small chunk right below the CB band (around 26.xx MHz); remember Cable modems are like DSL in that they are mostly Asymmetrical.....the rest of the backhaul bandwidth IS available.....all you need is 6Mhz for the analog NTSC....However, digital microwave or other means is probably better (less prone to outside interference, etc).