Ok, we also have 22 and 23. Analog.

Isn't 23 an analog channel (KMWB-DT) a WB affiliate and channel 22 the digital channel for KMWB-DT? According to the below link they are not both analog.

[Link: visi.com]

The point that I was previously making was that prior to digital broadcasts there could not be adjacent channels broadcasting in nearby markets.

The only exception was channels 4 and 5 because the 4 mhz spacing between them. Also, channels 6 and 7, and 13 and 14 are not adjacent because they divide the high and low band VHF (6&7), and VHF and UHF(13&14) bands.

There are many UHF stations that broadcast their digital signals on a channel that is one lower or higher then their analog broadcast. They do this so that they can use only one transmitting antenna to broadcast both analog and digital. If there is a separation between channels then they must use two transmitting antennas for the analog and digital channels.

Hope this helps,

Dave T

Thanks for the info.

I thought we had a new (3rd) PBS channel at 22. Must be dreaming, or it went elsewhere.

There has been a general increase in the number of adjacent channels on UHF. I don't know if the analog TV tuners are better, or if they somehow improved the transmitters, but think about it -- Cable TV has had adjacent channels since the beginning, so there has to have been equipment that can tune them in without interference. Adjacent channels have been totally forbidden, theoretically because of interference, since the early days of TV. This is such a widespread idea and policy that "adjacent channel" and "adjacent channel interference" are not just good descriptions, they are technical terms used in the discussion of how to keep TV stations from interfering with each other. Note that FM stations, which are spaced 200 kHz apart, still are not placed adjacent to one another, so they are at least 0.4 mHz apart in any one market.

Yes, 4 and 5 exist in many markets, because they are not, strictly speaking, adjacent. As pointed out, there is more frequency separation between them than the average two channels. 6 and 7 are also not adjacent, but we don't have a 6 and 7 here in Los Angeles, and I wonder if they ever existed anywhere in the old days when VHF was king.

So, doing a rough count of channels and taking adjacents into account, the old system might have given a market 7 VHF and 25 UHF stations, while the new system would give us 7 VHF and 38 UHF.

The tuners for digital broadcasts are better than the old analog tuners. Analog tuners are capable of functioning for adjacent channels only if signal levels of the adjacent channels are balanced or very similar. That is why there are adjacent channels for CATV systems. All the signal levels are balanced for the channels.

But for broadcasts channels that are received with an antenna the signal levels for the channels will vary depending on many factors such as the distance from the transmitters, the strength of the transmitted. Digital tuners are not effected like analog tuners. Even though channel 35 can be very high it will still be able to tune in channel 34 or 36 even if it is considerably lower.

Hope this helps,

Dave T

All these answers raise one more question of mine and that is why couldn't Dish or direct tv in the past have downloaded all channels to one receiver and converted them to analog so that one could view all channels throughout the house on existing coax?

The cable companies have done it for years.

Is it because you would need a separate SAT receiver for each channel before combining them into one analog coax cable?

I know it can be done because that is the way it is done with Analog cable.

The better half asked me this question and I did not have a good answer.

-Don B

Because the channels are on different transponders on the satellites. The signal doesn't all come from one source. The box is needed to switch between transponders. And the multiswitch is needed for multiple sat boxes to get along on the same dish.

There have been some TVs that had built-in sat boxes, which is essentially what you want. Not sure why it didn't catch on, probably DirecTV's fault.

"I know it can be done because that is the way it is done with Analog cable."

Digital sattelite isn't analog cable.

You'd need a tuner fro each channel, and a modulator for each.

The reason it works with analog cable is that the signals on the cable are compatible with standard TV tuners.

I realise that SAT is digital and that analog Cable is NTSC compatible.

None of this explains to me why the signal sources that Time Warner cable gets from OTA antennas, download from satellite which could be on different transponders, or land line links from affiliates are combined at the Time Warner Cable facility and than are sent along on one coax line where paying consumers can receive the NTSC analog signal on any NTSC tuner equipted TV in their house.

Bottom line is how does Time Warner cable merge all these varied signal sources into one coax line ?

Is it just a matter of dollars and it costs a lot of money to combine all these signals and put them out on analog NTSC coax?

-Don B

The answer to your question is Time Warner has a receiver for each channel and a modulator to convert the video and audio from that receiver to an RF channel that your TV set can receive. After the modulators they use signal combiners to combine the signal and then send it to a launch amplifier.

The signals sent by DirecTV and Dish are not modulated RF channels. That is why you need a receiver to convert the satellite signals and NTSC signal.

Hope this helps.

Dave T.

Dave T,

Thanks and it does.

The other day I stumbled across what I would guess is the local "antenna farm" for the alternative cable in our development. I am talking the Non-Time Warner cable. I think it was the only choice years ago considering the remoteness of the developement back when it was first built. Plus I think the covenant at the time did not allow antennas or dishes on the houses.

I was shocked at the number of dishes of multiple sizes and OTA antennas that were lying around - some in working order and some tilted at odd angles toward the ground and obviously not in working order.

This was my first revelation that a cable company does a lot more than just resend a NTSC signal throughout the neighborhood from a single large dishdown link.

Of course I realise that now a cable company like Time Warner also does Road Runner and Digital cable and voice over.

-Don B