OTA NETWORK Status: GlobalTV

[stampeder]

Originally Posted by cm3020prob

In the case of Montreal, CBS (22) is next to CBC (21), NBC (14) is next to Global (15), which I get no reception during the day. Fox (43) operates at a lower power than CBS and NBC so it can be difficult sometimes, ABC (13) is next to CTV (12) but it's at very low power, as in, forget it. But I get PBS-57 (38) and PBS-33 (32) without any problem as they have no co-adjacent channel problem.

Originally Posted by cm3020prob

If the american RF signal is far but strong enough, placing their transmitter on a RF channel next to the american one will make it difficult to receive.

Assuming that they are both DTV stations, the ATSC standard has dramatically reduced ACI (Adjacent Channel Interference) from the bad old days. The best proof of this I can think of is in Seattle where KOMO on 38 and KIRO on 39 have side-by-side towers pumping out about a megawatt each.

In your case though other interference sources may have an additive effect on the distant U.S. stations. Your own Montreal reception problems with adjacent channels has almost everything to do with your location in relation to those U.S. stations, so we can carry this on in your local reception thread as required but not in this present thread.

As for Shaw's reasoning for its choice of potential channels, I agree with the assessments here.

[FunkyTown]

I believe it's true that there's less interference, but these US stations are miles away. It seems it would only take a tiny amount of interference to blow them away.

[roger1818]

Stampeder, in your Seattle example, both stations are broadcast from a similar location with a similar power so it isn't comparable. With ATSC, adjacent channel interference becomes a problem when there is a large difference in received power. Optimally the frequency plan should be overhauled to have all the stations from the same or nearby towers use sequential channels with similar ERPs.

[OTA-London]

In London, at one time we had 18 TVO, 19 SUNTV, and 20 CJMT, all off the same tower, and no interference with any of them. Now 19, is off but still no problems at all.

[cm3020prob]

The problem I was trying to explain was this:

Graphic:
CH14, 650 kW ======> 82 miles ======> home <== 5 miles == CH15, 8 kW

Textual:
CH 14 (NBC) is 82 miles away (130 km) from your home.
CH 15 (Global) is 5 miles away (8 km) from your home.

When CH 15 is not broadcasting (overnight maintenance), you get CH 14 at 50%. Using an amplifier would get a preferable a 75% reception.
Unfortunately, when CH 15 (local) is broadcasting, CH 14 (distant) drops down to 25%. An amplifier will just boost CH 15, that you already receive at 95%, and spread onto CH 14, which drops the signal to 5%.

For Ottawa, you guys told me that it's difficult but not impossible to receive WNPI (PBS) which broadcasts on CH 23 (40 kW), but unfortunately, CHCH-DT-1 broadcasts on CH 22. WNYF-LD (Fox) is apparently using the same tower using CH 18 (4 kW), but CITY-DT-3 broadcasts on CH 17.

I admit, Global using CH 14 in Ottawa might be a long shot but looking at the contour, it's awfull close from Montreal, and it will be next to impossible for west-islanders to receive WPTZ anymore. Even worse when looking at the TVfool map, where the contour almost overlaps, but reception is still medium and possible. Eventho it's legal, it's not welcomed.

[tvlurker]

I don't see how 14 from Ottawa will interfere with anyone's reception of WPTZ on the island of Montreal. Aside from the fact that that TVFool does not support your theory (WPTZ receive level on the West Island is WAY more than 15 dB higher than ANY Ottawa UHF station), don't forget that until last August 31, channel 14 used to be used for 1.5 MW analog station in Herberts Corners, which is much closer to the West Island than Global's proposed new station at Camp Fortune. I don't believe there were any issues at that time with channel 14 interfering.

[roger1818]

I totally agree with tvluker. That is what I have been trying to say. On top of that, any antenna in Montreal pointed towards WPTZ will have much less gain on signals from Ottawa (how much depends on the angle and the antenna).

[majortom]

Originally Posted by tvlurker

I lost PSIP EPG data yesterday on 6.1 Ottawa, but strangely enough not on 41.2 (the SD version) Ottawa.

I noticed yesterday Global Toronto's EPG was back to normal. May have been fixed earlier in the week (?)

[cm3020prob]

Originally Posted by tvlurker

I don't see how 14 from Ottawa will interfere with anyone's reception of WPTZ on the island of Montreal. Aside from the fact that that TVFool does not support your theory

Beyond the island of Montreal, way west... Salaberry-de-Valleyfield, Saint-Polycarpe, Sainte-Justine-Station. Using TVFool's "Callsign Lookup", you can see that reception is medium in that area, so it's possible, then goes purple (very weak) from the Quebec/Ontario border.
Next, open 2012-0465-1, Estimated Contours PDF. The red contour almost reaches the Ontario/Quebec border. Since we know that signals go beyond contours, depending on terrain, and that Global MAY want to boost CIII-DT-6's power someday for more ATSC-M/H coverage, it will create interference, someday, somehow. But as of now, with proposed power, it's borderline. Global should take another channel number that will allow them to expand.

[roger1818]

Originally Posted by cm3020prob

Is it possible to receive WUTV Buffalo or WPTZ from Ottawa? Maybe, in tropo conditions. Moving CIII-DT-6 Ottawa to RF 14 will just make it impossible for Ottawa residents,

Originally Posted by cm3020prob

I admit, Global using CH 14 in Ottawa might be a long shot but looking at the contour, it's awfull close from Montreal, and it will be next to impossible for west-islanders to receive WPTZ anymore.

Originally Posted by cm3020prob

Beyond the island of Montreal, way west... Salaberry-de-Valleyfield, Saint-Polycarpe, Sainte-Justine-Station. Using TVFool's "Callsign Lookup", you can see that reception is medium in that area, so it's possible, then goes purple (very weak) from the Quebec/Ontario border.

First you say WPTZ won't be receivable in Ottawa (which we said it isn't currently). Next you say it won't be receivable on the West Island (which we depute). Now you say that you didn't mean west island but way west of the island. What is the real issue you have?

For fun though, I did TVFool analyses on those three towns (assuming 30 foot antenna) and found the difference between WPTZ and the strongest Ottawa UHF channel was as follows:

Salaberry-de-Valleyfield 42.2 dB
Saint-Polycarpe          30.2 dB
Sainte-Justine-Station   16.3 dB

So things might be getting close for Sainte-Justine-Station, but if you consider there is 153 degrees of separation, the difference in antenna gain will be substantial.

Next, open 2012-0465-1, Estimated Contours PDF. The red contour almost reaches the Ontario/Quebec border.

The noise limited contour falls just short of Alexandria, ON which I guess is getting close to the Quebec boarder. Not so sure what is so magical about that boarder though, considering we are talking about an American station.

Since we know that signals go beyond contours, depending on terrain, and that Global MAY want to boost CIII-DT-6's power someday for more ATSC-M/H coverage, it will create interference, someday, somehow.

Quite frankly I think they have applied for the maximum they can get and won't be permitted more. If they (or anyone else) want more ATSC-M/H coverage, more power isn't the answer, but additional transmitters.

But as of now, with proposed power, it's borderline. Global should take another channel number that will allow them to expand.

What channel do you propose? Channel 6 has already proven to be a poor option (no surprise there as VHF-LO has been very problematic in the US). CBOFT recently took channel 33 since people were having issues receiving it on 9 (even though VHF-HI is much, much better than VHF-LO). Channels 10 and 12 would cause even more problems, since they are used in Montreal. That only leaves 50, which has even further constraints due to co-channel issues with WWTI Watertown (which is much closer than WPTZ).

[tvlurker]

Leaving protection issues aside, if you have ever studied a realistic propagation prediction for WPTZ (TVfool is close enough, even though it is only Longley-Rice and not one of the more accurate tools), you will see that reception in most of eastern Ontario of WPTZ is shaded by Covey Hill in Southwestern Quebec. So reception of WPTZ west of the Quebec border is problematic already.

As far as Global goes, if they did care about more reliable reception in that small reception hole between Ottawa on channel 14 and Montreal on a low power channel 15, they would look at higher power options for Montreal. If they want to spend money on a new antenna, there certainly are higher power options (like 36). Other options would be a fill-in transmitter near Cornwall. Note that such a transmitter was approved years ago, on the proviso that Global apply for a different channel (they had applied for channel 11, which went to CHCH in Ottawa instead. They never reapplied for a new channel for Cornwall -- instead, they eventually partnered with TVA to take over CKMI Quebec City and put in relays in Sherbrooke and Montreal to create what eventually morphed into Global Montreal.)

But realistically, Shaw Media will have their hands full planning and paying for their commitment to replace all the existing analog transmitters with digital ones. Given that Global's Ottawa and Montreal coverage will both be drastically improved over what they previously had on analog*, trying to minimize the (decreased) lack of coverage in a relatively lightly-populated previously not-covered area between the two cities in not likely to be high on the priority list.

It is also interesting to note that, with channel 14 Foymount likely to stop broadcasting on July 31, the increased coverage on channel 14 to the west compared with channel 6 will give Shaw Media more options when replacing the Denbigh (nominally Bancroft) transmitter on channel 2 in the next few years.


*if you were worried about reception in Prescott-Russell and the United counties on channel 14, imagine how little coverage they had when they broadcast low power on channel 6 when CBC Montreal was broadcasting with 100 kW, to say nothing of the minimal power they used on channel 46 in Montreal, which barely covered the Island!

[roger1818]

Good points tvlurker, though I think you mean that Global's Ottawa coverage will be drastically improved over what they previously had on analog. What they have right now is much worse as before the analog shutdown (although the picture on analog 6 may not have been perfect for everyone).

[flavoie]

GREAT news on the proposed move of CIII Ottawa to 14. Sounds like I may be able to turn my subwoofer back on. Yes, ciii-6 was so low power I had to turn my subwoofer off to watch it.

[tvlurker]

Originally Posted by roger1818

Good points tvlurker, though I think you mean that Global's Ottawa coverage will be drastically improved over what they previously had on analog. What they have right now is much worse as before the analog shutdown (although the picture on analog 6 may not have been perfect for everyone).

Thanks, Roger. I edited workding to show that I meant that the proposed channel 14 is much better than the previous channel 6, but as you say, my experience is that Global's analog signal on channel 6 may have been receivable with rabbit ears, but it was rarely pleasant to watch. The digital signal (where it works) is great.

[Trip]

If anyone is looking for a coverage map for the CIII-6 signal on 14 to compare with the current one, here you are:

Channel 14 (Proposed): http://www.rabbitears.info/contour.p...=1450000&map=Y

Channel 6 (Current): http://www.rabbitears.info/contour.p...=1283204&map=Y

- Trip