Does noise margin matter more than distance from transmitter?

[Capslock118]

Hi everyone,

Here is my report: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d5ed63b0973f28c

So according to tvfools FAQ it's best to have a noise margin of 5db or more after all is considered i.e. cable distance, splitters, etc. tvfools FAQ also mentions that:
The primary benefit of the amp is to overcome further NM degradation from "downstream" losses

Ok so let's say I have a preamp to mitigate downstream losses. Further, let's say my antenna is kind of crappy and has no signal gain so in this conversation we are focused on talking about over-the-air losses.

Now we go back to the title of my thread, is the distance range that antennas advertise (i.e. "Up to 70 mile range!", "up to 25 mile range") just a marketing thing and it doesn't really matter?
or
is the noise margin in the report assuming that I have an antenna that can pick up signals from that distance?

For the record, I have read that the curvature of the earth starts to mess with signal quality starting at 70 miles distance. I'm more curious to know if an antenna advertised to pick up signals from up to 30 miles can really pick up signals much farther away or if there is something inherent in the design that prevents the antenna from picking up anything past 30 miles.

and if I am way off, please enlighten me, i'm just learning about all this stuff.

thanks,
-joel

[GroundUrMast]

You are 'spot on'.

Mileage estimates are the product of the marketing department. I have yet to see a scientific explanation provided with any mileage claim, therefor it's not possible to know how the number was determined.

Antenna gain expressed in units of dBd or dBi are at least claims referenced to a defined standard. The reputable manufacturer provides enough detail in their engineering documentation to give the knowledgeable buyer confidence that the antenna will perform at a measurable and repeatable level.

Here's a series of examples of how to use the data in your TVFR and antenna specifications: http://forum.tvfool.com/showthread.php?t=109

[teleview]

The following is a Teleview recommendation for broadcast Tv reception.

+5 to +10 noise margin is prefered , gives a little elbow room for signal fluctuations.

And higher + number noise margins are better yet.

However many locations have Reliable reception with 0 and even -10 noise margin.

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The mileage numbers for antennas are a general guide for sales people and the general public.

Does not do any good because at least 95% of sales people and general public do not know where any Tv transmitters are at and do not even know that broadcast Tv is transmitted from a transmitter tower.

And there is so much misinformation out there , that I think that most people prefer misinformation and avoid the truth.

There was a time , when Tv was new , that many people knew where the Tv transmitters were at and had a basic working knowledge of putting up a Tv antenna to get the one or two Tv stations.

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The reception of some of the New York digital Tv stations/channels is possible.

I recommend a Winegard HD7698P antenna with a Antennas Direct CPA-19 preamp.

Most likely will not receive them all but will receive many of them.

And locals to the north west and south west are strong and will be received also.

Here are some places to buy antennas and etc. , http://www.solidsignal.com , http://www.amazon.com , http://www.winegarddirect.com.