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  »  New  Antenna diversity system system for FM? Why not?..  Trickle Down?...  Off Air Audio Forum     1  17356  06-07-2009
  »  New  Antenna attenuator – you got to be kidding?..  Antenna attenuator – you got to be kidding?...  Off Air Audio Forum     0  11247  07-11-2008
  »  New  Antenna solutions for FM..  Hurricane Irene ibn Oz in Boston...  Off Air Audio Forum     27  126060  02-21-2008
07-12-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 1
Post ID: 13979
Reply to: 13979
Help with Math needed.
fiogf49gjkf0d
Guys, I need somebody help me with middle grad school math – I truly can’t do it.  I need to calculate if my antenna in the line of sight with my WCRB and if not then what kind elevation I shall have in order to get the line of sight.
 
The image below is well depicts the situation. My antenna is at 160 feet toll over the sea level and 12 miles away there is 949 feet toll transmitter antenna. 2000 feet away there is a 240 feet tall heal the might or might not cover the line of sight.  Who know how to figure it out? I do not remember geometry anymore… 

Antenna_line_of_sight.JPG

Rgs, The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-12-2010 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 2
Post ID: 13980
Reply to: 13979
Bad news I am afraid!
fiogf49gjkf0d
Well Romy:

A quick calculation shows that the angle of elevation is 1.24310 degrees (i.e tan inv of (949-160)/36360).

At a horizontal distance of 2000ft from the antenna, this angle of elevation results in an overall height above sea level of 203ft (i.e tan of elevation x 2000= 43 + 160 = 203ft). The 240ft tall heal will therefore be in the way of your line of sight... as you said it may or may not adversely affect your reception.

You could always set fire to it...

All the best
Rakesh
07-12-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 3
Post ID: 13981
Reply to: 13980
Thank you, one more.
fiogf49gjkf0d
Oxric, thank you very very much. Would you be kind to help me to find out what shall be the elevation of my antenna in order to reach the line of sight clarence over that hill?

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-12-2010 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 4
Post ID: 13982
Reply to: 13980
Or you could raise your antenna by 38.731ft
fiogf49gjkf0d
Romy:

My pleasure.

The actual angle of elevation required to clear the summit of the heal is 1.182 degrees (i.e tan inv 709(949-240)/34360(36360-2000)). Using similar triangles (h/2000=709/34360) or simple trig gives an overall antenna height of 198.731ft, so that you need to raise your antenna at least an additional 38.731ft to just clear the heal.

Rakesh

P.S You could move the antenna back if you wanted to maintain a height of 160ft but you would need to move 3877ft from the heal that is a further 1877ft back from the present position of the antenna, not a viable proposition at all I am sure. 
07-13-2010 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 5
Post ID: 13983
Reply to: 13982
By the way, what is a heal?
fiogf49gjkf0d
Romy:

I just suddenly realised that by 'heal' you probably meant 'hill'. For a moment I thought it was some strange geographical feature that I had not come across.

Regards
Rakesh
07-13-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 6
Post ID: 13984
Reply to: 13983
The 75 feet - this is over the "heal"....
fiogf49gjkf0d

Oops, I am sorry. Of cause it was hill, I need to add it to my dictionary

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=3823

The 40 extra feet in addition to my current 35? This would make 75 feet mast. Hm, this is complicate as it will be make the tallest structure in my neighborhood and it will make it very vulnerable to lighting…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-15-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,543
Joined on 05-28-2004

Post #: 7
Post ID: 13995
Reply to: 13984
10 Feet up– 8dB gain.
fiogf49gjkf0d
I raised the antenna on 10 feet. Got extra 8dB of signal, not a lot itself but it a lot from a point of view of signal to noise ratio and I now can get a the specific station that I want with an acceptable level of noise. Oxric, thanks for your help. If you play 24 bit files then I might send you my tomorrow’s recording and it might be something that you might like.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-18-2010 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 8
Post ID: 14022
Reply to: 13995
You are welcome
fiogf49gjkf0d
Hi Romy:

Please don't mention it.

Yes I can play 24 bit files and yes I don't mind trying your recording.

All the best
Rakesh
Page 1 of 1 (8 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Antenna diversity system system for FM? Why not?..  Trickle Down?...  Off Air Audio Forum     1  17356  06-07-2009
  »  New  Antenna attenuator – you got to be kidding?..  Antenna attenuator – you got to be kidding?...  Off Air Audio Forum     0  11247  07-11-2008
  »  New  Antenna solutions for FM..  Hurricane Irene ibn Oz in Boston...  Off Air Audio Forum     27  126060  02-21-2008
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