Jump to content

Recommended Posts

Parrothead
So, I recommend that you reduce that risk and install lower masts to suit 60% Fresnel clearance - easier and cheaper to do too!
Antenna heights of 22ft at the highway and 27ft at the farm will do that job nicely.

 

You could come 5ft lower and still have a pretty good link.

 

So, according to your calculations, mount them at 17' and 22', respectively?

 

 

This, for sure, is going to be interesting.

Share this post


Link to post
Share on other sites
Oz Jon

So, according to your calculations, mount them at 17' and 22', respectively?

 

 

This, for sure, is going to be interesting.

 

Yes, that will do fine (assuming that the ground levels you showed are about right and there aren't any additional buildings/trees etc obstructing the path).

 

And, if it's useful, you can tweak the heights a bit to reduce the highway end height and increase the farm end height in the ratio 2ft highway end for 1ft farm end.

Share this post


Link to post
Share on other sites
Parrothead

Yes, that will do fine (assuming that the ground levels you showed are about right and there aren't any additional buildings/trees etc obstructing the path).

 

And, if it's useful, you can tweak the heights a bit to reduce the highway end height and increase the farm end height in the ratio 3ft highway end for 1ft farm end.

 

It is pretty much all farm land over that 5 kilometers. But, there are structures and trees between the two points.

Share this post


Link to post
Share on other sites
Oz Jon

It is pretty much all farm land over that 5 kilometers. But, there are structures and trees between the two points.

Probably not a problem if they are just a few isolated objects (the odd small building or odd tree and certainly not a problem if they are outside the Fresnel ellipse) and you can still see the far antenna from the near antenna.

 

How about sending me a photo of the path antenna site-antenna site? for a more informed opinion.

 

[ps. maybe with a 5ft Cambodian standing at the .9ml point to indicate the vertical scale - LOL!]

 

pps.

I just had a look on Google Earth (zoomed in close). - Very sparse trees - so no problems, provided that the sight-line clears the buildings in the first 300m at the highway end.

Edited by Oz Jon
  • Like 1

Share this post


Link to post
Share on other sites
Oz Jon

I've modified my path profile drawing to show only the recommended arrangement with 17ft and 22ft antenna heights..

 

I've also drawn the 2nd Fresnel ellipse in red - (that's the one to be avoided, because it results in reflected signal tending to cancel the direct signal).

 

The only spot where that could be a minor problem is at the 2.5ml point.

Not much of a problem, because that isn't a very big flat/level patch, so not much troublesome reflected signal.

 

If you allow for a bit higher mast at the farm (say to allow for 25-26ft antenna at the farm and 10ft at the highway) then you will have a simple improvement available, if that turns out to be a problem.

 

edit. dotted lines didn't show - so here is a re-drawn version

 

post-1173-0-31508200-1461317152_thumb.jpg

Edited by Paul
attached image to post.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • If you would like to join to begin posting and become an active member, feel free to click on THIS LINK, to register. If you have any questions, feel free to post them in the Forum Operations / Issues forum. If you register, but then are unable to log in, please feel free to post concerns in the Having Problems Logging In? forum. We will address any and all questions, comments, or concerns, as quickly as possible. Welcome to the Living In Cambodia Forums! 

    Welcome to the forum!

  • Similar Content

    • Parrothead
      By Parrothead
      Provincial internet access in Cambodia.
       
      Chan spoke with her friend, who happens to work at Cootel and lives just down the road from the farm. She had her internet service there while on holiday, a little while back. So, we figured we would give it a go. She (the friend) helped schedule a test / installation trip for us.
       
      We met the installer from Cootel, yesterday, at the farm. He came armed with 2 different units, a fiberglass 9dB gain antenna and 10 meters of coaxial cable with both N and SMA connectors. One unit was a CPE-153W; the other a CPE-168W. He informed me that the CPE-168W allows faster access than the CPE-153W.

       
      The rear image (below) shows an Ethernet connector. While this is accurate for the CPE-153W, the CPE-168W has a USB connector to hard wire a computer to the modem / router. Devices may access the router via WiFi, as well. (I'm not sure of the range of the transmitter, though. The WiFi antenna is internal.)

       
      When he tested them, the CPE-168W, quite obviously, came out on top. The CPE-158W was about 1.5 Megabits down; .73 Megabits up. The CPE-168W was at 6.3 Megabits down; 1.5 Megabits up.
       
      Here is an image of the rear of my personal CPE-168W modem / router:

       
      To gather these speeds, he mounted the 88cm fiberglass antenna to a bamboo pole we had in the yard. But, this only placed it just above the roof.

       
      The monthly service is $15 USD / month, uncapped. If I buy 6 months, I get one month free. 
       
       
    • Parrothead
      By Parrothead
      Well, this afternoon, we had the first heavy rain since we arrived at the farm earlier this month. Even with the 9dB gain omnidirectional antenna, there was no, zero signal loss at the modem. Have a look at the :30 seconds video:
       
       
    • Parrothead
      By Parrothead
      @Oz Jon, I was informed today that Cootel was going to move tower locations (READ: already had moved), thus causing the signal to drop at the farm. We are talking a serious drop in signal, so much that they suggested we discontinue the service with them. My thread regarding our Cootel service.
       
      Fortunately, I had already begun to cover all my bases, by contacting the omnidirectional antenna manufacturer, via email, for price and availability on a yagi antenna offering similar specs (frequency range, impedance, etc.). And, I have been discussing with you, the possibly sending the signal from my apartment in the city, to the farm, as well.
       
      Anyway, below is the specs sheet for the omni, which I sent to him. He, quite obviously, did not read the subject line of the email, or the specs sheet, aside from the model number of the antenna. 

       
       
      Here are a couple of the (several) PDFs he sent to me:
       
      TDJ-1900ACY7.pdf
      TDJ-1900SP10.pdf
       
      Keep in mind, I was quite clear in the frequency range I needed, which was stated in the subject line, as well as on the specs sheet.
       
       
    • Parrothead
      By Parrothead
      Howdy,
       
      First, some images of the tower that broadcasts the signal:
       

       

       

       
      We stopped by there on the way back to the apartment today, to get a few images and to grab its GPS coordinates.
       
      The tower is located at: 12.974649, 103.053851 decimal, or 12° 58' 28.7364'' N by 103° 3' 13.8636'' E
       
      The farm's GPS coordinates are: 12.9867798, 103.0072846 decimal, or 12° 59' 12.4073'' N by 103° 0' 26.2246'' E
       
      I still have to work on the Google Earth elevations.
       
       
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use & Guidelines. Here is our Privacy Policy.