Topics

Estimate Line of Sight-Viewshed on Google Earth Pro


Brett Popovich KG7GDB
 

Hi Mesh Users,
The most successful installations of a MESH network will always be line of sight (LOS).
Wait, you may ask "Can't I just put up a tower at my house?"
We have discovered in our mobile surveys, that even with a tower up at 12 meters, you can't easily connect with a particular fixed neighborhood location such as another Ham's house. Your signal will be strong in some areas and totally blocked in others. Our topography in the Salem area is rolling hills, 
An ideal station location would be located at high elevation such as a hillside, or tall tower or building, with a clear view of the area you want to cover, with no trees, rooftops, or objects in the path (at least 7 feet above the clutter at the station).  We currently are looking for those sites in our area, and it is not easy to find them! 
Step 1) If you are evaluating a house, business, shelter or other location, you need a way to estimate the LOS from that spot, and a the height of your station mount.
--> If you can visit a potential site in person, use a spotting scope to identify clear paths and visual landmarks around the area. If you have safe access to a rooftop or balcony, take some photos to document the clearest viewpoints and landmarks. If you can see it, you can work it! 

I have found Google Earth Pro has a tool called the "Viewshed" which draws a circle of view at a place marker you add to a map.

  • Set a new place marker using the tool that looks like a Yellow Pushpin, and zoom in and drag it exactly where you want. A properties window will open.
  • Now, in properties window, choose the altitude tab.
  • In the menu choose relative to ground, and enter 12m, or your tower height in meters.
  • Check the box extend to ground.
  • Save this with a name to My Places.
  • Now right click item that item in your Places menu and select show viewshed. After a few seconds, Google Earth will generate a 10 km (5.4 mile) radius circle called the Viewshed.

This simulates what the sight sees from that elevation, including trees and buildings in the way.
-->You are looking for a green path covering the area you want to hit. (Gray means it is blocked or too low to see).
Zooming in, you will see 3D buildings and trees which block your signal.
If you want to move the marker, right click the place menu, and show get info. Once the properties window is open you can drag the marker or adjust height, then save again.

For a YouTube video demonstration, see:
https://www.youtube.com/watch?v=9SP1O8q2Lng

Please share your survey results with the group.

73,
Brett
KG7GDB


Darrel Karbginsky <grumpyoldcoder@...>
 

Brett,

 

Would you like the survey shared? Picture?

 

 

Cordially,

 

Darrel, W7DDE

 

This email is copyrighted, confidential, may be legally privileged, and is for the intended recipient only. Access, disclosure, copying, distribution or reliance on any of it by anyone other than the intended recipient is prohibited. Please delete if obtained in error.

 

From: Brett Popovich KG7GDB via Groups.Io
Sent: Friday, March 15, 2019 1:54 PM
To: Salemmeshnetwork@groups.io
Subject: [Salemmeshnetwork] Estimate Line of Sight-Viewshed on Google Earth Pro

 

Hi Mesh Users,
The most successful installations of a MESH network will always be line of sight (LOS).
Wait, you may ask "Can't I just put up a tower at my house?"
We have discovered in our mobile surveys, that even with a tower up at 12 meters, you can't easily connect with a particular fixed neighborhood location such as another Ham's house. Your signal will be strong in some areas and totally blocked in others. Our topography in the Salem area is rolling hills, 
An ideal station location would be located at high elevation such as a hillside, or tall tower or building, with a clear view of the area you want to cover, with no trees, rooftops, or objects in the path (at least 7 feet above the clutter at the station).  We currently are looking for those sites in our area, and it is not easy to find them! 
Step 1) If you are evaluating a house, business, shelter or other location, you need a way to estimate the LOS from that spot, and a the height of your station mount.
--> If you can visit a potential site in person, use a spotting scope to identify clear paths and visual landmarks around the area. If you have safe access to a rooftop or balcony, take some photos to document the clearest viewpoints and landmarks. If you can see it, you can work it! 

I have found Google Earth Pro has a tool called the "Viewshed" which draws a circle of view at a place marker you add to a map.

  • Set a new place marker using the tool that looks like a Yellow Pushpin, and zoom in and drag it exactly where you want. A properties window will open.
  • Now, in properties window, choose the altitude tab.
  • In the menu choose relative to ground, and enter 12m, or your tower height in meters.
  • Check the box extend to ground.
  • Save this with a name to My Places.
  • Now right click item that item in your Places menu and select show viewshed. After a few seconds, Google Earth will generate a 10 km (5.4 mile) radius circle called the Viewshed.


This simulates what the sight sees from that elevation, including trees and buildings in the way.
-->You are looking for a green path covering the area you want to hit. (Gray means it is blocked or too low to see).
Zooming in, you will see 3D buildings and trees which block your signal.
If you want to move the marker, right click the place menu, and show get info. Once the properties window is open you can drag the marker or adjust height, then save again.

For a YouTube video demonstration, see:
https://www.youtube.com/watch?v=9SP1O8q2Lng

Please share your survey results with the group.

73,
Brett
KG7GDB

 


Brett Popovich KG7GDB
 

Hi Darrel,

Yes, I think if have made a coverage map that you would like to share, there are two ways to share it.

1) Use Google Earth to Save Image allows you to show the screen and imbed the picture in an email message. 

—this is probably a safer way to share info on a public newsgroup.

2) Right click your Saved Place Holder from which you did the coverage, and save the .kmz file. This could be attached to a personal email message or perhaps uploaded to the files section on the salemmeshnetwork groups homepage.

 

However, I’m sensitive to privacy concerns as having public Google Earth .kmz access to sites with equipment installed exposes  those sites to increased risk of theft or vandalism. We need to decide what to do as a group policy.

 

AREDN has a feature which maps the active MESH nodes are connected to the Internet, and the plan usually is to use that feature to create a Ham accessible network which can be searched. We do need to publish the channel and location information on the network so that people can connect. 

 

Ideas? Comments?

 

-Brett

KG7GDB


Darrel Karbginsky <grumpyoldcoder@...>
 

Brett,

 

I do have a suggestion. Use GPG4Win (there is a Mac version too) and encrypt the sensitive files. The software is easy to use and I would even provide my lecture notes (slides in PDF format) on the topic. I suggest you create a key pair and publish the public key to those in the Group.  You could easily attach it to an email to the group. We could then encrypt the files or a message with your Public Key and you of course would be the only one able to decrypt with your Private Key.  I have a published Public key under my email: w7dde@... if you wish to give it a try.

 

Darrel, W7DDE

 

Cordially,

 

Grumpy Old Coder

 

This email is copyrighted, confidential, may be legally privileged, and is for the intended recipient only. Access, disclosure, copying, distribution or reliance on any of it by anyone other than the intended recipient is prohibited. Please delete if obtained in error.

 

From: Brett Popovich KG7GDB via Groups.Io
Sent: Saturday, March 23, 2019 10:46 AM
To: Salemmeshnetwork@groups.io
Subject: Re: [Salemmeshnetwork] Estimate Line of Sight-Viewshed on Google Earth Pro

 

Hi Darrel,

Yes, I think if have made a coverage map that you would like to share, there are two ways to share it.

1) Use Google Earth to Save Image allows you to show the screen and imbed the picture in an email message. 

—this is probably a safer way to share info on a public newsgroup.

2) Right click your Saved Place Holder from which you did the coverage, and save the .kmz file. This could be attached to a personal email message or perhaps uploaded to the files section on the salemmeshnetwork groups homepage.

 

However, I’m sensitive to privacy concerns as having public Google Earth .kmz access to sites with equipment installed exposes  those sites to increased risk of theft or vandalism. We need to decide what to do as a group policy.

 

AREDN has a feature which maps the active MESH nodes are connected to the Internet, and the plan usually is to use that feature to create a Ham accessible network which can be searched. We do need to publish the channel and location information on the network so that people can connect. 

 

Ideas? Comments?

 

-Brett

KG7GDB