Microwave link engineering with Google Maps
My webtool calculates the distance and bearing between two markers. It also calculates the Rx level, Fade margin, FSL and unavailability of a link between these two markers in % and minutes/year. Furthermore if you give a required availability it will calculate the maximum link length you can achieve using given parameters and shows this graphically on the map.
You can try out my webtool at http://members.chello.at/stephen.joung/indexMW_Distance20.html Here is a short description of how to use the webtool.
You can zoom in and out with your mousewheel or by using the control in the left top corner. You move the map about by clicking with the left mousebutton and holding the button down while you drag the map.
You can enter markers three ways:
- By clicking on the map where you would like to place a marker
- By entering coordinates in the boxes provided above the map.
- By entering an address in the box provided above the map. The resulting marker can then be dragged to the exact location required
The coordinates of the markers are then seen in DMS and Decimal degrees to the right of the map. Also the bearing from A-B and from B-A and the distance between the two markers can be seen. You can input Tx level, Rx Threshold, freq, polarization etc and the tool calculates the Rx level, Fade margin, FSL and unavailability of the link in % and minutes/year. You can change the parameters, ie Tx level or freq and the availability etc are automatically recalculated.
Toward the bottom of the form there is a box to input a required availability after you have done this you can press enter and the tool will calculate the max link length you can achieve with this availability and the freq, polarization, Tx level etc that you have chosen. Change any of the parameters and/or the availability required and the new max link length is automatically calculated. Click on either of the markers and the max link length is shown as a circle around the marker. Recalculate the link length with new parameters, ie horizontal polarization, new freq, Tx power etc and click on the marker again and a new circle is drawn representing the new link length. Click on any circle and info about this circle is given in a window. There is no limit to the amount of circles you can draw.
A new feature is dragable marker-B. Click on marker-B and the marker becomes dragable, drag it to a new location and release the button and all calculations are re-calculated for the new B location.
Any suggestions for improvement will be welcome.
You can now enter an address and a marker without A or B will appear. You can drag this marker to the exact position you need and it will turn into an A or B marker.This works worldwide.
I am looking for the site.
Hi Mohammad, I have just checked and the link above works. Here it is again, just click on it.
http://members.chello.at/stephen.joung/indexMW_Distance.html
Hi Steve,
You’ve a set of very useful tools, thank you very much.
I had a question on as to how you are calculating the maximum link length given the availability nos. If you could share some thoughts or guide me, that’ll be great.
Thanks again
Bunty
Hi Bunty,
Thanks. I’m on holiday for a couple of weeks but I will answer you when I get back
Really great tool.
Would it be possible to include a 28GHz profile?
Hi Mike,
I will include 28GHz and 32GHz a soon as I get time. Hopefully this week. By the way, I take it you have also used the path profile tool at http://members.chello.at/stephen.joung/indexDistanceElevation.html Used together these are a pretty good microwave feasibility planning tool, even if I do say so myself.
One other thing, if any of the ads on those pages interest you please click on them as this is my only source of income for my work.
Hi, I have now included 28GHz and 32GHz in the microwave engineering tool.
Remember to click on interesting ads
Steve, on the Distance, Bearing and Availability Calculator, in Firefox V2.0.0.17 (latest V2.X), a new window pops up but I can’t see the whole page. There are no scroll bars and I can’t maximize the window. There’s no prompt to print, the menu bar is gone and there’s no print option when I right click in the page. Basically, there’s no way to view the complete link budget and no way to print it.
Great mashup otherwise though… David
Steve, Forgot to mention the problem in Firefox (my previous comment) is when I press the green print button on the page – David
Hi David, you are the first to mention this problem and I cannot replicate it. However I have made sure that the window is resizable, included scrollbars and also moved the print button from the bottom of the page to the top left.
Please let me know if this fixes your problem.
This is a great tool! Thanks for making it available.
Thanks Todd, you’re welcome. I hope you have also seen the LOS part of the tool also at http://members.chello.at/stephen.joung/indexDistanceElevation.html
Are you interested in selling this source code? We would love to have this on our intranet system for our wireless installers to access. We use feet and miles and lower frequencies (5.8ghz, 2.4ghz, 900mhz) as well, but we could make those changes if we could purchase the source?
Hi Travis,
I have also answered you by email as I am sure you would rather continue this on a one-to-one basis.
I would definitely be interested in selling the source code. I could offer it to you with documentation (rudimentary at the moment but I would improve it) and some assistance in adapting it to your WiMax/GSM/CDMA applications.
I would also include a new php script I have written which enables the free SRTM3 height data to be installed and read from your own server thereby removing the reliance on Geonames.org. The Geonames free servers have been a bit unreliable lately, which is why I wrote the script, and the guaranteed rate prices are here http://www.geonames.org/commercial-webservices.html#A You would also be able to use the more accurate height data available for the USA.
Regards,
Stephen Young.
We are to link sites using microwave.what is the formula in calculating the RSL (received signal level) when only given parameters such as Output Power, Practical Threshold and Noise Factor from manufacturers specification?we are suppose to calculate the rsl for us to solve the anntena gain and diameter…from this data we will be able to know what equipments with standard values, similar or within the range that we will use. I appreciate this microwave calculator but we need to calculate manually to show how did we come up with this values. hope you could help me with this.god bless
Hi Sam,
thanks to the beauty of the decibel this is simple to work out.
First calculate your output power in dBm, you will find a tool to do this if you click on “Radio Engineering Tools” on my webpages. The formula is simply xdBm=10 log(power) where log is base 10 and power is in milliwatts.
Then calculate the “Free Space Loss” for the frequency you are using, again there is a tool to do this in the “Radio Engineering Tools” on my webpages. Here is a link to Wikipedia which explains this better than I can http://en.wikipedia.org/wiki/Free-space_path_loss
Now you simply take the transmit power, deduct any waveguide losses at the Tx site, add the antenna gain at the Tx site, deduct the FSL, add antenna gain at RX site, deduct waveguide losses at RX site and what is left is the RSL.
For example, for a link of 4km with 16dBm Tx power at 38GHz with one 0.3m and one 0.6m antenna and no waveguide:
RSL = 16-0+35.6-136+41-0 = -43.4dBm
Regards, Steve.
tnx…i already have that formula…but we need to calculate first the rsl without using the “gain of the antenna” at the moment.(w/c is given in the specs of the manufacturer of the antenna to be used) What i mean is,we have to design a link in which from the calculated parameters (from the given data like path distance, operating frequency,power output,practical threshold and noise figure of a certain microwave radio and typical cable,waveguide and connector losses)we will be able to match it to the existing equipments in the market in which its specification like antenna gain and diameter matches our calculated values to achieve a reliability of 99.9999%
I noticed from the manufactures data sheet the commonly given parameters are just the Output Power and Practical Threshold.So we really need to solve for the RSL to be able to solve other parameter which i mentioned above.
Do you recommend assuming values for RSL or assuming value for antenna gain? hehehe
i will be graduating this march if i complied this project study with flying colors… ;0
If you have an availability target then you should calculate (using for instance ITU-R or Crane Model) what RSL you would require for that availability, then you choose the antennae that will give you that RSL.
When you refer to reliability I assume you mean the availability due to propagation effects. This is applicable for flat fading which are long fades of over 10 seconds, such as caused by rain, which occur in links with frequencies over 15GHz. For links with frequencies below 10GHz selective fading is predominant and this, because of the short duration, is more a problem of quality than availability.
If I were you I would get a good microwave link planning reference, I recommend Trevor Manning’s Microwave Radio Transmission Design Guide
Good luck with the exams.
Hi
This software is look like well.I think one point has been forgatten to add the calculation. This point is absorbtion loss vs frequency.itis not consider.,for example the software is not calculate for 23 GHz link absorbtion loss
comment by rifki ozkan
Hi Rifki,
The microwave calculations are on page http://members.chello.at/stephen.joung/indexMW_Distance20.htm.
The Free Space Loss, which is what I assume you mean by absorption loss, is calculated for all of the frequencies in the selection list including 23GHz. It is shown in the box named FSL
i need to download the micrwave links budget calculator on my pc, would you please help me
No, not unless you want to buy the tool. The tool is copyrighted.
This calculator is just what I have been looking for.
Is it possible to add 13GHz and 15GHz profiles?
Thanks
the problem is that for frequencies between 10-15GHz selective fading (multipath) and flat fading (rain) are both significant. At the moment the tool concentrates on the higher frequencies and performs no multipath calculations. I could include multipath calculations but I am busy at the moment on a new project – making it possible to save links.
I could include the flat fading calculations for 13GHz and 15GHz without multipath and add a warning that multipath hasn’t been considered. Would this be ok?
Thanks Steve, that would be great.
Ok, I have added 13GHz and 15GHz with a warning. Please be aware that the distance calculated for these distances will be much greater than is really possible because the selective fading has not been included in the calculations.
Please recommend the site to colleagues and please click on interesting ads, this is the only income I get for my efforts.
By the way I am working on a new version of the tool which enables links and radio types to be saved. For several reasons I will have to charge for these additional services, but the existing services would remain free. Just to get a feeling for how many people would be interested in these additional services can I ask you if be prepared to pay for these improvements?
Steve, thanks for adding the 13 = 15 GHz info.
To answer your question, I probably wouldn’t use the additional services you mention as I’m not involved with link design etc. Im just trying to increase my understanding of microwave links. I will be however be recommending the site to my colleagues.
Thanks again.
Hi! I was surfing and found your blog post… nice! I love your blog.
Cheers! Sandra. R.
I can see this as a great tool for ENG use. Would love to use this tool with a 2 GHz choice and with longer shots than 80km.
now that I have played with it a bit, code seems to have an error when dealing with long paths. Shows -55.8 rsl at all locations even at impractical distances.
Even if long paths cannot be graphed, would be nice to have edge or terrain blocking notice flag.
Would be nice to anchor one site and move the other around on the map.
7GHz pull down available on one of the two tools- Why?
In the MLOS tool the limit is 80km because the height data is collected for every 90m and distances over 80km would cause to many requests. In the MLET tool please see the answer to Andy Paddon (#23 above). This tool calculates propagation outages caused by flat fading and this applies mainly to frequencies above 18GHz. For 18GHz a distance of ~20km is possible with an availability of around 99.99% so I wouldn’t use the tool for longer distances. What distances and frequencies were you using?
You *can* anchor one site and move the other around. As stated in the basic instructions “After you have entered your markers you can click on Marker B to make it draggable and then drag it to another location”
The 7GHz is in the MLOS tool to show theFresnel zone. It is not icluded in the MLET tool because multipath (selective fading) calculations are not done.