Design Microwave Link Using Pathloss 4.0 Planning Tool

 

Pathloss 4.0 demonstration

 

Followings are the basic steps using in Pathloss 4.0 to calculate the Microwave Link Budget.

1. Import digital terrain map

Menu Configure ------à Terrain Database

Loading the height (elevation data) information:

Note: Cambodia map data (STRM) used in this demonstration.

Menu Site Data -----à Create background, Show background

 

2. Import sites

Menu Site Data  -----à Site list  -----à  Import  -----à Site Text File

File format used to import is in *.csv format and based on the format setting in the Import Text File window:

Note: *.csv file import is without header and use comma for field delimiter character, otherwise File Error message notified:

Select the *.csv file in particular location and Open it:

Then site locations will be displayed in Network or Map grid module:

 

 

Save as Pathloss’s Network files as *.gr4

An individual site could be added immediately on the Network or Map Grid window:

Menu Site Data -----à Add site

Move cursor to the position we wish to add and press on Add Site button, then input Site Name in the Add a new site box. This new site will be updated in the Site list.

3. Microwave link import

Import pathloss file (*.pl4) of one or multiple microwave links.

Site Data  -----à Site list, import  -----à Pathloss File

 

Link topology will be displayed in the Network Module:

New links imported will be updated in the Link List as well.

 4. Microwave link creation

On the Network map, press and keep the left mouse on one site location and drag to another site location intended to establish the Microwave link, release the mouse then link icon created.

 Left click on the link icon, press on Terrain Data in order to generate the terrain profile

 

Menu Operations  -----à Generate Profile

Double click on the Structure column of Terrain Data window if any obstruction such as tree, building, tower etc. needed to be added into the profile.

For example, building obstruction with 15 meters height

Note: after terrain profile of the link path created, popup menu from the left click on the link icon will list the functions that can also be available in the menu Module:

Left click on the link icon and select Summary (or menu Module -----à Summary) to see the link information in summary.

Menu Files -----à Save, to save the link with proper name into the drive’s folder as *.pl4 file.

5. Antenna height

Click on the calculator icon for optimized antenna height, Pathloss tool will calculate automatically the antenna height for free of obstacle based on the frequency input (higher frequency band will create smaller Fresnel Zone, hence required antenna height will be lower compares to lower frequency band).

 

 Antenna height depends on the obstruction along the link such as tree, building and also k- factor.

For a long distance link, the effect of k-factor is clearly seen in the terrain profile where the earth tends to be curved for smaller k-factor than the bigger. Below example between k=0.69 and k=1.33 comparison.

Note: Antenna configuration (such as 1+0, SD...) need to be specified in the Microwave Antenna Configuration window:

Configure------Antenna Configuration

6. Equipment parameter and frequency channel lookup

The information or parameters needed for link calculation could be imported/added in the module Worksheets:

 There are parameter inputs in the worksheets: antenna, transmission line, branching, radio equipment, frequency channel, rain information and path profile data.

a- Lookup antenna code index

Click on antenna icon for antenna input:

Before we can look up the antenna, antenna Code Index need to be imported first.

Browse for folder to locate the specific antenna Code Index:

 

 

We can view the pattern of any specific antenna whose code index have been imported. And also can add the right antenna into the link we established.

We can add these Code index into the Microwave Antenna Lookup Table:

 

Those information in Lookup Table could be saved as *.mat file format for other network projects.

Select the right antenna you want to use in the project then the information in the Antenna window will be updated accordingly.

b- Transmission line

Where the Trunk Microwave is used, the losses information of the waveguide connect between Radio and Antenna need to be included in the calculation. 

Locate the *.txl format in the stored data location:

Select the one needed in our design.

c- Branching network input

This needed when hybrid coupler used for HSB configuration where two radios are used.

Note: Practically 1.7 dB can be used as miscellaneous loss (dB) for both sites.

d- Microwave radio equipment code index

Same as Microwave antenna, the radio parameters for calculation could be added from the radio code index or Microwave radio lookup table. Relevant information in the table need to be added from the radio code index and also could be save as *. mrd file format for other network projects.

From the Worksheet module, click on the radio icon:

From the Radio Code Index:

From the radio lookup table, we need to add the radio parameters from Code Index:

We can view the other specification of any specific radio:

Select the right radio you want to use in the link. The information in the radio equipment will be updated accordingly.

e- Assign frequency channel to the link:

Click on Channel Icon in order to lookup the right channel you’re going to assign for the link.

 

Click on the Lookup in order to import the planned frequency channels as a whole.

We can open the list of frequency channels in *.txc file format that previously saved as *.txc file from the table. We can add channel one by one or import the frequency text file to the Pathloss channel table with the right table format:

The list of frequency table could also be exported back to the drive as *.csv file format. Of course this file could be imported back to this TX Channels table as mentioned earlier.

Select the channel to be assigned to the link.

The assigned channel table will be updated and this will be used for the link:

f- Load rain file data according to ITU’s rain zone

Click on the Cloud Icon in Microwave Worksheet module, load the rain file and select rain region N.

 

After all the necessary information added to the link for calculation in the Worksheet module, the final calculation result is produced.

7. Link budget analysis

- If the availability is achieved based on the objective?

- Normally for annual availability (multi-path + rain) objective should be 99.995% for PDH and 99.997% SDH link design

- If all the requirements are met and objective is achieved, save and print the report for implementation.

8. Interference Analysis

Select the area where group of links you want to analyze

 

Menu Interference -----à Calculate interference

We can decide the scope of analysis, the selected against all the links in the network or vice versa.

 

Press Calculate button, save the calculation file

There are some reports we can do post analysis

9. Print Profile

The PDF version of this introduction could be downloaded via this link