Saturday, 18 November 2017

Android App for RF and Optical Link Budgets

Link budgets are used in wireless communications to design parameters such as antenna sizes, bit rates, transmit power etc.  A quick link budget explains why Voyager 1 only transmits at ~ 160 bit/s, even though we use a 34m antenna on Earth to receive its signal!

About 10 years ago we wrote a java program for link budget calculations during an ISU workshop.  Here is a version of the code.  The tutorial we wrote for this application is still very relevant and discusses the effect of antenna gains, EIRP, bit rates etc.

Recently this software has been converted to an Android app.   Here are a couple of screen shots (from the initial release):


The LHS shows entry of some LB parameters for a cubesat downlink.  After completing all the boxes with blue lines, the "CALC" button produces outputs shown on the RHS.

Version History:

2nd Dec 2017: an updated version of this app now includes several sample link budgets, with a few comments on the parameters in each case.  These include two satellite links, one terrestrial application and a high-altitude balloon example.

Jan 2019:  Now updated to 0.5 on Google Play.   This version retains your LB parameters for re-use at a later time and includes some information on spectral efficiency.

May 31st 2019: version 0.6 uploaded to Google Play. This version includes more tutorial links, plus additional link budget examples (5G at 38 GHz, and 70cm Earth-Moon-Earth).   Users can save their own link budget parameters, with a textual description.

October 2019 version 0.7 of this app now includes Free Space Optical (FSO) communications.  Optical links are increasing attractive as RF bandwidth becomes scarcer and bit rates increase.  This version includes 3 FSO examples:  Mars to Earth, LEO downlink and an Inter-satellite link.    Version 0.71 adds one example (high rate optical downlink from LEO),  small layout improvements and updates the Android API to 28. 

Please note that this app requires a screen resolution of at least 1080 by 1920.

Privacy Policy: 

This app does not collect any information from users.  As mentioned above, recent versions of this app allow users to save their own link budgets on their own device, but none of this data, or any usage statistics,  are collected by the app.