RFCLB

Downloading the RFCLB Workbook

♦   About Link Budgets   ♦



Of the many analyses that support a developing communication system, the link budget stands out in its ability to provide overall system insight. By examining the link budget, one can learn many things about the overall system design and performance. For example, from the link margin, one learns whether the system will meet the requirements comfortably, marginally, or not at all. It will be evident, if there are many hardware constraints, and whether such constraints can be compensated for in other parts of the link. The link budget is often used for considering system tradeoffs and configuration changes, and in understanding subsystem nuances and interdependencies. Together with other modelling techniques, the link budget can help predict weight, size, and cost. [..] The link budget is one of the system manager's most useful documents; it represents a "bottom-line" tally in the search for optimum error performance of the system.“ [3]

Bernhard Sklar, 'Digital Communications, Fundamentals and Applications,' 2nd Edition, Prentice Hall, PTR, page 297.

Cassini
Legacy of Cassini/Huygens arriving at Saturn. (Credit: NASA/JPL/ESA)

RFCLB – What is it ?

RFCLB (Radio Frequency Communications Link Budget) is a Spreadsheet Workbook (shareware) for the computation of Spacecraft RF-Link Design Control Tables. It is tailored to space system applications and covers the functions of

  • Telemetry, Tracking, and Commanding (TT&C)
  • Payload Data Transmission (PDT)
  • Δ-DOR Navigation.

The development of RFCLB started in 2014, supplementing a series of university courses in spacecraft engineering. Since then, the tool has continuously evolved as a Students Project (mentored by a lecturer and former senior staff member of the European Space Agency). Making RFCLB here available for download follows the spirit of free and open exchange of scholarly and academic work for science and technology.

RFCLB enables detailed insight into methods and core-budget calculations. This is a distinct advantage over other tools that might feature an appealing Graphical User Interface but are lacking transparency for users interested in applied equations and underlying principles.

RFCLB also includes user conveniences such as the automated import and export of design data from/to Interface Control Tables in MS-Word files [1,2]. This capability can massively reduce in projects the repetitive typing effort of manual data-transfer into/from TT&C link budget spreadsheet tables.

RFCLB can help students and practising engineers to apply, or to enhance, their skills in spacecraft TT&C link design, analyses and the relevant system trade-offs. The development of the tool follows recommendations of the Consultative Committee for Space Data Systems (CCSDS); this makes RFCLB suitable for professional spacecraft TT&C engineering.

RFCLB UserForm
RFCLB-UserForm  'MARGINS (dB) and TT&C-/PDT-OVERVIEW'

HAM Radio
CubeSats and AMSAT Applications
So far, RFCLB is primarily designed to support spacecraft TT&C system design.
In RFCLB, the basic link modelling principles and equations are equally relevant to other applications, such as (bent-piping) CubeSats and AMSAT Amateur Satellite systems.
In TT&C applications, the groundstation transmit- and receive-functions are commonly co-located at the same site and use the same antenna.
In AMSAT communications, the link via a satellite is established between two stations, where different electrical and propagation conditions may apply. In future revisions, RFCLB will be supplemented accordingly.

Before downloading the RFCLB Workbook ...

      Please, consider the following:
  • RFCLB requires Microsoft Excel® 2016, or higher, or Microsoft 365 on PC-Windows. RFCLB is incompatible with Excel on Macintosh operating systems.
  • RFCLB uses Visual Basic for Applications (VBA), the programming language built into Excel; VBA-macros must be allowed to run. With disabled macros, RFCLB would not work. (RFCLB has been verified to be virus-free. If preferred for added confidence, the user can subject the RFCLB Excel file to local anti-virus software before loading into Excel.)
  • Export/Import and auxiliary functions are disabled in the downloadable RFCLB version; they can be enabled on request.
  • The downloaded RFCLB Workbook can be re-started up to 100 times.
  • For advice how to unblock files downloaded from the internet, please click here.

Download the latest RFCLB version (zip-file, 3.2 MB)
here: RFCLB_R5b.zip



     Keep Going
  • Latest RFCLB Revision, and Month:
  •   RFCLB Rev. 5β, August 2020.

References

  1. RFCLB, a short demonstration (MP4-movie; 8:22min, no audio, 114MB).
  2. Interface Control Table (ICT) Templates for the RFCLB Workbook, (pdf-version, for information).
  3. Bernhard Sklar, Digital Communications, Fundamentals and Applications, 2nd Edition, Prentice Hall PTR, 2001; (Chapt. 5: 'Communications Link Analysis').
  4. Sean Victor Hum, 'Link Budgets' (Basic Introduction), Univ. Toronto, Canada.

Supplement:  RF Transmission Line Loss Calculator

As a supplement to RFCLB, a tool has been developed to support RF-loss calculations in transmission line systems. The accurate assessment of end-to-end losses implied by (long) cable-connections (feedlines) between source and load, is a very common engineering task. The tool can be useful for students in microwave engineering, and for RF practitioners in general. The calculator is suitable at high and also at low RF-frequencies, for which the characteristic impedance of the transmission line must be considered as a complex value. This makes the tool useful especially also for HAM Radio Amateurs.

RF Transmission Line Loss Calculator
RF Transmission Line System with complex Characteristic Impedance.

The Microsoft Excel® Workbook RF Transmission Line Loss Calculator is available for download (Excel .xlsm-file, 444kB). (Click for a Screenshot.pdf here).
The Workbook requires Excel 2016, or higher. It applies VBA-macros; therefore, it is incompatible with Macintosh Systems.
The file has been verified to be virus-free. If preferred, the user can subject the Excel file to local anti-virus software before loading into Excel. For advice how to unblock files downloaded from the internet, please click here (pdf-file).

Download:  TLine_Loss_Calc_R120.xlsm

  • Revision Log:
  •   Rev. 1.2.0 ; November 30, 2020


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