RFCLB

Downloading the 3 RFCLB Workbooks

♦   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.

Voyager 2
Voyager 2 Spacecraft
(launched on August 20, 1977; Mission Status, NASA/JPL;   Yoyager 2 at LinkedIn)

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'. (Click image to enlarge.)

CubeSat
CubeSats and AMSAT Applications
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.

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 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. (In Microsoft Office, macros from the Internet will be blocked by default. For steps to take to allow VBA macros, please consult the Microsoft article, 28/02/2023. An easy approach to unblock a downloaded file, is described here: Unblock.)
  • The downloaded RFCLB Workbook can be re-started up to 200 times and will expire on December 31, 2024.

Download the latest RFCLB version (zip-file, 4.3MB)
here: RFCLB_R5b.zip

  • Latest RFCLB Revision:
     RFCLB Rev. 5beta   June 08, 2023.

References

  1. RFCLB demonstration (MP4; 8:22min, no audio).
  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; (Chapt. 5: 'Communications Link Analysis').
  4. Sean Victor Hum, 'Link Budgets' (Basic Introduction), Univ. Toronto, Canada.

♦   Transmission Feed Lines   ♦

RF Feed Line System-Loss Calculator (Transducer Power Loss)


Is your software for RF-System design suitable to analyze this example?

RF Feed Line Example

The transmission line with complex characteristic impedance Zo implies a loss between input power P1 and output power P2. The example (values selected for simplicity) can identify software design-tool limitations. What would be the power-loss obtained by your software tool? Is the loss either 1.05dB; or 0.74dB; or 0.35dB; or a different value?
The actual loss is 0.35dB which is less than the matched line loss of 0.6dB for the 100 feet long Feed Line. One might wonder if, or why, such result is correct, or why a software tool might obtain a different (wrong) result. The following tool can provide insight and is a general end-to-end loss-calculator for RF Feed Lines.


As a supplement to RFCLB, a tool has been developed to support system loss calculations in RF Feed Line systems. The accurate assessment of end-to-end losses implied by (long) cable-connections (feed lines) between source and load, is a very common engineering task. The tool can be useful for students in microwave engineering, and for RF engineers in general. The calculator is suitable 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 applications.

RF Feedline Power-Loss Calculator
RF Transmission Line System with complex Characteristic Impedance. (Click image to enlarge.)

The Microsoft Excel® Workbook RF Transmission Line Loss Calculator is available for download as zip-File (1.7MB) including auxiliary files.
The Workbook requires Excel 2016, or higher, or Microsoft 365 on PC-Windows. 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 downloaded file to local anti-virus software. (In Microsoft Office, macros from the Internet will be blocked by default. For steps to take to allow VBA macros, please consult the Microsoft article, 28/02/2023. An easy approach to unblock a downloaded file, is described here: Unblock.)

Download:  TLine_Loss_Calc_R161.zip

  • Latest Revision:
     Rev. 1.6.1beta   October 6, 2023

♦   RF Receiver Cascades   ♦

Rx-System Performance Assessment (Cascade Analysis)

As a further supplement to RFCLB, a tool has been developed for cascade analyses in receiver systems. The assessment of end-to-end system noise performance implied by cascaded active and passive components from antenna to receiver, is a very common task in RF and microwave engineering. The tool can be useful for students, engineers and RF practitioners in general. The calculator is intuitive, and the user is supported by comments inserted in the tool.

Rx-System Cascade Calculator
Rx-System Performance Assessment (Cascade Analysis). Click image to enlarge.

The Microsoft Excel® Workbook Cascade is available for download (Excel .xlsm-file, 1.6MB). The Workbook requires Excel 2016, or higher, or Microsoft 365 on PC-Windows. 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 downloaded Excel file to local anti-virus software before loading into Excel. (In Microsoft Office, macros from the Internet will be blocked by default. For steps to take to allow VBA macros, please consult the Microsoft article, 28/02/2023. An easy approach to unblock a downloaded file, is described here: Unblock.)

Download:  Cascade_R6_5.xlsm



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