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Thread: How far can i go? A model to tell you and show you the distances for diff setups

  1. #1

    How far can i go? A model to tell you and show you the distances for diff setups

    There is some detailed explanation to this model below. It is easy to use and you can only change the parts of it that you are supposed to change so dive in and have a go if you don't want to read the below.
    ******** Here is the link to it ********
    NOTE: After the second fix this now works fine if you have a comma as a decimal place (hello most Europeans!). The graph now is also fully working, plus some other minor improvements.
    On start up you will need to click -Enable Content- to enable Macros for it to work as it has some coding in it to do its thing.

    It looks like this:




    Background: Derrick has made this most excellent thread on the theory behind calculating how far any given setup will allow you to go whilst still maintaining video reception / control link. It has excellent contributions from the likes of IBCrazy and others on this most important topic. To help me ensure i understood it correctly i put the theory into an excel model. I want to share the model with the community as i believe it can help those new to this better understand the theory and it also has plenty of practical applications. I recommend reading at least the first couple of pages of Derrick's thread first before using this model. Any questions on the theory, post over there. Questions on the use of this model, feature / improvement requests (error identifications!) post here.

    Common abbreviations used: Transmitter: Tx, Receiver: Rx, Video: V, Receiver Sensitivity: RS, Radio Control: RC, Link Margin: LM, Decibel: dB

    How does the model work?:
    Very quick recap on the theory in Derrick's thread and its relevance to this model:
    1. The strength of the link between your Tx and Rx (i.e. V or RC Tx and V or RC Rx) for any given distance is described in terms of Link Margin.
    2. When LM =<0 you have lost connection. Therefore you want a setup that has a LM>0
    3. Link margin is measured in dB.
    4. Every factor that effects your link has a dB figure (e.g. a Tx antenna has a gain of 2dB, an Rx one of 11dB, your Tx has a Tx Power of 28dB etc.)
    5. Don't worry if you don't know what a dB is - just think of it as the common currency used to describe components in your system to allow easy calculations in reference to LM.
    6. To calculate LM you need to know, the frequency of the system (e.g. 5.8, 2.4 etc), the sensitivity of your Rx, the power of your Tx, the gain of your Rx and Tx antenna and your distance
    7. With these things known you can also work out the the LM for any given distance
    8. Your aim is to have a setup & distance with a LM ideally of > than 6db, definitely > than 3db, and must be > 0dB.
    9. The reason for wanting this buffer is that there are other factors in your environment that can eat into your link margin. These include radio frequency noise where you are flying, components with lower dB than their manufacturer says they have, reduced dB due to say noise in your aircraft or ground station, atmospheric influence on the link, alien doo daas etc.

    The model itself:
    • You put in the details required to calculate LM for a set of specifications and it will tell you the LM for distances up to 80km.
    • It will tell you at what distances you will reach the drop dead LM of 0db, the be-very-careful distance of 3db and the should-be-much-more-comfortable distance of 6db.
    • For where manufactures specs are typically in dB it asks for them in dB (RS, Tx & Rx antenna gain). For transmitter power you put them in mW and it will convert them behind the scenes into dB.
    • You enter the frequency your system is working in using GHz (or select from the dropdown).
    • You can enter the figures straight in or you can pick from a drop-down list of known manufactures specifications for various bits of kit (grouped by frequency) - with your help this will be added to over time, see below.
    • You can do all of this for up to 5 different scenarios and it will also plot a graph comparing the LM performance
    • If you have something to measure the noise in your area for your frequency (e.g. RFExplorer) then you can put this noise in the model to give you your LM/distances. Do this by setting RS to either the RS or the noise (whatever is the highest - closest to zero)


    What questions can this model help answer for me?: Well two main questions (1) how far should i be able to get for a given setup and (2) - everything else being equal, how does one setup compare to another in terms of the distance i should be able to get? Specific versions of this question:
    • Penetration etc aside, how much impact does changing the frequency i use have on the distance i should be able to get?
    • Which will get me more distance - getting a higher gain antenna or changing my Tx power?
    • What should be the relative increase in distance i get from one Tx compared to another


    Cautions!!!
    • -- This produces only theoretical distances and link margins - other factors may (are likely to!) reduce your range, hence the three bands.
    • -- Check any equations and calculations yourself before you rely on anything in here
    • -- Be aware that some manufacturers products do not work well with others - check FPVlabs for advice or use tried and tested combinations
    • -- Some manufacturers claims on the performance of their gear can be unreliable. Best way is to measure it yourself if you have the kit (e.g. IRC Power Meter), and also take advice from FPVlabs as to whose specs can be relied upon. Any details in here have not been validated


    At the moment the model has some preloaded manufacturers specs for 5.8, 2.4 and 433. If people would like me to add in any other specs then please request that in this thread - provide
    • the dB (or mW) value of the item,
    • the name of the manufacturer / item
    • a hyperlink to where the info was found.
    In the posts below I have listed the details I already have per frequency and will add to those posts as i add to the model with your additions

    $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$
    EDIT: I have built a small local version of my model that works on iOS or OSx - "numbers", so i can run it on my phone and plug in the noise floor number in the field when red of my RFExplorer. Here is a link to it for anyone that has "numbers" and would find this useful. No drop downs, just use the raw figures - change yellow cells only.
    https://www.dropbox.com/sh/3d243zo07d4iw1p/HxUeMbNL-H


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    Last edited by DiscoTuna; 14th May 2014 at 08:54 AM.

  2. #2

    5.8: specs in the model already

    If people would like me to add in any other specs then please request that in this thread - provide: (1) the dB (or mW) value of the item, (2) the name of the manufacturer / item, (3) a hyperlink to where the info was found.

    This is already in the model


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    Last edited by DiscoTuna; 4th February 2014 at 02:47 AM.

  3. #3

    2.4: specs in the model already

    If people would like me to add in any other specs then please request that in this thread - provide: (1) the dB (or mW) value of the item, (2) the name of the manufacturer / item, (3) a hyperlink to where the info was found.

    This is already in the model

    Click image for larger version. 

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    Last edited by DiscoTuna; 4th February 2014 at 02:48 AM.

  4. #4

    2.3: specs in the model already

    If people would like me to add in any other specs then please request that in this thread - provide: (1) the dB (or mW) value of the item, (2) the name of the manufacturer / item, (3) a hyperlink to where the info was found.

    This is already in the model

    Click image for larger version. 

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    Last edited by DiscoTuna; 4th February 2014 at 02:50 AM.

  5. #5

    1.3: specs in the model already

    If people would like me to add in any other specs then please request that in this thread - provide: (1) the dB (or mW) value of the item, (2) the name of the manufacturer / item, (3) a hyperlink to where the info was found.

    This is already in the model:

    Nothing ., but you can of course type your own figures directly into the model.
    Last edited by DiscoTuna; 4th February 2014 at 02:51 AM.

  6. #6

    1.2: specs in the model already

    If people would like me to add in any other specs then please request that in this thread - provide: (1) the dB (or mW) value of the item, (2) the name of the manufacturer / item, (3) a hyperlink to where the info was found.

    This is already in the model

    Nothing ., but you can of course type your own figures directly into the model.
    Last edited by DiscoTuna; 4th February 2014 at 02:52 AM.

  7. #7

    900Mhz: specs in the model already

    If people would like me to add in any other specs then please request that in this thread - provide: (1) the dB (or mW) value of the item, (2) the name of the manufacturer / item, (3) a hyperlink to where the info was found.

    This is already in the model

    Nothing ., but you can of course type your own figures directly into the model.
    Last edited by DiscoTuna; 4th February 2014 at 02:52 AM.

  8. #8

    433Mhz: specs in the model already

    If people would like me to add in any other specs then please request that in this thread - provide: (1) the dB (or mW) value of the item, (2) the name of the manufacturer / item, (3) a hyperlink to where the info was found.

    This is already in the model

    Click image for larger version. 

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    Last edited by DiscoTuna; 4th February 2014 at 02:54 AM.

  9. #9
    Ouwe Zeikerd Carbon's Avatar
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    Umm.. it's admirable your effort but a lot of this can be found online and depends heavily on environment, antennas, setup, ect.

  10. #10
    Yeah - I am aware of some of those models. My model calculates distance considering those factors and does some other things that i have not seen in the other models, particularly around allowing you to easily compare different setups in terms of the range you will get for each. This all comes from me trying to get my head around round this stuff so i built a model to make sure i really get it. I think people will find it useful. Also, unlike the online models, this has all the formulas in for people to look at if they so choose.
    Quote Originally Posted by Carbon View Post
    Umm.. it's admirable your effort but a lot of this can be found online and depends heavily on environment, antennas, setup, ect.
    Last edited by DiscoTuna; 4th February 2014 at 03:09 AM.

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