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CC1310: Problem in range test measures with SimpleLink cc1310EMK evaluation module kit

Simone Trinchero
Prodigy 155 points
Part Number: CC1310
Other Parts Discussed in Thread: CC-ANTENNA-DK2

Hi,

We have a question about a SimpleLink cc1310 evaluation module kit.

We did some range tests in various conditions (using the default range test firmware).

Talking about RSSI values the problem is that, in open space with a distance of 300 meters, we loose 12-13 dB respect to the expected Friis value (-60 dB), in fact we obtained -72/-73 dB. In one measure we obtained -69 dB (best condition reached).

Have you any ideas to explain this lost? Or any suggestions to improve the RSSI during transmissions ?


Thank you for the help.

  • 0
    TI__Guru**** 317180 points
    Did you do the calculations accoring to the excel sheet found here :e2e.ti.com/.../375556 Have you taken the height above ground into account?

    The actual RSSI is a function of a lot of different variables in the real world. Multipath and fading effects will be dependent on the environment you have the radios in.
  • 0 in reply to TER
    Prodigy 155 points

    hi,
    thank you very much for the informations. We found it very useful.

    I wonder if you can help me to understand some more details:
    -in the excel file, in the section "Mean Effecitive Gain (MEG) of Tx antenna:" may I set the antenna W5017 ? (That is inside the SimpleLink™ Sub-1 GHz CC1310 Evaluation Module Kit).
    -in the same section, what does it mean exactly MEG, could you suggest me where to find some more info on that?
    -Again in the excel file, in the section Attenuation between Rx and Tx: -> Link Margin I don't understand what is and the difference between "none" and "No antenna diversity".

  • 0 in reply to Simone Trinchero
    TI__Mastermind 33590 points

    Hi,

    The Mean Effective Gain (MEG) is basically the mean efficiency of the antenna. This is useful when comparing antennas when the radio unit is not in a fixed position. There is no point in stating an antenna gain or directivity for a particular angle/polarisation when the radio unit is continuously changing positions. 

    Example 1: DN024 antenna (#9) from the CC-Antenna-DK2:

    Peak Gain = 3.52 dBi

    Directivity = 4.47 dBi

    These parameters are relevant for a fixed position.

    If  the directivity is deducted from the peak gain: 3.52 - 4.47 = -0.95 dB then this is the efficiency or the mean effective gain. The measurements are taken for both vertical and horizontal polarisations, 15 degree steps for the azimuth plane and elevation plane.  

    Example 2: a perfect dipole would have a peak gain and directivity of 2.14 dBi which is 0 dB mean effective gain. Dipoles have nulls towards -15 dB. Depending on the positioning of the dipole antenna, the gain to your link budget can be from -15 dB to 2.14 dB. 

  • 0 in reply to Simone Trinchero
    TI__Mastermind 33590 points
    Link Margin:

    The level of the link margin depends on the level of margin that is required. Theoretically, this can be 0 dB and the radio link will still work. However, a certain link margin should be taken and this is normally in the range of 10 dB to 20 dB.

    For a system that requires a strong and reliable “fail safe” RF link then the margin could be increased furthermore. Similarly, for a system that can accept re-transmissions and temporary link losses then this can be reduced. With multi-path propagation effects, the signal level can vary up to 15 dB so having a link margin >15 dB will take this into account. When not using antenna diversity, the recommended link margin is 20 dB and with antenna diversity this can be reduced to 10 dB link margin.