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CC2541 BER Test

Ryan Erickson
Intellectual 625 points
Other Parts Discussed in Thread: CC2541

Using the latest v1.3.1 HostTestApp I can perform a  BLE packet error rate (PER) test with the CC2541.  I am now interested in performing an actual bit error rate (BER) test  for BLE so I can check against the specs listed datasheet.  How can I do a BER test?  It would be very useful if there we commands for performing a BER test in the HostTestApp.

  • 0
    Guru 18595 points

    Hi Ryan,

    do not know about special HCI commands but perhaps you could do the BLE's maximum throughput test in the wiki and send, for example, 10000 packets. By capturing all this with the packet sniffer, at the end you can obtain the number of errors in one of the labels. Next, divide the number of errors by the total of bits.

    Just an idea! Have a nice day :)

  • 0 in reply to kazola
    Intellectual 625 points

    Thanks for the idea.  This will not work for what I want to do.  I need to do a BER and be able to do it in an automated test.

  • 0 in reply to Ryan Erickson
    TI__Prodigy 520 points

    Hi Ryan,

     

    You can calculate the BER directly from the PER.  The BT Sig Spec calls for testing sensitivity with a PER limit of 30.8%.  This translates to a BER of 0.1% while using the max BLE packet size (37 octet payload).  I would recommend just testing PER with a pass/fail threshold of 30.8%.

     

    Thanks,

    Chris

  • 0 in reply to Christopher Grajewski
    Intellectual 625 points

    Hello Chris,

    Thanks for the answer.  Can you better explain how the 30.8% PER equates to 0.1% BER?

    For example a max sized BLE packet has 376 bits.  If I miss a packet don't I have to assume I just missed 376 bits? 

  • 0 in reply to Ryan Erickson
    TI__Genius 10955 points

    The calculation is as follows: Assume a model receiver where all the bits have the same error probability and bit errors are statistically independent events. If any bit in the packet, except for the preamble, is incorrect, the packet will be lost, as the access address has to be error-free if the packet is to be received, and the header and payload is protected with CRC. This means that 368 bits have to received error-free for the maximum length packet to be received correctly. If the bit error rate is 0.1%, or 0.001, this means that the packet error rate is:

    1-((1-0.001)^368) = 0.308010241105056