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EVM Measurement

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Hi andreaso,

we would like to get a better understanding of your measurement scenario to be able to improve support for your application, as such i've got a couple questions for you:

  • How are you generating that LTE signal?
    • Is this the output of a fully functional base station (or user equipment?) which was picked up over the air (Or using a power splitter)
    • or, alternatively, is this a restricted testing signal which wouldn't be as dynamic as the above and works within limited (fixed) constraints? This question is crucial in determining the complexity of the required decoder. Parameters of interest are:
      • Are you measuring an uplink or downlink channel? (Basestation vs UE)
      • Which physical channels are you interested in (Or all)
      • Which CP configuration are you working with?
      • Which frame types are being used?
      • How are resource allocations handled in your scenario?
    • As a result of the last question, are you trying to characterize the performance of a transmitter or some other part of the chain?
  • Which measurements exactly are you interested in? These are what i have gathered from your post:
    • EVM
    • SNR
    • Frequency error (Note that this measurement will almost certainly require a highly accurate reference clock to be useful, this may be achieved using the GPS Reference option or some other external reference)
    • Phase / Magnitude error
    • Note that BER measurements require knowledge of the underlying data or at least running the demodulated data through the FEC decoders (At "good" SNRs), and are thus much more difficult to make. But if you're doing these measurements at the transmitter there should be no bit errors anyways.

Hi,

The LTE signal is generated by a fully functional basestation and we are measuring the downlink channels. During the testing scenario we feed the signal directly into our analyzer while taking care not to burn it by using attenuators. We also measure 3g and 2g signals. Ideally we want all the measurements you mentioned, which essentially are what a typical MXA will give you. We already  have an extremely accurate clock source which we use as reference. Is this something you can offer as a processing block soon ?

Thank you

 

 

Quote from andreaso on 29/09/2022, 12:01

Hi,

The LTE signal is generated by a fully functional basestation and we are measuring the downlink channels. During the testing scenario we feed the signal directly into our analyzer while taking care not to burn it by using attenuators. We also measure 3g and 2g signals. Ideally we want all the measurements you mentioned, which essentially are what a typical MXA will give you. We already  have an extremely accurate clock source which we use as reference. Is this something you can offer as a processing block soon ?

Thank you

 

 

Additionally I would like to ask whether it's possible to send me a beta version of the EVM measurement block you are working on, just for evaluation purposes. In a few days I will have to make a decision to keep it or send it back and this feature is a must for us.

In the meantime I will try and get an extension on the days I can test before returning it just to have enough time to evaluate it properly.

First results look nice. Need to add some layout and usability thow:

Looks good.I have a few questions...

  • Can you give me a bit more details regarding the signal you are testing ? Will the block work with 2G & 3G signals as well ?
  • Can it provide the frequency and phase error ?
  • Will it automatically detect downlink signals for easier setup of the measurement process ?
  • Are there any presets for 3gpp compliance ?

Step by step. We will see what we can add within the next days but for sure will implement LTE soon.

Recognizes Slots & Sync symbols.
Can display secondary synchronization symbol within constellation chart etc.
Now adding all functions to a new standalone block. More soon!
LT Decoder

Any updates in regards to the release date of this block ?

All needed decoding's and calculations should be in place now.

Working on the final layout:

LTE Decoder

That's really good news. Please keep this thread up to date. I would like to test it as soon as it's available.

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