• State Resolved
  • Locked Locked
  • Replies 11 replies
  • Answers 2 answers
  • Subscribers 32 subscribers
  • Views 1373 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

IWR6843: Information needed to calculate link budget with 6843 EVM series

HOGYUN RYU
Intellectual 345 points
Part Number: IWR6843
Other Parts Discussed in Thread: , , , IWRL6843

Hello, how are you?

I am trying to calculate link budget for a radar system by using IWR6843(with ISK EVM ant) and IWR6843AOP.

During that, I have few questions to get it.

Q1.
Normally in radar system, link budget is determinded with Power, Losses and Ant Gain of T/Rx.
However, I can't find some values in datasheets of 6843 and 6843AOP, especially receiver gain of 6843AOP.

Q2.
In TI mmwave radar system, I guess there is a minimum received power for signal processing like receiver sensitivity.
But I don't see it in datasheets.
Is there the specification information of IWR6843 & IWR6843AOP?

Q3.
In mmwave sensing estimator & datasheets of 6843(AOP), there is a difference of transmitter output power.
Output powers of 6843 and 6843AOP are both 12 dBm in the estimator.
But, 6843AOP has 15dBm output power in the datasheet.
Is this the reason why 6843AOP's specification is described as "Single transmitter output power EIRP" not likely just described as "Output power" in 6843's datasheet?
What is the exact difference of the meaning?

Q4.
6843AOP has almost 2 dBi(or dB) of max gain in the figure8-1 in its datasheet.
But, the default value of T/Rx antenna Gain in the estimator is 5.2 dB.
Why it has different gain?

Q5.
In a datasheet of 6843 evm series, there is a unit for radiation pattern of 6843ISK, dBFS.
I don't understand exact meaning of dBFS.
Please describe it to me.

Q6.
Also, figures of EVM's radiation pattern show antenna gain values as combining Tx and Rx.
Could I use the gain values as sumation of T/Rx gain when I calculate link budget?

There are many questions, but I want you to understand me all, please.

Regards

  • 0
    TI__Genius 11850 points

    Hi,

    Thanks for your query. Please allow us a couple to days to respond to your questions

  • 0 in reply to Abhishek Karkisaval
    Intellectual 345 points

    There is more question.

    Q7.
    In the figures of radiation pattern mentioned in Q5, the antenna gain values are around 100 dB for 6843ISK and AOP.

    Are they considered as a sumation of T/Rx gain(antenna gain or/both receiver gain?).

    I wonder how the gain could be around 100.

  • 0
    TI__Expert 3730 points

    Hi, 

    Below is the response for your questions.

    Q1.

    Normally in radar system, link budget is determined with Power, Losses and Ant Gain of T/Rx.

    However, I can't find some values in datasheets of 6843 and 6843AOP, especially receiver gain of 6843AOP.

     

    The table gives the typical range of Receiver gain and Tx output power of xWR6843

    The Rx gain, Noise figure (NF) and 1dB Compression point are related to each other. So, it is a trade of between these three parameters. You can choose the value of gain based on your system requirement along with the values of NF and 1dB compression point. Similar thing is applied for the AOP as well.

    The receiver gain can be adjusted in SDK (Software Development Kit) by changing the configuration file.

    You can download the mmWave SDK from: https://www.ti.com/tool/MMWAVE-SDK

     

    For xWR6843AOP: The table gives the typical range of Receiver gain and Tx output power of xWR6843AOP.

    The IWR6843AOPEVM includes four receivers and three transmitters. At 4-Ghz bandwidth it operates from 60 to 64 GHz, with a maximum output power of 12 dBm and a maximum antenna gain of about 5.2 dBi around 60 GHz.

    You can visit the mmwave resource explorer for further details regarding xWR6843AOP:

    dev.ti.com/.../node

     

    Q2.

    In TI mmwave radar system, I guess there is a minimum received power for signal processing like receiver sensitivity.

    But I don't see it in datasheets.

    Is there the specification information of IWR6843 & IWR6843AOP?

    The minimum received power is a function of many other parameters such as IF bandwidth, Rx antenna gain, Noise figure etc. Hence it cannot be specified.

    Q3.

    In mmwave sensing estimator & datasheets of 6843(AOP), there is a difference of transmitter output power.

    Output powers of 6843 and 6843AOP are both 12 dBm in the estimator.

    But, 6843AOP has 15dBm output power in the datasheet.

    Is this the reason why 6843AOP's specification is described as "Single transmitter output power EIRP" not likely just described as "Output power" in 6843's datasheet?

    What is the exact difference of the meaning?

     

    Output power is the power transmitted by the Tx antenna.

    Single transmitter output power EIRP (in dB) is the power transmitted by one transmitter antenna (in dB) added to the gain of the respective transmitter antenna (in dB).

    For AOP design, consider EIRP values (Output Power in dB + Antenna Gain in dB – Losses in dB) for link budget analysis and for ISK, consider typical values of Tx power and antenna gain.

     

    Q4.

    6843AOP has almost 2 dBi(or dB) of max gain in the figure8-1 in its datasheet.

    But, the default value of T/Rx antenna Gain in the estimator is 5.2 dB.

    Why it has different gain?

    We will come back to you with the response for this question in a few days.

     

     

    Q5.

    In a datasheet of 6843 evm series, there is a unit for radiation pattern of 6843ISK, dBFS.

    I don't understand exact meaning of dBFS.

    Please describe it to me.

    dBFS stands for dB relative to Full-Scale. These values are relative and not the absolute values. It is used for -6dB beam-width calculation.

    For example: -5 dBFS means, the reading is 5dB below the Full-scale reading.

     

     

    Q6.

    Also, figures of EVM's radiation pattern show antenna gain values as combining Tx and Rx.

    Could I use the gain values as sumation of T/Rx gain when I calculate link budget?

    No, you cannot use summation of Tx/Rx gain as the gain values are relative. You need to have absolute values of Tx/Rx gain and power for link budget analysis.

     

     

    Q7.

    In the figures of radiation pattern mentioned in Q5, the antenna gain values are around 100 dB for 6843ISK and AOP.

    Are they considered as a sumation of T/Rx gain(antenna gain or/both receiver gain?).

    I wonder how the gain could be around 100.

    The figure shown in the datasheet gives the relative values of all the Tx-Rx gains combined. They are not the absolute values. These are computed with a Tx and Rx combination together. To calculate the -6dB beam width, you must go 12db (Tx (-6dB) + Rx(-6dB)) below the peak.

  • 0
    TI__Expert 3730 points

    Referring to the Q4, below is the response:

    Q4.

    6843AOP has almost 2 dBi(or dB) of max gain in the figure8-1 in its datasheet.

    But, the default value of T/Rx antenna Gain in the estimator is 5.2 dB.

    Why it has different gain?

    Figure 8-1 in the datasheet of IWR6843AOP shows typical antenna gain plots normalized to boresight at various frequencies for the four receivers in both Azimuth (H-Plane) and Elevation (E-Plane) planes. So, these values are not the absolute gain values for the antennas.

    As this figure depicts, the 62GHz plot has crossed the 0 dB line at 0 degree. It is same for all the plots in fig 8-1.

    The gain values shown in Sensing Estimator are the typical values of the absolute gain of the Rx and Tx antennas. 

  • 0 in reply to Swarnendu Chattopadhyay
    Intellectual 345 points

    Hi,

    From the answers, I have more questions.

    About Q2,
    I understand there are many parameters to consider of minimum received power.
    Could you specify one case with any value fixed for the parameters?
    Or let me know the formular?

    About Q3,
    In according to your answer, the loss from internal Tx port to packaging antenna port is assumed about 3dBm?
    So, to calculate link budget, should I use ERIP of AOP/ISK EVM 12dBm as actual value?

    About Q4~Q7,
    I still need absolute gain values of T/Rx antennas to determine the link budget.
    Should I just use the gain values 7 dB for ISK, 5.2 dB for AOP from the default setting value of the sensing estimator?
    Then, I am going to assume as following.

    Tx power + Tx ant Gain + FSPL + Rx ant Gain + Rx gain + losses(all others) = Rx power

    * Tx power + Tx ant gain = EIRP 12dBm (from estimator)
    * FSPL : well known formular
    * Rx ant Gain : 5.2 or 7 dB (from estimator)
    * losses : TBD
    * Rx gain : 17 dB (from the figure 8-1 of 6843's datasheet in case of when NF is typical, 12dB)

    I want you to correct me if any abnormal.
    Regard.

  • 0 in reply to HOGYUN RYU
    TI__Expert 3730 points

    Hi Hogyun,

    Please find the responses of your queries below:

    About Q2,

    I understand there are many parameters to consider of minimum received power.

    Could you specify one case with any value fixed for the parameters?

    Or let me know the formular?

    Response: - In radar typically, we do not refer to sensitivity levels of a receiver, but just the SNR required for object detection. Based on the threshold set in the detection algorithm the sensor would be more sensitive or less sensitive.

    Basically, from the mmwave IC point of view the receiver noise figure and TX output power are key performance parameters that decide the max range (assuming we are SNR limited and not IF frequency limited). The exact SNR required to detect the object would depend on the object detection algorithm used during processing, so it would vary from user to user and hence there is no one sensitivity number for such devices.

    “Could you specify one case with any value fixed for the parameters?”

    Response: - For the Noise Figure, Rx gain and P1DB, there is no standard formula to relate. It depends on the silicon how they will be related.

    The above plot (for IWR6843) assumes a particular RF gain target setting.

    About Q3,

    In according to your answer, the loss from internal Tx port to packaging antenna port is assumed about 3dBm?

    So, to calculate link budget, should I use ERIP of AOP/ISK EVM 12dBm as actual value?

    No, the losses are not 3dBm.

    Transmitter output power for IWR6843AOP:

    Transmitter Output power for IWR6843:

     

    For the AOP, the antenna resides within the package. That is why, the single transmitter output power for AOP is given as Effective Isotropic Radiated Power (EIRP), that adds the antenna gain (in dB scale) along with the output power.

    Whereas, for IWR6843, the antenna does not reside within the package but developed separately on PCB. So, antenna gain cannot be specified for IWR6843. That is why the transmitter output power for IWR6843 just gives the absolute power without addition of the antenna gain.

    Also, sensing estimator parameter settings for IWR6843AOP needs a little bit of correction. We will consult with the respective team and get back.

    In order to do link budget analysis, consider EIRP values (Output Power in dB + Antenna Gain in dB – Losses in dB) for IWR6843AOP and consider typical values of Tx power and antenna gain separately for IWR6843ISK.

    About Q4~Q7,

    I still need absolute gain values of T/Rx antennas to determine the link budget.

    Should I just use the gain values 7 dB for ISK, 5.2 dB for AOP from the default setting value of the sensing estimator?

    Then, I am going to assume as following.

     

    Tx power + Tx ant Gain + FSPL + Rx ant Gain + Rx gain + losses(all others) = Rx power

     

    * Tx power + Tx ant gain = EIRP 12dBm (from estimator)

    * FSPL : well known formular

    * Rx ant Gain : 5.2 or 7 dB (from estimator)

    * losses : TBD

    * Rx gain : 17 dB (from the figure 8-1 of 6843's datasheet in case of when NF is typical, 12dB)

     

    “I still need absolute gain values of T/Rx antennas to determine the link budget”

    Response: -    RF Specification for IWR6843AOP:

    Tx EIRP (Effective Isotropic Radiation Power) value and the typical EINF (Effective Isotropic Noise Figure), provided in the datasheet itself are the key performance parameters. Link budget can be calculated considering absolute values of Receiver Noise figure and Tx output power but not Rx gain as receiver sensitivity is dependent on the object detection algorithm and thus varies user to user.

     

    “Should I just use the gain values 7 dB for ISK, 5.2 dB for AOP from the default setting value of the sensing estimator?”

    “Rx ant Gain: 5.2 or 7 dB (from estimator)”

    “Tx power + Tx ant gain = EIRP 12dBm (from estimator)”

    Response: - Sensing estimator parameter settings for IWR6843AOP needs a little bit of correction. We will consult with the respective team and get back.

    Also, to get the EIRP number, along with Tx power, Tx antenna gain and losses also need to be considered.

     

    “Rx gain: 17 dB (from the figure 8-1 of 6843's datasheet in case of when NF is typical, 12dB)”

    One question for you: How did you calculate Rx gain to be 17dB?

    Response: - Rx gain is achieved as a sum of RF gain and IF amplifiers gain. The below figure is for IWRL6843. This plot assumes a particular RF gain target setting. Changing the RF gain target can degrade the noise figure. The RX gain needs to be set based on the highest signal level expected at the RX input.

    Above is the NF, In band P1DB vs Receiver gain plot. The plot needs to be updated for IWRL6843AOP. We will get back to you on this.

  • 0 in reply to Swarnendu Chattopadhyay
    Intellectual 345 points

    Hi,

    "One question for you: How did you calculate Rx gain to be 17dB?"

    17 dB is a typo, not 17 then 37.

    In according to the datasheet of IWR6843, there is a typical NF value of 12.

    So I assumed rx gain value around 37dB due to the figure 8-1.

  • 0 in reply to HOGYUN RYU
    TI__Expert 3730 points

    Hogyun,

    I understood. Thanks for the clarification. Please give me feedback on the rest of the responses and let me know if you have any other queries. We will get back to you for the said things after consulting with the respective team.

    Thanks and Regards

    Swarnendu Chattopadhyay  

  • +1
    TI__Expert 3730 points

    Hi Hogyun,

    Briefing the responses for your queries regarding calculation of link budget:

    For IWR6843AOP

    Single transmitter output power EIRP = 15 dBm (It includes Tx output power, Tx antenna gain and losses) IWR6843AOP Datasheet

    Maximum antenna gain = (about) 5.2 dBi around 60 GHz. IWR6843AOP Documentation

    Receiver gain depends on the object detection algorithm used during processing.

    Effective Isotropic Noise Figure (EINF) = 9 dB IWR6843AOP Datasheet

    For IWR6843ISK

    Transmitter output power = 12 dBm IWR6843 Datasheet

    Peak antenna gain = (about) 7 dBi across the operating frequency band of 60 GHz IWR6843ISK Documentation

    Receiver gain depends on the object detection algorithm used during processing.

    Noise Figure = 12 dB IWR6843 Datasheet

    If you need any other information or have any other queries, please let me know.

    Regards

    Swarnendu

  • 0 in reply to Swarnendu Chattopadhyay
    Intellectual 345 points

    Thanks you for the kind answer.

  • 0 in reply to HOGYUN RYU
    TI__Expert 3730 points

    You are most welcome!

    Regards

    Swarnendu