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gy299
Level 1
Level 1
First like given First question asked Welcome!

Hello there,

 

I recently got a BGT60TR13C DEMO board for my research. I have downloaded the Python API and the radar fusion GUI, which both work well and are quite useful. However, I have some questions regarding the parameters of the radar sensor itself. For real-time applications, I need to know more about the chirp and frame design. Below is a screenshot of my configuration of the sensor:

gy299_0-1702029946501.png

As you can see, now we have some known parameters:

chirp_repetition _time = 591μs

frame_repetition_time = 0.04 sec

ADC_sampling_frequency = 2 MHz

num_samples_per_chirp = 64

num_chirps_per_frame = 64

 

However, I have some confusions in the following questions, could you confirm whether my understanding is correct? If not, could you provide the right answer?

a) The chirp repetition time here is actually the up-chirp time + the inter-chirp idle time, right?

b) As ADC_sampling_rate * num_samples_per_chirp = 32 μs, comparing with the chirp_repetition_time 591 μs, this is weirdly small. Does that mean the up-chirp time is actually 32 μs and the rest of the time is just the inter-chirp idle time? In this case, the sensor's duty cycle is less than 10%, this can't be true. Is there a possibility that the actual up-chirp time is a fixed value and it is much longer than my calculation, you are just sampling some of the data from the start of the chirp based on the setting of num_samples_per_chirp? Where can I find these parameters, such as the actual up-chirp time, inter-chirp idle time, and the inter-frame idle time?

c) As chirp_repetition_time * num_chirps_per_frame = 0.037824 sec, so the inter-chirp idle time is : frame_repetition_time - 0.037824 = 0.002176 sec. Is this correct? Did I miss anything in the calculation?

d) Is there a way to get the actual time index of each ADC data point? Or you normally just use the entire frame data as one measurement of range-doppler and the small time differences in real-time can be neglected? In this case, it is equivalent to getting 25 measurements per second, and the time index for the measurement is simply  0.04 * chirp number.

e) This question is specifically related to the python api. The rx_mask will determine which receiver is activated. For example, When rx_mask = 1, the R1 is activated. But how this actually works? It seems like rx_mask = 7 will activate all receivers 1,2, and 3. What if I want to select receiver 2 or 3 solely?

 

Thank you very much for your time and patience, and I am looking forward to your replies.

 

Best regards

 

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1 Solution
Honey_D
Moderator
Moderator
Moderator
5 comments on blog 50 likes received 250 replies posted

Hello @gy299 ,

  1. All the radar parameters are processed and evaluated in terms of chirp. A chirp is a signal whose frequency varies with time and can be depicted as shown below:
    Honey_D_0-1702276343219.png

    the PRT or chirp repetition time is the time interval between two consecutive tchirp_start i.e. chirp execution starts. 

  2. The ADC sampling rate fadc defines how fast the samples are acquired and has therefore a big influence on the sampling time Tadc during which the ADC acquires data. The total time spent executing a single chirp is represented as Tramp. The idle time between consecutive chirps is represented as Tpre_ramp and is also referred to as shape end delay. For further detail please refer to Section 3 Shapes, Frames, and Channel Set Definition from datasheet 

  3. The interchirp idle time is described in datasheet section 3.1 on how the shape of the chirp is formed, what you are referring is the frame repetition time is the period also called frame time is the time interval between the beginnings of two consecutive frames, which is calculated as 
    frame_time=number_of_chirpsPRT+frame_end_delay

  4. You can use ifxdaq to get timestamp for each sample https://community.infineon.com/t5/Radar-sensor/BGT60TR13c-ifxdaq-radar-timestamp-issue/td-p/624811  time stamp possible. Regarding the processing for range doppler map, complete frame is considered while processing the data, you can read more about same in section Algorithm supported by Radar SDK 

  5. You can select the receiver antenna in Radar Fusion GUI as shown in figure:
    Honey_D_1-1702277902714.png

    The rx_mask is can be used to activate multiple antennas as per the requirement. The combination are described as: 

    Honey_D_2-1702280878742.png
    Please refer to fileradar_sdk/doc/html/pg_radarsdk_json.html#json_device_config for more details on the configuration parameter

For further details on parameters of radar systems, please refer to RFS SDK Documentation from radar_sdk/doc/html/index.html, you can get the details once you install RDK

Hope this helps!
Best Regards,
Honey

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2 Replies
Honey_D
Moderator
Moderator
Moderator
5 comments on blog 50 likes received 250 replies posted

Hello @gy299 ,

We are looking into the query and will get back to you as soon as possible

Regards,
Honey

0 Likes
Honey_D
Moderator
Moderator
Moderator
5 comments on blog 50 likes received 250 replies posted

Hello @gy299 ,

  1. All the radar parameters are processed and evaluated in terms of chirp. A chirp is a signal whose frequency varies with time and can be depicted as shown below:
    Honey_D_0-1702276343219.png

    the PRT or chirp repetition time is the time interval between two consecutive tchirp_start i.e. chirp execution starts. 

  2. The ADC sampling rate fadc defines how fast the samples are acquired and has therefore a big influence on the sampling time Tadc during which the ADC acquires data. The total time spent executing a single chirp is represented as Tramp. The idle time between consecutive chirps is represented as Tpre_ramp and is also referred to as shape end delay. For further detail please refer to Section 3 Shapes, Frames, and Channel Set Definition from datasheet 

  3. The interchirp idle time is described in datasheet section 3.1 on how the shape of the chirp is formed, what you are referring is the frame repetition time is the period also called frame time is the time interval between the beginnings of two consecutive frames, which is calculated as 
    frame_time=number_of_chirpsPRT+frame_end_delay

  4. You can use ifxdaq to get timestamp for each sample https://community.infineon.com/t5/Radar-sensor/BGT60TR13c-ifxdaq-radar-timestamp-issue/td-p/624811  time stamp possible. Regarding the processing for range doppler map, complete frame is considered while processing the data, you can read more about same in section Algorithm supported by Radar SDK 

  5. You can select the receiver antenna in Radar Fusion GUI as shown in figure:
    Honey_D_1-1702277902714.png

    The rx_mask is can be used to activate multiple antennas as per the requirement. The combination are described as: 

    Honey_D_2-1702280878742.png
    Please refer to fileradar_sdk/doc/html/pg_radarsdk_json.html#json_device_config for more details on the configuration parameter

For further details on parameters of radar systems, please refer to RFS SDK Documentation from radar_sdk/doc/html/index.html, you can get the details once you install RDK

Hope this helps!
Best Regards,
Honey