Questions about CIR Sample-to-Tap Index Mapping and Secondary Peak after First Path on SR150 Hi, I am using the following device, SDK, and firmware: ・Target device: Murata Type 2BP EVK (NXP Trimension SR150) ・SDK version: v05.11.05 ・Firmware: PNP_RhodesV4_SE_v05.11.05.bin I have two questions regarding the CIR data obtained from the SR150. 1. Relationship between CIR samples and Tap Index Could you please clarify the relationship between the 16 CIR samples obtained from the SR150 and the corresponding Tap Index? As I understand it, the 16 CIR samples, cir[0] through cir[15], do not contain information that directly indicates their absolute Tap Index. Is there a way, or a formula, to determine which Tap Index corresponds to cir[0]? I would also like to understand the relationship between the First Path Index available in the diagnostic information and the array indices cir[0] through cir[15]. For example, if the CIR sampling window is determined relative to the First Path Index, I would like to know how many taps before or after the First Path Index cir[0] corresponds to. 2. Secondary peak observed shortly after the First Path When examining the CIR, I have observed cases where a relatively distinct secondary peak appears approximately 3–4 samples (taps) after the detected First Path. The attached figure shows an example of this behavior. In this example, the main CIR peak is observed around Tap Index 834, while another local peak appears around Tap Index 837, approximately 3 taps later. The secondary peak is highlighted by the red circle in the figure. 20260907.png20260907.png Could you please clarify the possible cause of this secondary peak? In particular, could this be a known or expected response caused by the SR150's internal correlator processing, such as the autocorrelation characteristics of the transmitted/received pulse or sidelobes of the correlation response? Thank you in advance for your support. Best regards, Re: Questions about CIR Sample-to-Tap Index Mapping and Secondary Peak after First Path on SR150 Hi @Ricardo_Zamora, Thank you for your response and for clarifying the support path for the SR150. I understand that the detailed information is under NDA and cannot be shared publicly. I will contact the appropriate module partner or our direct contact regarding these technical questions. Thank you again for your support and guidance. Best regards, Re: Questions about CIR Sample-to-Tap Index Mapping and Secondary Peak after First Path on SR150 Hello,
Hope you are doing well. Sorry for the inconvenience this might cause you but as the information of this product it's under NDA (Non-Disclosure Agreement) the information it's not public.
For more information about the chip could you please contact one of our distributors available in the Distributor Network|NXP? Or if you have any direct contact who helped you getting this device, please contact them.
If you are looking for information about our UWB products or you are interested in this technology, I would recommend you check these Development Kits and Modules from our Partners (Trimension UWB Partners).
In case you are interested in one of these Kits/Modules, you would need to go directly with them to know the process and the support that they can provide them, as the support path for this technology is through them.
The documentation and software are distributed by the corresponding UWB Module partner. By selecting a module, you will be guided to our partner’s page where you can access datasheets, application notes, and the required enablement
Regards,
Ricardo
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