Which n Value (3, 4, or 5) Should Be Used for nRF54L15 Bluetooth Qualification Intermodulation Testing?

[muratec_icc]

Hello Nordic team,

 

I have a question regarding the Bluetooth LE RF-PHY Intermodulation Characteristics test (Bluetooth Core Specification Vol. 6, Part A, Section 4.4).

The specification states that for the intermodulation test, n can be 3, 4, or 5, and compliance with at least one of these alternatives is required.

While reviewing the nRF54L15 Product Specification, I found the RX intermodulation performance specification listed as "5th offset channel" for both 1 Mbps and 2 Mbps operation. This appears to correspond to the n = 5 condition defined in the Bluetooth Core Specification.

We are currently preparing Bluetooth SIG qualification for an nRF54L15-based product, and the test lab has asked us which n value should be used for the Intermodulation Characteristics test.

Could you please clarify the following?

1. Does the "5th offset channel" specification correspond to n = 5 as defined in Bluetooth Core Specification Vol. 6, Part A, Section 4.4?

2. Which n value (3, 4, or 5) was used for Nordic's Bluetooth SIG qualification testing of the nRF54L15?

3. If Nordic qualification data is referenced or reused, should the same n value be used for our Bluetooth SIG qualification testing?

Thank you for your support.

Best regards,

[Ressa]

Hello,

Yes. The nRF54L15 Product Specification's "5th offset channel" parameters correspond directly to the n = 5 alternative defined in Bluetooth Core Specification.
Nordic characterizes and qualifies RX intermodulation performance using n = 5 for both 1 Mbps and 2 Mbps operation. This is consistent with the parameter naming in the Product Specification and with Nordic qualification practice on other nRF5-series devices (e.g. nRF5340).

Since Bluetooth Core Spec only requires passing one of the three alternatives (n = 3, 4, or 5) , and different data rates may even use different alternatives , your test lab is not obligated to match Nordic's choice exactly. That said, if you are inheriting or referencing Nordic qualification data/QDID for the RF-PHY layer (unmodified RF front end), using n = 5 keeps your results consistent with the characterized data in the Product Specification and avoids any ambiguity.


Best regards,