How to maximize DUTY with PRBS9 using DTM?

RE: How to maximize DUTY with PRBS9 using DTM?

toshi.g — Mon, 30 Jan 2023 01:19:35 GMT

thank you for your answer.
I understand that this is normal.

RE: How to maximize DUTY with PRBS9 using DTM?

ketiljo — Fri, 27 Jan 2023 10:52:14 GMT

Yes, this is normal. The two peaks you see in the 125kbps spectrum is caused by repeating pattern in the data. It's property of how the coding is done. You'll see this on all BLE transmitters at LR S8.

RE: How to maximize DUTY with PRBS9 using DTM?

toshi.g — Fri, 27 Jan 2023 07:51:19 GMT

Hello,
I used start_tx_modulated_carrier to measure radio waves at communication speeds of

2Mbit, 1Mbit, 500Kbit, and 125Kbit.

I am concerned that the measured waveform at a communication speed of 125 Kbit

is not smooth and has two sharp peaks.

Are these measurement results normal?

That's all for the question.

RE: How to maximize DUTY with PRBS9 using DTM?

ketiljo — Fri, 13 Jan 2023 08:04:43 GMT

[quote user="toshi.g"] 1.When start_tx_modulated_carrier is used, a random value is continuously transmitted with a[/quote]

Correct!

[quote user="toshi.g"] 2. This random value may be treated the same as the value generated by PRBS9.[/quote]

Coreect!

RE: How to maximize DUTY with PRBS9 using DTM?

toshi.g — Fri, 13 Jan 2023 05:54:04 GMT

I understood as follows.
1.When start_tx_modulated_carrier is used, a random value is continuously transmitted with a

duty of 100%.
2. This random value may be treated the same as the value generated by PRBS9.

I would request a certification agency to evaluate using a program that contains start_tx_modulated_carrier.

Thank you for your answer.

RE: How to maximize DUTY with PRBS9 using DTM?

ketiljo — Thu, 12 Jan 2023 11:10:15 GMT

[quote user="toshi.g"]　1.If I use start_duty_cycle_modulated_tx in radio_test, I can set a random value with duty99% and send it.[/quote]

It's better to use start_tx_modulated_carrier as this will give you 100% duty cycle

[quote user="toshi.g"]2.Random value seems to be generated by nrf_rng_random_value_get.[/quote]

Yes, this have random payload

[quote user="toshi.g"] According to the standard, it is necessary to test in a state that gives the worst result.
There is no problem if you can guarantee that the method(nrf_rng_random_value_get) other than PRBS9 is Worst.[/quote]

Yes, this will give the widest carrier bandwidth as the data is random, similar to PRBS9. PRBS is just a method to generate random numbers.

RE: How to maximize DUTY with PRBS9 using DTM?

toshi.g — Thu, 12 Jan 2023 10:12:19 GMT

thank you for your answer.

Q1.
Do you agree with this understanding?
　1.If I use start_duty_cycle_modulated_tx in radio_test, I can set a random value with duty99% and send it.

2.Random value seems to be generated by nrf_rng_random_value_get.

Q2.
I have been requested by a certification body to:

According to the standard, it is necessary to test in a state that gives the worst result.
There is no problem if you can guarantee that the method(nrf_rng_random_value_get) other than PRBS9 is Worst.

Will nrf_rng_random_value_get meet this requirement?

that's all. Answer please.

RE: How to maximize DUTY with PRBS9 using DTM?

ketiljo — Thu, 12 Jan 2023 09:24:20 GMT

Contiguous transmission is not possible with DTM. It will be about 60%

The only possible way to setup a modulated carrier with 100% duty cycle is to use the radio test example from the SDK.

NSC https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/peripheral/radio_test/README.html

nRF5: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/nrf_radio_test_example.html

This is straight forward to use with CLI over UART.