Minimum Bandwidth Requirement for FCC Certification

[KrishNa]

Hi All,

We are currently in the process of FCC certification for one of our product that uses nRF51822. Our testing house said the the test has failed because of not qualifying the minimum bandwidth requirement.

We used the radio test example provided in the SDK12.2 for this purpose and the radio settings used are as below

1) Tx Power = RADIO_TXPOWER_TXPOWER_Pos4dBm  (4dBm)

2) Frequency = 2402 MHz

3) Mode = RADIO_MODE_MODE_Nrf_2Mbit      (Nrf 2Mbit)

The testing house has sent us the image of the failed results as attached below

and it says like this

According to FCC 15.247,  systems using digital modulation, the minimum 6dB bandwidth shall be at least 500 kHz.

I dont know what went wrong. Please help us to resolve the issue at the earliest as we are approaching the production deadline.

Best.

Krish

[FormerMember]

Which commands you use when setting up the test? When I test here, I use the below commands and get the following result, which is within the 500 kHz requirement:

Commands:

a

2

m

2

p

0

o

 

[KrishNa]

Hi Kristin/nRF Team,

We are awaiting your response. We are stuck at our certification lab and not able to move forward from past week.

Please expedite and help us to resolve the issue earliest.

Update: Do i need to send Constant carrier Tx or Modulated Carrier Tx for FCC.

Thanks in Advance,

Best,

Krish 

[FormerMember]

The code you are using looks fine, except that you should use modulated tx carrier. For testing the bandwidth, modulated TX carrier has to be used. 

"6dB bandwidth" is measured on a modulated signal. When setting up the radio, use radio_modulated_tx_carrier() to generate a signal with a random payload.