CC1200 Spectrum mask and BW using 2-FSK, operating mode #1

Nikos Karamolegkos

Other Parts Discussed in Thread: CC1200

Hi,

I am working with a remote equipped with the CC1200 for a sub-1 GHz applications. I would like to know what is the theoretical bandwidth and the spectrum mask of CC1200 radio. Where can I find this information?

Thanks,
Nikos

over 7 years ago

0 TER over 7 years ago

TI__Guru**** 317180 points

The spectrum mask is dependent on the type of modulation and the modulation index. I can calculate the OBW given the modulation format, datarate and deviation. Not sure what you mean by theoretical bandwidth, do you mean the RX bandwidth? If that is the case, the receiver filter can be viewed as a brick wall filter and the RX BW is then the same as set in the register.

0 Nikos Karamolegkos over 7 years ago in reply to TER

Prodigy 50 points

For the spectrum mask the modulation is 2-FSK with modulation index=1, data rate 50 Kbps and deviation 50 KHz. I am using SUN PHY layer with 34 channels, channel spacing 200KHz and operating mode #1 (which is 2-FSK). Concerning the bandwidth I would like to know what is the occupied bandwidth that I will see on a spectrum analyzer?

0 TER over 7 years ago in reply to Nikos Karamolegkos

TI__Guru**** 317180 points

For 50 kbps, 50 kHz deviation and 2-FSK the 99% OBW is 174 kHz.

0 Nikos Karamolegkos over 7 years ago in reply to TER

Prodigy 50 points

Thank you. Can you show me how this value is calculated?

0 TER over 7 years ago in reply to Nikos Karamolegkos

TI__Guru**** 317180 points

I measured since I didn't get the script to work. Matlab or similar can be used for the calculation since the output spectrum is close to the theoretical.

0 Nikos Karamolegkos over 7 years ago in reply to TER

Prodigy 50 points

Thank you for your support. I am trying to understand how exactly you calculate this value. What is the OBW for frequency deviation 25 KHz?

0 TER over 7 years ago in reply to Nikos Karamolegkos

TI__Guru**** 317180 points

For FSK a fairly good estimate would be datarate + 2*deviation. For GFSK the actual OBW will be less. Also see e2e.ti.com/.../2127468

What are you planning to use the calculated values for?

0 Nikos Karamolegkos over 7 years ago in reply to TER

Prodigy 50 points

I will make a simulation and I would like the results to be as close as possible to the real word. I used a real time spectrum analyzer today and I measured OBW almost 110 KHz which very close to the theoretical value that you suggest (i.e datarate + 2*deviation). Therefore, for data rate 50Kbps and f_dev=25KHz the OBW will be 100 KHz. Thanks for your help

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CC1200 Spectrum mask and BW using 2-FSK, operating mode #1