CC1200 900MHz Blocking and Selectivity parameters in High Performance mode

Hi,

It changes the Synthesizer parameters which in-tun it effects the phase noise.

How did you test Blocking/Selectivity parameters?

Did you use SmartRFStudio to setup CC1200?

Could you please poet some results for our comparison?

Thanks,

PM

Hi,

What registers are responsible for High Performance mode and Low Performance mode? What CC1200's settings determine High Performance mode and Low Performance modes?

I’m preparing information you requested.

Regards,

Alex

Hi,

If you are using SmartRFStudio, you can see it the changes to the Registers easily. There is a button for High performance and low power mode in SmartRFStudio. I obeserved 3 to 4 registers (FS_DVC0, FS-DVC1, FS_DSM1 changes its values.

Thanks,

PM

 Hi,

Yes, I'm using SmartRf Studio. Could you help me to find this "magic" button (screen shot or Tab's name)?

All registers you mentioned are not documented.

Thanks,

Alex

I upgraded SmartRF Studio and I can see the High and Low performance modes now.

Hi,

I recommend to start with the typical configurations showed in the Device control panel top window for your testing.

For blocking and selectivity tests, please make sure that no noise falls into the desired band from the interferer source. Some thimes we may need to use Notch filter to supress the in-band noise from the interferer source.

Thanks,

PM

Hi PM,

As you requested, some information about our test set up and results:

• The modulated carrier signal was set at -90 dBm into the radio.
• An interfering CW tone was introduced, via an external RF combiner, at specific offset frequencies relative to the carrier.
• The amplitude of the interfering tone was increased to the point where the radio ceased to receive data.
• This test was also performed with the modulated carrier signal set to 3 dBm above the sensitivity floor, with similar observed results.

 Typical measured data – based on 2 radios;

 Modulated carrier @ 912.000 MHz

 19.2 kBps, Frequency deviation=9.6 kHz, RX filter BW=40kHz;  SYNC_CFG0.RX_CONFIG_LIMITATION=0    

± 100 kHz             36 dB

± 200 kHz             38 dB

± 500 kHz             40 dB

± 1 MHz                45 dB

± 2 MHz                60 dB

172 kBps, Frequency deviation=58 kHz, RX filter BW = 230kHz, SYNC_CFG0.RX_CONFIG_LIMITATION=1            

± 500 kHz             44 dB

± 1 MHz                47 dB

± 2 MHz                62 dB

± 5 MHz                68 dB    

Thanks,

Alex

Hi,

It seems the readings are closer to our data sheet mesuremets but we can't compare with our data sheet mesurements because of different settings and data rates.

I propose to do it one of our standard configuration from "Typical Settings" of SmartRFStudio on your setup. For example, you can select 38.4kbps, 2-GFSK, Rx Bw 100KHz, ARIB Std. Then the results can be compared with our data sheet mesurements.

Please make sure no in-band noise enters into the device from the interferer source. The interferer broaband noise level (in the desired channel) should be less than -105dBm (for -90dBm desired channel input) at any level of interferer (even at 0dBm). Sometimes we need to use notch filter in the inerferer path to attenuate the in-band noise from the interferer source.

Thanks,

PM

Thanks.

Does the following formula for AGC_REFERENCE (page 33 of "C1200 User Guide"): 

AGC_REFERENCE = 10 log10 (RX_FILTER_BW) - 92 - RSSI_OFFSET,

include indirectly the DVGA_GAIN parameter? Is the RSSI_OFFSET a final value from the register AGC_GAIN_ADJUST?

Thanks,

Alex 

The RSSI_OFFSET is a function of the DVGA_GAIN. If you go to the cont. Rx tab in SmartRF Studio you will get the RSSI offset we have measured for the datarates we have settings for in Studio.