Hi Team,
My customer needs some help with the following questions:
1.The receive sensitivity of CC1125 is low when receiving signals defined by the DMR ETSI TS 102 361-1, which is about -108dbm. Is this due to the lack of a "root rise cosine" filter corresponding to the transmitter at the receiving end of CC1125? If so, what can be done about it? If not, what could possibly cause it?
2.According to the user's guide, we should set the coincident frequency deviation of receiver and transmitter. And we tested when setting different frequency deviation[greater than 0.4khz], the receive sensitivity decreases sharply. Is there any method that the receiver can automatically track the transmitting signal difference of the transmitter within the bandwidth of the channel filter.
3.According to the user's guide, using the FeedBack to PLL [register FREQOFF_CFG] could improve receive sensitivity. We tested all the possible register value, the best receive sensitivity occurs when setting FREQOFF_CFG to 0x38,which is still lower than we close FeedBack to PLL[set FREQOFF_CFG to 0x20], why?
4.Still from the user's guide.we know there is a CORDIC dore inside CC1125,which can get the sampling value of signal amplitude and phase in real time.But the guide is too simple to understand. Register 0x2F84 (ANG1 - Signal Angular after CORDIC [9:8]) and 0x2F85 (ANG0 - Signal Angular after CORDIC [7:0]) store a 10bit phase sampling value.
a. Is the sampling value a signed number or an unsigned number? If it is a signed number, is it expressed in the form of binary complement?
b.What is the Angle range corresponding to the sampling value, 0°~360° or other Angle range?
Any helpis going to be appreciated:)
