SWRS046I November 2006 – September 2018 CC1020
PRODUCTION DATA.
The CC1020 device has a built-in test pattern generator that generates a PN9 pseudo random sequence. The PN9_ENABLE bit in the MODEM register enables the PN9 generator. A transition on the DIO pin is required after enabling the PN9 pseudo random sequence.
The PN9 pseudo random sequence is defined by the polynomial x9 + x5 + 1.
The PN9 sequence is ‘XOR’ed with the DIO signal in both TX and RX mode as shown in Figure 5-31. Hence, by transmitting only zeros (DIO = 0), the BER (Bit Error Rate) can be tested by counting the number of received ones. Note that the 9 first received bits should be discarded in this case. Also note that one bit error will generate 3 received ones.
Transmitting only ones (DIO = 1), the BER can be tested by counting the number of received zeroes.
The PN9 generator can also be used for transmission of ‘real-life’ data when measuring narrowband ACP (Adjacent Channel Power), modulation bandwidth or occupied bandwidth.