CC1120: 24bit Preamble, Manchester Receiver

When you write "24bits of 1's,", do you mean 24 bits that will be manchester coded meaning a ...010101... on the air?

If so you should be fine.

Yes, it is sending 1's and 0's

But,

still having problems, can you confirm my RFStudio settings

To verify settings I need to know the full spec of the signal you are trying to receive.

Why is CHAN_BW set to 0x02? 

not sure why the bandwidth is so large.

here is all / most of the information that I have on this project.

The transmitter is based on a Maxim MAX7044 ASK device. It is modulated using a PIC with a bit-banged Manchester stream at 500bps.

The center frequency is 418Mhz. The preamble is 24bits, the Sync is 16 bits (0x2DD4), 72 bits total, repeated several times with a 10ms gap between packets.

I need to make a sniffer using the CC1120. I have attached two captures from the Signal Hound Spectrum analyzer for what i am seeing.

Thanks for your help 

8357.document1.pdfdocument2.pdf

- Could you try to start from the 4.8 kbps setting and just change the datarate? Have you checked that a '1' is power and not the other way?

418Mhz.pdfnot sure what you mean by change the datarate to 4.8 kbps. I don't have the ability to change the xmit parameters.

here is a .pdf of the input to the MAX7044 and the RF output. this shows a '1' is power

Change 4.8 bps to 0.5 kbps on CC1120, keep the other settings as is.

so after many hours of changing register settings and reading thru the forums, I have successfully setup a transmitter that matches the device I am trying to sniff.

I had to send the sync word as part of the data packet, no big deal. I read that the preamble and sync words were not Manchester encoded, that helped.

But, now I am back to the original issue of creating a sniffer at 418 with Manchester.

Below is the register settings of the CC1120, I still cannot detect sync or preamble. Do the register settings look ok

Thx

const registerSetting_t preferredSettings[]=
{
{CC1120_IOCFG3, 0xB0},
{CC1120_IOCFG2, 0x06}, // sync detect
{CC1120_IOCFG1, 0xB0},
{CC1120_IOCFG0, 0xB0},
{CC1120_SYNC3, 0x2D},
{CC1120_SYNC2, 0xD4},
{CC1120_SYNC1, 0x2D},
{CC1120_SYNC0, 0xD4},
{CC1120_SYNC_CFG1, 0x0B},
{CC1120_SYNC_CFG0, 0x0B}, // set to 0x03 for TX
{CC1120_DEVIATION_M, 0x06},
{CC1120_MODCFG_DEV_E, 0x1B},
{CC1120_DCFILT_CFG, 0x1C},
{CC1120_PREAMBLE_CFG1, 0x20},
{CC1120_PREAMBLE_CFG0, 0x2F},
{CC1120_FREQ_IF_CFG, 0x40},
{CC1120_IQIC, 0x46},
{CC1120_CHAN_BW, 0x0A},
{CC1120_MDMCFG1, 0x66},
{CC1120_MDMCFG0, 0x05},
{CC1120_SYMBOL_RATE2, 0x40},
{CC1120_SYMBOL_RATE1, 0x62},
{CC1120_SYMBOL_RATE0, 0x4E},
{CC1120_AGC_REF, 0x20},
{CC1120_AGC_CS_THR, 0xF8},
{CC1120_AGC_GAIN_ADJUST, 0x00},
{CC1120_AGC_CFG3, 0x91},
{CC1120_AGC_CFG2, 0x20},
{CC1120_AGC_CFG1, 0x29},
{CC1120_AGC_CFG0, 0x4F},
{CC1120_FIFO_CFG, 0x00},
{CC1120_DEV_ADDR, 0x00},
{CC1120_SETTLING_CFG, 0x03},
{CC1120_FS_CFG, 0x14},
{CC1120_WOR_CFG1, 0x08},
{CC1120_WOR_CFG0, 0x20},
{CC1120_WOR_EVENT0_MSB, 0x04},
{CC1120_WOR_EVENT0_LSB, 0xFE},
{CC1120_PKT_CFG2, 0x04},
{CC1120_PKT_CFG1, 0x00},
{CC1120_PKT_CFG0, 0x00},
{CC1120_RFEND_CFG1, 0x0F},
{CC1120_RFEND_CFG0, 0x09},
{CC1120_PA_CFG2, 0x7F},
{CC1120_PA_CFG1, 0x56},
{CC1120_PA_CFG0, 0x7E},
{CC1120_PKT_LEN, 0x06},
{CC1120_IF_MIX_CFG, 0x00},
{CC1120_FREQOFF_CFG, 0x22},
{CC1120_TOC_CFG, 0x0B},
{CC1120_MARC_SPARE, 0x00},
{CC1120_ECG_CFG, 0x00},
{CC1120_CFM_DATA_CFG, 0x00},
{CC1120_EXT_CTRL, 0x01},
{CC1120_RCCAL_FINE, 0x00},
{CC1120_RCCAL_COARSE, 0x00},
{CC1120_RCCAL_OFFSET, 0x00},
{CC1120_FREQOFF1, 0x00},
{CC1120_FREQOFF0, 0x00},
{CC1120_FREQ2, 0x68},
{CC1120_FREQ1, 0x80},
{CC1120_FREQ0, 0x00},
{CC1120_IF_ADC2, 0x02},
{CC1120_IF_ADC1, 0xA6},
{CC1120_IF_ADC0, 0x04},
{CC1120_FS_DIG1, 0x00},
{CC1120_FS_DIG0, 0x5F},
{CC1120_FS_CAL3, 0x00},
{CC1120_FS_CAL2, 0x20},
{CC1120_FS_CAL1, 0x40},
{CC1120_FS_CAL0, 0x0E},
{CC1120_FS_CHP, 0x28},
{CC1120_FS_DIVTWO, 0x03},
{CC1120_FS_DSM1, 0x00},
{CC1120_FS_DSM0, 0x33},
{CC1120_FS_DVC1, 0xFF},
{CC1120_FS_DVC0, 0x17},
{CC1120_FS_LBI, 0x00},
{CC1120_FS_PFD, 0x50},
{CC1120_FS_PRE, 0x6E},
{CC1120_FS_REG_DIV_CML, 0x14},
{CC1120_FS_SPARE, 0xAC},
{CC1120_FS_VCO4, 0x14},
{CC1120_FS_VCO3, 0x00},
{CC1120_FS_VCO2, 0x00},
{CC1120_FS_VCO1, 0x00},
{CC1120_FS_VCO0, 0xB4},
{CC1120_GBIAS6, 0x00},
{CC1120_GBIAS5, 0x02},
{CC1120_GBIAS4, 0x00},
{CC1120_GBIAS3, 0x00},
{CC1120_GBIAS2, 0x10},
{CC1120_GBIAS1, 0x00},
{CC1120_GBIAS0, 0x00},
{CC1120_IFAMP, 0x01},
{CC1120_LNA, 0x01},
{CC1120_RXMIX, 0x01},
{CC1120_XOSC5, 0x0E},
{CC1120_XOSC4, 0xA0},
{CC1120_XOSC3, 0x03},
{CC1120_XOSC2, 0x00},
{CC1120_XOSC1, 0x03},
{CC1120_XOSC0, 0x00},
{CC1120_ANALOG_SPARE, 0x00},
{CC1120_PA_CFG3, 0x00},
{CC1120_AGC_GAIN2, 0xD1},
{CC1120_AGC_GAIN1, 0x00},
{CC1120_AGC_GAIN0, 0x3F},
};

Do you need only one receiver or are you going to produce volume with this application? 

" I have successfully setup a transmitter that matches the device I am trying to sniff.": Have you setup this with CC1120? How have you verified that the two transmitters are the same? 

Note that CC1120 does't manchester code preamble/ sync. Hence if the sync word is manchester coded from the transmitter, you have to adjust the sync word you are looking for accordingly. 

I need a single sniffer to replace the one that we are using, the source code has been lost on that device.

the CC1120 version will be rolled into a new product as soon as it ready.

The transmitter that I have running on the CC1120 is being decoded on my legacy sniffer, The legacy receiver is based on a Linx module.

The preamble from the transmitter is 24 ones. Encoded as Manchester, it looks like 0x55 pattern. The sync is 0x2DD4.

So, what you are saying is I need to adjust the sync pattern I am looking for to take into account the Manchester encoding.