How to get right digree? Nrf52811 direction finding

[miaojb12]

This is the config fun followed。

one sample every 125ns,one ant get 12us =96 samples.

and first 2+32 samples is ignored。

********************************************************************

// 1st ant 96 data of phase
0: -67 -55 -43 -31 -19 -7 6 18
8: 29 42 53 66 77 89 102 113
16: 125 137 149 161 173 186 198 -190
24: -179 -167 -156 -145 -134 -122 -111 -98
32: -86 -74 -61 -49 -36 -24 -12 2
40: 15 27 39 51 62 73 83 93
48: 103 114 124 134 145 157 169 180
56: 191 -198 -186 -174 -162 -149 -137 -124
64: -111 -99 -86 -74 -62 -50 -39 -28
72: -17 -5 8 20 31 42 54 66
80: 78 89 101 113 123 131 137 141
88: 143 141 78 -33 -35 -34 -28 -21

// 2nd ant 96 data of phase

96: -10 7 24 39 49 57 63 72
104: 82 95 110 124 137 150 162 173
112: 185 196 -194 -183 -171 -159 -148 -137
120: -127 -116 -104 -93 -81 -68 -57 -45
128: -34 -22 -10 4 15 27 39 51
136: 64 76 88 100 112 123 136 148
144: 160 172 184 195 -194 -183 -172 -160
152: -149 -137 -125 -111 -99 -87 -76 -65
160: -54 -43 -32 -20 -8 5 17 28
168: 40 52 65 77 89 100 112 124
176: 137 149 161 174 186 198 -192 -181
184: -171 -161 -150 -141 -131 -122 -113 -103

// 3rd ant 96 data of phase

192: -94 -84 -73 -61 -47 -35 -21 -8
200: 7 21 35 48 62 74 86 99
208: 111 122 134 147 158 171 181 193
216: -197 -187 -176 -165 -153 -140 -128 -117
224: -106 -94 -82 -71 -58 -46 -34 -23
232: -12 2 14 26 39 51 63 75
240: 88 100 112 124 136 148 159 172
248: 183 196 -193 -181 -169 -158 -147 -135
256: -124 -113 -101 -89 -77 -65 -54 -43
264: -32 -21 -11 2 14 25 38 51
272: 63 76 88 99 109 117 120 117
280: 109 97 84 75 71 71 76 86

// 4th ant 96 data of phase

288: 99 114 128 140 150 159 169 180
296: 192 -196 -183 -171 -159 -148 -136 -124
304: -112 -100 -87 -75 -62 -49 -36 -24
312: -13 -2 10 20 31 42 54 65
320: 78 90 102 114 125 137 148 161
328: 173 184 197 -193 -182 -170 -159 -147
336: -136 -125 -114 -102 -90 -78 -66 -54
344: -41 -28 -16 -4 10 21 34 46
352: 58 70 81 93 104 115 126 138
360: 150 162 174 186 198 -191 -181 -169
368: -158 -146 -133 -121 -108 -94 -78 -58
376: -35 -14 6 19 31 41 52 63

// 5th ant 96 data of phase

384: 76 89 103 116 126 136 146 155
392: 165 175 184 194 -196 -186 -175 -164
400: -153 -142 -130 -119 -108 -96 -85 -73
408: -61 -48 -35 -22 -9 4 16 28
416: 40 52 64 75 87 99 111 122
424: 134 146 158 170 181 193 -197 -185
432: -174 -163 -152 -140 -128 -117 -105 -92
440: -80 -68 -56 -44 -31 -19 -8 6
448: 18 30 42 54 67 78 90 103
456: 115 126 138 150 163 175 186 198
464: -190 -179 -166 -154 -141 -129 -117 -106
472: -94 -82 -71 -59 -48 -36 -25 -13

********************************************************************
void or_cfg()
{
NRF_RADIO->DFEMODE = RADIO_DFEMODE_DFEOPMODE_AoA;
NRF_RADIO->DFECTRL1 = 1<<RADIO_DFECTRL1_SAMPLETYPE_Pos| // 1:MagPhase 0:IQ
//--time 10*8 us
10 << RADIO_DFECTRL1_NUMBEROF8US_Pos |
//--crc behind
1 << RADIO_DFECTRL1_DFEINEXTENSION_Pos |
//--1:4us 2:2us 3:1us --> one sample len
2 << RADIO_DFECTRL1_TSWITCHSPACING_Pos |
1 << RADIO_DFECTRL1_TSAMPLESPACINGREF_Pos |
6 << RADIO_DFECTRL1_TSAMPLESPACING_Pos ;

//NRF_RADIO->DFECTRL2 = ((-32<<16)&0xfff0000)| //sample
// 0<<0; //switch

NRF_RADIO->CTEINLINECONF = 1 << RADIO_CTEINLINECONF_CTEERRORHANDLING_Pos |
0 << RADIO_CTEINLINECONF_CTEINFOINS1_Pos;

//DFE pin config
NRF_RADIO->PSEL.DFEGPIO[0] = ANTE;
NRF_RADIO->PSEL.DFEGPIO[1] = ANTS;
NRF_RADIO->PSEL.DFEGPIO[2] = ANTW;
NRF_RADIO->PSEL.DFEGPIO[3] = ANTN;

NRF_RADIO->SWITCHPATTERN = 1;//--for data recv
NRF_RADIO->SWITCHPATTERN = 1;//--for ref
NRF_RADIO->SWITCHPATTERN = 1;//--4us temp about 32 samples

NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;//5
NRF_RADIO->SWITCHPATTERN = 1;

NRF_RADIO->SWITCHPATTERN = 2;
NRF_RADIO->SWITCHPATTERN = 2;
NRF_RADIO->SWITCHPATTERN = 2;
NRF_RADIO->SWITCHPATTERN = 2;
NRF_RADIO->SWITCHPATTERN = 2;//5
NRF_RADIO->SWITCHPATTERN = 2;/**/

NRF_RADIO->SWITCHPATTERN = 4;
NRF_RADIO->SWITCHPATTERN = 4;
NRF_RADIO->SWITCHPATTERN = 4;
NRF_RADIO->SWITCHPATTERN = 4;
NRF_RADIO->SWITCHPATTERN = 4;//5
NRF_RADIO->SWITCHPATTERN = 4;

NRF_RADIO->SWITCHPATTERN = 8;
NRF_RADIO->SWITCHPATTERN = 8;
NRF_RADIO->SWITCHPATTERN = 8;
NRF_RADIO->SWITCHPATTERN = 8;
NRF_RADIO->SWITCHPATTERN = 8;//5
NRF_RADIO->SWITCHPATTERN = 8;
//-------------------------------------
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;//5
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;
NRF_RADIO->SWITCHPATTERN = 1;

NRF_RADIO->DFEPACKET.PTR = (u32)df_buf;
NRF_RADIO->DFEPACKET.MAXCNT = O_sizeof(df_buf);
}

[Dmitry]

Hi,

could you visualize your data as a plot or at least put CSV here? It's really hard to parse tons of digits in the head 

From your config - all 96 samples falls under the first antenna - we won't see any phase change.

IMHO switch pattern is too complex and outstretched, you should use as short switching slot as your antenna switching IC allows, ideally not longer than 2 usec (longer slot -> more crystal jitter influence -> lower accuracy). That's why reference period is separated - you have enough time on a single antenna to calculate frequency offset, and you have no chance to do that with two samples (4us sample spacing) - at least 8 samples are needed.

[miaojb12]

yes, your are right aboat -360/+360 degree turnover.
we resove it .
1:Straight line fitting with 1st and 5th ant, get slope1 and slope5.
2:slope_average=(slope1+slope5)/2. maybe this slope is a nearly one with true slope.
3:while(slope_green - slope_average > 360degree/48us){
slope_green -= 360degree/48us;
}
while(slope_green - slope_average <- 360degree/48us){
slope_green += 360degree/48us;
}
4:slope_green is not turnover now .
//----------------------------------------------------------------------
we have tested about slope_average and slope_green.
slope_green is much more stable than slope_average.

dynamic range
slope_green <0.2%
slope_average <1%

but now, we did not get the right phase .
we don't knoue if there something wrong with hardwear.

//-------------------------------------------------------------------
PS:Do you mean the jitter is random.
but, In my mind, we take more data, just for reduse the fluctuations of jitter,
is not it?

[Dmitry]

miaojb12 said:

but now, we did not get the right phase .
we don't knoue if there something wrong with hardwear.

I cannot say anything more with no info... it would be good if you can take two sample sets in CSV format under two different angles.

miaojb12 said:

but, In my mind, we take more data, just for reduse the fluctuations of jitter,
is not it?

Yes, averaging works, but longer distance between samples increases error (that's what I see on my device, though you may have better crystal) - if you can get rid of it just by decreasing slot length, I see no reasons to work with such a long slots. See what I mean:

[miaojb12]

Just like your PIC mean,I don't think BLE will work find.

I think crystal will change with temperature, but it changed slowly.

In a shot time, crystal is must be same frequency,this is base of PLL working

[Dmitry]

Jitter is the real fact. My pic is a bit exaggerated. Okay, if it's not an issue for you.

Do you have any success in phase detection?