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DW1000_DEVICE_TX_PWR does not match dw1000_dev_cfg power settings #3

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fjmolinas opened this issue Dec 2, 2020 · 2 comments
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@fjmolinas
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The syscfg for the uwb-dw1000 sets the default TX_POWER for the device to -14.3:

DW1000_DEVICE_TX_PWR:
description: 'Tx Power dBm'
value: ((float)-14.3f)
DW1000_DEVICE_ANT_GAIN:
description: 'Antenna Gain dB'
value: ((float)1.0f)

On the other side the default dw1000_dev_cfg power settings sets a gain of 9dB as the default, but if DW1000_BIAS_CORRECTION_ENABLED is enabled the correction is not based on the configuration settings
in the default config but on the macros DW1000_DEVICE_TX_PWR and DW1000_DEVICE_ANT_GAIN.

.txrf={
.PGdly = TC_PGDELAY_CH5,
//.power = 0x2A4A6A8A,
.BOOSTNORM = dw1000_power_value(DW1000_txrf_config_9db, 2.5),
.BOOSTP500 = dw1000_power_value(DW1000_txrf_config_9db, 2.5),
.BOOSTP250 = dw1000_power_value(DW1000_txrf_config_9db, 2.5),
.BOOSTP125 = dw1000_power_value(DW1000_txrf_config_9db, 2.5)
},

https://github.com/Decawave/uwb-core/blob/c6cf518e39a49f7084b229ee4ed7ab7ee80b2e5d/lib/uwb_rng/src/uwb_rng.c#L1027-L1039

I'm therefore quite unclear on what each of these values mean and what values should be considered for BIAS_CORRECTION

@ncasaril
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ncasaril commented Feb 25, 2021

The DW1000_DEVICE_TX_PWR isn't used. It should be removed. Thanks for pointing this out.

edit: The bias correction does reference this value still as per your comments. However this hasn't been used in a while.
I'd say do not use the bias correction. The receiver do oversteer if you have too much power coming into the antenna creating this bias, but this should only be a problem if you're having the antennas less than say 2m apart and high tx power. You can see if you're oversteering the receiver by checking the rssi.

@fjmolinas
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The DW1000_DEVICE_TX_PWR isn't used. It should be removed. Thanks for pointing this out.

edit: The bias correction does reference this value still as per your comments. However this hasn't been used in a while.
I'd say do not use the bias correction. The receiver do oversteer if you have too much power coming into the antenna creating this bias, but this should only be a problem if you're having the antennas less than say 2m apart and high tx power. You can see if you're oversteering the receiver by checking the rssi.

Hi @ncasaril thanks for the explanation, that clarifies things for me. Cheers!

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