Bias-T enable in 5 x SDR mode

1

Using the KrakenSDR as just 5 x RTL SDR can the standard RTL-SDR driver enable the Bias-T on each receiver, or is different GPIO used ?

2

It’s a different GPIO for each bias tee. But the rtl_bias tee has a generic GPIO option that you can use

rtl_biast -g 1 -b 1

This turns on GPIO 1. -g2 turns on GPIO 2 and so on.

3

Thanks, I figured that all bias-t outputs are controlled by device 0 GPIO
i.e to set CH3 on use ‘rtl_biast -d 0 -g 3 -b 1’ which seems to work.

Is each devices eeprom setting ‘Bias Tee always on’ OR’d with the GPIO or can the bias only be controlled by device 0 GPIO?

4

The bias tee always on EEPROM setting won’t work with the KrakenSDR unfortunately as the bias tee GPIO used in RTL-SDR Blog devices is actually what is used to control the noise source in the KrakenSDR. That RTL-SDR Blog driver has specific features intended only for RTL-SDR Blog devices, not KrakenSDR.

If you need to turn them all on on boot, then it’s probably best to use a script.

5

@dspdave
I recently set up a Kraken SDR to do 5x separate tasks, some of which required Bias-T and some of which did not.
A lot of the steps are poorly (or not at all) documented.

Of note: don’t accidentally turn the noise source on.

My Notes: GitHub - alorman/KrakenSDR-Notes: Notes on Using the Kraken SDR for ADS-B/AIS/LiveATC