bladeRF with Linrad on J61. The effects of incorrect DC offset

bladeRF with Linrad on J61. The effects of incorrect DC offset
(Dec21 2013)

Below are images showing the output from the A/D converters on J61 of the bladeRF with different DC offset voltages.

Figure 1. 600 mV (big errors)
Figure 2. 645 mV (small errors)
Figure 3. 770 mV OK
Figure 4. 895 mV (small errors)
Figure 5. 975 mV (big errors)

The signal is close to the Nyquist frequency, the transformer input does not allow signals at very low frequencies.

The images speak for themselves. 770 is the average of 645 and 895.

Fig. 1. DC offset = 600 mV.

Fig. 2. DC offset = 645 mV.

Fig. 3. DC offset = 770 mV.

Fig. 4. DC offset = 895 mV.

Fig. 5. DC offset = 975 mV.