Does the SDR power consumption vary by # aircraft or is it constant?

FlightAware ADS-B Flight Tracking
1

I was assuming constant but I thought I noticed the 978 SDR being cooler than the 1090.

2

Using a lower sample rate: Around 2 MHz instead of 2.4 MHz.

The maximum data clock for both is the same 2 MHz.
But dump1090-fa does oversampling, dump978-fa does not.

Also i believe the encoding is different.

3

Is the 2MHz max for all SDRs or just the FA versions? I’m using NooElec Smart SDRs.

Also, how do you change the sample rate? Is that in a config file that has to be edited or is it changed through a command prompt like the SDR’s serial#?

4

The sample rate is selected in the programming of dump1090-fa and dump978-fa.

Old dump1090 versions used 2 MHz as well, quite a few less messages received.

5

The R820T2 RTL2832U based RTL-SDRs can sample up to 3.2 Msps, but above 2.4 Msps samples are dropped.

6

Yeah, the modulation is entirely different.

dump978 uses 2.083333MHz because that’s exactly twice the underlying bitrate of UAT which makes the demodulator simpler.