[TenTec] SDR dynamic range

[Katz Ajamas]

No red seen here :-)

The number of bits specification for an A/D converter usually tells us the
dynamic range of conversion. It rarely tells us the signal handling
capability of the converter. That's buried deeper in the datasheets.

I like extremes as examples.

Consider a 1 bit A/D converter. The bit indicates whether the current
sample is more or less than the sample taken immediately before it..

By sampling at a rate that is many times the highest frequency, we end up
with the number of consecutive unchanged bits representing the time to
change in polarity of the waveform. This can be imagined as a staircase up
and down waveform.

One way we might reconstruct this waveform is by turning a current on and
off with the bits. The voltage(V=Q/C) will depend on the state of the bit,
and the size of the capacitor(and it's discharge rate). If these are chosen
well, the voltage change will approximate the original waveform.

How well it approximates the original depends on the number of steps in the
staircase which is determined by the sample rate relative to the bandwidth.

Google sigma-delta converter for more detailed explanations and sketches.

73, -Bob