This tool provides the minimum sampling rate to reconstruct a signal with a specified bandwidth.
- Enter the bandwidth of the signal
- Select the Receiver type (either Direct-conversion or Super-heterodyne)
- Enter Baseband or Intermediate Center Frequency
The calculator uses Nyquist to compute the required sampling rate.
Direct Conversion Receiver (Zero-IF)
A signal with bandwidth 125 MHz requires a sampling rate of at least 125 Mega-samples per second (MSPS). Note that this is an IQ receiver so there are two ADC channels each sampling at this rate.
A signal with bandwidth 125 MHz centered at an Intermediate Frequency of 500 MHz requires a sampling rate of at least 1125 MSPS.
A super heterodyne receiver always requires a higher sampling rate than a direct conversion receiver.
The cost of the Analog-to-Digital Converter increases with an increase in sampling rate. This is one of the reasons many cheaper radios use the direct conversion architecture. The flip side however is that the ZIF architecture has DC and IQ offsets that have to be corrected.
Superhet radios by contrast are more expensive but cleaner from a spurious standpoint (no artefacts).
- Sampling Rate – A basic calculator that computes this quantity based on the number of samples collected over a time interval
- Aliasing – if the signal is sampled at lower than the minimum rate, it will be aliased. It is possible to digitize at a lower rate in a super het receiver.