HF radar ADC dynamic range requirements

This paper has examined the feasibility of excluding conventional receivers from HF radar receiving systems and feeding the amplified and filtered output of the receiving antenna directly to the ADC. Provided that adequate filtering is included in the signal path, the SFDR of current commercially available ADCs capable of sampling around 65 MHz (100 dB) determines that in excess of 99% of radar channels could be accommodated. All radar channels would be covered if the ADC SFDR were increased to 120 dB. On the basis of the above analysis it may be concluded that currently available ADC technology offers scope for the ADC to digitise the amplified signal from a HF antenna without the requirement of a conventional receiver. The repercussions for a 400-channel HF radar receiving system are clearly significant and warrant additional work, principally experimental verification. Specifically, digital data collected in accordance with the above requires analysis in order to demonstrate that the original external noise levels characterising clear radar channels have not been degraded to any significant extent by the proposed receiving system.