Real Time RF Range Delay Emulation

This effort investigates and assesses the feasibility of a digital delay-line approach to accomplishing high-fidelity wideband RF range delay emulation. A system architecture combining wideband frequency translation with high-speed A/D and D/A conversion technologies is proposed covering the full 18GHz RF band while supporting 800MHz of instantaneous bandwidth. A digital delay-line implementation can support programmable delays up to tens of milliseconds with 250psec resolution as well as wideband linearity. Our approach to achieving wide linear dynamic range (in excess of 55dB) minimizes signal distortion from several aspects including: (1) the active time-delay mechanism (i.e. discrete-time delay and linear interpolation) has a highly linear transfer function, (2) we exploit recent performance gains in COTS analog / digital conversion technologies including high sample rate / high resolution devices with excellent spur-free dynamic range (SFDR) and Signal-to-Noise Ratio (SNR) (60dB or better), and (3) harness the power of digital signal processing and in-house receiver distortion analysis expertise to accomplish a high degree of equalization and spur rejection to compensate for the distortion of RF/IF analog components. Our digital approach will also provide enhanced features including the ability to apply independent time delays simultaneously to multiple (spectrally non-overlapping) signals within a common instantaneous band.