Abstract
For civil and military applications, the ability to instantaneously capture and process wideband RF (radio-frequency) signal is of great importance. In this paper, a novel photonics-assisted RF channelized receiver aiming for instantaneous broadband RF signal reception is proposed and experimentally demonstrated. The channelizer is composed of two branches. In one branch, an optical frequency comb (OFC) is generated through a phase modulator (PM), while in the other the optical carrier is frequency-shifted via a polarization modulator (PolM) and then modulated by the captured unknown RF signal. Next, the frequency information of the unknown signal is derived from the frequency sum and the power difference of two specific beating tones, while the incorporation of the comb spacing and the amplitude profile of the OFC enable resolving the ambiguity cases. In the experiments, four receiving channels are constructed using five selected comb lines. The reception and analysis of several RF signals including single-tone, multi-tone and linear frequency modulation (LFM) ones within 1-40 GHz are experimentally validated, which can be extended up to 72 GHz in theory. The proposed channelizer is characterized with ambiguous-free capability, low measurement errors less than 2 MHz, and an SFDR of ∼92 dB·Hz2/3.
Highlights
With the rapid evolution of modern microwave systems toward broad bandwidth, high frequency coverage and multiple frequency bands, the reception and processing wideband RF signal are of paramount importance
We proposed and experimentally demonstrated a novel and simple ultra-wideband channelized receiver with ambiguous-free and high accuracy based on an optical frequency comb (OFC)
The lower first-order sideband of polarization-modulated signal is selected by fiber Bragg grating (FBG) to act as the new optical carrier
Summary
With the rapid evolution of modern microwave systems toward broad bandwidth, high frequency coverage and multiple frequency bands, the reception and processing wideband RF signal are of paramount importance. They can be roughly divided into three categories: The first type is instantaneous frequency measurement (IFM) receiver which is based on frequency to power mapping. The most prominent shortcoming of frequency to power mapping scheme is that it can only process single-tone signal. A coherent optical RF channelizer with large instantaneous bandwidth and in-band interference suppression can be seen in [23]. We proposed and experimentally demonstrated a novel and simple ultra-wideband channelized receiver with ambiguous-free and high accuracy based on an OFC. By appropriately changing the comb spacing, ambiguous-free reception can be achieved, as listed in Table 1 for performance comparison
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