Contiguous Output Research Articles

A Circular Waveguide Dual-Mode Filter With Improved Out-of-Band Performance for Satellite Communication Systems

This letter presents a novel design for a 3-D-printed circular waveguide dual-mode (CWDM) filter with a modified cavity shape. The modification leads to a wide spurious-free stopband, which is highly desirable for channel separation in waveguide contiguous output multiplexers (OMUXs) in satellite communication systems. The new resonant cavity design is a result of applying shape deformation to a basic circular cavity in order to move away and suppress parasitic modes. A fourth-order Ku-band channel filter with two transmission zeros (TZs) is designed, fabricated by additive manufacturing (AM) in one piece and measured. In comparison with the state-of-the-art design of a stepped CWDM filter, an improvement of approximately 35% wider spurious-free range is achieved.

A flexible system-on-a-chip control hardware for atomic, molecular, and optical physics experiments.

We have implemented a control system core for experiments in atomic, molecular, and optical physics based on a commercial low-cost board, featuring a field-programmable gate array as part of a system-on-a-chip on which a Linux operating system is running. The board features Gigabit Ethernet, allowing for fast data transmission and operation of remote experimental systems. A single board can control a set of devices generating digital, analog, and radio frequency signals with precise timing given either by an external or internal clock. Contiguous output and input sampling rates of up to 40MHz are achievable. Several boards can run synchronously with a timing error approaching 1ns. For this purpose, a novel auto-synchronization scheme is demonstrated, with possible application in complex distributed experimental setups with demanding timing requests.

Stepped Circular Waveguide Dual-Mode Filters for Broadband Contiguous Multiplexers

A stepped circular waveguide dual-mode (SCWDM) filter is fully investigated in this paper, from its basic characteristic to design formula. As compared to a conventional circular waveguide dual-mode (CWDM) filter, it provides more freedoms for shifting and suppressing the spurious modes in a wide frequency band. This useful attribute can be used for a broadband waveguide contiguous output multiplexer (OMUX) in satellite payloads. The scaling factor for relating coupling value M to its corresponding impedance inverter K in a stepped cavity is derived for full-wave EM design. To validate the design technique, four design examples are presented. One challenging example is a wideband 17-channel Ku-band contiguous multiplexer with two SCWDM channel filters. A triplexer hardware covering the same included bandwidth is also designed and measured. The measurement results show excellent agreement with those of the theoretical EM designs, justifying the effectiveness of full-wave EM modal analysis. Comparing to the best possible design of conventional CWDM filters, at least 30% more spurious-free range in both Ku-band and C-band can be achieved by using SCWDM filters.

Message Delay in TDMA Channels with Contiguous Output

In a recent paper [1], Ko and Davis have considered the problem of deriving the exact message delay for TDMA channels with multiple contiguous output. Their analysis yields an expression for the average message delay, under the assumption of a Poisson message arrival process. In the present paper a much more general treatment of the same problem is presented, resulting in a closed form expression for the whole probability generating function of the message delay, which is valid for a general arrival process.

Delay Analysis for a TDMA Channel with Contiguous Output and Poisson Message Arrival

An analysis of the exact delay of a TDMA or a loop communication system with a contiguous output and a Poisson message arrival process is presented. The nonlinear relationship of a contiguous output with arbitrary arrival process can be expressed by an infinite series. In the case of a Poisson message arrival process, the series can be summed to a closed form. The derived result, which is validated by simulation, is a vast improvement over the previously used approximate model of multiple frames with single output.