A Practical Design of Lumped, Semi-lumped & Microwave Cavity Filters

Filters play a critical role in RF and Microwave systems and the type used depends on the application. It is used in the receiver front end to improve selectivity and in transmitter for spurious /harmonic rejection where low insertion loss and narrow bandwidth are the major requirements. This paper, deals with the design of a narrow band cavity filter in L band with centre frequency of 1575.42 MHz. It is planned to use at the front end of a GPS receiver where the system has to withstand the harsh environment of launch vehicle. The cavity filter is designed for the required specification, simulated and optimized using the software Advanced Design System (ADS) and ElectroMagnetic Professional (EMPro).

https://ieeexplore.ieee.org/iel7/7807442/7823972/07824022.pdf

Design of L band cavity filter for GPS receiver

In space missions, geographically separated TTC stations support data reception between launch vehicle and earth in real time. GSO-based INSAT segment can act as telemetry data relay platform between the host vehicle and the ground station. It has better coverage for supporting TTC requirement. Telemetry via INSAT (TIST) is used to overcome the visibility constraints of conventional TTC ground stations, ship-borne terminals and air-borne terminals, especially in the descent phase. TIST covers events in such scenarios without any hindrance by transmitting data to GSO satellite and receiving it back at ISRO earth stations. It employs digital modulation with channel coding for establishing the link from the launch vehicle to satellite. The satellite transponder upconverts the signal and transmits the information in real time to ISRO ground station. The system was tested in the RLV-TD mission of ISRO and transmitted the critical vehicle parameters in real time in order to evaluate the performance of the vehicle. This scheme is the first of its kind in ISRO launch vehicle, where communication is established between a moving launch vehicle and a single satellite in GSO orbit.

K. S. Smitha

Papers

Design of L band cavity filter for GPS receiver

A Novel Strategy for Data Transmission in Aerospace Vehicle Using Space-Based TTC Network—Telemetry via INSAT