291 Defence Science Journal, Vol. 67, No. 3, May 2017, pp. 291-297, DOI : 10.14429/dsj.67.10365  2017, DESIDOC 1. INTRODUCTION In Flight testing centre, command transmission system (CTS) is used to generate and transmit remote command signals to the airborne vehicle through RF link to execute some functioning inside the vehicle as per necessity in real time fight testing scenario. Real-time command transmission operation requires a very highly reliable and ruggedised platform. The commands transmitted by CTS is received and decoded by on board command reception system at fight vehicle (FV) and the commanded operation is done accordingly. One ground receiver system (GRS) is also needed to monitor the transmitted command and to observe the presence of the command in air. Hence the newly developed GRS system is incorporated with existing software defned radio (SDR) based CTS 1 . The design of GRS entails real-time signal reception, processing as well as evaluation of the received signal. The system also has to make real-time communication with remote control unit (RCU) with various demanded protocols. RCU is utilised for remote operation of the CTS. The system fexibility that incorporates to various modulation schemes need to be made sure for future up-gradation. The CTS has already been developed in SDR 3-5 platform. Hence it can be an outstanding alternative for developing a smart as well as reconfgurable GRS on the same and single SDR platform. Different kinds of CTS systems were utilised for test of different fight vehicles. So, different kinds of GRS systems are also needed for verifcation of functionality of CTS. The recently developed SDR based GRS system incorporated in the same platform where CTS has been developed, resolves the issue of price of design as here just software updation has been required to implement the brand-new GRS system. Quick modelling of various types of complex communication system is possible by using SDR platform now a day 4,5 . FPGA integrated with the compact-RIO platform is being used for development of many real-time applications 6,7 . For optimisation of DSP and memory intensive applications, the receiver procedures have been realised in FPGA 8 . The simulation and design of various modules of receiver are executed in LabVIEW FPGA module of NI’s Flex-RIO system. It helps to simulate different modules of the framework in a quicker way and the important advantage is that the same simulation fts in real hardware implementation. LabVIEW programming is used for a quick prototype. To design the various mechanisms of the GRS system NI Flex-RIO system has been used. The main components of Flex-RIO system are LabVIEW FPGA 6-12 and LabVIEW RT, which makes it happen to realise different modules of the GRS system in faster way. The fxed point data type has been used to improve the resource utilisation in FPGA 13-14 . The GRS system contains a real-time controller (RTC), host computer system and SDR based CTS (Fig. 1.). The RTC delivers a communication interface between remote control unit (RCU) and host computer that incorporates both CTS system and GRS system. Host computer is used for confguration, local mode operation and analysis of intermediate signal processing of the GRS system. A Software Defned Radio based UHF Digital Ground Receiver System for Flying Object using LabVIEW Amiya Ranjan Panda !,* , Debahuti Mishra # , and Hare Krishna Ratha ! ! Institutions Integrated Test Range, Chandipur - 756 025 India # Department of Computer science and Engineering, Siksha ’O’ Anusandhan University, Bhubaneswar -751 030, India *E-mail: amiya87@gmail.com ABSTRACT This study demonstrates the design and implementation of a software defned radio based digital ground receiver system using LabVIEW. In fight testing centre, command transmission system is used to transmit specifc commands to execute some operation inside the fight vehicle. One ground receiver system is needed to monitor the transmitted command and monitor the presence of the command in air. The newly implemented ground receiver system consists of FPGA, RTOS and general processing unit. The analog to digital conversion and RF down conversions are carried out in high speed PCI extension for instrumentation express cards. The communication algorithms, digital down conversion are implemented in FPGAs. The communication system uses digital demodulation and decoding scheme and realised by NI PXI-7966R with Xilinx Virtex 5, SXT, FPGA. The performance of the receiver system has been analysed by linearity measurement of pre-amplifer Gain, Noise fgure, frequency, power and also measurement of sensitivity. The results show successful implementation of the ground receiver system. Keywords: FPGA; LabVIEW; Receiver; Software defned radio; SDR Received : 07 September 2016, Revised : 30 March 2017 Accepted : 12 April 2017, Online published : 24 April 2017