Telemetry, telecommand and safety sub-systems for scientific ballooning from Hyderabad V. Anmireddy * , R. Vasudevan, D. Anand, T.V. Rao, B.V.N. Kapardhi, D. Trivedi, R.K. Manchanda Tata Institute of Fundamental Research, National Balloon Facility, ECIL P.O. Box 5, Hyderabad 500 062, India Received 28 May 2009; received in revised form 27 April 2010; accepted 27 April 2010 Abstract Highly sophisticated balloon-borne scientific payloads have stringent requirement on the telemetry and command system. The devel- opment and fabrication of the on-board TT&C package for telemetry, tracking, command, safety and ranging for these experiments is done in-house at the National Balloon Facility (NBF) at Hyderabad. In the last few years, we have made major improvements both in the ground station and the on-board sub-systems, thereby improving the data quality, data handling speed and the general flight control along with aviation safety. The new system has telemetry data rate up to 1 Mbps. A reduction in weight, power and cost of the reengi- neered on-board integrated package has also lead to the ease of operation during field tests prior to launch and at remote recovery sites. In this paper, we describe the details of the new control package, its flight performance and our plans for portable S-band telemetry and telecommand system to cater to the balloon flights from Antarctic station and long duration balloon flights. Ó 2010 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Scientific ballooning; Telemetry and telecommand 1. Introduction Error free transmission and reproduction of the data from the balloon control instruments and the scientific pay- loads as well as the telecommand uplink are the most impor- tant function in present day balloon-borne experiments. In addition, the aviation safety requirements have become much more stringent with the increase of air traffic in and around Hyderabad. The control instrumentation group at the NBF has been providing this support to the user community since 1971. A brief description of the NBF is given elsewhere (Manchanda, 2006). In early days the con- trol packages were very simple, which comprised of a timer cut-off by using an alarm clock, simple Pulse Code Modula- tion/Frequency Modulation (PCM/FM) telemetry to han- dle 10 kbps data rates using vintage hardware. No safety sub-systems were used and the tracking was done using the- odolite and Met Radar. In 1980, the control instrumentation and safety systems were upgraded to cater to the user requirements and avia- tion concerns. Very High Frequency (VHF) telemetry with data rate up to 40 kbps, VHF telecommand, Medium Fre- quency (MF) beacon, radio sonde and the Met Radar were used for ground tracking. A Global Position System (GPS) receiver for balloon location and height measurement was added in 1996. Due to increasing complexity and the operational requirements of the various experimental balloon-borne payloads, there has been a growing needs for a much more versatile and flexible uplink and the downlink telemetry system which can handle a variety of data types and data rates. In an effort to meet these new requirements, we have made substantial enhancement in our ground station and in the on-board packages. These include S-band telemetry and telecommand system, which can handle higher data rates up to 1 Mbps, an Air Traffic Control (ATC) 0273-1177/$36.00 Ó 2010 COSPAR. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.asr.2010.04.037 * Corresponding author. Tel.: +91 040 27122894; fax: +91 040 27123327. E-mail address: anmi.reddy@gmail.com (V. Anmireddy). www.elsevier.com/locate/asr Available online at www.sciencedirect.com Advances in Space Research 46 (2010) 960–967