1 / 20

Involvements & Associations:

Extensive involvement and support in the ongoing “LASE” program Major responsibility of developing electronics for “HEXIT” payload Association with the forthcoming “LAXPC” balloon flight program Involvement in other developments and activities which come up from time to time.

mason
Download Presentation

Involvements & Associations:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Extensive involvement and support in the ongoing “LASE” program Major responsibility of developing electronics for “HEXIT” payload Association with the forthcoming “LAXPC” balloon flight program Involvement in other developments and activities which come up from time to time Involvements & Associations:

  2. Hexit Detector Detector assembly (Rear View) Detector assembly (Front View) Collimator FOV 8.5° X 8.5°

  3. Use of dedicated CSPA IC from Lecroy type TRA1000. Design of compact PCB using SMD’s and fitting of Amplifier directly on the neck of the PMT for improved signal to noise ratio. CSPA charge gain of 200mv/pc (Cf=5pf) Charge Sensitive Preamp: Top view Bottom view

  4. Range of interest for analysis: 20 kev – 800 kev Accept the genuine events in the interested range (fast pulses from NaI crystal),process,digitize. Reject the non genuine events (slow pulses from CsI crystal) Event Processing logic criteria (EPL):

  5. Pulse shape discriminator is a circuit which discriminates the fast rise time pulse (NaI) from the slow rise time pulse (CsI) and generates a logic level (0 state-Fast , 1 state-slow) for the use of further circuits to reject or accept and analyze the event. Pulse Shape Discriminator (PSD):

  6. Technique used for achieving PSD:

  7. Block Schematic of EPL:

  8. Timing diagram of EPL: 8 us

  9. Analysis's genuine events in the range of 20 Kev to 800 kev) Time tags genuine event with an accuracy of 2.5 µsec Highly accurate, stable and reliable time tagging achieved by use of oven controlled crystal oscillator of 12 MHz Records counts for analyzed genuine events, not analyzed genuine events and non genuine events for diagnostics. Wide Dynamic range of the order of 40-50 On board (10 bit, 512 channel) Spectrum information transmitted in telemetry for ease in data analyzing Features of Event processing logic:

  10. Data Buffering and Onboard Spectrum Analysis: On being interrupted by EPL the Digitized data of the 13 tubes and Their sum+ arrival Time info is read and kept in DPRAM for the Telemetry Encoder Depending on the pulse height Info. Of summed data 512 channel Spectrum is stored in the DPRAM in two banks(one bank being transmitted while the other bank being filled)

  11. Testing of the electronics for gain and Temperature stabilty:

  12. Snaps of Event Processing Logic Unit:

  13. Reads various data like Pulse height information, count rate, star tracker data, house keeping data like temperature, pressure, voltages etc. and organizes and transmits the data serially as per the telemetry format Telemetry format comprises of 24 word per frame and 127 such frames comprise a Sub frame. Various house keeping data are multiplexed as per the required telemetry format. The data transmission rate is 100khz Telemetry Encoder:

  14. Telemetry Format:

  15. Telemetry Format (house keeping):

  16. Automatic Star tracker for Balloon borne Instruments:

  17. Automatic Star tracker for Balloon borne Instruments:

  18. RTC chip type DS12287 that has a built in back-up supply to retain data for up to 10 years and requires no external components except the crystal is used, which provides real time, date and calendar for carrying out real time calculations A built in command interface allows changes to all stored parameters, including adjustments to real time clock, during flight. Has a capacity to store precessed coordinates for up to 127 target sources for easy selection during flight. Incorporates 12 bit shaft encoders which gives an angular resolution of ~0.09 in azimuth and zenith. LCD display provided on the front end enables to see various parameters like time, date, actual and calculated coordinates, target being tracked etc., which is vital for carrying out the ground checks and field adjustments. Includes a single chip motor driver (L298) for azimuth and elevation motors (+ 12 volts operation), which is a digitally compatible chip not requiring any additional interface circuit thereby reducing the component count and hence the servicing and maintenance. Salient Features of Automatic Star Tracker

  19. The P based circuits have a tendency to latch-up when faced with situation of handling infinite do loops or transient pick-ups. The solution to such condition is a hard power reset. A Supervisory circuit (watchdog circuit) is built into the system to monitor the functionality of the P. In case of abnormal hang–ups of the P, watchdog circuit forces a power reset to the CPU after some waiting period. As a further redundancy to the above, a Master Reset to the P is also provided through the Ground (Command) Link. In case of Failure in the GPS segment (corrupted data or no lock) the Star Tracker bypasses the data from the GPS and carries out computations using the fixed position coordinates stored in the onboard memory along with the flight plan data or these values can be changed via Ground (Command) Link. Fail Safe Features of Automatic Star Tracker

  20. Snaps of other subsystems: PWM SERVO CIRCUIT TCXO UNIT HV DCDC Unit Telemetry Encoder

More Related