AMSAT-SA Digital Transponder, telemetry and command system. By Anton Janovsky (ZR6AIC) and Cor Rademeyer (ZS6CR)

How do we build a transponder with no power?

Transponder and Telemetry Requirements

Uplink / Downlink Power for transponder 1.2W 5V or 3.3V Sleep mode for no RX (Telemetry only) Telemetry every 60 seconds 1K2 FSK (1s pre tone for phase lock) Over drive beacon beep (ALC) Transponder low power in eclipse 400mW / high power in sun 650mw. OBC Sleep mode and Safe mode. What else ? Frequency Agile RX 435Mhz (120dB gain) TX 1.2Ghz (130dB gain) or 145Mhz (120dB gain) Cmd to enable and disable transponder Cmd to deploy antenna Cmd to change telemetry mode Telemetry CW / FSK 1k2 Telemetry data: transponder status, battery & solar panel voltage, temperatures, transponder status

Constraints Size Power Available Components Cost

Procedure Selecting a low power SDR transponder chipset (AD9361 or LMS6002D) In Loopback mode Selecting a low power Telemetry chip set. (ARM Teensy 3.2 or STM32) Selecting a low power Command chipset (ARM Teensy 3.2 or STM32) Selecting components that will not be affected by radiation and temperature ranges Selecting inter-board connection standard Build prototype PCB with AD9361 or LMS6002D Antennas and Power Supply out of scope. (Using Kletskous configuration)

AD9361 (Digital Transponder) Analogue Devices AD9361 (Digital Transponder) RF 2 × 2 transceiver with integrated 12-bit DACs and ADCs Band: 70 MHz to 6.0 GHz Supports TDD and FDD operation Tunable channel bandwidth: <200 kHz to 56 MHz Dual receivers: 6 differential or 12 single-ended inputs Superior receiver sensitivity with a noise figure of 2 dB at 800 MHz local oscillator (LO) RX gain control Real-time monitor and control signals for manual gain Independent automatic gain control Dual transmitters: 4 differential outputs Highly linear broadband transmitter TX EVM: ≤−40 dB TX noise: ≤−157 dBm/Hz noise floor TX monitor: ≥66 dB dynamic range with 1 dB accuracy Integrated fractional-N synthesizers 2.4 Hz maximum LO step size Multichip synchronization CMOS/LVDS digital interface Loopback / Test Mode

Lime Microsystems SUMMARY FEATURES. LMS6002D Multi-band Multi-standard Transceiver with Integrated Dual DACs and ADCs Single chip transceiver covering 0.3-3.8GHz frequency range Digital interface to baseband with integrated 12 bit D/A and A/D converters Fully differential baseband signals Few external components Programmable modulation bandwidth: 1.5, 1.75, 2.5, 2.75, 3, 3.84, 5, 5.5, 6, 7, 8.75, 10, 12, 14, 20 and 28MHz Supports both TDD and FDD operation modes Low voltage operation, 1.8V and 3.3V

Hypothesis Don't Demodulate and then Modulate but rather forward I Q data. Why ? Staying in original digital format will reduce signal to noise and delay Modulation, demodulation, upconversion, downconversion, and filtering all in a compact, surface-mount electronic package Frequency / mode / bandwidth …. is all configuration and can be changed on the fly. SDR is normally more reliable than conventional components

Styling Digital reduce Signal to noise. Conventional SDR Styling Digital reduce Signal to noise.

Hypothesis support I think this is what’s going to happen because… Complex configuration by chipset providers. Possible long software development time. Chipsets are expensive and chip package is difficult to work with and not easy to solder. 10 mm × 10 mm, 144-ball chip scale package ball grid array (CSP_BGA). Variables that may affect the outcome... PCB design with surface mount chips and multi layers. ARM processor speed and power limitations. Using STM32 or Teensy 3.2 ? Expensive Device ? Power consumption of device?

New SDR no Demodulator and Modulator Max 8Dbm Need amp

Analog Devices Expensive Device ? Chip mount for PCB assembly? Where from here?

Lime Microsystems The LMS6002D is a fully integrated, multi-band, multi-standard RF transceiver for 3GPP (WCDMA/HSPA, LTE), 3GPP2 (CDMA2000) and 4G LTE applications, as well as for GSM pico BTS. It combines the LNA, PA driver, RX/TX mixers, RX/TX filters, synthesizers, RX gain control, and TX power control with very few external components.

Questions? Loop back Mode

Chipset selections Analogue / RF Lime Microsystems Analog Devices Digital /Command and Telemetry. Teensy 3.2 STM32F4

Teensy 3.2 Digital DSP processing. Example of a SSB demodulator. http://www.pjrc.com/teensy/gui/ https://github.com/rheslip/Teensy_SDR http://rheslip.blogspot.co.za/2015/03/teens y-sdr-transceiver-description.html

Teensy 3.2

Teensy 3.2 On Board A/D On Board D/A DSP processing

Ref links Selection Document. https://docs.google.com/document/d/1_2r-B8iiAui_RTj3PwHk-NetWGhnMZxiM9g8XWDqNk4/edit#heading=h.xhayf8hf2wer http://rheslip.blogspot.co.za/2015/03/teensy-sdr-transceiver-description.html https://github.com/F5OEO/rpitx http://ebrombaugh.studionebula.com/radio/txdac/index.html https://www.etherkit.com/rf-modules/si5351a-breakout-board.html http://www.simplecircuits.com/files/Download/QEX_release.pdf http://www.amrad.org/projects/sdr/ https://myriadrf.org/projects/rdk/ http://www.eevblog.com/forum/projects/the-sdr32-a-stm32-based-software-defined-radio/ http://www.stm32-sdr.com/styled/index.html (PSK) https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms2-ebz/software/baremetal?rev=1395324588#code_size_information ( AD9361 NON OS Drive) https://github.com/GomSpace/libcsp (Cubesat Space Protoco) https://github.com/robots/APRS (STM32 APRS code) https://michaldemin.wordpress.com/2012/02/27/cheap-afsk-tnc/ (AFSK stm3 2) https://github.com/athirasubhash/AX25MODEM (AX25 for STM32) www.analog.com/en/education/education-library/videos/3845680080001.html (Video Analog devices) https://datasheets.maximintegrated.com/en/ds/MAX2837.pdf (IQ front end Maxim) https://www.maximintegrated.com/en/products/analog/data-converters/analog-front-end-ics/MAX5863.html (A/D and D/A MAXIM) https://github.com/mossmann/hackrf/blob/master/firmware/common/max2837.c (max2837 c Library) http://www.g4jnt.com/DDSVHFBeaconDriver.pdf (DDS beacon generation)