# Presentation: 743338

## Code 567 WidebandDownlink TechnologiesJuly 16, 2002Bernard L. EdwardsAssociate HeadMicrowave Systems Branch - Code 567NASA Goddard Space Flight Center

## NASA / GSFC Code 567 WidebandDownlink Technologies

- A number of Code 567 technology development activities have been initiated to increase the available downlink data rates for future NASA missions.
- Ka-Band technology developments include:
- Ka-Band Phased Array Antenna
- Ka-Band Transition Program for the Space Network and Ground Network
- Fourth Generation TDRSS User Transponder with compatible Ku/Ka Upconverter
- Ka-Band downlink for the Solar Dynamics Observatory
- Other technology developments include:
- X-Band Phased Array Antenna (Flown on EO-1)
- High Data Rate Parallel Digital Receiver
- Just Starting to Investigate Optical Communications

## Ka-Band Phased Array Antenna

- The High Rate User Phased Array Antenna (HRUPAA) is a transmit only Ka-Band Phased Array Antenna developed for transmitting data from a low earth orbiting spacecraft to either a ground station or TDRS H,I,J.
- The HRUPAA can support data rates of a few Mbits/second to TDRS H,I,J, and hundreds of Mbits/second to a ground terminal.
- In 1997 GSFC awarded Harris Corporation a $7 M cost-plus contract to provide an Engineering Model (EM) antenna.
- The EM antenna is suitable for ground based testing and demonstration of  the technology, and has been tested in the Goddard Electro-magnetic Anechoic Chamber and Near Field Antenna Measurement Lab.
- The technology is now ready for a flight project to fund construction of a space qualified HRUPAA for an operational demonstration.

## HRUPAA Performance Summary

- 

**25.25 GHz to 27.50 GHz**

- 

**±60 degree scan**

- 

**~ 5.2 kg mass**

- 

**2 dB system compression**

- 

**<12 dB **

**sidelobes**

- 

**750 km orbit**

- 

**33**

** ****dBW**

** ****EIRP**

- 

**~82 W power consumption**

- 

**LHCP, 11 dB cross-polarization isolation**

- 

**55**

**o**

** ****C operational interface temperature**

- 

_**<**_** 50 W dissipated to spacecraft**

- 

**1773 Fiber Optic Command / Control Interface**

## NASA Space Network (SN) and Ground Network (GN) Reference Architecture

## SN and GN Background

- NASA’s Ka-band allocation will support space-to-space and space to ground communications for high rate Earth exploration satellite service
- Space Network (space-space): 25.25 GHz - 27.5 GHz
- Ground Network (space-ground): 25.5 GHz - 27.0 GHz
- NASA has made investments in Ka-band with TDRS H,I,J and associated technology developments
- TDRS H and I are in orbit.  TDRS J is scheduled to launched later this year.
- However -
- NASA’s ground stations (WSC) that supports TDRS H,I,J are not capable of supporting the 650 MHz-wide Ka-band channel.  Currently the SN provides support at S-band and Ku-band.
- NASA’s ground network is currently not Ka-band capable in the allocated frequency band. Currently the GN provides support just at S-band and X-band via direct links to ground stations located worldwide.

## Ka-Band Transition Project

- In early 2000, NASA/GSFC initiated the Ka-Band Transition Project (KaTP) as a first step in transitioning the SN and GN to Ka-band operations.
- Goals of the Project:
- Develop a new SN high rate telemetry service using the TDRS H,I,J 650 MHz-wide channel.
- Develop a GN ground station to demonstrate direct-to-earth Ka-Band operations.
- Provide a test bed within the SN and GN to demonstrate new communications technologies, including high data rate demonstrations (up to 600 Mbps).
- Project Schedule:
- System Design Review occurred in December 2000
- Currently performing hardware acquisition and integration activities
- High data rate demonstrations scheduled for Fall of 2002

## KaTP High Data Rate Demonstration

- KaTP high data rate demonstration will:
- Characterize the performance of the physical return links at rates up to at least 600 Mbps
- GN: Direct-to-earth Ka-band downlink
- SN: return Ka-band link relayed via TDRS H
- Characterize the acquisition and tracking performance of the GN Ka-band antenna.
- Assess the effects of hardware distortion on the overall link.
- Characterize the GN and SN system designs.
- Provide an end-to-end system (i.e., “reference link” or test system) to help characterize new high rate Ka-band hardware.
- The demonstrations will assess the RF link performance via measurements of bit error rate and the signal spectra.

## Ka-Band Downlink for the Solar Dynamics Observatory

- Mission Goal:  Observe the Sun’s dynamics to increase understanding of the nature and sources of solar variability.  Launch scheduled for 2007.
- In-house developed Ka-Band downlink will support continuous 150-200 Mbits/second from GEO.
- Spherical antenna coverage (dual gimballed HGAs).
- Designed to work over entire space-to-ground Ka-band frequency allocation.
- SDO RF System Block Diagram:

- Ka-Band SQPSK
- Modulator/Exciter,
- 26.5 GHz

- 5 W Ka-Band
- Power Amplifier

- Waveguide

- Gimballed 0.5 or 1 m. parabolic dish

- Ka-Band SQPSK
- Modulator/Exciter,
- 26.5 GHz

- 5 W Ka-Band
- Power Amplifier

- Waveguide

- W/G Transfer
- Switch

- Coax
- Transfer
-  Switch

- Gimballed 0.5 or 1 m. parabolic dish

- 75-100 Mbps

- 75-100 Mbps

- I

- Q

- I

- Q

- LHCP or
- RHCP

- LHCP or
- RHCP

- 75-100 Mbps

- 75-100 Mbps

## Preliminary SDO Ka BandDownlink Calculation

## EO-1 X-Band Phased Array Antenna

**Characteristics:**
**Weight:****	****	****	****5.5 kg**
**Envelope:****	****	****25 x 36 x 15 cm**
**Prime Power:    ****	**** ****	****45 W**
**EIRP:****	****	****	****> 22 dBW at all scan angles**
**Frequency:****	****	****8.225 GHz**
**Bandwidth:****	****	****400 MHz**
**Data Rate:****	****	****105 Mbps**
**Scan Angle:****	****	****± 60 deg**
**Temperature: ****	****	****0 to 40° C**
**Command Interface:****	****Mil Std 1773 Fiber Optic**
**Developed by Boeing in Seattle, WA**
**64 elements @ 45 mW/element**
**Integral beamsteering controller (Litton RSN)**
**Space qualified: radiation, shock, vibration**
**Launched November 2000**
**Downloading ~200 Gbit/day**

## High Data Rate Parallel Digital Receiver

**  **Demodulates and bit synchronizes:
-  BPSK, QPSK (regular or staggered ) and potentially 8-PSK and 16-QAM modulations
-   Supports balanced and unbalanced power between I and Q channel
-   100 Kilo-bits per second to 300 Mega-symbols per second per channel (600 Mbps QPSK)
-   Tracks dynamic carrier phase and symbol timing with Doppler rates up to 1% of the date rate
-   Produces 10 bit soft symbols or one bit hard decision
-   Implementation loss less than 2 dB
-   Input: Down converted analog signal at bandwidths up to 300 MHz
-   Operates in a PCI slot of a standard personal computer

## Conclusion

- Code 567 is developing technologies to increase the downlink data rates for future NASA missions.
- Technology development efforts are currently concentrated on Ka-Band.  Depending on the specific mission requirements, some technology is available today.
- The branch is just starting to investigate optical communications for high data rate missions to be launched in the next decade.