Portable Fast Sampler

A low-cost fast sampling system has been developed for astromical observations. The system has been used at the Arecibo Observatory, NASA's tracking station in Madrid (DSS-63), the NRAO VLBA antenna in St-Croix, and the NRAO 100-m Green Bank Telescope. This sampling system has been replicated in four copies at JPL for NASA's tracking stations in Goldstone, California (DSS-14, DSS-13, DSS-12, and DSS-25) where it is used extensively for asteroid, Mercury, and Venus observations. This page is a collection of example data acquired with the portable fast sampler at various stages of its construction.


Binary asteroid 1999 KW4

Asteroid 1999 KW4 First radar images of an asteroid at less than 10 meter resolution. This image of a binary asteroid was obtained at Arecibo on May 27, 2001 with a resolution of 7.5 meters. (R1490 by Margot and Nolan and R1482 by Ostro et al.)


Asteroid 6489 Golevka

Asteroid 6489 Golevka First radar detection of a solar system object at NASA's tracking station in Madrid, Spain. The echo from the asteroid is at the expected frequency of -40 Hz. (PI: J.L. Margot)


Asteroid 1999 JM8

Asteroid 1999 JM8 For a while (before NEAR lowered its orbit close enough to EROS), these were the highest resolution images of an asteroid ever obtained. Observations took place at Arecibo, Aug 1-9, 1999. (PI: S. Ostro)


The millisecond pulsar

The millisecond pulsar Timing of pulsar 1937+21 at Arecibo, showing the pulsar period at 641.9 Hz. (PI: J. Cordes)


The rings of Saturn

The rings of Saturn Saturn's rings observed with the Arecibo radar system at a wavelength of 12.6 cm. (PI: P. Nicholson)


The electron component in incoherent scatter from Earth's ionosphere

The electron spectrum The electron component of the spectrum in incoherent scatter of radio waves by the ionosphere at an altitude of 1000 km during a geomagnetic storm. (PIs: S. Gonzalez, M. Sulzer, R. Behnke)


The sampling system is based on digitizers from Analog Devices, programmable logic devices from Altera, an interface card from EDT, and a fast PCI bus computer. Linux-based PCs are used to control the data-taking systems remotely. The computer clock is set with the Network Time Protocol and the data-taking start is triggered by the observatory 1 PPS. Large SCSI disks are used for data storage.

The available sampling modes are as follows:
Channels Quantization Sampling rate
2 2 5 - 40 MHz
2 4 5 - 20 MHz
2 8 5 - 10 MHz
4 2 5 - 20 MHz
4 4 5 - 10 MHz
4 8 N/A

Many people contributed to this project: Donald Campbell and Edgar Castro provided overall support, Bill Sisk offered many hardware/design suggestions, Jeff Hagen contributed a lot of software (including a Linux driver for the EDT card), Mike Nolan and Arun Venkataraman helped with data storage considerations. Last but not least, the Arecibo electronics department put the system together: Wilfredo Rosado and Ernesto Ruiz were the main players, but I received much help from Jesus Rios and Luis Murray also.


Jean-Luc Margot, November 1999.

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