The shortest integration time of the existing system is limited by the amount of time required to dump all of the data to the computer. The system is capable of an integration time as short as 320 msec. The new interface will dump the data in less than 320 msec. The existing system also wastes a great deal of time changing from a cross-correlator to an auto-correlator as is required during pass-band calibrations. The new interface will make these configuration changes instantaneous.

The digital power meter is a device that measures the zero lag auto-correlation level. This number is used to normalize the correlation function measurement produced by the correlator. Current practice is to estimate this number from an analog power meter on the assumption that the power level did not shift during the integration. The digital power meter will produce a direct measure of the exact number required for normalization.

The existing telemetry is made up of integrated circuits that are no longer available. A lightning strike destroyed a large number of these chips. Fortunately, we had a sufficient number of spares to repair the damage. A replacement design, fully compatible with the old system, is being prepared using programmable logic arrays.

The existing pulsar machine can not measure all four Stokes parameters of a polarized signal. A simple addition to the existing electronics will add this capability while retaining all of its current flexibility.

A simple diode sample and hold circuit with very high input bandwidth can be used to produce digital spectrum analyzers with bandwidths of the order of 30 GHz using readily available inexpensive parts, strip-line techniques and modern pulse forming methods. A modest 10 GHz design is being prepared for potential use in the next generation of spectrum analyzers for radio astronomy.

"The Hat Creek Millimeter-Wave Hybrid Spectrometer for Interferometery" W.L. Urry, D.D. Thornton and J.A. Hudson Publ. Astron. Soc. Pac., Vol. 97, pp. 745-751 Aug. 1985

Also in:

Instrumentation and Techniques for Radio Astronomy edited by Paul F. Goldsmith IEEE Press.

"The New Bima Correlator (Based on the Bos Chip) and Its Internal Calibration" W.L. Urry, J.A. Hudson, W.J. Welch and D.D. Thornton New Generation Digital Correlators Workshop Proceedings N.R.A.O. Tucson, Arizona Feb. 93.

Memo # 20 "Deformation of Antenna # 3 Using Structural Analysis," W.L. Urry, 23-Jul-87.

Memo # 49 "Correlator Normalization With Power Level Change," W.L. Urry, 5-Sep-96.

Memo # 63 "Proposal for a Wide-Band Digital Correlator," W.L. Urry 5-Jan 1998.

Memo # 71 "A New Correlator Architecture Eases Wiring Problem," W.L. Urry, 13-Nov 1998

Last Revised: 5/12/1999