Publications

Refine Results

(Filters Applied) Clear All

Alternate waveforms for a low-cost civil GPS receiver

Published in:
MIT Lincoln Laboratory Report ATC-86

Summary

This report examines the technical feasibility of alternate waveforms to perform the GPS functions and to result in less complex receivers than is possible with the GPS C/A waveform. The approach taken to accomplish this objective is (a) to identify, after a quick broad overview, a few promising waveforms, (b) to complete the architectural synthesis of a GPS system based on the new waveforms, (c) to analyze the performance of these systems in providing ranging and communication capability and (d) to assess the impact on receiver hardware and software. One conclusion is that the class of pulsed waveform, when combined with emerging matched filter technology, permits the use of a greatly simplified receiver design. Although very specific, the design was intended as a vehicle for performance analysis only and many refinements and alternatives within the same class are possible. Other classes of waveforms such as tome ranging and chirped FM waveforms, although adequate, do not seem superior to the present PN encoded CW waveform for GPS. Finally, if the "alternate" waveform is simply the present C/A waveform but with substantially increased power level, it is shown that with the present designs the performance will be greatly increased or, alternatively, performance margin can be traded for a simplified receiver implementation.
READ LESS

Summary

This report examines the technical feasibility of alternate waveforms to perform the GPS functions and to result in less complex receivers than is possible with the GPS C/A waveform. The approach taken to accomplish this objective is (a) to identify, after a quick broad overview, a few promising waveforms, (b)...

READ MORE

DABS channel management

Author:
Published in:
MIT Lincoln Laboratory Report ATC-43

Summary

This report provides a full discussion of the design of the DABS channel management function. Channel management regulates all activity on the RF channel, scheduling ATCRBS interrogations and DABS roll-call interrogations and replies. Channel management arranges for multiple interrogations when required to satisfy both the surveillance and the communications functions of the sensor, and for reinterrogations in the event of link failure. The report consists of three major parts: Part I, Channel Control; Part II, Roll-Call Scheduling; and Part III, Transaction Preparation, Target List Update, and Transaction Update. Together they encompass the five basic subfunctions of channel management.
READ LESS

Summary

This report provides a full discussion of the design of the DABS channel management function. Channel management regulates all activity on the RF channel, scheduling ATCRBS interrogations and DABS roll-call interrogations and replies. Channel management arranges for multiple interrogations when required to satisfy both the surveillance and the communications functions...

READ MORE

DABS timing: clocks, synchronization and restart

Author:
Published in:
MIT Lincoln Laboratory Report ATC-29

Summary

The DABS sensor timing subsystem, which consists of two clocks driven from a common station standard, is the subject of this paper. The subsystem configuration is described and the rationale for this design briefly given. Emphasis is on the techniques for sychronization to an external standard, coordination with other sensors and system restart after a failure or deliberate shut-down.
READ LESS

Summary

The DABS sensor timing subsystem, which consists of two clocks driven from a common station standard, is the subject of this paper. The subsystem configuration is described and the rationale for this design briefly given. Emphasis is on the techniques for sychronization to an external standard, coordination with other sensors...

READ MORE

A maximum-likelihood multiple-hypothesis testing algorithm, with an application to monopulse data editing

Author:
Published in:
MIT Lincoln Laboratory Report TN-1973-7

Summary

A simple algorithm for multiple-hypothesis testing, based on a generalization of likelihood ratio testing between pairs of hypotheses, is developed and applied to a specific problem. The problem arises in connection with an amplitude comparison monopulse system in an Air Traffic Control application. In particular, it is desired to measure target azimuth in a beacon system in the presence of interference and multipath. The multiple hypotheses relate to the presence or absence of a desired signal, with or without either of two kinds of interfering signal. The analysis leads to a new technique of data editing, or processing, to detect the presence of interference.
READ LESS

Summary

A simple algorithm for multiple-hypothesis testing, based on a generalization of likelihood ratio testing between pairs of hypotheses, is developed and applied to a specific problem. The problem arises in connection with an amplitude comparison monopulse system in an Air Traffic Control application. In particular, it is desired to measure...

READ MORE

Interrogation scheduling for the discrete address beacon system

Author:
Published in:
MIT Lincoln Laboratory Report ATC-8

Summary

This report is an attempt to define the interrogation scheduling problem which arised in the implementation of the discrete address beacon idea. The interfaces of this problem with other parts of the beacon system design are discussed, and several specific algorithms for scheduling are analyzed for arrays and rotating antennas.
READ LESS

Summary

This report is an attempt to define the interrogation scheduling problem which arised in the implementation of the discrete address beacon idea. The interfaces of this problem with other parts of the beacon system design are discussed, and several specific algorithms for scheduling are analyzed for arrays and rotating antennas.

READ MORE

Showing Results

1-5 of 5