dcthomso@cs.strath.ac.uk (Duncan C Thomson IE87) (12/05/89)
I am doing a final year project which will require correlation of an (ultransonic) signal with a reference signal. I am currently trying to decide whether to do this in software or in hardware. Does anyone know of any hardware correlators? How fast are they? How much do they cost? Who manufactures them? Who supplies them (preferably in the UK?) Thanks in advance, -Duncan
commgrp@silver.bacs.indiana.edu (12/05/89)
dcthomso@cs.strath.ac.uk (Duncan C Thomson IE87) writes: >I am doing a final year project which will require correlation of an >(ultransonic) signal with a reference signal. I am currently trying >to decide whether to do this in software or in hardware. >Does anyone know of any hardware correlators? >How fast are they? >How much do they cost? >Who manufactures them? >Who supplies them (preferably in the UK?) >Thanks in advance, > -Duncan One type of correlator can be made as follows: __ __ __ __ |\ in >--|__|---|__|---|__|- ... -|__|----| \ | |____________________| >----- out |___________________________| / |/ The input is an AC-coupled detected pulse train (e.g., a series of ultrasonic pulses converted to dc by a receiver). Each box is an analog delay-line IC (Radio Sh** used to sell two-channel analog- delay chips made by EG&G). The delay lines are clocked at n times the input pulse repetition frequency (prf), where n is the number of stages per delay line (typically 256). The outputs of all the delays are summed in an op amp. Repetitive signals marching through the delay line at the right prf are added; other signals and noise average to zero. I don't remember the equations; I think signal/noise ratio improves as the square root of the number of delay-line taps (summer inputs). The effect is that of a very narrow-band filter. The output is dc voltage. Response time is slow, as it takes a while to fill the whole delay train with signal. This interesting circuit was used in an inductive audio-frequency mine-rescue beacon receiver manufactured by General Instruments. Faster versions can be built with other types of delay line; some old radar receivers used acoustic delay-lines consisting of tubes filled with mercury. -- Frank Reid W9MKV reid@gold.bacs.indiana.edu
gd@milkfs.itstd.sri.com (Greg DesBrisay) (12/06/89)
SAW devices can be used to make good correlators. I'm not sure of the cost these days. If you simply want to correlate a digital data stream, then several chips manufactured by TRW might do the job for you. Some TRW correlators are the TMC2023, TDC1023, TMC2220, and the TMC2221. (ref. TRW LSI Products Data Book, 1988) TRW Application Note TP-17 entitled "Correlation--A Powerful Technique for Digital Signal Processing" by Dr. J. Eldon is listed on the last page of the TRW catalog. That might be a source of good info. TRW's LSI Products Sales Office in England is: Unit #28 Frederick Sanger Road Surrey Research Park Guildford, Surrey GU2 5YD England Phone: (0483) 302364 Good Luck! Greg
michael@fe2o3.UUCP (Michael Katzmann) (12/06/89)
In article <1048@baird.cs.strath.ac.uk> dcthomso@cs.strath.ac.uk (Duncan C Thomson IE87) writes: >I am doing a final year project which will require correlation of an >(ultransonic) signal with a reference signal. I am currently trying to decide >whether to do this in software or in hardware. > >Does anyone know of any hardware correlators? > I know TRW make a few. >How fast are they? > Very (10's of Megs I think, though its a few years sice I looked at the docco) >How much do they cost? > If you have to ask, you probably can't afford them. The CSIRO in Australia (division of Radio physics) built a custom correlator for the AT (Australian Telescope), which is cascadeable and looked very nice. I don't know whether there was ever thought about licencing it's manufacture commercially. A DSP approach may be possible (if a bit slow), I think INMOS has an app note on one of their DSP chips for this sort of work. (See SGS-THOMPSON-RCA-INMOS..) --------------------------------------------------------------------- email to UUCP: uunet!mimsy!{arinc,fe203}!vk2bea!michael _ _ _ _ Amateur | VK2BEA (Australia) ' ) ) ) / // Radio | G4NYV (United Kingdom) / / / o _. /_ __. _ // Stations| NV3Z (United States) / ' (_<_(__/ /_(_/|_</_</_ Michael Katzmann Broadcast Sports Technology. 2135 Espey Ct. #4 Crofton Md. 21114 USA Ph: +1 301 721 5151
sampson@attctc.Dallas.TX.US (Steve Sampson) (12/07/89)
TRW makes some correlators on a chip. The TMC2023 for instance does 64 bits at 30 MHz. There's a couple other models. See the Data Converters - DSP products book P.O. Box 2472, La Jolla, CA, 92038.
tgg@otter.hpl.hp.com (Tom Gardner) (12/08/89)
About a decade ago Reticon Inc made correlators based around CCD bucket-brigade analogue shift registers. No, I don't have any more up-to-date info..... tom gardner