Thanks to all responses to my enquiry . They are all via SEGMIN (as it happens), and none via GRVMAG.
There were several views expressed, all the way from “surely its intuitively obvious” to “got to be an extension of Shannon’s sampling theorem”. I’m personally wary of “intuitively obvious”, because my 1980 paper on cross-line aliasing was recommended for rejection by referees and AE, because something entirely erroneous was intuitively obvious to them. I was just lucky that Mike Schoenberger, the then Editor, had a broader intuition…. The one I’m following up on (thanks very much Andrea) is from Andrea Balza of EDCON, passing on information from Alan Herring. Essentially its that the Papoulis paper and book expounding an extension of Shannon’s sampling theorem does the job. So It HAS been published,. Just not anywhere directly accessible to the Geophysical community. Regards Alan Reid ----- On 19 Feb 2019, at 20:05, Andrea Balza <[email protected]<mailto:[email protected]>> wrote: Greetings Alan My name is Andrea Balza. I work for EDCON-PRJ and noted that Richard Hansen was noted in your email. I asked Alan Herring and Michael Hall if they could answer your question. Here is what Alan said : "It is my understanding that this idea is attributed to the theorem of Papoulis: https://en.wikipedia.org/wiki/Athanasios_Papoulis Alan " In that link there is the sampling theorem link https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem which I believe explains the proof. I also have parts of Papoulis book on the Generalized Sampling Expansion. I could ask Mike Hall to see if I can get them to you if they are of interest. Hope this helps! On Tue, Feb 19, 2019 at 1:46 AM Alan Reid via SEGMIN <[email protected]<mailto:[email protected]>> wrote: Dear GrvMag and SEGMin listers I’m addressing both lists because the matter concerns both… Years ago, the late great Richard Hansen told me he’d proved that, for a conventional airborne magnetic total field survey, cross-line gradient measurements gave you the equivalent of halving the line spacing. The proof was for noise-free data, but hey, it's an indication of a usefulness that’s widely recognised and exploited. I subsequently asked Richard for his proof and he’d lost it, but he re-proved it another way. Regrettably, I’ve now also lost that proof. And Richard is no longer available to ask…… Hence the enquiry and the challenge. 1. Does anyone know of a published proof? If so, please may we have the reference (and even maybe a link to a pdf? 2. If not, does anyone have a proof they’d be prepared to offer for publication. I’d happily welcome it to “Geophysical Prospecting”, and I’m sure “Geophysics” and some other journals would be equally welcoming. 3. If neither of the above, the challenge is to produce a proof. It’d make a decent basis for an MSc, a pretty chapter in a PhD, and/or a worthwhile paper. From a personal perspective, it’d also “complete” the survey design criteria I published in 1980. Regards Alan B Reid PhD Reid Geophysics Ltd 7 Keymer House Michel Grove Eastbourne BN21 1JZ UK Phone: +44 (0) 1323 735520 Mobile: +44 (0) 781 692 4728 Skype Name: alanbarryreid mailto: [email protected]<mailto:[email protected]> web: http://www.reid-geophys.co.uk<http://www.reid-geophys.co.uk/> ----------------------- SEGMIN community mailing list service ([email protected]<mailto:[email protected]>). Change your personal options here: https://lists.geosoft.com/mailman/options/segmin/andreabalzam%40gmail.com Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin Archives: https://lists.geosoft.com/mailman/private/segmin/ NOTE that <Reply> will reply to all members of the list. -- Best Regards, Andrea E. Balza Morales EDCON-PRJ, inc. 720-401-6661 Denver, CO Alan B Reid PhD Reid Geophysics Ltd 7 Keymer House Michel Grove Eastbourne BN21 1JZ UK Phone: +44 (0) 1323 735520 Mobile: +44 (0) 781 692 4728 Skype Name: alanbarryreid mailto: [email protected]<mailto:[email protected]> web: http://www.reid-geophys.co.uk
----------------------- SEGMIN community mailing list service ([email protected]). Change your personal options here: https://lists.geosoft.com/mailman/options/segmin/archive%40mail-archive.com Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin Archives: https://lists.geosoft.com/mailman/private/segmin/ NOTE that <Reply> will reply to all members of the list.
