Re: [time-nuts] Bombe clock
Other than the fact that his description of how the bombe worked is totally wrong... On May 21, 2019, 5:00 PM, at 5:00 PM, Mark Sims wrote: >Everbody needs one of these... > >https://www.ebay.co.uk/itm/The-Covert-Bombe-Clock-from-Bad-Dog-Designs-Codebreaking-in-Secret/123775434764 > >https://www.youtube.com/watch?v=O4ctUqgj7aY >___ >time-nuts mailing list -- time-nuts@lists.febo.com >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Bombe clock
You and the builder of this clock win the internet today! Content by Scott Typos by Siri On May 21, 2019, at 1:54 PM, Mark Sims wrote: Everbody needs one of these... https://www.ebay.co.uk/itm/The-Covert-Bombe-Clock-from-Bad-Dog-Designs-Codebreaking-in-Secret/123775434764 https://www.youtube.com/watch?v=O4ctUqgj7aY ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] timing properties of "spectru spreading", clocks
Hi David, thanks for that succinct explanation. The SSC is a "fudge" to defeat the measurement technique, which has nothing to do with the psychological effect of the interference, or the BER effect on the legitimate user. In fact it is often easier for the legitimate user of the frequency to avoid a fixed clock harmonic than deal with one spluging all of the band. It legitimises poor design! Alan Melia G3NYK RSGB EMC Committee mmember On 21/05/2019 18:00, Dave B via time-nuts wrote: Date: Mon, 20 May 2019 20:41:51 -0500 From: "Bill Byrom" To: time-nuts@lists.febo.com Subject: Re: [time-nuts] timing properties of "spectru spreading" clocks Message-ID: <5e9c8b54-c30e-4e03-aba2-d4d96e5d8...@www.fastmail.com> Content-Type: text/plain;charset=utf-8 SSC (spread spectrum clocking) is widely used in both commercial (servers etc.) and consumer products. The big advantage is at harmonics of the spread clock, where the higher frequency energy can more easily escape the product case, shielding, and cables. CISPR (EU) standards in general specify a receiver bandwidth of 120 kHz for signals below 1 GHz and a receiver bandwidth of 1 MHz for signals above 1 GHz. Hi. "Spread Spectrum" clock's were designed as a quick and dirty fix for out of specification emissions from all sorts of digital based products (and some non digital!) It does *not* reduce (or increase) the level of leakage, it just spreads it over a wider spectrum. (Never mind the quality, feel the width!) It was specifically designed to "Fool" the Quasi Peak (QP) detectors used in the EMC Emissions test receivers, so that a lower "Under the limit" reading is produced. Such emissions tests are usually done in two stages. A fast pre-scan with a Peak detector. If the product passes that, job done. If any signals extend over the Peak threshold limit, then those frequencies are again tested with the QP detector, that is quite slow to respond. If the signal is still over the limit, it's a fail. If it's now under the QP limit (as it often is for SS signals) it's a pass. The limits are there to protect broadcast signals, not to limit interference to other systems, or small signal communications links. In reality, it's a "bean counter" induced fix to poor technical design. "Short term cost saving". Just look up the history of the QP detector, it's utterly inappropriate for what it's now being used for. It's original purpose was to get some sort of quantitative and repeatable measure, for pulse interference to AM broadcast signals, such as that experienced from poorly suppressed spark ignition systems in passing vehicles. That of course go past and away after a short spell. Declaration: I work in the EMC "Industry". I'm also a government licensed Radio Amateur, who's utterly P'd off with the RF pollution from poorly designed and/or implemented digital systems and switched mode power converters. Such levels of wide band interference is already starting to bite the hand that feeds it. Some LED lighting systems can and do wipe out terrestrial DAB reception! Of course, it's not the LED's themselves, but the SMPS based "drivers". The EMC rules are lax, and they are not monitored, let alone enforced in the marketplace. A lot of the industry is fed up with it all too. The soap box is creaking. 73. Dave B G0WBX. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Bombe clock
Everbody needs one of these... https://www.ebay.co.uk/itm/The-Covert-Bombe-Clock-from-Bad-Dog-Designs-Codebreaking-in-Secret/123775434764 https://www.youtube.com/watch?v=O4ctUqgj7aY ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] timing properties of "spectru spreading", clocks
Date: Mon, 20 May 2019 20:41:51 -0500 From: "Bill Byrom" To: time-nuts@lists.febo.com Subject: Re: [time-nuts] timing properties of "spectru spreading" clocks Message-ID: <5e9c8b54-c30e-4e03-aba2-d4d96e5d8...@www.fastmail.com> Content-Type: text/plain;charset=utf-8 SSC (spread spectrum clocking) is widely used in both commercial (servers etc.) and consumer products. The big advantage is at harmonics of the spread clock, where the higher frequency energy can more easily escape the product case, shielding, and cables. CISPR (EU) standards in general specify a receiver bandwidth of 120 kHz for signals below 1 GHz and a receiver bandwidth of 1 MHz for signals above 1 GHz. Hi. "Spread Spectrum" clock's were designed as a quick and dirty fix for out of specification emissions from all sorts of digital based products (and some non digital!) It does *not* reduce (or increase) the level of leakage, it just spreads it over a wider spectrum. (Never mind the quality, feel the width!) It was specifically designed to "Fool" the Quasi Peak (QP) detectors used in the EMC Emissions test receivers, so that a lower "Under the limit" reading is produced. Such emissions tests are usually done in two stages. A fast pre-scan with a Peak detector. If the product passes that, job done. If any signals extend over the Peak threshold limit, then those frequencies are again tested with the QP detector, that is quite slow to respond. If the signal is still over the limit, it's a fail. If it's now under the QP limit (as it often is for SS signals) it's a pass. The limits are there to protect broadcast signals, not to limit interference to other systems, or small signal communications links. In reality, it's a "bean counter" induced fix to poor technical design. "Short term cost saving". Just look up the history of the QP detector, it's utterly inappropriate for what it's now being used for. It's original purpose was to get some sort of quantitative and repeatable measure, for pulse interference to AM broadcast signals, such as that experienced from poorly suppressed spark ignition systems in passing vehicles. That of course go past and away after a short spell. Declaration: I work in the EMC "Industry". I'm also a government licensed Radio Amateur, who's utterly P'd off with the RF pollution from poorly designed and/or implemented digital systems and switched mode power converters. Such levels of wide band interference is already starting to bite the hand that feeds it. Some LED lighting systems can and do wipe out terrestrial DAB reception! Of course, it's not the LED's themselves, but the SMPS based "drivers". The EMC rules are lax, and they are not monitored, let alone enforced in the marketplace. A lot of the industry is fed up with it all too. The soap box is creaking. 73. Dave B G0WBX. -- Created on and sent from a Unix like PC running and using free and open source software. :: ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
