Re: Can someone...
Job -2 had (in 2017) 16,000+ 32bit systems with a contract life beyond 2026 (upstream and downstream oil/gas)
Some of it is several thousand feet below the sea.
26 posts • joined 23 Jan 2012
A common-mode ferrite clamp on the cable an inch or two down the line from the USB connector can help too. It's not awlays the screening leakage - common mode currents can be a problem just as much as data lines or RF on the power rail.
Be aware that many clip on clamps, while having significant attenuation to common-mode RF on the outer braid, can nip the cable so much as to cause damage. I prefer to manipulate the "lips" at either end of the clamp slightly outwards to ensure that they splay out a little rather than dig in too much. If they slide use a dab of hot glue.
Like many things EMC, it's not a panacea. Nor is it a pancake either. Alas.
ITYM 430MHz? Anyways - there are many legitimate licensed users of that region of spectrum and car key fobs have zero protection from them, being ISM equipment operating on a basis of non-interference.
Also, as a previous poster pointed out, saying you;rer only allowed to use a 5% duty cycle, that may be so, but when a device is modified either deliberately, by human hand or by baby spit, that won't be the case.
Rules are rules, faults are faults and malicious intent is effective.
Society is to blame for accepting shit products like this a panaceas (sp? I didn't do well in French at school ;)
I haven't had a single letter from my doctor's surgery delivered to me in 15 years, despite them claiming to send me one every two months.
This is more than likely due to Royal Mail incompetence, as the address is rather hard to find on the ground *, but makes me worry if my medical soul is going to be sold without me even noticing.
* The surgery claim they "can't do anything about it" and it's "my fault, not theirs" - a great start to data security methinks
Actually, it's worse, by orders of magnitude, not just not really that useful, even as a control channel. You can't just transmit VFT over a 3kHz channel width, the actual bandwidth at VLF is measured in Hertz or milliHertz, not kiloHertz. This in no way corresponds with the baseband frequencies of analogue telephone line comms systems, which is where the 300 baud assumptions are comings from. It's far, far worse than you imagine, making it impractical to use as a control system. It reduces the practicality to "on or off", which is effectively pointless, as optical losses are measured continuously.
300 baud is do-able data rate for FEC transmissions in the HF and MF regions of the spectrum, even at LF. At these frequencies, the bandwidth of the antenna and associated matching system are high enough not to impact on the bandwidth of the channel.
A radio transmitter with a wide bandwidth (as a percentage of the centre frequency) is so difficult to match that losses become untennable at even a few tens of herts from then centre frequency. This restricts the bandwidth of the channel (and hence the available shifts and data rates, even in the post-Shannon era, to very low rates indeed.
Radiating a good 7kHz-wide voice signal at 150kHz is difficult, but consider that it's 2.4~ish% of the centre frequency. This example is the bottom of the "LongWave" broadcast spectrum. It's also comparable to some Loran and similar navigation services. Even that produces severe matching problems (trading bandwidth for Q, as Q decreases, bandwidth increases but so do the losses in the amplifier>antenna matching network.
Now, make that 1.5 kHz, the middle of the ULF spectrum, taken as a purely mathematical example. Instead of 150 kHz and you have the same %-age off the centre frequency at only 700Hz from the centre frequency. It's this that limits the effective usable spectral bandwidth of the system, generating the signal isn't so much a a problem, but coupling it to an antenna is, given that the antenna efficiency itself will also be extremely low, due to the long wavelength at ULF. it's doesn't take long before several different power losses of 30dB add up to give you massive power loss. Try minimising antenna losses that by reducing resistive losses and ground losses (requiring massive ground mats and extremely long radial systems. Then you have to increase transmitter power to compensate the matching losses. Before long you're looking at 50kV insulators and several kiloamps of antenna current as you try to trade Q against bandwidth against losses against costs. There's a reason morse was used in the marine MF band and not voice - around 500kHz or lower and matching become a very serious business, so mobile transmitters become problematic in terms of wider matching, given the limited transmitter power available. At higher frequencies, noise (both natural and manmade) was more of a reason to limit signal bandwidth (usually in the receiver system, using high-Q filters, often piezo-quartz filters in superhet designs. These were in the days preceeding DSP weak-signal methods that have revolutionised radio systems in the last 25 years. The antenna matching was far easier due to the manageable antenna proportions at high-MF and HF.
Reducing the spectral utilisation helps immensely, giving a practical (for a superpower defense budget) throughput of single-figure of baud.
For the old US and Russian systems, 76 and 82 Hz respectively using chunks of the planet as the antenna systems (yes, the planet), the problems increase by magnitudes again, making them Extremely Low Fart-rate systems
It's far easier to tap at a friendly landing station; failing that tap undersea. Such "intervention" as these subsea jobs are called is far from impossible, as others have noted. Whether it's worthwhile or not given the expense is another matter. Live-working on 10kV DC systems is not impossible using isolated ROV and robotic systems - I've personally seen it done (on a CCTV feed!) on oilfield jobs at 600Vdc+ with minimal problems other than pumping the environment dry and using live-working tools and equipment. and that was using human divers, albeit carefully. These jobs are not done by choice, only by necessity, but are nonetheless doable in relative safely for the operators concerned.
source : I used to design, tune and match VLF systems. I then spent several years on subsea comms: wideband, voiceband and narrowband, using Hertzian, acoustic and tug-on-a-rope methods.
My broadband ISP (A&A, a.k.a Andrews and Arnold), who are also my VoIP provider, offer an effective known-cold-caller-blocking service on their SIP VoIP service with auto-blocking based on honeypots, the cold-call numbers are then blocked by ticking options on the VoIP number's control pages. This is in addition to ACR, which they have always had.
They are pushing to get the ICO to actually do something when given evidence of unsilocited calls, but even when given clear evidence of crime, they are sadly refusing -
watch this space though, he doesn't give up lightly
Looking at this in context of a non-tor, non-pirating, law-abiding UK taxpayer and voter, it seems quite simple. That is to say, it seems to me that a person in a position of power is amplifying risks over (at least) 100-fold (probably 1000-fold) to influence political and financial decisions.
Smells like something actionable to me, at worst, incompetently informed and out of touch, at worst, deliberate lies?
Do I look French to you? :) Yeah, I know it didn't look right when I clicked submit. My excuse:
I've been up the whole night toking the same Durban Bushweed they smoke at Canonical.
Easy mistake - I simply typed the first three letters into the HUD and....oh, err, nvm, I meant to start Sabayon.
Any more sh!t like this from Canonical and I'll be installing Sabayon distro instead.
This makes a fsking mockery of everything I've been telling customers about Ubuntu since 6.06.
First the buttons, then the DisUnity, now DUH. Shameful contempt and very unprofessional IMHO.
The mainstream press will start to rip them to pieces, freedom my ass!
WTF are they smoking at Ubuntu Towers : Durban Bushweed. Far too bloody much of it for my liking.
I'm beginning to look on Canonical as damaging to the reputation of Linux in general. This Unity b/s has cost me 160of my perfectly-good desktops going back from Lucid 10.04 LTS back to Windows 7. The national bosses "can't risk Unity being permanent".
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