davepage

5 miesięcy temudiscuss

Could obtain better quality at the higher channel counts by phase shifting the audio for each channel such that the modulation peaks do not exactly align for each (as they do now). Even inverting the audio for half the channels would help.

davepage

2 lata temudiscuss

Location: Baltimore, Maryland, USA

Remote: Yes

Willing to relocate: No

Technologies:

    Hardware: Instrumentation & conditioning, filtering, ADC/DAC, RF Applications (IEEE 802.15.4), phase locked loops, IGBT & SCR control, power supplies, microcontrollers, memory, peripherals, USB, Ethernet, EtherCAT, CAN, PCI, ISA, TEDS (IEEE 1451.4), UART, SPI, I2C, PWM, quadrature encoders, PID control, IIR/FIR filters, phase locked loops, synchronous detection, IMU, INS, optical sensors, cold gas thrusters, EMC, RFI

    Software: C++, C#, MATLAB; C; Python; VHDL, Verilog; Assembler; Familiar with Javascript, SQL, Visual Basic, UNIX shell and tools; Windows, QNX RTOS, Real Time Linux, bare metal; Eclipse, Visual Studio, TI Code Composer Studio, MPLab, GNU, Atmel Studio; Xilinx, Altera, OrCAD, Eagle CAD, LTSpice, git

Résumé/CV: http://dave-page.com/cv

Email: [email protected]

Hi there! I am a very experienced embedded systems designer and manager with a proven track record delivering results. I can help define requirements, create an electronic design, write software, and build a conforming prototype.

davepage

7 lat temudiscuss

The Boeing/Ethiopian ETH-2 bulletin quoted in the above linked AAIB preliminary report on page 33 says "Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT ..."

davepage

7 lat temudiscuss

It does not appear to be "precisely" the procedure, in that sufficient nose up trim was not selected by the yoke manual trim switch prior to pulling the trim cutouts. And then they did not work the mechanical trim wheel hard enough to reset the residual nose down trim.

And, the crew left the power setting at climb throughout almost the entire sequence, so they oversped the airframe.

And, when they (against procedure) (apparently) turned the electric trim system back on, they did not use the yoke manual trim switch to fix the nose down trim problem -- which is a big mystery.

The MCAS design inhibits its FCC trim down output when manual trim is utilized. So, if they had just continuously pushed the nose up manual trim switch on the yoke until they got the trim to neutral, then pulled the cutout (either the first time or second time), the accident could have been avoided.

History shows this is not a good human factors design on the part of Boeing, but the crew does not look good, either, IMO.

davepage

8 lat temudiscuss

After the scandal, they added an opt-out setting (but on the privacy policy page, where the nominal user will not think to look for it).

davepage

8 lat temudiscuss

It did not

davepage

8 lat temudiscuss

FWIW, I set an ATM PIN for a US issued CC and found the PIN worked for retail terminals in NZ. YMMV

davepage

8 lat temudiscuss

The hardware looks quite good, but do I want to give Xiaomi (an entity controlled by the PRC) access to my web browsing history, identity, contacts, calendar, files, location, calling history, SMS, etc? (these permissions are requested on Android by the associated app).

davepage

8 lat temudiscuss

Keeping things simple, if the input data SNR is, say, 16 bits, and the PID coefficients are 16 bits, then there is 32 bits of significand at the output of the control gain multipliers. For single precision float, this is truncated to 23 bits. So, the system may settle when the transducer input is near zero (and the exponent can scale down to maintain sufficient precision), but then fail to settle well at the ends of the transducer range (where the transducer input is near +/-2^15 and the exponent in the single needs to stay high to avoid saturation). Also, consider the numerical integrator is running an infinite series of adds, so therein lies a trap for error growth, as well.

I have made this mistake before, and the sometimes strange control behavior can be frustrating. Considering the small performance penalty for using doubles on modern hardware, it is excellent advice.

davepage

9 lat temudiscuss

Most modern FPGAs have a PLL (or DLL) implementation [0] which can multiply the external clock by some rational number. e.g. 50MHz external crystal clock is multiplied by 5/2 to obtain a 125MHz internal clock.

0. https://www.xilinx.com/support/documentation/user_guides/ug3...

davepage

9 lat temudiscuss

Possible in a G650ER

http://australianaviation.com.au/2014/05/gulfstream-offers-l...

davepage

11 lat temudiscuss

Of course I am a hypocrite. My partner wants to visit the US; I would prefer to live elsewhere. But, sometimes compromise is needed in relationships.

'failed state' is certainly hyperbole here -- there are large elements of society which continue to function, despite the problems at the national government level. It would truly be a failed state if, for example, the national government's performance level were propagated to the whole society.

davepage

11 lat temudiscuss

Took 14 months with Congressional intervention just to get my partner a immigrant visa -- which is presumably the easiest.

America has been so obsessed with thinking of itself as the "best country in the world!(TM)" for so long, it has meanwhile regressed into a failed state.

davepage

11 lat temudiscuss

Well, maybe. From a regulatory perspective, the radio users have more FCC clout than insouciant interference sources like Comcast and TW, neglecting whatever regulatory capture may exist.

davepage

11 lat temudiscuss

Shortwave listeners and amateur radio folks were upset about powerline internet: http://www.arrl.org/broadband-over-powerline-bpl

From an engineering standpoint, sending broadband over the power infrastructure is seriously ugly, because the SNR is poor, shielding is poor, and spectral distortion is high. Power lines were never designed to be constant impedance, low loss and shielded for broadband frequencies. Due to all the impairments, the transmit power must be relatively high, and coupled with the poor shielding, interference with legitimate radio users is inevitable.

davepage

11 lat temudiscuss

Sure... the Russians and Chinese (not the same people) just happened to simultaneously break some strong encryption, and the UK just happened to discover this somehow, before anything significant happened. Perfectly propaganda.

Perhaps the next press release will claim, 'paying taxes reduces the risk of death by 42%!'

davepage

11 lat temudiscuss

I agree. More layers of complexity than short term memory slots is a mandatory property of belief systems -- as more effort will be required to find the contradictions then is likely to be allocated.

And certainly handling such individuals with kid gloves is important to mitigate the intransigence reflex. I only ask because I wish to discover some more effective strategy to aid some of the more zealous individuals to improve their moral consistency. Fear is far more powerful than reason, however.

davepage

11 lat temudiscuss

In terms of moral introspection, I perceive a continuum of information quality from vague suspicion to almost complete certainty. Morally, I would have a very, very difficult time making life-changing affirmative moral arguments to complete strangers without almost complete certainty.

And, I could never, never ascribe almost complete certainty to a piece of information not complying with the vacuum intellect test (i.e. could an intelligent person not exposed to culture reasonably be expected to arrive at a similar conclusion, if given sufficient resources for independent experimentation).

So, quantum mechanics, as weird as it is, could pass the vacuum intellect test. Could I personally see a vacuum intellect reinventing the tenets of Christianity including the concept of hell? That seems completely implausible to me. Sure, one could argue divine intervention (again) -- but that violates the vacuum constraint.

So, question: By what moral thesis does one permit one's self to venture out into the world and attempt to convince other people to redirect their limited resources onto something which is not almost completely certain?

davepage

11 lat temudiscuss

"Illegal" and "wrong" are not in any way related. All spy agencies conduct activities which are clearly illegal under the laws of their target countries. But are these activities always "wrong?" Conversely, spy agencies may conduct activities which are legal under their own laws, but are morally wrong -- harassment of MLK, for example.

And "unambiguously legal" is overselling the point: PPD-20 includes offensive capabilities amounting to acts of war -- which would presumably be illegal absent congressional approval. China surveillance includes illegal surveillance of US nationals and well as mass surveillance, which is arguably inappropriate policy. Tempora is a program conducted by the UK -- arguably illegal as signatory to EU treaty. Spying on Germany is likely to support economic espionage, which would be illegal under WTO treaty, etc. Al Jezeera is a journalist organization, which provides a useful Arab propaganda counterpoint to US propaganda, and is not itself a sponsor or advocate of terrorism. The various spying methods exposed are executive overviews and lack sufficient technical detail for implementation, and are thus appropriate for public policy discussion.

The US state security apparatus is also not elected -- yet it clearly does control policy through overclassification and outright misrepresentation of its activities to congressional oversight.

Were Mr. Snowden's actions illegal? Yes, clearly, but that is a question of no meaningful value in this context, as most NSA activity is illegal somewhere, and some NSA and FBI activity is clearly illegal within the US.

Were these actions wrong? That remains to be seen.

Even if they were wrong, is there a net moral benefit which could excuse the costs? That is a complicated question. Do the fruits of NSA, CIA and FBI espionage achieve their stated goals? Is US foreign policy successful? Does the US reliably achieve its military objectives?

So, rather than yet again repeating the mistakes made over the last 100 years -- with some exceptions, an otherwise disgraceful litany of paranoia and short-sighted pragmatism -- perhaps it is a good time to reexamine politically whether foreign policy as practiced by the US is appropriate and efficacious. The responsibility for this interminable chain of dismal failures must be accepted by the US government and US electorate as a whole. The status quo -- mindless subservience to nationalism, patriotism, and religion along with a generous dose of political amnesia -- is completely unjustified at this point.

This discussion cannot ever fully occur when the mechanisms informing that foreign policy are forever hidden from political debate by a veil of overclassification motivated by criminal activity.

Mr. Snowden has caused that debate to begin -- his stated intent. One could therefore reasonably conclude his actions are moral and justified as well as illegal under US law. US law is therefore the problem, not Mr. Snowden.

davepage

11 lat temudiscuss

Essentially the American state religion to which your refer is largely predicated on the concept that any law may be ignored by those in power so long as the intent is to produce "good outcomes" for some state perception of good. (i.e. 'the constitution is not a suicide pact' or read "Enemies: A History of the FBI")

Law (so far) is merely stains on paper until interpreted by the mind of an individual in some context (time, place, society). Societal context is some collective consensus over right and wrong -- some popular mush of common sense, the influence of which can be seen in the evolution of, for example, supreme court decisions over socially controversial issues. Where large numbers of individuals subscribe to a particular set of beliefs about what the law is, and proceed to act accordingly, a very convincing illusion of government emerges. And one may refer to this as a state religion in the sense it is entirely an emergent property of belief rather than reality.

Thus, absolute law is a myth. Pardons are an outlet for the elected leadership to short-circuit the legal process when, in a given instance, punishment is perceived to exceed the crime. It is thus arguably irrational to assert that a pardon is premature in the Snowden case, considering the outcome thus far.

Of course, those capable of issuing such pardons are themselves true believers. Snowden has committed blasphemy against the state religion. Thus a pardon can only occur should some popular unrest threaten those in power.

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