Activity for TonyStewart
| Type | On... | Excerpt | Status | Date |
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| Edit | Post #286867 |
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— | over 2 years ago |
| Edit | Post #286867 | Initial revision | — | over 2 years ago |
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A: Design high -pass filter with 2 points of the bode plot Filter design 101 - 1. given hypothetical high-pass (HPF) filter -3dB gain HPF at fc 2. attenuation of -8dB at fc/2 3. Assumptions gain = 0 dB at f>> fc 4. Ripple between -3dB and 0 dB is unknown but assume 0dB max for simpler case. 5. steepness of skirts << fc is unknown but we know 1s... (more) |
— | over 2 years ago |
| Edit | Post #282053 |
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— | over 2 years ago |
| Edit | Post #282053 |
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— | over 2 years ago |
| Comment | Post #282053 |
@#8176 The reality is your results of variations are real and certainly affected up to 10 or more wavelengths from reflections.
The other reality is s21 is also affected by these reflections with multipath, so the net effect is to measure RSSI where possible in your receiver and test the variation... (more) |
— | over 2 years ago |
| Comment | Post #286211 |
Anti-aliasing filters are always needed when the spectrum above the Nyquist rate fs/2 will degrade SNR with the resulting difference frequency output. Thus dynamic range and spectral values ought to be estimated with desired SNR.
Typically a sampling rate might be 3x the upper frequency is the sp... (more) |
— | over 2 years ago |
| Comment | Post #286215 |
**Is this interesting?**
All voltages are relative to some reference. The local ground is defined as zero volts, just like Protective Earth PE ground. So if one side of the cap. is 0V then the voltage drop is the same as "the voltage" (relative to 0V.)
**What is reactance, really?**
It is ... (more) |
— | over 2 years ago |
| Edit | Post #286866 |
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| Edit | Post #286866 |
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| Edit | Post #286866 | Initial revision | — | over 2 years ago |
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A: Circuit which create ac sine wave from dc pulsed signal This is about as simple an analog inverter that I can simulate, but warning, not for the beginner with resonance issues. The bridge diodes are 2f multipliers reduced to logic level with divide by 2 FF, then complementary inversion switches with a center tapped transformer with the tap having the i... (more) |
— | over 2 years ago |
| Edit | Post #286862 |
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| Edit | Post #286862 |
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— | over 2 years ago |
| Edit | Post #286862 |
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| Edit | Post #286862 |
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| Comment | Post #286862 |
Thanks Olin, I added details to explain for others to understand why it is 180 + 180, with the assumption he knows there exists a frequency point at which -180 deg occurs from 3rd order (x90deg) phase shift) from 2L's and 1 C in a Pi filter. This is a slight change, from the Hartley. (more) |
— | over 2 years ago |
| Edit | Post #286862 |
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| Edit | Post #286862 |
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| Edit | Post #286862 |
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— | over 2 years ago |
| Edit | Post #286862 |
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— | over 2 years ago |
| Edit | Post #286862 | Initial revision | — | over 2 years ago |
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A: Results of analysis of Hartley oscillator dont make sense This LC circuit depends on several criteria for stable linear oscillation; - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo. - adequate bias current and impedance ratios with... (more) |
— | over 2 years ago |
| Comment | Post #286859 |
Not precisely, but you can filter the harmonic content of a broadband pulse to pass a narrow BW filter. Or you can phase modulate a square wave and filter any harmonic or fundamental.
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— | over 2 years ago |
| Edit | Post #286215 | Initial revision | — | over 2 years ago |
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A: What reactance actually is? Reactance is the lossless part of impedance that stores and releases energy E=1/2 LI^2 or 1/2CV^2 . Much like a spring stores energy when compressed or expanded. L is a conductor that stores current with charges flowing. Q=LI. C is an insulator with some dielectric constant , Dk, relative to a... (more) |
— | over 2 years ago |
| Edit | Post #286211 |
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— | over 2 years ago |
| Edit | Post #286211 | Initial revision | — | over 2 years ago |
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A: When do I need to put anti-aliasing filter in front of SAR ADC? Anti-Aliasing filter depends on the following parameters; 1. Signal BW 2. Sampling Rate 3. Sampling duration and thus BW of sample 4. LPF attenuation of alias spectrum above 1. From your SNR spec or dynamic range desired for resolution When sampling rates of 64x are used, ofte... (more) |
— | over 2 years ago |
| Comment | Post #286209 |
Level shifting can be accomodated with >10k resistors to limit ESD diode current rating specified.
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— | over 2 years ago |
| Comment | Post #286209 |
IF you want to detect tri-states, you need to specify the condition for the high-Zstate such as back driving with a 10k resistor 1/0 and detect that. (more) |
— | over 2 years ago |
| Edit | Post #282054 |
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— | over 3 years ago |
| Edit | Post #282054 | Initial revision | — | over 3 years ago |
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A: Capacitor ESR vs. Impedance Capacitors are lossless with 0 ESR and rise in temperature and become less reliable by 50% for every 10’C rise due to I^2ESR=Pd losses. However the current spectrum must be known with the ESR frequency graph in order to estimate losses. The ultimate goal is to attenuate ripple voltage by the imp... (more) |
— | over 3 years ago |
| Edit | Post #282053 | Initial revision | — | over 3 years ago |
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A: Is there a way to reliably measure antenna return loss outside a lab? The RSSI detector in the receiver is the best field tool. In Windows I had a tool (Wifi Radar?) that read the Broadcom IC RSSI and displayed a time plot of the results as I changed laptop orientation a couple of degrees and the results might change from -74 to -84 dBm and result in occasional errors ... (more) |
— | over 3 years ago |
| Edit | Post #281598 |
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— | over 3 years ago |
| Edit | Post #281598 |
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| Edit | Post #281598 | Initial revision | — | over 3 years ago |
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A: Why are antenna PCB traces square instead of rounded? Corners and chambers that are a small fraction of a wavelength are not significant in the <4Ghz band. More significant is the tolerance and loss tangent on the substrate. They would hardly be measureable even with a 2 ps TDR. Emissions are not significantly different. WHAT COUNTS is the RL and lo... (more) |
— | over 3 years ago |
| Edit | Post #279302 |
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— | over 3 years ago |
| Comment | Post #281444 |
But we only wore tinfoil hats when I bought a Lingren EMI proof chamber. In the 90’s. (more) |
— | over 3 years ago |
| Edit | Post #281597 |
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| Edit | Post #281597 |
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| Edit | Post #281597 | Initial revision | — | over 3 years ago |
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A: Estimating the input capacitance of an BLDC motor controller To answer some of your questions: Cable inductance: - - approx 1uH/m +/-50% depends slightly on l/d ratio , while cable impedance from sqrt(L/C) depends on twists/ft 50pF/m while coax is 100pF/m Bulk storage Cap - - C value should store Energy Ec for load power x sag time between puls... (more) |
— | over 3 years ago |
| Comment | Post #279493 |
I remember when Qmodem would compute the bit rate differently, and shown higher than output expected. On dialup using 56k modems in high speed mode with a faster serial port, they would count the start and stop bits in the transfer rate, which then of course got translated into , I forget 64 levels ... (more) |
— | over 3 years ago |
| Comment | Post #279493 |
Can you give an example where Baud Rate is higher than Bit Rate? (more) |
— | almost 4 years ago |
| Comment | Post #279493 |
... So don't byte me for saying your Byte rate example is not related to bit rate vs baud rate or symbol rate. but does affect character rate. characters are not symbols in this sense yet are symbols in language. (more) |
— | almost 4 years ago |
| Comment | Post #279493 |
There are many types of Baud Symbols that compress bits in time, frequency, phase or time in many combinations by sending many per unit of a bit. such as 9600 modems using 1200+2400 Hz tones with multiple levels to get 8 bits per Baud symbol in a 2400~3000 Hz bandwidth. ( I think, I forget)
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— | almost 4 years ago |