Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. logbook

    Any tips for a new RF engineer?

    I'm with Dan on this one. When you get there you will soon find out what things you need to focus on. Working life is a succession of continuous learning.
  2. logbook

    reasons why digital LP filter can't be done with FFT / IFFT

    >One problem with FFT is that it doesn't conserve phase information. So, when you do the IFFT, you may get something that isn't at all what you expected. NOT TRUE! If you retain the complex data (rather than just the magnitude) you can do an FFT/IFFT and get exactly the same response. I have...
  3. logbook

    Question

    You haven't stated the frequency of operation and the nature of the transmission line. You could for example use a 10dB directional coupler. In this case the insertion loss would be about 1dB. The bottom line is we need more information! How much are you willing to attenuate the tapped off...
  4. logbook

    How to test a USB2 cable with a BERT (bit error rate tester)?

    The eye opening is only a qualitative way of measuring the noise. The BER is a very sensitive measure of the noise. Now if you have a huge signal to noise ratio you won't have errors. If the cable is long and/or has high loss, the signal will be greatly reduced and the noise may then cause...
  5. logbook

    Frequency Interference

    Bursa, perhaps there is an error in the translation. When I said ... "I just can't imagine anyone using a Military frequency for a garage door opener!" This was an idiomatic way of saying "I can understand that some people are so dumb that they would do this"
  6. logbook

    Frequency Interference

    Thanks VE1BLL. I just can't imagine anyone using a Military frequency for a garage door opener! The Military are not known for low power operation. I suppose these devices are coded so your opener doesn't open your neighbour's garage door. Then we are just talking about raw carrier wave power...
  7. logbook

    Frequency Interference

    The first thing anyone would want to know is what the operating frequency is. Ham operators can't do anything without an appropriate antenna! The instruction booklet for the garage opener should state the frequency.
  8. logbook

    SNR of a pulse

    You are looking for an “industry standard” metric for signal-to-noise ratio of a pulse which does not change according to pulse repetition period. I would like to say that no such definition exists, although I clearly don’t know everything. Therefore all I can definitively say is I don’t know of...
  9. logbook

    0-100 mVAC to 0-10 VDC convertor

    http://sound.westhost.com/appnotes/an001.htm Figure 4. Change R3 10K -> 1K R4 20K -> 2K R5 20K -> 100K Then put a big capacitor across R5 to give the required filtering.
  10. logbook

    USB to Ethernet IC

    Ethernet is hard. A standard microcontroller would not have the required PHY. You are probably best to use one of the modules and mount that on your pcb as a sub-assy.
  11. logbook

    plc communication over high voltage cables using inductive coupling

    A power system is not matched in the sense of the source impedance equalling the load impedance. This would be grossly inefficient. The source impedance is low and the load impedance is relatively high. If you try to impress a voltage across the source this will be difficult because the low...
  12. logbook

    "Force" Window function

    Agreed, but when you are coding a standard window for application software your hands are tied with respect to the algorithm. The only possibility is to offer an "enhanced force" window function and explain what you have done in a manual.
  13. logbook

    "Force" Window function

    IRstuff. I read that quote you gave but failed to spot the relevant data. Perhaps it was just too simple. So I went off and hunted through the Dogpile list and found that Modal Space paper. Now re-reading your quote I see that the data was already there in plain sight and I just missed it. Scary!
  14. logbook

    "Force" Window function

    Got it :-) The article on the Dogpile list titled "Modal Space" describes it. It's just a unity rectangular window around the region of interest and zero elsewhere. Thanks IRstuff.
  15. logbook

    "Force" Window function

    I have been asked to help code the "Force" window function in a C++ application. I did the original window functions rectangular, Hamming, Hann, flat-topped, and so forth, so I have the original papers by Harris, Nuttal etc, but I had never heard of the Force window until asked. I have googled...
  16. logbook

    Help, spatial frequency content analysis results

    How big is the fundamental? It looks like there is a large spike off the top of the graph. What you are describing as a sinc^2 function looks like side-lobes on the FFT. Google for "spectral leakage". Using the von Hann window function reduces the spectral leakage and your side-lobes are...
  17. logbook

    Help, spatial frequency content analysis results

    My mistake. Looks like the pictures are really big and my slow dialup link just didn't display anything.
  18. logbook

    Help, spatial frequency content analysis results

    I tried the link but couldn't see the pictures. The page has rectangular place holders but the images wouldn't display :-(
  19. logbook

    How do I measure bit error rate?

    BER (Bit Error Ratio) is the modern expansion by the way. It is impossible to specify the BER for a passive transmission line. Basically your slip ring system is a noise source. You should quantify it as such. Suppose you are transmitting baseband digital pulses of signal level 0V for a low...
  20. logbook

    Converting a rail-to-rail waveform for a single rail analog amplifier

    redtreetoad, what you don't say is if your waveform has DC content. If the signal has values that vary at a rate below say 10Hz you may have trouble using the transformer coupling or AC coupling suggested above. If the repetition period is more like 50Hz then transformer or capacitive coupling...

Part and Inventory Search

Back
Top