Can this osciloscope measure FM frequencies of 100 MHz or more?

Discussion in 'General Electronics Chat' started by circuitfreak2000, Apr 8, 2015.

  1. circuitfreak2000

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    Apr 7, 2015
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  2. nsaspook

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    yes.
     
  3. circuitfreak2000

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    Apr 7, 2015
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    What kind of bandwidth does the OSC need to be able to measure FM frequencies?

    One the box of the Hantek it says Bandwidth 20Mhz/60/100/200MHz. What does this mean then?

    Have a look
    [​IMG]
     
  4. nsaspook

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    Last edited: Apr 8, 2015
  5. circuitfreak2000

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    I'm only interested in the Hantek model as it costs only around $65 USD, which is the most I could ever spend on an OSC. So it's either that one or none :oops:
     
  6. cmartinez

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    It only measures 20 Mhz, as it says on the webpage. I own two Hanteks, and the box is just a generic one in which they check the appropriate selection box with a marker indicating which model is inside. Since this model is none of those listed at the top of the box, they have placed an extra label on the side detailing its contents.
     
    Last edited: Apr 8, 2015
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  7. nsaspook

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    100mhz of real bandwidth is not cheap. You usually get what you pay for.
     
  8. Dr.killjoy

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    The scope you posted was rated for 20 mhz and I would stay below that .. Otherwise I would suggest buying a used analog scope for about the same price and it's a lot better IMO...
     
  9. ScottWang

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    Aug 23, 2012
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    Using rating 20Mhz to measure 100Mhz waveform, you may just see the appearance of the waveform, if you just want to know the frequency then you can adding a TC74AC390 that it could reach up to 160Mhz, you could divide the input frequency by TC74AC390 and then you can measuring the input frequency over 100Mhz.
     
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  10. Hypatia's Protege

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    It depends what you want to observe --- analysis of harmonic distortion will require several octaves (over the fundamental) of flat response... Note, however, that it is less than practical to observe the carrier with a TDO --- Spectral profile is far better observed with a frequency domain oscilloscope (a.k.a. spectrum analyzer) -- On the other hand many common communications systems parameters (e.g. deviation, IMD, CMD, etc...) may be assessed via 'detection' techniques and, hence, modest bandwidth (where a TDO is applicable)...

    Best regards
    HP:)
     
    Last edited: Apr 8, 2015
  11. tonyStewart

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    May 8, 2012
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    YES it means it will not measure any frequencies more than 20MHz

    However the numbers do refer to higher sampling rates which improves performance. But are still limited to the signal filter response of 20 MHz

    Since FM is from 88 to 108MHz you need at least 100MHz BW to even consider looking at the waveform but it wont see harmonic distortion.
     
  12. tonyStewart

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  13. KLillie

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  14. dl324

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    And that spec is for a sine wave. Viewing a reasonable approximation of a 20MHz square wave would require at least 3X that bandwidth.

    For a couple hundred dollars, you could probably pick up a Tek 1GHz analog scope (used and 30 years old, of course!). Or you could go with a more affordable 7704A (200MHz) with appropriate plug ins. But you need a lot of bench space or a scope cart...
     
  15. tonyStewart

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    - transmitters demand a spectrum analyzer for complex measurements.. compression intercept, THD, deviation ratio , pilot tone spectra. adjacent channel interference, frequency stability and f measurements with a harmonic marker, etc
    - baseband requires a scope.
     
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  16. Hypatia's Protege

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    I wish to add my voice to TonyStewart's (post #15) --- Quality work (be it engineering or technical) requires proper equipment! 'Workarounds' amount to little more than rationalized guesswork -- Parsimony has no place in the lab or shop!!! :rolleyes:

    Best regards
    HP
     
  17. Hypatia's Protege

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  18. circuitfreak2000

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    Apr 7, 2015
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    Thank you all for the comments. Very helpful.

    I suppose as a start, I just need to be able to see if the FM transmitter is working and what frequency it is transmitting at (95.6MHz, 101Mhz, etc.) so I know what frequency to tune in on a radio. If the 20Mhz the Hantek offers are not enough than I have to search locally for a used analog OSC with at least 100 MHz bandwidth or higher.
     
  19. circuitfreak2000

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    Apr 7, 2015
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    In some videos I have seen some people use a small handheld device with a simple LCD screen and it was able to show the frequency number value in MHz by simply holding the device close to the RF transmitter.

    What kind of device is that and would it replace the need for a scope for this kind of purpose?

    So far I was able to build most circuits without having a scope. I only have a few multimeters and they served well for most needs so far. I like building analog circuits, but other than RF stuff I haven't seen the urgent need for a scope. Other than RF frequency testing, what do you use your scope for usually?

    I think eventually I will see myself using mostly micro controllers such as the ATMEGA, ATTINY or the new ESP8266. It just allows you to make more complex stuff on a smaller scale than using pure analog circuit design and ICs. In that case is a scope still something that would be useful and frequently used?
     
    Last edited: Apr 9, 2015
  20. alfacliff

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    Dec 13, 2013
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    using an osciliscope to measure freuency isnt a good idea, get a counter, more accuracy, and resolution, as well as cheaper. there are frequency converters for osciliscopes that mix the observed signal with an oscilator to get it down to the bandwidth of the scope. the freque3ncy resolution of measuring a scope without built in counter isnt good enough for more than a guess.
     
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