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Thread: Teensy Convolution SDR (Software Defined Radio)

  1. #201
    Senior Member DD4WH's Avatar
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    Regarding the radio-signal reception of WHF - can it be done so that when this demodulator is turned on, the Sample Rate will set 192k by default? We have to search 192k in the menu for a long time....

    And need to disable the LPF filters when we turn on this demodulator WHF - for bypass.
    I understand that there are not enough controller ports, but you can use, for example, pin3, on which a logical level will appear when the WHF is turned on ....
    But this level should disappear at pin29 above a frequency of 30 MHz.
    Or disable all logic levels at the outputs of the control of LPF above 30 MHz and simple logic on the 5-OR chip, after this frequency, will turn on baypass for WHF.

    And there is an error in the Teensy Convolutio SDR pinout list.
    26pin - LP Filter Band 1 (<320 kHz)
    27pin - LP Filter Band 2 (320.....930 KHz)
    31pin - LP filter Band 3 (930...1975 KHz)
    30pin - LP Filter Band 4 (1975....5375 KHz)
    29pin - LP Filter Band 5 (5375 KHz...37000 KHz)
    Hi Valery,

    1.) sample rate: yes, that is already implemented in the newest version of the software!

    2.) yes, that is also possible, but you would have to alter the function setfreq according to your specific hardware

    3.) Filter pinouts: no, there is no error, it works with my hardware. BUT, you would have to modify the software for your specific hardware/filter layouts [which is not coplicated, just go into "setfreq" and alter the frequencies according to your needs]

    All the best 73s,

    Frank DD4WH

  2. #202
    Junior Member
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    Daugavpils, Latvia
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    Frank, thanks for your reply!
    It is very interesting to me why your compiled file does not work after loading, whereas with the compiled file from Wolfgang DH1AKF everything is fine, the receiver works very well.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  3. #203
    Senior Member+ Frank B's Avatar
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    Frank, i tried RFSIM99 instead (I tried elsie but was not able to use it correctly) - and more important - the exact parts. You can see the parameters if you enter the inductor- partnumber in digikey. You can see the q-factor and resoance frequency, in the digikey result table.
    The result is is a bit different:Click image for larger version. 

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    Only -1.53 db, and the graph looks different. I read RFSim99 is very exact and gives reliable results.

    Any thoughts? Have I done it correctly (I don't have experience with this stuff ??


    The board will have the frontend only, including the filterbank.
    I'm thinking about adding a MMIC amplifier beforethe filters.

  4. #204
    Junior Member
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    Apr 2019
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    Daugavpils, Latvia
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    Frank B, it makes no sense to assemble such complex designs of input filters for a receiver with a mixer of this type.
    Fifth-order low-pass filters are quite enough:
    http://yl2gl.ucoz.net/news/sobiraem_...2019-03-15-146
    You only need to weaken the reception on the odd harmonics - the third and higher....

  5. #205
    Junior Member
    Join Date
    Mar 2019
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    6
    Hi Frank DD4WH

    I would like to make use of your AM_demod header.
    Is it a simple matter of adding the .h .cpp files for compiling and adding the audioconnection code with a switched output path for the AM-demod block?

    Hope you have time to reply, Rob

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