[TangerineSDR] Frequencies for FT8 & WSPR

[Dave Larsen]

Bill

This is the code I was referring to.  It seems to do the same as Pavel's
code without the verlog.  it runs on RPi3 with a localkiwsdr
The code in the kiwisdr interface is not Rob's code.

https://github.com/rrobinett/wsprdaemon

I just mention as Rob shows up on the tangerinesdr and Hamsci zooms and has
presented at both Hamsci and TAPR DCC in 2019

Dave

On Thu, Nov 26, 2020 at 1:12 PM Phil Erickson via TangerineSDR <
tangerinesdr at lists.tapr.org> wrote:

> Hi Bill,
>
>   I think you should be setting the mode to USB and the dial to 7.074 MHz
> (example for 40 meters).  The DE, if it is doing true USB, will keep the
> upper sideband and reject the lower one.  (There are multiple methods, but
> the coherent phasing method is perhaps easiest when you have guaranteed I/Q
> that are 90 deg out of phase.). You can play with that yourself by finding
> a web SDR and setting it up that way.  See attached screenshot.
>
> 73
> Phil W1PJE
>
> On Wed, Nov 25, 2020 at 11:50 AM Engelke, Bill via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
>> Hello All:
>>
>>
>>
>> A week ago in the TangerineSDR telco, we touched on an issue regarding
>> frequencies for FT8 and WSPR. I’m interested to know what folks think about
>> what should be done here.
>>
>>
>>
>> The question is this:  when setting the Data Engine (i.e., the radio
>> part) to a frequency for FT8 or WSPR reception, we have used the term
>> “center frequency,” thus suggesting we might set the DE to the center of
>> the respective sub-band (see table below). Perhaps that is compatible with
>> IQ sampling, where we recognize the frequency of the signal by the phase
>> difference between I and Q; so signals below the center would have a
>> negative phase shift (“negative frequency”), signals above a positive shift.
>>
>>
>>
>> I have a question:
>>
>>
>>
>>    - The decoders for both WSPR and FT8 assume the receiver is set to a
>>    dial frequency (per the WSPR and FT8 band plans) and receiver is in USB.
>>    This produces a baseband signal (that can be collected by a sound card) in
>>    the audio range. I am fuzzy on the correct way to convert this signal – do
>>    we set the DE’s frequency to the dial frequency and assume that the decoder
>>    will ignore everything in the negative frequency area, or do we set the
>>    DE’s frequency to the center of the sub-band?
>>    - Just as a note, Scotty and Martin, who are planning to do the FPGA
>>    programming, voiced some concerns about whether the DE could actually be
>>    set to the required frequency (be it “dial frequency” or “center of the
>>    sub-band”), due to open questions about the clock’s output (?) – I am fuzzy
>>    about the details here, but as recall, the way we left it was that Scotty &
>>    Martin are going to have a look at the Pavel Demin FPGA code to see how he
>>    accomplished it (which may answer the question above). What I do know is
>>    that the Raspberry Pi does not have the capacity to accept a wide-band data
>>    feed( (i.e., encompassing all FT8 & WSPR frequencies) and doing the
>>    filtering to slice out the sub-bands for the decoder; that would take a
>>    high-end desktop.
>>
>>
>>
>> If anyone has any thoughts, please post. Below is the table of
>> frequencies:
>>
>>
>>
>> *Frequencies for FT8*
>>
>>
>>
>> (4000 samples/sec)
>>
>>
>>
>>
>>
>> Dial Freq. in MHz
>>
>> in Hz
>>
>> lowest signal
>>
>> center
>>
>> top of band
>>
>> 1.84
>>
>> 1840000
>>
>> 1840200
>>
>> 1841500
>>
>> 1843000
>>
>> 3.573
>>
>> 3573000
>>
>> 3573200
>>
>> 3574500
>>
>> 3576000
>>
>> 7.074
>>
>> 7074000
>>
>> 7074200
>>
>> 7075500
>>
>> 7077000
>>
>> 10.136
>>
>> 10136000
>>
>> 10136200
>>
>> 10137500
>>
>> 10139000
>>
>> 10.074
>>
>> 10074000
>>
>> 10074200
>>
>> 10075500
>>
>> 10077000
>>
>> 18.1
>>
>> 18100000
>>
>> 18100200
>>
>> 18101500
>>
>> 18103000
>>
>> 21.074
>>
>> 21074000
>>
>> 21074200
>>
>> 21075500
>>
>> 21077000
>>
>> 24.915
>>
>> 24915000
>>
>> 24915200
>>
>> 24916500
>>
>> 24918000
>>
>> 28.074
>>
>> 28074000
>>
>> 28074200
>>
>> 28075500
>>
>> 28077000
>>
>> 50.313
>>
>> 50313000
>>
>> 50313200
>>
>> 50314500
>>
>> 50316000
>>
>> 50.323
>>
>> 50323000
>>
>> 50323200
>>
>> 50324500
>>
>> 50326000
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> *Frequencies for WSPR*
>>
>>
>>
>> (375 samples/sec)
>>
>>
>>
>>
>>
>> Dial Freq. in MHz
>>
>> in Hz
>>
>>
>>
>> center
>>
>>
>>
>> 0.136
>>
>> 136000
>>
>>
>>
>> 137500
>>
>>
>>
>> 0.474
>>
>> 474000
>>
>>
>>
>> 475500
>>
>>
>>
>> 1.8366
>>
>> 1836600
>>
>>
>>
>> 1838100
>>
>>
>>
>> 3.5686
>>
>> 3568600
>>
>>
>>
>> 3570100
>>
>>
>>
>> 7.0386
>>
>> 7038600
>>
>>
>>
>> 7040100
>>
>>
>>
>> 10.1387
>>
>> 10138700
>>
>>
>>
>> 10140200
>>
>>
>>
>> 14.0956
>>
>> 14095600
>>
>>
>>
>> 14097100
>>
>>
>>
>> 18.1046
>>
>> 18104600
>>
>>
>>
>> 18106100
>>
>>
>>
>> 21.0946
>>
>> 21094600
>>
>>
>>
>> 21096100
>>
>>
>>
>> 24.9246
>>
>> 24924600
>>
>>
>>
>> 24926100
>>
>>
>>
>> 28.1246
>>
>> 28124600
>>
>>
>>
>> 28126100
>>
>>
>>
>> 50.239
>>
>> 50239000
>>
>>
>>
>> 50240500
>>
>>
>>
>>
>>
>>
>>
>> -73- Bill , AB4EJ
>> --
>> TangerineSDR mailing list
>> TangerineSDR at lists.tapr.org
>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>>
>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com
> --
> TangerineSDR mailing list
> TangerineSDR at lists.tapr.org
> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>


-- 
KV0S - Dave Larsen
Columbia, MO, USA
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