[GreenKeys] 850 Stream

[Harold Hallikainen]

True, it makes no difference on the internet stream what tones are used
(as long as we stay below the Nyquist frequency). I think the 2 kHz +/-
425 Hz is the most reasonable now to run on both internet and HF for 850
Hz shift. This allows the same equipment to be used for both.

As to which tone is which, and if it gets inverted on RF, I think it's
largely tradition. The tones may have been brought over from 1930s
telephone standards. Back 50 years ago, I learned "LSMFT" or Low Space
Makes Fine Teletype (on RF, anyway). For some reason, we received in LSB
mode, so the audio tones were "upside down" from the RF.

Harold
https://w6iwi.org


On Sun, February 5, 2023 3:09 pm, Alf Fisher wrote:
> On 05/02/2023 18:30, Harold Hallikainen via GreenKeys wrote:
>> I agree with 1575 (mark)-2425 (space). With military radios, I think
>> this
>> results in space being on the higher frequency since they generally run
>> USB.
>>
>> 50 years ago, when I ran 2125, 2975, I was directly FSK keying a Viking
>> Ranger and receiving with a National NC-300. I could get the 2975 Hz
>> that
>> way. Most SSB transceivers will not, of course, pass 2975 Hz.
>>
>> Harold
>>
>
> As I understand it, this is audio streaming via the internet so it wont
> have the bandwidth restrictions of a SSB Tx/Rx so there will be no
> problems sending 2975 Hz or higher frequencies.
> Please correct me if I've got it wrong.
>
> Also please can someone explain the rationale behind downshift on mark
> or downshift on space or is it just a convention.
>
> 73,
> Alf
> G3WSD
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