On 05/07/2017 23:49, Joe Taylor wrote:
Hi all,
If you knew you had to send an ID with a packet, could you not reduce
the amplitude of the whole data packet by a db or so and re-allocate
that power to the CW ID? It certainly doesn't have to be loud, much
like repeaters do id-under-voice. That way the FT8 signal taken by
itself would still be constant envelope, and the CW id could be sent
way down at FDial+100Hz. If the OOK nature of CW is the issue, you
could always treat it as FSK using 1 Hz and 100Hz. The 1Hz component
would get chopped out in the radio, leaving the ID and FT8 signal.
Such a scheme would NOT produce a constant envelope signal. Sending
the CW ID at a frequency offset by 100 Hz, or using FSK for the CW,
would make the signal much wider than an FT8 signal.
the classification of the speed of sending morse is weird anyway.
definition of a word ???? definition of a character ????
Morse code speeds are conventionally defined in a very precise way.
See, for example, http://www.kent-engineers.com/codespeed.htm .
The width of the main spectral lobe of a CW signal in Hz is roughly
equal to the speed in WPM. Fairly strong secondary lobes occur at
multiples of this number. Sending the CW ID at (say) 100 WPM, in
order to squeze it into a 15 s Tx interval, would make the CW ID much
wider than an FT8 signal.
Most likely we will implement CW ID as a separate, dedicated
transmission when the T/R sequence length is less than 30 s.
NB: Since June 15, 1983 FCC does NOT require US amateurs to use a CWID
with data modes.
-- 73, Joe, K1JT
Hi Joe & all,
there will certainly be some countries where a periodic CW id is
required. As has been discussed off this list two possible options are
to have a manual CW id button or to send the CW id in some future T/R
period.
For the former we still have an issue in that we do not really want to
have stations sending on/off keyed CW transmissions while others are
sending messages. That might be mitigated by using FSK CW with a width
similar to the primary mode i.e. FT8. the keying rate would still have
to be slow enough as to not consume excess bandwidth. This is assuming
that F1B modulated CW with a shift of around 50Hz is acceptable as a CW id.
The latter would have similar issues but sending the id at the start of
the next transmit period would probably be the least disruptive, it
could be inserted either stand alone if no message is to be sent or in
place of the first few seconds of a transmit message. The remaining
transmit message would have some small chance or being decoded if the CW
id was less than 5s long.
Either form of deferred CW id should perhaps lock out any frequency
changes of dial frequency or Tx audio offset so as not to "detach" the
CW id for anyone wishing to identify the sending station.
Another issue is that a station replying to a CQ call should not send a
deferred CW id as it will become QRM to the station running the
frequency. In fact it is hard to see how a station that is not running a
frequency can send a CW id at any meaningful time.
These are all tricky issues to resolve.
73
Bill
G4WJS.
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