Re: Input Needed for RadCom Column

Andy G4JNT

Unfortunately, the old people who run the system still mandate CW idents.  I see no point whatsoever in them, but whatevs...

The period of plain carrier, also mandated,  is essential as it gives a constant measure for any beacon.

But the proper modulation type is a free-for-all.  So a combination of fast mode plus slow mode is quite possible.   JT9 woul dbe good for that as it can have a lot of generator code in common, just changing the symbol rate and tone shift .  In fact for uWaves,  the same tone shift for fast and slow mode could even be maintained.

On Wed, 22 Jan 2020 at 17:25, Neil Smith G4DBN <neil@...> wrote:

Something like the sound of a pump key with a CO/PA two-valve transmitter circa 1956 would do the job. Decent click, bit of droop, gradual drift, good amount of chirp, and a few character spacing and symbol length errors to add some idiosyncratic "swing".  Instant recognition of the "fist" without hearing more than a couple of characters.

Is a CWID actually required at all under the beacon licence?  The beacon could have a theme tune instead.  Local folk song melody, or a nice short ID like the Radio Tirana ident from the 70s.

I'd certainly be keen to have a decent slow mode like JT4F/G or PI4 which would work via rainscatter as well as weak troposcatter, but also a fast mode like JT9F-fast that would work off aircraft, and some plain carrier to look at the shape of the troposcatter spectrum over 20s or so.

Neil G4DBN

On 22/01/2020 17:09, Andy G4JNT wrote:
So. you're saying, for the olde-mann ident stage, it would be preferable to introduce a carefully designed, non-linear chirp along with a bit of PR noise.   That can be done with a PIC / DDS combination, so a direct upconversion based beacon should be able to manage it.   But a PLL or RDDS based one can't hack it

For all  the use the CW ident is, might as well do something special and use some artistry for its sound.

Now there's a thought for any GB3SC# update - a custom CW ident 

On Wed, 22 Jan 2020 at 17:01, Neil Smith G4DBN <neil@...> wrote:

It is a GLORIOUS sound Adrian, expecially after it has travelled 342km to reach here, which, as you know, it does quite often. I like PI7RTD as well, and all of the others the whoop and slide and chirp. Perfection is boring, at least for the CWID.

Neil G4DBN

On 22/01/2020 15:56, Adrian G4UVZ via Groups.Io wrote:
Whilst the idea of keying the 5Mhz sounds interesting ..I fear that the df/dt of the keying by the time it had gone through the PLL would be  pretty you can hear the exisiting keying is no wonderful!  
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