The centre frequency would be based on that programmed in from the last
update in conventional command mode - and could be that stored in EEPROM.
It would be nice to calculate the increment from the stored clock freqeuncy,
but as this is stored in a semi-floating BCD format calculation could be a
bit hairy. Why did I not define this aspect more carefully and store its
binary value :-( Probably will just store the Jason increment value in
another section of EEPROM which is set up at the same time as the clock
frequency. Alberto's serial code will be multiplied by this increment value
and added to the frequency registers to update the DDS immediately. So
leading to a potential tone frequency inaccuracy of up to 4 * DDS step size
resolution.
Don't see the advantage of GPS timing this mode, the timing is generated by
the Jason driver software. In fact, it may be necessary to ensure a
constant delay through the controller so the updates are consistant, but I
guess a few 100us uncertainty per tone won't matter
Andy G4JNT
-----Original Message-----
From: Alan Melia [mailto:[email protected]]
Sent: 2002 July 24 13:12
To: [email protected]
Subject: LF: Re: Jason code on DDS Module
Hi Andy, I think I and probably Brian would be interested in this. Would you
have the frequency increments around say an preloaded nominal frequency in
the PIC and accept Alberto's serial code ?? or were you just intending to
look for frequency words ?? and we write the coding algoritm. With your
'synch' system this would mabe enable GPS timed Jason to be sent ?? Though I
am not sure whether this would be an advantage without some "tweaking" to
Alberto's decoder.
Copy of Johan's 80m QRPP signal a few nights ago showed that the signal was
detectable in the waterfall but not really decodable (Ver 092 or 3 at the
time) due to the high level of static
Cheers de Alan G3NYK
[email protected]
-----Original Message-----
From: Talbot Andrew <[email protected]>
To: '[email protected]' <[email protected]>
Date: 24 July 2002 12:45
Subject: LF: Jason code on DDS Module
Is anyone interested in adding JASON support to my DDS board controller ?
Probably by issuing a "J" command which puts the PIC controller into a loop
looking for 9600 baud words on its serial port, then requiring a reset to
get back to normal. Or by setting a link / switch on one of the spare I/O
pins.
If there is enough demand this could be done with higher priority !
Andy G4JNT
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