Yes , with one correction , ( for audio drive)
The carrier placement routine, when Tx is selected , scans the Rx
audio band and selects the lowest s/n spot frequency in that range
So if you are using a transverter (or on frequency exciter ) then
the TX frequency is decided by the audio drive frequency inside the
limits (red-lines) for that mode/speed
If using manual frequency selection, then a Tx frequency must be
selected, that will produce a carrier/hetrodyne that falls inside the
audio pass band (red-lines) defined by convention as 'dial set usb
frequency'
Changing the speed also requires a change of frequency to place the
carrier inside the correct filter , automated if using audio-drive.
Narrow IF filters are not desirable and reduce the performance of
the demodulator , better simply use SSB filter
NB : The pass band edges are quite sharp , so ensure you are
'inside' and not 'on the line' or you may fail to decode .......
also tx / rx frequency alignment may place you out side .... i
Keying , recommended that the TX be held in 'tx' , to prevent tx/rx
change over times from altering the keying times .... not 100% a
problem , but to enable decodes the lower levels , time +/- and
frequency +/- need to be as close to the generated values as
possible
GL ..73 -G..
--------------------------------------------------
From: "Albert" <[email protected]>
Sent: Tuesday, July 10, 2012 2:58 PM
To: <[email protected]>
Subject: Re: LF: OPERA Question
Stefan,
Download the Opera program. In the waterfall you will see two red lines,
put the cursor on the lines and read the frequency (upper left window of
the waterfall display) Op4 differs from Op8 etc a frequency within this
band is the input of the USB TX so 477kHz + (a frequency between the red
lines). When using CAT control Opera will choose a not occupied freq. in
the appropriate pass band.
73, Albert
|
