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Re: LF: OPERA Question

To: <[email protected]>
Subject: Re: LF: OPERA Question
From: "Graham" <[email protected]>
Date: Tue, 10 Jul 2012 16:56:59 +0100
Importance: Normal
In-reply-to: <[email protected]>
References: <C3F731D3B3D442FDBAA8720F953F74A5@AGB> <F09855DF575643A69705E0C805514AC1@2a2d7ed321c6425> <E0F8753816EF48A5A08EA8B704F787EA@AGB> <[email protected]> <CC76ACE4114B46C287B68D45D8B20D19@AGB> <[email protected]> <A590C5270A984DEFB1E0CDB5FA76DC51@AGB> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
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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..


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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




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