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JEL
søn 26. aug 2018, 06:44
Registeret medlem #4511
Oprettet: fre 01. apr 2011, 09:27
Sted: Danmark
Indlæg: 49
Jeg har luret lidt på hvorfor HAM-folket bruger LSB på 3 og 7 MHz, mens diverse militær bruger USB omkring samme frekvens-område.

Er der nogen god forklaring på det, eller er det bare mere eller mindre tilfældigt?
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signalspan
søn 26. aug 2018, 11:11
Registeret medlem #4366
Oprettet: fre 19. nov 2010, 19:37
Sted: Karlstad, Sverige
Indlæg: 111
"The standard operating practice for SSB is to use LSB below 10 MHz, and USB above 10 MHz. This is not a regulation, nothing forbids you from using the "other" sideband, but then who would you talk to?

The convention is, so I've heard, largely historical, based on the design of an early SSB rig. The IF was 9 MHz, which is 5 MHz below the bottom of 20 meters and 5 MHz above the top of 80 meters. When mixed with a 5-5.5 MHz VFO, the sum frequency was at 14.0-14.5 MHz, which covered 20 meters, and the difference frequency was at 4.0-3.5 MHz, which covered 80 meters.

I wrote the 80 meter frequency range backward to indicate that with this approach the higher the VFO frequency, the lower the mixer output frequency. This also meant that if you started with an upper sideband signal on 9 MHz, you still had a USB signal on 20, but an LSB signal on 80, and thus the convention was born.

Now, with the digital modes, all bets are off. I've heard old RTTY ops say that RTTY is LSB everywhere, and new PSK ops say that PSK is USB everywhere, and that if things don't work to just use the software "invert" switch. I'll leave it to someone else to enlighten us on that part. "

https://forums.qrz.com/index.php?threads/usb-or-lsb.211213/
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JEL
man 27. aug 2018, 00:59
Registeret medlem #4511
Oprettet: fre 01. apr 2011, 09:27
Sted: Danmark
Indlæg: 49
Tak :)
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signalspan
man 27. aug 2018, 15:27
Registeret medlem #4366
Oprettet: fre 19. nov 2010, 19:37
Sted: Karlstad, Sverige
Indlæg: 111
Værsgo.
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