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LSB or USB?

Discussion in 'Working Different Modes' started by AG6HO, Jan 3, 2011.

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  1. W5RKL

    W5RKL Ham Member QRZ Page

    Hi Steve,

    The PEP statement I provided, using a dipole antenna which is what the ARRL ham band chart for 60 meter states, was obtained from the FCC part 97 rules and regulations under part 97.303 titled "Sharing Requirements", paragraph "(s)", which states, in part:

    "(s) An amateur station having an operator holding a General, Advanced or Amateur Extra Class license may only transmit single sideband, suppressed carrier, (emission type 2K8J3E) upper sideband on the channels 5332 kHz, 5348 kHz, 5368 kHz, 5373 kHz, and 5405kHz. Amateur stations shall ensure that their transmission occupies only the 2.8 kHz centered around each of these frequencies.Transmissions shall not exceed an effective radiated power (e.r.p) of 50 W PEP. For the purpose of computing e.r.p. the transmitter PEP will be multiplied with the antenna gain relative to a dipole or equivalent calculation in decibels. A half wave dipole antenna will be presumed to have a gain of 0 dBd. Licenses using other antennas must maintain in their records either the manufacturer data on the antenna gain or calculations of the antenna gain. No amateur station may cause harmful interference to stations authorized in the mobile and fixed services; nor is any amateur station protected from interference due to the operation of any such station."

    73s
    Mike
     
    Last edited: Jan 3, 2011
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Yep. ERP is the guiding factor, if we are interested in being lawful.;)

    You could run about 300W PEP output from a mobile to a whip and probably be within the 50W ERP limit. But only about 12-13W output to a 4-square array or similar. That's the snag, unfortunately. It really does limit what we can work on this rather excellent band; so does restricting transmissions to USB only.

    If we could use CW and 500W ERP, working the world on 5 MHz would be a piece of cake.:)
     
  3. K5TCJ

    K5TCJ Premium Subscriber QRZ Page

    Understanding that the method of producing SSB in early SSB equipment pretty much dictated the use of LSB on 75 and 40, except for tradition.....why do we continue to use LSB instead of universally using USB on all bands?

    Tim K5TCJ
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Why not use LSB on all bands?;)

    To make the best use of our phone band allocations, we should use USB near the low end of each band and LSB near the high end of each band.:)
     
  5. AG3Y

    AG3Y Guest

    Well, Steve, a lot depends on how you look at that. If your signal is 3.5Khz wide, it really doesn't matter WHERE the supressed carrier would be ( above or below the sideband being trasmitted ) because it would be - - - - well, SUPRESSED!

    The confusion factor comes into play, because most radio dials ( in fact, almost ALL radio dials ) read out the frequency where the CARRIER would be, IF INDEED, the CARRIER was present. So placing your carrier at the very top edge of a band, and transmitting in LSB would, in theory, keep all your emissions within the allocation, but so would transmitting 3.5Khz BELOW the top edge of the band, using USB ! And, it is conceivable that the entire bandpass from the edge of the band down 3.5Khz would be full of audio sidebands, if your voice's characteristic were of that nature.

    In short two different radio stations, one transmitting USB and the other LSB would BOTH occupy a swath of frequencies 3.5Khz wide with all the energy within 3.5Khz of the upper edge of the allocation.

    This is all in theory, of course, because there are other factors such as the characteristic of the voice of the operator, the shape of the filter's skirts, the carrier offset employed in the radio, etc. etc. But you get the idea!

    73, Jim
     
  6. N5VEI

    N5VEI Ham Member QRZ Page

    USB or LSB

    If you are talking about voice LSB for 40 and 80. But if you are doing digi, most programs and interfaces use USB on all modes. The only program I know of that uses LSB (I think) is Easypal for digital image stuff.
     
  7. AG3Y

    AG3Y Guest

    Easypal will work in either sideband. The only requirement is that both stations be using the same sideband. That is easy enough to figure out, because almost all DRM work that I am familiar with is done in the "Voice-Image" portions of the band, and there is usually a lot of comments from the operators, etc. that go along with the DSSTV transmissions.
     
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