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Sunday, May 26, 2013

Thoughts on DSB PSK-31



To QRP-L: 

I have a JUMA TRX-1 cw and dsb transceiver. It seems to me that if I transmit an psk signal there would be two signals generated, one on usb and another on lsb. Is this correct? It does not seem like a good thing to do to me.
Thoughts?
73 Larry WB4HLX

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Larry: 

I've been experimenting with DSB PSK for the last few weeks.  Sure, you are using twice the needed bandwidth,  but in this mode that means you are using only an additional 31 HERTZ! That's not a lot.  Also, if (as I am) you are using a Direct Conversion receiver, in your waterfall you will also be looking at two sets of frequencies -- those going about 2 kHz above center AND 2kHz below.  This helps you avoid causing interference:  If the frequency looks clear on your screen, you can be reasonably sure you won't be bothering anyone with your extra sideband.

This is similar to the AM question: there too you are using additional spectrum.  But it is allowed.

Doug DeMaw and other esteemed technical gurus have promoted DSB as a useful mode that -- through its relative circuit simplicity -- encourages the building of homebrew gear.  DeMaw wisely advised against using high power when running DSB.

I've been having fun with PSK DSB.  I've had many contacts.  I'm running less than one watt to a dipole.   One curious thing that I've noticed:  PSK seems to be sideband independent:  When I tune in a PSK signal on my FLDIGI waterfall, the software will decode it even if I have the FLDIGI set for LSB or USB. 

You might also want to try JT-65.

Good luck. 

Glad to hear that I'm not alone.           Center             Glad to hear that I'm not alone.

73   Bill N2CQR
http://soldersmoke.blogspot.com

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

2 comments:

  1. Didn't you really mean this Bill?

    .enola ton m'I taht raeh ot dalG Center Glad to hear I'm not alone

    ReplyDelete
  2. Mike: No! I'm on PSK-31, so it decodes properly on either sideband! :-) 73 . 73 Bill

    ReplyDelete

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