Is what I am hearing true? That BPL has no affect on digital voice!
>From: "Andrew O'Brien" <[EMAIL PROTECTED]> >Reply-To: [email protected] >To: <[email protected]> >Subject: [digitalradio] First digital voice QSO ! >Date: Sat, 30 Sep 2006 21:06:27 -0400 > > >I think John W2FS and I completed our first digital voice HF QSO this >evening. > >John and I had a QSO on 14.236 MHz , USB. today September 30, 2006 from >2315 to 2329 UTC.. We used WinDRM as the software, a SDR 1000 Flex >radio, and ye olde Kenwood TS440. This involves digitalizing the signal >via free soundcard based software , transmitting the data, and decoding the >data at the receive end. There is a 1-2 second "lag" as the encode/decode >processing takes places but otherwise the conversation is similar to any >other voice QSO. > >We are rookies and this , and need to adjust the audio levels somewhat, >However the audio quality using this mode is far superior to the normal >analogue HF SSB signals. The process uses a 2.5 kHz bandwidth , SSB. > >Here is proof of my end of the QSO > > > > >The above picture indicates reception of W2FS with a signal to noise ratio >of 22.5 , using 10 watts. (we live about 100 yard from each other !) Using >Mode B , 16=Amplitude Quadrature Modulation (16QAM) and the MELP codec. >The waterfall in the picture above is best described by the WinDRM software >help file. > >Receive Waterfalls >There are two waterfalls, the 'classic" waterfall with its sweep from the >bottom of the display to the top. The OFDM spectrum will be shown with an >even intensity level across its 2.3 or 2.5 KHz band width. Typically, some >change in intensity at the bottom and top of the spectrum (darker area) may >be seen but should not affect performance. Within the waterfall, three >frequency pilots (carriers) of slightly higher intensity can be seen. They >stand out in the waterfall because they have higher gain (transmitted at >twice the power). These pilots are modulated with known fixed phases and >amplitude which optimize DRM's performance for initial synchronization >duration and reliability. The high-lighted red markers of the waterfall's >sweep indicate where these pilots are located when the transmitter and >receiver DC offsets match. The "moving" waterfall moves from top to bottom >with the red marker's indicating the position of the pilot signals >remaining fixed at the top of the display. The moving waterfall adds a >visual method to monitor the health of the decoded signal in the form of a >vertical line on each side of the waterfall spectrum. During the decoding >process, green vertical lines indicate data is being received without >errors and red lines indicate errors were received (segments lost). These >green/red indicators move with the spectrum instantly showing when and >where data errors occurred. The horizontal line across the top of this >display indicates the bandwidth of the OFDM signal. The signal in the >waterfall should fully extend the width of this indicator. > >John and I did this at our first attempt, so it is not a very difficult >process. I had the software configured in less that 5 minutes. IF I can >do it, everyone else will find it a no-brainer ! > >If you would like to give it a try, the free software can be found at >http://n1su.com/windrm/ the software also decodes digital pictures sent >via HF amazingly well. > >Let me know if you need help. > >Andy K3UK ><< w2fsdv.gif >> Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
