Hi Jeff, I did read your test results and ran them this afternoon myself. I have some data that may counter your theory or I may end up agreeing with you. However, I am going to respond in detail off reflector because I have already made one incorrect public hypothesis today that I had to retract. :>(
Regards, Gerald Gerald Youngblood, K5SDR President and CEO FlexRadio Systems(TM) 13091 Pond Springs Road, #250 Austin, TX 78729 Phone: 512-535-4713 Ext. 202 Email: ger...@flexradio.com Web: www.flexradio.com <http://www.flex-radio.com/> Tune In Excitement (TM) PowerSDR(TM) is a trademark of FlexRadio Systems On Thu, Mar 3, 2011 at 7:35 PM, Jeff Anderson <jca1...@sbcglobal.net> wrote: > Hi Gerald, > > From my own experiments, I'm not convinced that it's a problem with the ALC > algorithm itself (i.e. that it isn't "ALC overshoot"), but rather with the > placement of the ALC algorithm within the code. > > With "stock" code, my measurements show that severe TX overshooting can > occur, and it seems to depend upon the type of waveform used for testing. > Of course, it's always possible that I made a mistake in my measurements, > so if anyone would like to replicate my tests, please do! The testing > procedure is simple and straightforward, and I describe it in my blog > posting at http://k6jca.blogspot.com/ . All one needs is a scope and > some way to monitor one's RF signal with it. (One item I forgot to mention > in my blog post was TX bandwidth. I no longer recall what it was for my > testing, but 3.8KHz is probably in the ballpark . If anyone is going to try > to repeat my tests, it might be worthwhile to experiment with TX bandwidth > (both low-cutoff as well as high-cutoff) to see if/how bandwidth affects TX > overshoot). > > Best regards, > > - Jeff, k6jca > > > Gerald Youngblood wrote: > >> Steve et. al. >> >> Well, I am going learn not to propose a public hypothesis based on reading >> an email. ;>) After testing in the lab, there is no glitch whatsoever >> when >> switching Tune on and off. I set the spectrum analyzer to 0 Hz span, >> which >> makes it able to catch the power of real time glitches. There were none >> at >> all. It was perfect. >> >> Please disregard my earlier speculation as to the faster TR times causing >> a >> problem with spikes on the transmitter. I was simply wrong. >> >> However, we will definitely look further into the ALC overshoot reports. >> I >> did some initial measurements but they are inconclusive so far. >> >> Regards, >> Gerald >> >> >> Gerald Youngblood, K5SDR >> President and CEO >> FlexRadio Systems(TM) >> 13091 Pond Springs Road, #250 >> Austin, TX 78729 >> Phone: 512-535-4713 Ext. 202 >> Email: ger...@flexradio.com >> Web: www.flexradio.com <http://www.flex-radio.com/> >> >> >> Tune In Excitement (TM) >> >> PowerSDR(TM) is a trademark of FlexRadio Systems >> >> >> > _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
