Stig and Jim, Dale is telling the plain truth, if your main interest is getting your signal through in noisy conditions and DX pileups. The basses convey very little speach information, but eat up the limited power of your transmitter. Unless you want to broadcast a Hi-Fi music program on ham bands use a good quality multi-channel equalizer to attenuate the lower frequencies of your modulation. And if you want real information carrying audio punch, you may use a PROPERLY MADE compressor or even RF clipper. However, never use compressors and/or clippers, if the the basses are not attenuated.
Almost four years' time already I have tried to convince our Flex software wizards and gurus to implement an integrated audio processor that would enhance the speech signal intelligibility in noise at least as well as explained in the following "ancient" articles. Sorry for this repeated use of the bandwidth, but please, please, read carefully and understand these: http://kotisivu.dnainternet.net/ahti/sdr-1000/filtclip.pdf http://kotisivu.dnainternet.net/ahti/sdr-1000/speechproc.pdf My understanding is that these functions can be implemented by the DSP means much more elegantly than 30 years ago by the hardware means. I sincerely hope that some of our software experts would take my request seriously. 73, Ahti OH2RZ On 04/06/07, Dale Boresz <[EMAIL PROTECTED]> wrote: > Stig, > > I think your power meter is misrepresenting your power levels. I suspect > that you are not using a peak-reading power meter, and that your power > meter's ballistics are such that it averages the peaks more efficiently > at the low audio frequencies than it does at the midrange and upper > frequencies, thereby making it appear that when you boost the low end, > you're getting extra talk power. Most likely, all that you are doing is > concentrating the bulk of your transmitted energy into a very narrow > range of frequencies that are in fact chewing up a lot of power and > inflating your meter reading, but actually reducing your 'talk power'. > > The panadapter of the SDR-1000 has been a very interesting tool for me, > as I have noticed may stations that have as much as a 20 to 30 dB peak > at the low end of their transmitted frequency range (say around 40 to 70 > Hz) and are showing S9 on the meter. However, the part of their signal > which is actually carrying the intelligibility is in fact averaging > around S4. (S9 minus 30 dB). If the excessive peak was removed (the > lower frequencies would remain - they just would not be boosted so > much), the remainder of the audio passband could be amplified all that > much more, such that the average of the remainder of the passband > carrying intelligibility would in fact really average out to S9 instead > of S4. Note though: Unless you are using a true peak reading power meter > (something like a Coaxial Dynamics 83000-A) or an oscilloscope to > monitor peak power, it will look as though you are transmitting at a > much lower power level since the actual peaks will not be properly > displayed. Attempting to drive everything harder to make the power meter > read higher will result in a very distorted and severely over-driven signal. > > 73, Dale > WA8SRA > > _______________________________________________ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > FlexRadio Knowledge Base: http://kb.flex-radio.com/ > FlexRadio Homepage: http://www.flex-radio.com/ > > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
