Jack, I can imagine the challenge for being blind and working with a Windows computer today compared to the early text based machines. Recently, there was an article in QST written by two blind hams who developed an add-on for one of the MFJ antenna analyzers. Ironically, they pointed out that many of the digital devices of today have made it more difficult to use technology.
Digital voice is probably as good as it can get unless there is some breakthrough in the laws of physics. The noise floor of the receivers is also about as good as we can get, and often below what is even needed. If you connect your receiver to the antenna and notice an increase in noise, you are above the noise floor of the receiver. And that is normal for almost any kind of antenna on HF. Even on VHF, since the noise floor is mostly dependent upon the atmospheric conditions, not the receiver, assuming the receiver is a reasonably good performer. The D-Star DV voice requires just over 6 kHz of bandwidth so it will not be an option for HF because it is too wide. More than double a typical analog SSB width signal. As you have found, the even narrower digital voice signal that must fit into the very narrow analog filter bandwidth, just does not have the ability to compete with SSB when signals are below the threshhold. Digital modes really shine for data since we do not require the huge data throughput necessary in real time for voice and can actually work well below the noise and can even compete with CW. 73, Rick, KV9U Jack McSpadden wrote: >Hi Rick and thanks for helping me to understand some of the finer points of >data vs digital voice. When PSK31 first got started a few years ago, I got a >rig interface for my Kenwood 570DG I owned at the time and worked it very well >for a couple years. I am blind and had to arm wrestle my screen reading >software to make it work properly for me. To lock in on a signal, the program >I finally register was MIXW and have kept it updated. To achieve a lock on a >signal since I couldn't see the waterfall, I used the auto seek function of >f11 and f12 as well as the arrow keys and it sufficed and made many satisfying >contacts. Now this Digital voice thing has gotten under my wig and I really >have enjoyed it . I wasn't aware that keyboarding in the phone band would be >prohibited and thanks for making me aware of that. Yes, the SN factor with >the AOR modem is an issue right now, but I truly feel that we hams need to put >the hurt on our manufacturers to come out with some better receivers with a >lot lower noise floors and the ability to kill noise when desired, not just >DSP. I owned an Atlas 210X (don't laugh too hard) and believe it or not, it >had the lowest noise floor of any radio I have ever owned, bar none. Their >scheme was to use a double ring diode mixer rather than an amplifier stage >right after the input from the antenna and boy I could get on a QRN night and >hear even the mobiles through it and everyone wondered what I was using. >Anyway, I personally feel there will be a digital hf voice mode on some >transceiver within the next 4 to 5 years if not sooner. I know Icom has Dstar >but it is mostly VHF and above. I also think they could narrow the bandwidth >a little more and still maintain a fairly decent quality signal with some FI >to it. So again, forgive my ramblings but I am a true believer in digital >modes of communications, I just need to get busy and learn more of it >technicalities. >Your ham friend and fellow digital radio buff, >Jack wa5rop > > > >------------------------------------------------------------------------ > >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.5.432 / Virus Database: 268.17.8/648 - Release Date: 1/23/2007 >11:04 AM > >
