| Home |
| Search |
| Today's Posts |
|
#11
February 10th 04, 04:13 AM
|
|||
|
|||
"Leo" wrote in message ... On 9 Feb 2004 15:25:04 -0800, (N2EY) wrote: Leo wrote in message . .. I understand that Morse is good for getting through poor conditions better than voice. Much better than any form of analog voice. Makes sense, it is narrowband and binary (well, tri-state if you count the spaces...) encoded. Exactly. From the experimenting (read: fooling around) that I have been doing over the past couple of months, I have been repeatedly amazed with the ability of BPSK-31 to get clean copy through pretty bad conditions. Even DX signals that appear as weak vestiges on the waterfall display can be easily decoded with near 100% accuracy, using just a PC sound card as an interface. The soundcard is only part of the system. The decoder is quite smart, in that it stores and examines the received data and does a "best fit" decoder. You can read all about it at several websites. Good point - I've compared it to RTTY from the decoding standpoint - RTTY seems to be much more prone to losing characters or dropping out entirely when the signal is weak or noise is high. But it's important to realize what constitutes "poor conditions". Against purely amplitude noise it's quite robust. But against phase noise of various types it is not robust at all. All depends on the situation. Frequency stability of my old Heath TX is a problem, but I'm working on it..... What rig is it? Heath SB-400. The Pride of 1964  With a narrowband signal like this, it doesn't take much drift! I'm seeing a frequency decrease of up to 15 Hz, beginning a few seconds after keying. B+ to the VFO appears to be well regulated - maybe not tight enough though. Might have to replace the 0A2 with a few zeners - haven't tried that yet.... Now there's something that will get through when nothing else will. Not really. You will find times when the PSK-31 signal is clearly audible in the speaker, well above the background amplitude noise, but the decoder cannot make sense of it because the phase distortion is too bad. Haven't experienced that yet - at least when I see that, I'll know what is causing it! And, it types itself out, too. (that's a real boon for the perennially lazy - like me) It was meant as a replacement for conventional RTTY - as a "keyboard to keyboard" mode. For example, the speed was chosen to be about what *average* conversational keyboarding hams use. btw, the code used in PSK-31 uses shorter symbols for the most common characters and longer ones for the least common. Just like Morse code, which is where the designers got the idea. Didn't know that - great idea, though! I believe that BPSK-31 was created within the amateur community - Yup - G3PLX, and a number of folks who helped him by testing it out on the air and others who have developed software packages. A local ham of my acquaintance (one of those longtime 20 wpm 1x2 Extras with multiple EE degrees - we share two alma maters, btw) was one of the team who helped test it out. PSK-31 is another great tool in the toolbox, but not a replacement for good old Morse Code. Haven't formulated an opinion on that one yet - stay tuned! 73 de Jim, N2EY 73, Leo Just to add to information, I heard a couple of hams talking shortly after the major solar flares of this past fall were finally over. They had commented on the fact that the distortion on PSK31 was so bad that they had had to switch to Morse. Dee D. Flint, N8UZE |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| Using a Pool Cage As an Antenna? | Antenna | |||
| Use a Pool Cage As An Antenna? | Antenna | |||
| From the Extra question pool: The dipole | General | |||
| REQ:latest Ham University with curent tech pool willing to share?/sell cheep | Equipment | |||
| REQ:latest Ham University with curent tech pool willing to share?/sell cheep | Equipment | |||
Threaded Mode
