On Wednesday 10 September 2025 22:11:16 gene heskett via tde-users wrote:
On 9/10/25 23:12, William Morder via tde-users wrote:
On Wednesday 10 September 2025 18:47:24 dep via tde-users wrote:
A long day and night with Commodore OS, in case anyone's interested.
Maybe somebody else out there who knows more about these things (thinking of you, Gene!) might be able to tell me why this cannot possibly work.
Bill
Yes it /could/ work, Bill, but introducing the noisy world of broadcast does entail an attention to detail involving frequency accuracy and some sort of an error correcting algorithm where sufficient redundancy exits in the code format to make self correcting code practical. Fire coding comes to mind, but even that requires sufficient redundancy to fix multi bit errors created by a leaky crossbar on a power pole. A pole originally equipt with 2400 volt rated glass insulators, up-graded to carry 7200 volts w/o replacing the insulators, compounded by the diagonal steel braces holding the crossbar level but with the center bolt into the pole not having been re torqued since it was originally bolted up in 2400 volt REA days. There does not exist in this scenario, a method to demand a re-transmission of corrupted data. All the common methods today, rzsz, tcp, probably a dozen other's, all work because its a 2 way path. Corruption detection is easily done with a crc on each sectors (256/512) worth of data, but w/o the on demand retransmission, is hellishly difficult. Yes, that case IS 2 way. But the speed of light time delay doesn't make it easily done. Our voyager satellites are delivering only femtowatts of signal at goldstone, so I expect half of the available bandwidth is devoted to error detection & correction. At that power level, I'd be amazed if they are functioning at over 1 bit per second. Their plutonium thermally generated power is nearing the end, and it will take electronic magic to get data from them in another decade. And one hell of a budget item for boiling helium to maintain the half degree kelvin the electronics at the focal point of the goldstone dishes need to be able to hear the voyagers in the face of that half degree of thermal noise. It's all we got in this case.
Cheers, Gene Heskett, CET.
I knew you would be able to give me the long answer with technical details about radio's limitations. I will have to read this again later, when I am more awake. (This email is one of those "woke up in the middle of the night" replies.)
Also, as I said, I have a shortwave receiver, and the idea of transmitting data over shortwave is what got my attention. If shortwave, why not other parts of the spectrum? Why not radio itself?
Anyway, I will have to look into this a bit more. As I said in another reply to Andrew, just a few minutes before, I conceive of this as a kind of backup plan for internet access, in emergency situations, for example, or when one finds onself in a remote place without the usual ways of connecting; just to be able to send and receive emails or text, or to use a text-only browser, could be a lifesaver in extreme circumstances.
Bill