Subj : Weekly nodelist report on noteworthy changes (278)
To   : Dmitry Protasoff
From : Michiel van der Vlist
Date : Mon Oct 07 2024 21:32:00

Hello Dmitry,

On Monday October 07 2024 17:26, you wrote to me:

 DP>>> It's also no longer possible to get a home phone

 MV>> Eh.. ?? You were talking about modem over Voip. That should work
 MV>> in the UK.

 DP> 1 line in Moscow is still connected to a proper phone network which is
 DP> working perfectly. This is not possible in the UK.

It isn't possible here in The Netherlands either. Classic analog telephony has been fased out many years ago. What you now get over the 600 Ohm pair is "dry DSL". You get a DSL modem with a connection for an analog telephone. So it is VOIP. I guess that is the situation in almost all of Europe. Russia is behind the state of the art...

 DP> And for VoIP it's actually easier to connect UK phone number to
 DP> existing modem pool in Moscow. Makes no sense to have 2 modem pools ;)

If you say so...

 DP>>> and CSD has been disabled on UK GSM networks.

 MV>> CSD??

 DP> Yeah, old GSM way to transfer Data. It's actually a Data call (in ISDN
 DP> terms), with 9600 available maximum speed. So you can call any modem
 DP> number from GSM modem (or back).

Ah yes.. now that you mention it. Back in the days I has a Siemens C35. I am not sure about the number but it did have that build in modem supprt. I had a "data cable" to connect it to the serial port of my laptop and I could call out. I had three telephone numbers with it. One fo voice, one for data and one for fax. I never used the fax. IIRC it cpould actually also do 14K4 under some circumstances. Problem: it was bloody expensive!

[..]

 MV>> going to argue, it is true that cell phones have taken most of
 MV>> "the magic" out of amateur radio.  *1)

 DP> Getting local HAM license is on my todo list ;)

Now that we have made a link to HAM radio.. that reminds me of another "special modem" that I once had.

We (me and some other HAMs around here) were experimenting with data over HAM radio. So we connected those home made V23 modems that I mentioned before to the mike input and speaker output of a simple VHF FM tranceiver. And wow, it worked! Then after having played around with it for a while I thought I can make some shortcuts. Instead of FSK modulating an audio carrier and feeding that to the audio input of the FM transmitter, why not bypass the modem and audio in the transmitter and use the digital signal to diretly FSK the oscilator of the transmitter? And so I did. I used a shift of 5 kHz on the 144 MHz transmitter. On the receiving end I extracted the ones and zeros directly from the receiver's FM discriminator. Thereby converting the tranceiver to a "modem". We got reliable 4800 Bps connection that way. Those were the days! 

Cheers, Michiel

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