1940's ERA celular telephone... - Page 1
Forum section: electronics / general

author: BrianHG
author_rank: Super Contributor
timestamp: January 16, 2023, 04:50:13 pm
content: Yes, it really did exist.LOL: At the end I like how they show the car install and called that 'compact' or the need for a second car battery for extra power for the transmitter...At least it was FM modulated.

author: Halcyon
author_rank: Unknown
timestamp: January 19, 2023, 09:35:25 am
content: Radiotelephones were considered 0G technology. That paved the way for AMPS which was basically considered 1G, before the introduction of GSM and CDMA (2G) which was digital.There are a bunch of interesting historical videos on the AT&T Tech Channel on YouTube.

author: ebastler
author_rank: Super Contributor
timestamp: January 19, 2023, 03:49:20 pm
content: Quote from: BrianHG on January 16, 2023, 04:50:13 pmNice video, thanks!I am not sure whether this qualifies as a "cellular phone system" yet? While there obviously were local "cells" defined by the reach of the radio towers, there was no automatic locating and hand-over service: If you wanted to call a mobile station, you needed to know which base station's reach they were in, and if they moved out of reach during a call, the call would be dropped.In Germany, the transition to a proper cellular system only began in 1984, with the "C-Netz". It allowed you to reach a mobile station country-wide under one fixed phone number, and would hand over calls from cell to cell when the station was moving. Both the C-Netz and the B-Netz which it replaced were analog systems, hence are considered 1G systems in the nomenclature Halcyon mentioned.

author: pcprogrammer
author_rank: Super Contributor
timestamp: January 19, 2023, 04:37:36 pm
content: It is nice to see this old material preserved. Loved how it started a bit like a cartoon with the music used. Also nice "advanced" split screen and overlay technology used to make itIndeed the remark near the end when they install the units for transmission and reception and call it compact, very funny.Wonder if it was capable of handling more then one call at a time on the same station?

author: Stray Electron
author_rank: Super Contributor
timestamp: January 19, 2023, 05:45:57 pm
content: Quote from: ebastler on January 19, 2023, 03:49:20 pmIt wasn't what I would consider Cellular Telephone but my father and my father in law both used radio telephones in the very early 1960s and they could have their calls routed to the normal land line telephone service and have the operator dial long distance numbers for them. So they could theoretically connect to just about any other telephone in the world at that time. Yes, those connections and going through the operator and even the long distance calls were all expensive as hell but it could be done. On very large projects being build for the US Gov like the DEW Line and Cheyenne Mountain and the original construction of Cape Canaveral, in Florida calls like that were frequently made from the field and back to the project management offices in Washington DC and to equipment suppliers in order to avoid extremely expensive construction delays. I remember one of my father's coworkers making a call from Florida to England in about 1962? that lasted for about 20 minutes and that cost well over $1000. (in 1962 dollars!)

author: tom66
author_rank: Super Contributor
timestamp: January 20, 2023, 08:25:43 am
content: As you moved out of range of one tower, would the operator transfer the call for you? Or was this strictly (in the case of driving on the highway) for short calls? Did you always have to know where your driver would be, to locate the tower to use, or did they have some method of "pinging" to determine where a receiver was?It's remarkable how well modern phones handle the "hand off" process between cell towers at 70 mph!

author: BrianHG
author_rank: Super Contributor
timestamp: January 20, 2023, 08:43:07 am
content: Quote from: tom66 on January 20, 2023, 08:25:43 amBased on my video and the more refined specs in Halcyon's video, it looks like the transmission you receive comes from a really strong central transmitter, so, that direction and receiving call notifications covers 1 +1/2 city wide. It is the short distance which the car's transmit to multiple receive antennas operation. Considering that those antennas might have private wiring to the transmitter station to coalesce the call onto a regular phone line, auto selecting between the not strongest, but strong enough for clarity of the 2 adjacent received signal on that 1 frequency is something analog tube electronics with the added hard wiring to the central transmitter antenna can handle.Remember, we are only talking about 33 channels (if I remember from the video correctly), which was then increased to 150.(EDIT, in 1940's there were 21 channels, in 1950's, it was increased to 33 channels. If they had better crystals and narrow band IF saw filters in the 1950s with a narrow band FM audio, there would have been enough room for tons of channels in the newly allocated 450MHz band. But to handle the flood of calls there, only going PLL tuning and MCU computer code could create an effective phone on such a crowded network.)

author: Halcyon
author_rank: Unknown
timestamp: January 20, 2023, 09:10:45 am
content: Quote from: tom66 on January 20, 2023, 08:25:43 amDepending on the equipment used by your telco, modern mobile phone networks are capable of handover speeds well beyond that.I've used phones on aircraft before without too many issues. Problems arise as you start to go to the flight levels of commercial aircraft where the signal is extremely weak.In countries with high-speed trains, this fast handover process is a consideration. Apparently Ericsson have been developing technologies to cope with these high speeds and there are various specifications that guarantee some form of data capability at hundreds of kilometers per hour. The Rel-16 specification apparently guarantees "fundamental mobility performance" at speeds of up to 500 km/hr. ("Fundamental" says to me voice calls, SMS and some low-rate data.)