how does a cell phone get it right to transmit over 7km

[Nigel Goodwin]

Originally posted by jacquesl
Yea, packet radio will probably be the best option for me now, but I want some scary fast speed over long distances I already checked out the packet radio, but it didn’t tickled me so much, but I’m going to do a monster search on Google now.

The faster the speed, the higher the bandwidth, and the lower the range - unless you increase the power to compensate?.

The only thing is, how the pc manages it to switch PTT button automatically then you want to TX stuff

The TNC does it all, most have micro-processors in them, the PC simply sends and receives serial data, the TNC packets it up, and keys the transmitter as required. I've still got one here, I did 2m packet for a number of years - I think it's a Kantronics KPC2 - or something like that?, I haven't seen it for years. I actually wrote my own PC software for it - in Turbo Pascal 5, it was that long ago - pre-Windows.

[jacquesl]

I’m very interested in this packet radio stuff. How do you use this packet radio and why and can multiple users connect to each other, or is it only point to point ?

[Nordic]

I went to Bazaruto Island off Mozambique with a cruise ship once.
I had this ancient nokia.. the kind you could use for self defence due to its size.... in the evenings all the ship staff would come to the deck at the rear to see if they could get reception on their fancy phones from overseas... I only lost reception after about 2 days of sailing... everyone else had very dissapointed looks.

[jacquesl]

For 1200 baud or 2400 baud, packet radio seems to be slow, it doesn’t make any sense why it’s so slow why not use 2 x 2-ways on each base station and have a dedicated send and receive channel open to operate 2 radios sound better to me. So no more PTT button respond time delay needed, will it increase the speed with a monster amount?

[Pano]

WIth very good, directional antennas 7 KM could be within reach of WiFi - right?

There are lots of DIY WiFi antennas on the web. Might be worth looking into. Or did you want mobile?

[Nigel Goodwin]

Originally posted by jacquesl
For 1200 baud or 2400 baud, packet radio seems to be slow, it doesn’t make any sense why it’s so slow why not use 2 x 2-ways on each base station and have a dedicated send and receive channel open to operate 2 radios sound better to me. So no more PTT button respond time delay needed, will it increase the speed with a monster amount?

There may be licence restrictions preventing it?, it's been so long I can't remember now - also it's not trivial to operate full duplex, you certainly need to be crossband to make it practical.

The PTT isn't a problem due to the packet system, it pressed PTT and sends the packet, then drops the PTT and awaits the reply.

Packet stations can also relay other peoples data, you can reach right across the country through other peoples stations - although it's obviously a slow business!.

The speed is mainly governed by the bandwidth, a voice width channel can only do slow speeds.

[Nordic]

Even more, J. will be familiar with the places.. I had a wifi connection with its base station on UCT, and I'm at the far end of Milnerton.

[jacquesl]

Ok I’m going to stick with Wifi stuff from now on, do anyone know about WiMax stuff and where to buy it?

Nordic do you know any shops in SA where to buy these small connecters and cables to connect to my wireless access if I want to build a homemade high gain antenna and stuff?

[Pano]

Originally posted by Nordic
I had a wifi connection with its base station on UCT, and I'm at the far end of Milnerton.

Ummm...how far is that? More than 7 Km?

Just FWIW, the farthest cell phone connection (verified) that I know of was my buddy George. Minimum distance would have been 45 miles (72 KM) - more likely 50 (80 KM) or more. Pretty crazy!