WHAT IS PACKET RADIO ? WHAT CAN YOU DO WITH PACKET RADIO ?
Packet Radio is more than just a way of communicating with other radio amateurs. Especially when the Amateurs can use TCP/IP programs, then there is a World open. TCP/IP gives the Amateur a lot more features, than with simple Packet Radio possible. So there is the possibility, to send and receive all messages just using the computer, without at a BBS to log in. Which messages can both locally and World Wide. Also send and receive files or even entire sub directories is one of the possibilities. For posts about the longer distance some programs might also find the shortest route to the other station and regular testing. For don't know the route, to the Amateur stations, can also be picked up at stations heard an existing route with other drives. For example, a route list, almost World wide. When the Packet Radio network ready is a Utopia so, then the Packet Radio Network has become a combination of many LANs, in a WAN. LAN = Local Area Network with the Amateurs near WAN = Wide Area Network with all Amateurs in the world.
There are Amateurs, who claim, that Packet Radio nothing with doing radio electrical experiments. But where in the World is ever with a large Wireless Network worked ? The Radio Amateurs, who do not always come with new ideas and that this complete, ideas into something that years later only in the commercial implementation to business and private use. Take FM, which is now on every radio is, take the TV that nowadays in any home State, besides, all wireless voice connections were already far ahead of WW1 at Amateurs in use. Packet Radio is a way, in order to convey clear text of Amateur Amateur Amateur A to b. B When A is not within range of Amateur, then other Amateurs as Repeater work. Because we work with Packet Radio with a simplex connection. We speak not of Repeater but from Digipeater. For a connection may be used up to 8 Digipeaters. There are also protocols developed, to the connection, that is primarily intended for text, to use to send and receive binary files. The most common way is using a so-called Packet Radio TNC.
This is a Terminal Node Controller, with there in software for a special version of the AX25 protocol, which was modified for the simplex radio link AX25 Amateur AX25. The software is developed by the TAPR Tucson Amateur Packet Radio club, and distributed as Public Domain around the World. A Packet consists of a header, stating who send it and to whom it goes and through which digipeaters. Furthermore, there is also the length of the data field in and the type of Packet. The names of the stations in the Header are the ordinary call signs of the Amateur Stations. Most drives work with 1200 Baud signals, only when someone has multiple transceivers will faster modems. The previous saves for clarity on broadcasts in the FM mode, for single sideband is usually 300 Baud. With FM is worked on the bands above 28 MHz. In The Netherlands we use Packets with a data field of up to 255 Bytes. The longer the Packet, the greater the chance of a transmission error and then the Packet is repeated, because Packet Radio guarantees error-free transmission. The Packets are smaller, then drops the return in relation to the length of the total Packet with the Header.
A Packet length of 255 bytes usually gives the highest return and the lowest band use. With Packet Radio many may work on the same frequency, by that each station always wait with the transmission of a Packet, to the frequency a few seconds is free. In those few seconds can than other drives that you do not hear their Packet broadcast. Practice has shown than when a frequency more than 5 links go this all is noticeable to the speed of the connection. Other modes with Packet Radio: In contrast to data traffic via a line connection, we use amateur frequencies with Packet, where at we should pick up the call sign of the station in the Packet. That is why we have to the other modes for Packet Netrom and CP/IP always under a AX25 Header places, for the call signs.
