Back To The Future With Packet Radio - Part 07

This will be last of our packet radio series, at least until later in the year when we will be bringing this story right up-to-date. Although we've covered a lot of ground in this series to date, there's a lot to discover still... chat rooms, 'walls' where you can leave messages, and even teletext style pages that will take you back to the days of Ceefax! You can explore other nodes in other countries by linking to them either by trying HF connections or AX / IP links, then continue exploring with RF links from that point.

Connecting to a chat room on a node in Australia and talking to a user in the US

In this part we will take a look at how you can go and meet yourself on another node by using streams.

Until now we have just used a single connection to another node, but what if we could have multiple links running concurrently? We can do that by using streams.

These are individual 'channels' that you can use to set up connections to different users or nodes - once connected they remain separate, so one stream is not connected to another one. To set up using multiple concurrent streams, we need to know how to address them first.

The TNC that we used (PacComm Tiny-2 Mark2) has up to six streams available. These are labelled as A through to F. To ensure that the TNC knows you are referring to a stream, and not just starting a command or text string with those letters, we use the stream identifier | (this is the 'pipe' symbol) before the stream letter. You can set this to be whatever you want, but you must ensure it is something that you are not normally going to use!

Let's open up the first stream and connect to the Bridgwater node, GB7BWR. From the command prompt, we use:

cmd: |A C GB7BWR

This connects us to the node and we are in converse mode on that node... anything that we type in now will be actioned by that node. This means if were to try to open up our second stream, we'd be asking GB7BWR to do it, whereas we should be asking our TNC to do it.

To achieve this, use <CTRL-C> to get back to a command prompt (you will not be disconnected from GB7BWR). Now you can set up a second stream to connect to another node...

cmd: |B C MB7NSC

This is shown in the image below and after connecting to MB7NSC we used <CTRL-C> again to get back to the TNC command prompt:

Opening up two streams with a connection to two different nodes

We now have two concurrent streams, to two different nodes. We can issue commands to each node by putting the TNC into converse mode (by entering k at the command prompt) and prepending the command with the stream identifier string. In the image below we asked each node to tell us about the ports that it has available, starting with GB7BWR then MB7NSC...

|A ports

|B ports

viewing ports on two nodes

In the next image, we wanted to find out who was using the MB7NSC node by using the USERS command. However, for a bit of fun, we issued a command to GB7BWR to connect to MB7NSC first. 

|A C MB7NSC

We are now directly connected to MB7NSC as well as being connected to MB7NSC via GB7BWR. We are on the same node twice (look for G7BEH rather than G5JJ!). "Uplink 1" is the direct connection (stream |B in this case) and "Circuit (GB7BWR G7BEH)" shows G7BEH also connected but via GB7BWR.

The USERS command shows we are on the same node twice

We can see the link status of our streams by getting back to the command prompt, <CTRL-C>, and issuing the CS command. Here we can see our two streams and the respective nodes they are connected to.

Stream status with CS command

To disconnect from a node and close a stream down, we can issue the BYE command. However, we need to tell the relevant node (rather than the TNC) we want to close down the connection. You can see in the image below that issuing the |B BYE command from the command prompt doesn't work, as the TNC doesn't know what to do with it. Telling the TNC to swap into converse mode (K) then issuing the command works...

Make sure you're in the right mode!

We will leave packet radio for a little while but aim to return to it later in the year, bringing it right up-to-date. Although we have delved into packet radio as it was back in the day, there are many new options as part of a modern solution with packet radio; until then, if you have an old TNC knocking around in a drawer or cupboard, drag it out, dust it off and put a new backup battery in it. Switch it on, enter your callsign into it using the MYCALL command and explore the world in a different way...