Monday, January 31, 2011

Packet lives!

I thought packet radio was all but dead. Yesterday I heard Richard MM1BHO mention that there was a packet node in Scotland on 70cm at the same location as the GB3LA repeater which is a monstrous signal here. I asked Richard to tell me the frequency so I could have a listen. I wasn't optimistic about hearing anything as 70cm has always seemed a bit of a dead loss for me. I had to wait a while to hear anything, and when I did, I found the packet signal was 20dB over S9 which is the strongest signal I've ever heard on 70!

I then spent a couple of hours trying to sort out a way of receiving the packet. TrueTTY seemed like a good choice. It decoded the packets and displayed them on its screen. But I couldn't find any software that would work with its virtual TNC.

I also tried AGW Packet Engine in sound card mode. That, too, decoded packets, so I got the AGW Terminal software as well. But I could not transmit. The software keyed the PTT when it was supposed to, but there was no audio modulation.

Finally I bit the bullet, shut down the APRS gateway and put the Kenwood D710 into packet mode. I then set up AGWPE to talk with the Kenwood's TNC. That worked, and I was able to connect to the node whose call is GB7WD. I was wondering what to do next when Clive GM4FZH connected to me and I had my first chat over packet radio since the mid-1980s!

I'm afraid after all that time I have forgotten just about anything I knew about packet radio so I'm still pretty clueless as to what to do. I don't know how to set up a mailbox, or even where to set one up. There seems to be a shortage of material on the interweb aimed at packet newbies (or oldies like me where the onset of Alzheimer's has erased any memory of what we once knew!)

I think packet radio is something I will enjoy playing with again. I went back to AGWPE soundcard mode and found that the reason I was not getting any audio was because although the software says it uses the left channel which online references claim is the tip of the stereo jack, it was actually present on the ring. After resoldering the connector on the audio cable I was able to transmit packets as well as receive them, and G4ILO is now listening on the GB7WD frequency on the A side of my TM-D710 while my 2m APRS gateway is using the B side. There are just so many things to do in this hobby!

5 comments:

Anonymous said...

Hi Julian,
I used to use packet in the late 90's with a Baycom modem and Winpack software with AGW packet engine.
BBS and the ability to send messages around the world like email as well as DX cluster, was great.Learnt about computers messing with packet.
My local BBS at that time was GB7NND which could be accessed with a patch lead and dummy load as the aerial on 70Mhz with ex PMR as dedicated radio :-)
I wished there was a BBS around here.

Fenris said...

Pretty astonishing that we are still playing with 1200bps AFSK after nearly 30 years!

Sadly, in this respect, amateur radio seems essentially incapable of making any progress in either data rates, connectivity or on-air efficiency.

Julian said...

Why, we are still using Morse after 100 and analogue voice and RTTY after several decades. I think the technologists who want ham radio to be on the bleeding edge lose sight of the fact that for hams what is important is a) a lot of other people using the same mode and b) the ready availability of (preferably cheap) equipment.

Look at the reluctance to embrace D-Star or digital audio in general. Whilst this may in part be Luddism, it is also down to the fact that you can't make a bunch of enthusiasts who must pay for their gear with their own money all suddenly switch to a new mode that needs new equipment.

Besides which, if packet was now using some high speed mode I bet I wouldn't be able to build a modem for it using a $3 chip and a handful of junk box parts. The other often overlooked benefit of old technology is its simplicity.

Fenris said...

While I can see your point Julian, the whole benefit of having the 44.x.x.x IP address range is lost if it doesn't connect to very much at a decent speed.

I don't think many backbone packet links ever got above 9600bps, I would have thought that it should be possible to get links via VPNs across the wider internet at significant speeds.

As you say, it's down to users' desires and money, but it still amazes me that we don't have faster links after all this time.

Julian said...

I agree, and perhaps we would if there was a real incentive for it. But the internet is fast and cheap, effectively free for most people here because nowadays it is bundled in with phone and home entertainment packages. And most hams have embraced the internet to the extent of using it for every aspect of the hobby apart from exchanging the 599 report with the DX or contest station. I don't think there are enough people interested in making the investment to create a radio network that duplicates the internet. And without a critical mass of participants the whole thing would be a waste of time.

The 1200bps packet node I've been using can more than handle the traffic from a handful of users. It's idle most of the time. Like all the local repeaters. :(