Sunday, February 21, 2010

Yet Another Digimode

Another new digimode has made its presence on the airwaves. Called ROS, it uses spread spectrum techniques in a bandwidth 2.2kHz wide and offers a choice of two symbol rates, 16 baud and 1 baud. The latter will be of great interest to QRP operators as it is claimed to allow communication at signal levels of 35db below noise, which is better even than WSPR. ROS is an interactive mode, so you can type what you want and have a real QSO, unlike WSPR and the other JT modes that can only send a limited number of fixed messages. What's more it isn't an all-or-nothing mode like the JT modes, so you can receive a message that's part garbage and use your own intelligence to correct the errors if possible.

An interesting feature of ROS is that the software will automatically send an emailed reception report to any transmitting station that includes his email address in his transmission. Quite how it achieves this I don't know, since I don't have an email client set up on my shack computer (I do all my email through Gmail.) So I was quite surprised after receiving my first ROS signal from G3ZJO running 1 watt on 40m to see him send "HI" to me on his next over (as you can see in the screengrab.)

This is yet another program that only recognizes the "default" sound card so I am once again receiving using the HB-1A transceiver and am unable to transmit using the mode.

The weak signal capabilities will no doubt make this mode of interest to the QRP fraternity as well as VHF operators working EME and troposcatter. I think the ability to receive an emailed reception report is also rather cool, and a bit more personal than seeing your signal spotted on a website.

However I do wonder what will happen once the massed hordes start using it on HF and begin cranking the power up to try to work further afield. There isn't enough space on the HF digital mode bands for many simultaneous contacts to take place using a 2.2kHz wide mode.

I'm now listening on 14.101.0 MHz USB so if you try this new program and put your email address in your message you might get a report from me.

8 comments:

Eric Söderman said...

Why can´t you just change the default sound card while playing with this software? Eric SA5BKE

g4ilo said...

You could, but then there's a chance that you'll broadcast all the Windows sounds and other things that also use the default.

Paul - PC4T said...

Hello Julian, I think they read your previous article about too many digital modes, and now they will annoying you to bring up ROS. Hi. But nevertheless, it sounds very interesting. 73 Paul

g4ilo said...

Hi Paul.

I think it probably is an addition to the too many, at least on HF. But before one can voice an opinion on it one ought to try it (not that this inhibits many contributors to QRZ.com discussions!)

Paul - PC4T said...

Hello Julian, I was only joking... I will certainly try the software, by starting tomorrow and coming week. I think 20 meter will be alright, there is enough space. 10 meter also. I miss 15 meter? When it is really better than WSPR, it would be promising. Isn't amateur radio something by doing experiments? 73 Paul

g4ilo said...

Hi Paul. I think people might misunderstand my comments about these new digimodes. I think the potential of these modes is great. It's just that it is no good trying to decode weak signals if a dozen people are all trying to use the same frequency.

I think the way to go with this mode is to try during the week when it is quieter. And perhaps to make some skeds over challenging distances using something like the K3UK Sked Page instead of calling CQ and ending up working people you could have worked just as easily on PSK31.

Steve Silverman said...

Hi Julian

Spread Spectrum isn't allowed in the US below 432 MHz unless there has been a rule change that I am unaware of. But ROS looks very cool, especially the email and QSO features.
Steve KB3SII

g4ilo said...

Quite a few US hams seem to be using it. They appear to feel that since the bandwith is within the audio bandwidth it's legal. It looks and sounds more like a slow 2.2kHz wide MFSK.