Tuesday, March 23, 2010

Narrow minded

Due to having been banned from using the software I have not been keeping up with what is going on in the development of the ROS digital mode. However there have been a few interesting postings about it. In the digitalradio Yahoo group Skip KH6TY has posted the results of some tests conducted with ROS on 432MHz which appear to show that it suffers badly from the effect of doppler shift and flutter experienced at those frequencies, failing to decode over paths where Olivia was successful and even SSB was readable.

This has prompted a rebuttal from the ROS author, which however seems to overlook the problem of doppler distortion encountered by Skip. He has posted a series of comparisons between ROS 2250/8 and Olivia 32/1000 which purport to show that ROS holds up while Olivia prints garbage. He concludes: "The difference between both systems is about 5dbs (3.16 in natural units). This means that ROS8 need 3.16 times less power than OLIVIA 32/1000 to establish a QSO to 150 characters/minute."

Assuming that this is true, I nevertheless feel that a tradeoff of bandwidth for power or speed is inappropriate in the context of the narrow HF band allocations for digital modes. Most amateur QSOs do not need to go at 150 characters/minute (most people can't type that fast). On the other hand the 2250Hz wide ROS transmission blocks three channels that could be used for Olivia 32/1000, and even more channels that could be used for a narrower mode. The use of 2250Hz ROS effectively limits the number of people who can simultaneously hold a digital QSO.

Even if it is true that Olivia needs 3 times the power than ROS to get through, Olivia is still a better choice of mode in the real world, because it is easier to increase the power 3 times or to switch to a slower mode than to find extra space within the HF allocations to accommodate the use of such a wide mode.

ROS would be less of a problem if people used it only in circumstances where it would not be possible to communicate using a narrower mode. Unfortunately that discipline does not exist among today's radio amateurs. People are using ROS to make contacts with others whose signals are strong enough that 30Hz wide PSK31 could be used. This is just selfish, and it is the reason why I feel that such a wide digital mode should not be permitted on HF at all.

9 comments:

M0JEK said...

... and also Olivia mode is available on many platforms ...

73

S.o.a.I said...

To be honest I don't care if every time I used ROS the guy mailed me 10 dollars. He's an ass and I'm boycotting his stuff.

It's okay to be passionate about the things you create. But when logic and reason are replaced by spite and nastiness... well that's where I draw the line.

73
Jay aka KD8EUR

g4ilo said...

But even if he was a nice guy would the mode be worth using? I can't help thinking that if he was an experienced ham himself he would never consider introducing a 2.25kHz wide mode on the HF bands. But perhaps that's just me being narrow minded?

Keith said...

The tests should have been carried out using the EME settings - much narrower 0.5Khz
I must admit I have discontinued ROS use here due to harrassment on 20M.

Julian - on ligher note Rebecca and Steven passed their Foundation at weekend.

G0EMM

S.o.a.I said...

You're right Julian, even if he was a great guy its a doomed mode. Then add to that all the drama and now it's got no chance in my book.

Anonymous said...
This comment has been removed by a blog administrator.
Theodore said...

The biggest problem with the mode is that he has named it after himself.
That means that he has his own ego tied up with valid criticism, never a good combination.

I deduce he is also not a licenced amateur, so that is like asking a plumber to repair my TV set.

But his vindictive attacks on commentators, is by far the greatest concern.
I never thought I would see the day when a developer put a "blacklist" into a Ham Radio application!

I will stick to Olivia, the gentlemens mode, for weak signal work.
ROS can ROT.

73s

Kelly Keeton said...

I just wanted to say thanks for continuing to keep us informed about the mode with all the prior fun you went thru. I really value your opinion and find my self reading your blog for news and input rather then all the opinionated OM sources that we normally have 73 DE K7MHI

mvandewettering said...

I think that as hams we should try to be as permissive as possible and encourage experimentation with new modes. That being said, there is a right way and a wrong way to do so, and ROS was mostly done the wrong way. I think if we promote a mode for wide use, we should provide a demonstratable benefit to the radio service.

Mark K6HX