Jam tomorrow

I have not been keeping up with the development of the controversial ROS digital mode as for reasons given in earlier posts I decided it was not something I wanted to use. However a recent post in the Yahoo digital modes group brought to my attention a development that seems rather alarming. The ROS software has recently included an anti-jamming switch the purpose of which is described as “improves rejection against strong CW and Beacons interferences.”

Polite usage of the amateur bands require that you check the frequency is in use before making a call so no-one should be jamming anybody. Furthermore, no-one should be using ROS in the CW or beacon sub bands. So what exactly is the purpose of this switch and why should anyone need it?

Perhaps an inkling of what may be going to happen can be drawn from some of the comments relating to the performance of the anti-jam switch, for example:

  • “The New ROS/2000 passed the test successfully during the CW Contest last weekend.”
  • “More test with the New ROS/2000 in other hostile environment. This time during a PSK63 Contest on Sunday.”

As I said all along (indeed, this was my original objection to the use of this mode) ROS is just too wide for use in the narrow digital allocations of the HF bands. There just isn’t the space for it, unless it remains a niche, occasionally used mode, which clearly its developer and supporters don’t intend it to be. As another comment in the ROS forum states: “The bands will fill up once people realize how good this mode is.”

The development of anti-jam techniques suggest that ROS is being readied to engage in war with users of other modes. When users can’t find a clear frequency they will just operate on top of other modes. The principal claimed advantage of the wide ROS mode is that it enables contacts to be made under similar weak signal conditions to JT65A but that it permits keyboard chats to take place rather than the basic exchange of signal reports and locators. So it appears that a vast swathe of spectrum space is going to be made unusable for other modes simply so that people can exchange brag files.

We need strict regulation of digital modes on the amateur bands. The days of gentlemen’s agreements are over. There are too many modes competing for limited spectrum space, and too many hams who aren’t gentlemen.

Julian Moss, G4ILO, is a regular contributor to AmateurRadio.com and writes from Cumbria, England. Contact him at [email protected].

2 Responses to “Jam tomorrow”

  • doc w1eo:

    Not withstanding the FCC has stated it is considered spread spectrum and is therefore illegal for US hams to use it.

  • WA4ZKO:

    My thoughts in no particular order…

    The problem of ops not listening before transmitting applies to both sides (the digital and the non-digital) folks. I’m seen plenty of QRM both ways. Sometimes I suspect I’m hearing intentional QRM against in-progress digital QSO’s/connections, but tend to think most of the QRM is unintentional in nature…just poor operating.

    This weekend was a good example. This Sunday evening it took me forever to find an opening on 80m for a WINMOR based connection. I finally just parked on a well known WINMOR spot and waited while catching up on work email. After a pactor QSO in the bottom of the window ended, I waited to see that the freq (3.5865) was clear and I made my connection. About halfway through the connection I had at least 2 (maybe 3) CW contest ops begin QRM’ing me. Given the signal levels I’m fairly certain they heard my in-progress connection. WINMOR made the connect through all the QRM, but I just gave up on any further operating that evening.

    Many of the major HF Contests are turning the bottom of the bands into absolute zoos. Maybe we need to reign in the spectrum that contests are allowed in (aka consume) as not everyone contests?

    I do get a kick out of the complaints from folks operating non-digital modes in the “automated” sub-bands then complain because of the digital QRM. Well duh!

    The current bandplans can surely use some tweaking. Let’s face it there are a lot of modes trying to coexist in some very limited spectrum.

    I think the main need is to reign in the contestors from taking over the entire bands. So I suggest taking small portions of the CW/phone/digital subbands and mark them off limits for contesting. That way maybe those of us that are not contesting might have a chance at enjoying the bands too.

    Not picking on the CW contestors in particular, during some of theRTTY contests the bottom of the bands can get pretty ugly too.

    As a VHF/UHF Contester myself, I’m not anti-contesting at all. I just find many of the HF contests just appaling at the levels of QRM, chaos, and inconsiderate operating they create on bands.


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