New RM-11769 Proposed "Symbol Communication Subbands" in place of CW/Data

Thanks John.

 

Another no code general wants a free ride..

 

Someone recently argued that a dit and a dah is basically the same as 1's and 0's in digital modes--maybe, I dunno, but one difference is that some modes have a potentially huge bandwidth.

For example, I like JT65 but have better success on JT9 and wish it was more utilized--like many digital modes you can do a wider one (JT65) or a narrower one (JT9). And there are tons of other modes where narrower options exist. But because people want to use wider bandwidth modes, even when smaller modes of the same type exist (AFSK, RTTY, etc), it makes the segments look too small... and then here comes this idea to make everything a digital segment. Hmmm, smaller bandwidth=less band crowding and more happy people. Looks like the guy is trying to fix a problem through regulatory change, that is best and easiest handled by the community-at-large.

By comparison, I've never had any problem with CW crowding, even during some contests. I'm sure it happens--but not as much as JT65 on 40m these days!

 

And the only CW-only sub-bands I can think of are the bottom 2.5% (100 kHz) of each of the 6m and 2m VHF bands.

DX es 73 de NV2K

 

I'll buy the eggs and drive to Mo.

Nah, wouldn't be kind to the chickens to waste them on this guy.

 

And...for 6 meters that would be where the beacons are. The last thing we need is a bunch of digital hash covering up the propagation beacons (but any true weak signal 6 meter operator would NEVER do that anyway).

 

It may be worth pointing out that:

CW is the most efficient of all current manually generated communications modes. The bandwidth of a CW signal depends on two factors:
1 - The speed at which the transmitter is keyed and
2 - The shape of the keying waveform.

Signal bandwidth increases with increasing speed. Bandwidth also increases the closer the keying waveform approaches a perfect square wave. Most amateur equipment imposes a small rise and fall time to the keyed waveform to produce the best sounding CW and reduce keying artifacts (clicks).

Having said that, a 'normal' CW signal has a shape factor or 'K' of about 4.8. The accepted formula for CW bandwidth is BW = BPS X K where BW is bandwidth in Hz., BPS is baud rate per second, and K is the shape factor.

Baud rate is determined by the number of dit sized elements (bauds) sent in a minute. Using the word 'PARIS' to calculate CW speed. You will see that PARIS contains 50 keyed elements or bauds, so a speed of 1 word per minute is defined as 50 bauds per minute, yielding a baud rate of 50/60 or approximately 0.83 BPS.

It follows, therefore, that a CW signal at 1 WPM occupies 0.83 (BPS) X 4.8 (K) = 3.984 Hz. or rounding up, 4 Hz. Again, a 10 WPM signal would occupy 10 X 4 or 40 Hz. A 25 WPM signal occupies about 100 Hz. In practice, the bandwidth occupied is closer to 66 Hz. This very efficient use of bandwidth should be the prime consideration for not changing the current Rules in regards to CW use in the Amateur Service.


Have at it!

 

like I said, he's been a tech for 30 years and I would argue the real ham part all day and night.

 

Actually, an identical document was filed in the status of REQUEST as part of the public Comments filed against the League's Petition RM-11759.

Nothing in the document seems to indicate he has any awareness of the ARRL's Petition, even though it is grouped with that proceeding. What's not clear now is whether the FCC might eventually combine the two Petitions for consideration and eventual decision making.

 

I think I do. The proposal seems to do four things:

1. It looks like what he's trying to do is reduce potential confusion about what we mean when we say that the bottom portions of the bands are for "CW/digital", or to avoid confusion over the FCC's "radioteletype" wording. CW is authorized throughout the band, and the bottom portion of the band is also authorized for text send via radio emissions. It's not sufficient to describe it as "digital" because of the existence of digital voice and image, and referring to "radioteletype" brings 45.45bps, 170Hz shift Baudot transmissions to most of our minds. He's proposing new language that would avoid that confusion. (I'm not sure it's strictly necessary.)

2. His proposal would seem to limit non-manually sent CW to the bottom portion of the bands, authorizing only manually-sent code in the phone subband. (Is there really a need for such a change?)

3. His proposal would authorize digital phone on 630m if/when the FCC authorizes that band. (OK, but wouldn't it make sense to wait until a RM for 630m was at least out for public comment, and are any other countries doing this?)

4. His proposal is successful in getting other hams riled up. Whether this was his intent, I decline to speculate.

 

Yet another petition! First was the ARRL petition to cut 50 kHz from the 75m phone band, followed immediately by the lifetime licence proposal. Then came the petition to eliminate the 15 dB gain limitation. And now this. Not to mention the ARRL's Baud-rate petition that is still pending.

I filed comments on a couple of these, but I have no dog in the fight with the others. Problem is, they are coming in such rapid succession that I'm having trouble keeping track of them all. The people at the FCC must have time on their hands, because they have assigned them all RM- numbers. The could have just set on them without taking any action at all, which is what they normally do with frivolous petitions. They don't have to assign every petition they receive an RM- number.

 

Now that is funny! What purpose would adding that to the filing serve! IMHO it's probably truthful and completely exposes himself.

Thanks,

Ed

 

Just out of curiosity, would the ITU (International Telecommunication Union) be/have to be consulted? Affects communications beyond the borders of the USA. I don't really know the protocol.

 

FCC procedures and regulations require it to pass along a proposed RM when the petitioner has submitted a proposal using the FCC's prescribed procedure. That something like this has been made available for public comment doesn't imply the FCC is seriously considering it; it just means that someone cares enough to have jumped through all the hoops.

If the ITU required consulting, presumably the FCC would do that in deciding how to respond to the proposal. I think the only thing that might require coordination with the ITU is the proposal to allow digital voice on 630 meters. The rest of the proposal...well, it doesn't seem to actually do anything aside from tweak some terminology.

 

Thanks for this! I had no idea the bandwidth of CW changed with speed