> Frank k2ncc wrote: > I think the confusion I have with "quality phone > transmission" comment is the part that says > "...of the same modulation type."
Hi Frank, The FCC rule about HF signal bandwidth limit related to a "phone emission of the same modulation type", applies mainly to Image signals within the HF "Phone/Image sub-bands". That limit DOES NOT APPLY to Data/RTTY signals in the Data/RTTY sub-bands. Beware, there are a few narrow-minded hams continuing to spread disinformation about digital bandwidth limits. What motivates them to do so? Are they trying to scare us into self-inhibiting our freedoms? Or a desire to retard the advancement of radio technology? Whatever their reason is for using the "Big Lie" technique, it won't work in this case, because it is too easy now for USA hams to go to the source of true facts about bandwidth limits. That source is: the FCC rules on the web. The best way to understand the FCC rules about ham radio is to read the FCC rules, footnotes, tables, orders, definitions, specifications, and FCC opinions. I acknowledge that not everyone is quite as enthusiastic about reading this exciting material as I am. So, perhaps it will help to point out the parts of the tome that are pertinent to this discussion. Turn your hymnals to Part 97 :) - The FCC rules contain a table of frequency bands in paragraph (c) of "§97.305 Authorized emission types." - In that §97.305 table, one can see "Standards" that apply to each sub-band or segment of a ham band. These little details are the key to understanding. Some Notes apply to certain sub-bands but not others. Here are the important things to look for: - Observe that "Footnote (2)" can be found in the "Phone/Image sub-bands" but Footnote(2) cannot be found in the "Data/RTTY sub-bands"! - The text of this important Standard (2) is found in: "§97.307 Emission standards" paragraph (f) . Here is the full text of §97.307 (f) (2) - " No non-phone emission shall exceed the bandwidth of a communications quality phone emission of the same modulation type. The total bandwidth of an independent sideband emission (having B as the first symbol), or a multiplexed image and phone emission, shall not exceed that of a communications quality A3E emission." The main types of "non-phone emissions" this bandwidth limit applies to, only in the "phone/image subbands are: 1. Image content (such as video or photo) 2. FAX image (such as drawings or documents) The FCC rules define what a "Phone" signal is. It includes speech and some other things, such as selective calling and controlling tones. The FCC definition of the word "Phone" can be found in §97.3(c)(5) Definitions of terms that are used in Part 97 to indicate emission types. So, everything in the Phone/Image sub-bands that is not "Phone" is considered "Non-Phone". On an interesting side note, did you notice... there is no bandwidth limit for most common types of AM and SSB "Phone" signals in the HF bands? There is a non-specific limit for "angle modulated" signals such as FM voice... but that is a topic for another discussion. See you on 20 meters FM simplex! 73 Bonnie KQ6XA
