My comment was in regards to a question about why the rules need to be changed. They do because you can't mix voice, image and data on one frequency in the HF bands. The defect in the ARRL proposal for regulation by bandwidth was the 3 kHz limit that they chose for HF. I argued for 25 kHz and then 9 kHz as time went by, but with no effect. There are also limits on data bandwidth of 20 kHz in the VHF bands and 100 kHz in the 70 cm band that need to be changed.
There is no bandwidth limit in the HF RTTY/data segments as 97.307(f)(2) is only referenced in the table in 97.305 for the phone/image segments. I agree that digital phone has no bandwidth limit, but image does. 73, John KD6OZH ----- Original Message ----- From: expeditionradio To: [email protected] Sent: Tuesday, May 01, 2007 22:43 UTC Subject: [digitalradio] Digi Voice: No Bandwidth Limit (was Re: ARRL wake up ......) --- In [email protected], "John B. Stephensen" <[EMAIL PROTECTED]> wrote: > > 47cfr97.307(f)(2) limits the bandwidth of all transmissions in the phone/image segments to that of AM or SSB communications quality audio which is usually interpreted as 3 kHz. > John > KD6OZH Hi John, Digital Voice is "Phone" under FCC's definition. There is no bandwidth limit on a "phone" signal, implied or otherwise, for a digital voice signal. You either made an error or you are reading your FCC rules wrong. Here is what the rule actually says: ====== 97.307 (f) The following standards and limitations apply to transmissions on the frequencies specified in §97.305(c) of this Part. "(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." ====== As you can see, that rule is for non-phone. Currently, the non-phone modes defined by FCC in those §97.305(c) frequency bands are "image" "data" "RTTY" "multiplexed emission" and "CW". If you read them carefully, you will find that the FCC rules are really unclear regarding any finite bandwidth limit for these non-phone modes on HF. That is because these ancient rules were written in the middle ages of digital signal technology. I will be happy to provide a examples of how the rules allow very wideband data bandwidth on HF, if you like. 73---Bonnie KQ6XA
