I used 8 kHz because the FCC will specify the maximum bandwidth at -23 dB. Users want 6 kHz minimum bandwidth with minimal attenuation. Maufacturers of ham radio equipment usually specify the bandwidth of a 6 kHz crystal filter at the -3 dB points and the tolerance is often -0% / +25%. AM and phasing SSB transmitters have audio low-pass filters that roll off at 30-42 dB per octave.
73, John KD6OZH ----- Original Message ----- From: W2XJ To: digitalradio@yahoogroups.com Sent: Saturday, December 29, 2007 08:45 UTC Subject: Re: [digitalradio] Ham Radio ALE High Frequency Network (Re: FCC to Kill Digital Radio?) I would almost agree except for the 8 kHz wideband mode. That can easily be 6 kHz and accommodate AM as used in HF communications. A wider bandwidth just opens the door to more problems. I will file my comments based on yours except I will suggest a maximum of 6 kilohertz. John B. Stephensen wrote: > An ALE network and WinLink are both useful. My comments to the FCC were: > > "RM-11392 attempts to address problems of interference between narrow > and wide bandwidth text and data communition modes on amateur > bands, but the proposed rule changes will create more problems than > they solve. Historicly, communication in the amateur radio service > was either narrow-band (100-500Hz) text or wideband (2-7 kHz) voice > and each fequency band was partitioned into 2 segments. These were > originally for cw and phone, but now are rtty/data and phone/image. > > With the arrival of digital modulation techniques text, images and > voice may be transmitted alternately or simultaneously using the > same modulation method and with various occupied bandwidths. The > best solution for the future and the one that minimizes regulatory > burdens on both users and the FCC is to redefine these band > segments as being for narrow-band and wide-band emissions > regardless of content (voice, image, text or data). > > In my view, the optimal maximum bandwidths for frequencies below 29 > MHz are 800 Hz at for the narrow-band segments (usually the lower > frequencies in each band) and 8 kHz for the wide-band segments > (usually the higher frequencies in each band). 800 Hz allows for CW, > RTTY, PSK31, MFSK16 and other modes used for keyboard-to-keyboard > comunication and slow-speed image communication and file transfer. 8 > kHz is consistant with limits in other countries (when they exist at > all), allows existing AM stations to continue to operate and allows > simultaneous voice/text/image communiation using analog or digital > modulation. > > A small area (10-20 kHz) for automated stations must also be > established in the wide-band segments of HF bands to allow for > PACTOR-3 and similar protcols used for message forwaring as they > are invaluable during emergencies where the normal communications > infrastructure is compromised. > > If the rule changes are to extend beyond 29 MHz, maximum bandwidths > of 20 kHz should be adopted between 29 and 29.7 MHz and 200 kHz > between 50 and 225 MHz for the old phone/image segments. This allows > for exsting FM voice and medium-speed data stations in the 10, 6, 2, > and 1.25 meter bands. Any bandwidth limits above 420 MHz must be > 25 MHz or greater to accomodate existing stations using IEEE 802 > data trasmission and AM and FM TV. In my opinion, no bandwidth > limits are required above 420 MHz as long as emissions stay within > the designated bands for the amateur radio service. > > The rules changes outlined above should solve several problems and > decrease regulatory burdens in the future." > > 73, > > John > KD6OZH > > ----- Original Message ----- > From: expeditionradio > To: digitalradio@yahoogroups.com > Sent: Saturday, December 29, 2007 07:16 UTC > Subject: [digitalradio] Ham Radio ALE High Frequency Network (Re: FCC to Kill Digital Radio?) > > > The Ham Radio ALE High Frequency Network (HFN) > http://www.hflink.com/hfn/ > is the only HF 24/7 network on ham radio that can be accessed and used > for text messaging without an external computer or modem. HFN may also > be used with a regular HF ham radio and a laptop or PC computer > soundcard using one of several free ALE software programs. > > Ham Radio ALE High Frequency Network (HFN) would cease to exist if any > of the objectives of FCC RM-11392 petition were to succeed. > > HFN covers all of North America, and other parts of the world. > All HF bands. > All day. > All night. > > see map: > http://hflink.com/HFN_PILOT_STATION_MAP1.jpg > > HFN operates within FCC rules in the Automatically Controlled Data > Station HF Sub Bands... see chart: > http://hflink.com/bandplans/USA_BANDCHART.jpg > > The HFN system uses International Standard ALE (8FSK, with 2.2kHz > bandwidth) for selective calling, nets, bulletins, data, HF-to-HF > relay, direct text messaging, HF-to-Cell Phone texting, and short text > e-messaging. > > The primary purpose of HFN is to provide Emergency / Disaster Relief > Communications. When the system is not being used for the primary > purpose, it provides normal daily routine text messaging services, > propagation services, and many other types of features for hams. > > HFN ALE stations use a common frequency per band, sharing the same > "channel" on a time-domain multiplexed basis, with a combination of > automatic busy detection and/or collision detection systems. The > transmissions are normally sent in quick bursts. > > The system is free and open for all ham radio operators... > for more information about using HFN, click here: > http://www.hflink.com/hfn/ > > The Ham Radio ALE High Frequency Network does not require the internet > to function, but it uses the internet when it is available. It is the > only ham radio system of its kind that is truly interoperable on HF > for selective calling, voice, and text, with other non-amateur > services and agencies. For more information about this, see > Interoperable HF Communications: > http://www.hflink.com/interoperation/ > > Who among the "anti-automatic" and "anti-everything-that-is-not-PSK31" > hams are going to volunteer to replace the HFN if it were to be killed > by this petition? > > Please show us your alternative 24/7/365 manually operated system on HF. > Show us how you will monitor all HF ham bands simultaneously and > respond instantly. > > When will you sleep? How many hams will work 8 hour shifts every day? > How will we alert you on HF to run emergency traffic? Will you answer > the call? > > It is time for those who seek to put us back to the digital stone age > to step up to the plate and put their money where their mouth is. > > Happy New Year! > > 73 Bonnie KQ6XA > > . > > > >
