>Has anyone seen any comments from other hams or organizations yet? >Bonnie KQ6XA
Yes, I immediately received comments from two officials at ARRL! Paul Rinaldo's was: To: Skip Teller ; [EMAIL PROTECTED] Cc: Howard Teller ; Dennis Bodson Sent: Tuesday, May 15, 2007 8:02 AM Subject: Re: New HF Digital Protocol comment Skip, Thanks. Very impressive. 73, Paul, W4RI The following was my submission. After further on-the-air tests, I am now recommending PSK63 over DominoEX16 because of the more narrow bandwidth. Using VHF is still highly recommended, but HF can also be used effectively over several hundred miles with NVIS antennas. The concept was to start with a transmisson technique ( PSK63), which was excellent to begin with, and fast, and then add ARQ. Because PSK63 has a low error rate to beign with, few, if any, blocks need repeating, so the throughput penalty by using ARQ is very small. This is even more true on 2m where there is almost never and QRM or QSB to slow things down. _____________________________________ Access Method: PSK63, PSK125, or DominoEX16 Data Rate and Bandwidth: Throughput of 5 cps for PSK63, 8 cps for DominoEX16 and about 10 cps for PSK125. Bandwidth of PSK63, operated in linear fashion, is 63 Hz, 125 Hz for PSK125, and for Dominoex16, 355 Hz. Note: For email delivery, in which there is an unknown retrieval time for a message lying in an Inbox, an extremely fast data rate has little impact on the time from transmission to retrieval from the recipient's Inbox, which may amount to many minutes or even hours, depending upon when the recipient checks for incoming email. In addition, the time it takes to establish a reliable connection also has to be considered as part of that total elapsed time. With a multiplicity of stations beaming toward a disaster area in order to receive emergency messages, the elapsed time to achieve a connection on VHF is generally expected to be much less than trying to contact one of a few HF stations available. The operator in the disaster area also has the opportunity to select the strongest signal answering his CQ. Adaptivity: Manual switching of modes at the discretion of the operator, upon observation of the progress of the communication. Robustness: DominoEx16 is the most robust, operating at around -10 dB under the noise level, PSK63 about -7 dB, and PSK125 about -4 dB. None of the modes cited are especially immune to QRM, but the narrow bandwidth of PSK63 and PSK125 allows more stations to share the same space than wider modes where there can be more crowding, so the chance of QRM is greatly reduced, as many more clear frequencies are available. When used on VHF, if a signal can be copied, chances are it will remain copiable, so range on VHF is more important than S/N, although at the extreme, the better the S/N, the greater the range, all other things being equal. If the S/N is not sufficient using PSK125, then PSK63, at a lower throughput, can be used instead. This will be evident from the very start of the communication. Error control: The communication starts off without using ARQ, and if that is successful, both stations switch to ARQ, using whatever mode was found to be successful. Note: This protocol is not intended to be used for unattended operation, but only with a licensed control operator physically present at each end. It is essentially too narrow for reliable unattended mailbox use where synchronization of the frequencies of both stations, within an accuracy of 30 Hz, is necessary to use PSK63 or PSK125. Although the mistuning tolerance of Domino16 is adequate for mailbox use (at about 150 Hz), the inherent latency of Domino16 makes unattended mailbox operations problematic without special modification of the ARQ protocol timing. For roundtable contacts, no ARQ is needed, as PSK63 and Domino are very reliable at low S/N without using ARQ. ARQ is used only to guarantee absolutely error-free reception. FEC is not recommended as it cuts the data rate by half, while providing very little reduction in error rate. A useful technique for roundtables on VHF is for everyone to point his beam at Net Control, who then retransmits all incoming text at 100 wpm so nobody gets left out. This works well and has been in place on our 2m roundtable Net here for over a year. Because most people type at about 20 wpm, but PSK63 can transmit cut-and-pasted text at 100 wpm, retransmission does not cause much boring delay. Activity Detection: Because this protocol is not intended for unattended operation, and there is a live operator at both ends, the activity detection is optimal (human eyes, ears, and brain) and always under control of a live operator, at both ends. There is no "hidden" transmitter in this approach! In addition, QRL and QSY are applicable, whereas in an unattended mailbox system, QRL and QSY are of no value at all! Operating System: Initially, the operating system will be Linux, but with one caveat - distribution will be by "live" CD, which will run on a Windows computer as well as a Linux computer and not disturb the Windows installation, unless the user elects to install as a dual-boot system, and in that case, Linux will be run for the protocol, and Windows for everything else. The "live" CD will contain full Internet browsing and email access for forwarding or informational purposes. Hardware: A computer with at least a 222 Mhz processor and a soundcard or soundsystem is required. No additional "box" is needed. For VHF mobile operation, a TCXO-equipped (multimode) SSB transceiver of 5-10 watts linear output is required, with a horizontally polarized antenna if a 100 mile range is needed. Outside the disaster area, a 25 watt transmitter and a 5-10 element horizontally polarized beam is recommended for a 100 mile range. QST has already accepted an article for a high gain, bidirectional, inexpensive, wide beamwidth, antenna that can be used in place of a 5-element beam and not require rotation. Note: This protocol concept is intended to be used by a ham in a disaster area "broadcasting" "CQ emergency", in effect, to a multitude of listeners. For example, he may queue messages and then call "CQ emergency". This call will stand out among any other activity by triggering a red background color on a multichannel display, and the first person able to contact the ham calling "CQ emergency" will become the receiver of the messages. This person will then deliver the messages over the phone, cellphone, by SMS (requesting confirmation), or by email over the Internet (after alerting the recipient by phone or other means to be on the lookout for important messages), or can take urgent action if required (such as calling EMS, etc, that help is immediately needed). To simulate this experience, just download DigiPan 2.0 from http://mywebpages.comcast.net/hteller/digipan20/DigiPan.zip, run an audio cable from your transceiver earphone jack to the computer soundcard Mic or Line input, set the transceiver to 14.070 Mhz, USB, and set DigiPan's Configure, Colors, Multichannel coloring effect, to red for the string, CQ . Any time a CQ prints on the screen, the background for that station and callsign will turn from white to red and stand out clearly amongst all other signals. 73, Skip KH6TY
