Modem Development Project

The SAFE Community Ham Net ( www.webpal.org )
and
( www.webpal.org/SAFE/aaham.htm ) MODEM Development Project

The SAFE Community Ham Net wishes to develop a modem for a means of communication for its members to use in the event of a MAJOR catastrophe on the scope of what is called Armaggedon or nuclear WW3. We wish to find a RF Engineer who is sympathetic to our cause. By that - we mean one who is sympathetic to our group's parameters and dynamics and who will help us achieve our goal. Members of the SAFE Community have put into escrow funds to support this project, so the activity will be financially remunerated - but once again, we wish to find someone who is sympathetic to the cause.

Mission Parameters: Our mission is simple. - To provide an alternate means of communicating with each other when all other means of communication such as the telephone, Internet and Postal Service have become inoperative. The Net we envision will be widely dispersed but most participants will communicate only with other participants that are within a few hundred miles. This will, however, be a node based system and it is anticipated that key nodes, manned by experienced Hams with more sophisticated equipment than being developed here, will be able to relay messages over greater distances. The majority of our members at the present do not have a Ham license and so the equipment that they will be provided will operate as a receive only modem until they become licensed. At that point we will provide an activation procedure / key that will switch the device to being both send and receive.

Special Considerations of the SAFE Modem We have a number of special considerations for the SAFE Modem and the NBEMS (Narrow Band Emergency Messaging System) which we plan to use. 1. One requirement and one reason for selecting narrow band, is that it will permit MANY users simultaneously. 2. The system needs to be very simple to use - not requiring Morse code or a sophisticated understanding of Ham communications. For this reason we have chosen a digital mode that permits communication entirely through typing an one's computer keyboard. 3. The system needs to be highly reliable - and for that reason again we are going to use digital PSK16, a system that is particularly robust in error checking and which operates at noise levels that would make voice communication imposssible. 4. The system needs to be low power - given the conditions we anticipate at the time. We may go with as low as 5 watts. 5. Because of the need for simplicity, and to make sure that everyone is on the same page, we have selected a single frequency of 80m as the one we consider most likely to survive a catastrophic situation in regards to stratospheric and sun activity and which has excellent year-round stability. 6. Because of the nature of the selected frequency we are expecting all the participants in the net to use a NEVIS (NEar Vertical Incident Skywave) antenna, which has the best both daytime and night-time reception in a several hundred mile radius. 7. With a different antenna the selected frequency also has exceptional long distance propagation at night. 8. The system is very small which makes it very portable for those who might need to relocate under catastrophic conditions. 9. We expect to be able to connect to computer notebooks, desktops, and such, and perhaps even to I-phones. 10. It is most important that the system be very low cost so that many people can be part of the network.

Design Considerations: We have a schematic of a proven circuit that needs only slight modification to make it compatible with currently available components. * We wish to have a new schematic drawn -- in light of the changes. * We wish - and this is key - to have a PCB layout generated, using Gerber Files. * We wish to select a stock case, and have the PCB conform to the size of the stock case.

If you are sympathetic to our cause and interested in this project in this project - we would very much like to hear from you. If you don't feel qualified, don't have time for project or for some other reason can't do it but - you think you might know someone who would please refer us on to them or them to us. Bruce VE3 UAL and Greg VA3 GRF Bruce@www.webpal.org and gregfranklin@live.ca