Wide-Band Facsimile Transmission Over a 900-Mile Path Utilizing Meteor Ionization

Preliminary tests of facsimile transmission over a 910-mile path have been made at 40 mc by means of intermittent meteor ionization. Printed matter was scanned at a rate of 2 frames per second, with a resolution of 67 elements per inch. An all-electronic facsimile system recorded a picture when the received signal rose above a preset threshold. Tests were conducted employing bandwidths up to 110 kc with keying frequencies up to 73 kc, still maintaining the same optical resolution in the facsimile material. With the equipment used in the tests, it appeared that the maximum bit rate for acceptable facsimile was about 48,000 bits per second at 2 per cent duty cycle and about 86,000 bits per second at 1 percent duty cycle. Examples of signal recordings with received facsimile are shown. Preparations are being made to conduct similar tests, employing a higher information rate and wider bandwidth, on a frequency near 50 mc.