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October 5, 1957

Course Recorded

Navy Picks Up Radio Signals -- 4 Report Sighting Device

By WALTER SULLIVAN
Special to The New York Times
WASHINGTON, Saturday, Oct. 5 -- The Naval Research Laboratory announced early today that it had recorded four crossings of the Soviet earth satellite over the United States.

It said that one had passed near Washington. Two crossings were farther to the west. The location of the fourth was not made available immediately.

It added that tracking would be continued in an attempt to pin down the orbit sufficiently to obtain scientific information of the type sought in the International Geophysical Year.

Press Reports Noted

Soviet newspapers reported several weeks ago that the Soviet satellites would broadcast on frequencies in the neighborhood of twenty and forty megacycles. More exact frequencies were given by Soviet scientists at a conference on rockets and satellites that took place here this week.

Presumably the Naval Research Laboratory, which is responsible for the United States satellite program under the National Academy of Sciences, immediately set up receivers on those frequencies.

The tracking system established in this country to monitor its own satellites uses 100 megacycles, since much more accurate positions can be obtained with the higher frequencies.

The Russians at first agreed to use equipment "compatible" with that of the United States, but then announced the lower frequencies.

Deception Ruled out

American scientists believe this was because of a shortage of Soviet receivers capable of handling the higher frequency. It was not thought to be designed to hide the satellite since the Soviet signals are within easy reach of American listeners.

This was demonstrated last night as amateur and commercial radio stations, as well as the Naval Research Laboratory, reported hearing them.

Teams of visual observers 150 stations in the United States and other Western nations were alerted during the night to watch for the Soviet sphere at dawn and evening twilight.

They have been organized in "Project Moonwatch" to sight the satellite through binoculars or telescopes as it passes overhead.

At a typical station, each watcher wears a lapel microphone that is wired into a tape recorder that also receives radio time signals.

When the satellite is seen by someone to cross the section of the meridian he is responsible for, he shouts "mark" and notes which stars lay behind its path to establish its exact elevation. This information is then phoned to Cambridge, Mass., for analysis.

Ultimately, the United States is to have special cameras installed a dozen points around the world to take high precision photographs of the satellites against a star-studded background. These can be used for detailed studies of the satellite orbits.

Only one of those cameras has been set up so far and the last will probably not be in operation until next summer. The Soviet Union does not appear to have any such precision cameras and has expressed an interest in those being made here.

Soviet radio tracking of the satellite differs from that of the United States system, which is dependent on radio phasing devices. Such equipment is of limited value at the Soviet frequencies.

Hence the Russians are using a procedure that in the American view, is of low accuracy.

The Soviet tracking depends on radio doppler, a phenomenon comparable to the change in pitch of a whistle on a passing locomotive. While approaching it is shriller because the speed of sound is augmented by the train's motion. Once the train has passed the movement is subtracted from the sound, making the pitch lower.

The Soviet Union has asked radio amateurs and commercial stations to record the sound of the satellite on magnetic tape. The turning point of the frequency change will mark the instant of satellite passage and the degree change will show how close it passed.


Copyright 1997 The New York Times Company