US3835394A — Code receiver in staff locator

Claim 1

Independent Claim 376 words

Device for decoding of coded pulse trains transmitted by radio, which pulse trains consist of pulses of alternating voltage with different frequencies, the device comprising a radio receiver, a band-pass filter connected to the receiver and switchable between different preselected frequencies, a level detector means connected to the output of the bandpass filter for delivering a DC voltage pulse with a preselected amplitude and a duration substantially equal to half the cycle of an alternating voltage delivered from the bandpass filter, a pulse former means connected to the output of the level detector means for lengthening the duration of the voltage pulse delivered from the level detector means to a preSelected duration, which duration being of about the same duration as that of a pulse of alternating voltage delivered by the receiver, a pulse time supervisor means connected to the output of the level detector means for delivering a stepping signal upon receiving from the pulse former means a start pulse of a duration at least equal to a predetermined duration and also upon receiving subsequent code pulses and for delivering an inhibiting signal when a time interval between code pulses following the above mentioned start pulse exceeds a predetermined duration, a stepping means having an input connected to the output of the pulse former means and an output of the pulse time supervisor means for being set in starting position upon receiving the stepping signal from the pulse time supervisor means and for advancing one step for each subsequent stepping signal received from the level detector, said stepping means including first means for giving the bandpass filter which is connected to an output thereof a frequency setting assigned to each position of the stepping device according to a predetermined set code and second means for being reset to idle position on receiving an inhibiting signal from the pulse time supervisor means and third means for delivering on reaching an end position an acknowledgment signal, an alarm means connected to an output of the stepping means for producing an alarm signal on receiving the acknowledgment signal from the stepping means, and a loudspeaker means connected to the output of the alarm means for producing an audible signal when receiving the alarm signal from the alarm means.

Claim 2

Dependent Claim 376 words

Device for decoding of coded pulse trains transmitted by radio, which pulse trains consist of pulses of alternating voltage with different frequencies, the device comprising a radio receiver, a band-pass filter connected to the receiver and switchable between different preselected frequencies, a level detector means connected to the output of the bandpass filter for delivering a DC voltage pulse with a preselected amplitude and a duration substantially equal to half the cycle of an alternating voltage delivered from the bandpass filter, a pulse former means connected to the output of the level detector means for lengthening the duration of the voltage pulse delivered from the level detector means to a preSelected duration, which duration being of about the same duration as that of a pulse of alternating voltage delivered by the receiver, a pulse time supervisor means connected to the output of the level detector means for delivering a stepping signal upon receiving from the pulse former means a start pulse of a duration at least equal to a predetermined duration and also upon receiving subsequent code pulses and for delivering an inhibiting signal when a time interval between code pulses following the above mentioned start pulse exceeds a predetermined duration, a stepping means having an input connected to the output of the pulse former means and an output of the pulse time supervisor means for being set in starting position upon receiving the stepping signal from the pulse time supervisor means and for advancing one step for each subsequent stepping signal received from the level detector, said stepping means including first means for giving the bandpass filter which is connected to an output thereof a frequency setting assigned to each position of the stepping device according to a predetermined set code and second means for being reset to idle position on receiving an inhibiting signal from the pulse time supervisor means and third means for delivering on reaching an end position an acknowledgment signal, an alarm means connected to an output of the stepping means for producing an alarm signal on receiving the acknowledgment signal from the stepping means, and a loudspeaker means connected to the output of the alarm means for producing an audible signal when receiving the alarm signal from the alarm means.

Claim 3

Dependent Claim 99 words

Device according to claim 1 provided with a switch means having an input connected to an output of the stepping means and to an output of the pulse time supervisor means, said switch means being actuated by the pulse time detector means when a start pulse of at least twice the duration of said predetermined duration is determined, said switch means including means when, in its actuated state for connecting the bandpass filter to the stepping means in such manner for allowing the bandpass filter to be controlled in accordance with a second code set in the stepping device.

Claim 4

Dependent Claim 80 words

Device according to claim 1, where the pulse former means is provided with a digital counter means for counting, starting from zero, on delivery of a DC voltage signal from the level detector means, of at most a selected number of clock pulses, the selected number corresponding to the duration of said pulse from the pulse former means, and for again counting from zero at the start of every delivery of a DC voltage signal from the level detector means.

Claim 5

Dependent Claim 120 words

Device according to claim 3, where the pulse time supervisor means is provided with a digital counter means for counting, simultaneously with a pulse from the pulse former means, of a first preselected number of clock pulses, the selected number corresponding to the duration of said start pulse, and a second number of clock pulses, twice as large as the first, corresponding to a second kind of start pulse, and also for counting with said digital counter, after reception of either of the aforesaid kinds of start pulses, during the intervals between the pulses, of said first number of clock pulses, and for signalling to the pulse time supervisor on attainment of either or both said numbers of clock pulses.

Claim 6

Dependent Claim 61 words

Device according to claim 4, provided with one clock oscillator means connected to the level detector means and to the pulse time supervisor means for transmitting clock pulses to all the digital counters with a preselected unchangeable frequency about four times as high as that of the alternating voltages in the pulses in the pulse trains delivered to the bandpass filter.

Claim 7

Dependent Claim 77 words

Device according to claim 5, where the alarm means is connected to said clock oscillator means and where the alarm means includes frequency divider means operative, after actuation from the stepping means, for delivering a low frequency pulse train and a digitaL counter means for counting of a preselected unchangeable number of the clock pulses and, when the selected number of clock pulses has been reached, for causing the alarm means to interrupt the transmission of pulses.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1977-09-09	1978-03-11	1978-09-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1981-09-09	1982-03-11	1982-09-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1985-09-09	1986-03-11	1986-09-10	$7700.00	Window Closed / Lapsed

Code receiver in staff locator

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