Abstract: Disclosed is an inflatable bladder and a pressure plate which may be selectively positioned to hold the bladder so as to apply pressure to a blood vessel, for example. The bladder includes two sheets of flexible, non-elastic material. Expansion of the bladder may occur by inflation to separate the two sheets and press them outwardly against the pressure plate and the area of the subject to be compressed. An adjustable holder maintains the pressure plate in position. Pressure within the bladder may be monitored as an indication of the pressure exerted against the subject. Both the bladder and the pressure plate may be generally transparent to permit visual inspection and monitoring of the area being compressed.

Abstract: A navigational unit having a time-shared mode of operation for handling a plurality of different navigational signals is provided wherein IF components within the unit may have a dual dedication, i.e., used in common for handling all signals while normally present separate front end components and navigational display components may be dedicated exclusively to each separate signal, a central timing and control component coordinating the total operation.

Abstract: An apparatus for measuring and evaluating a subject's visual field presents a target image, consisting of a spot of light, at a series of selected locations within the subject's visual field. Means are provided to monitor his resulting eye movement and positions in response to each target presentation. A projection apparatus presents the target images at various locations and in a programmed sequence. The apparatus also includes means for making a photographic plot of those presented targets which the subject has seen or missed, as desired. Determination of whether subject has seen or missed a particular target is evaluated by logic systems which discriminate between eye movement and positions displaying characteristics indicative of whether the subject has seen or missed the target. The logic discriminates between blinks, hunting eye movements and other characteristic positions and movements which are indicative of the subject having seen the target.

Abstract: A radio receiver squelch circuit operative as a function of a comparison of the audio component level of the detected signal with the noise component level, so as to amplify and pass signals when the audio component exceeds the noise component by a predetermined ratio and to shunt the signals, thus squelching any output, when the noise component exceeds the audio component by a predetermined ratio. The circuit incorporates a hysteresis function such that the audio level required to initiate squelch is less than that required to break squelch.

Abstract: A circuit which allows the operation of a VOR receiver in the presence of unwanted interference signals without sacrificing a fast response to omnirange bearing selector changes. A switching-type synchronous filter is used to filter the 30 Hz AM channel signal in the receiver. The narrow bandwidth of this synchronous filter rejects unwanted interference signals without introducing phase shift into the desired signal. The switching signal for the synchronous filter is generated by the FM channel in such a manner that the switching filter center frequency follows the input frequency. The use of a synchronous filter allows rejection of interfering AM signals that lie outside a narrow pass band, while allowing the receiver to follow variations in frequency of the transmitted signal.

Abstract: A known reference signal is applied to a zero crossing detector and normal and inverted outputs from the zero crossing detector are applied to the input control terminals of a pair of bilateral switches. A measured signal of the same frequency but not necessarily of the same phase is simultaneously applied to the input terminals of the bilateral switches. The resultant output of the bilateral switches is connected to a parallel RC network. The capacitor acquires a charge proportional to the deviation from 90.degree., which is applied to a differential amplifier. The output of the differential amplifier is used to drive a meter which indicates the phase relationship of the two signals. The capacitor used to accumulate the net charge is ungrounded to eliminate errors resulting from unequal currents to ground.

Abstract: A ranging timer allows decoded data pulses to toggle a flip flop, thereby initiating a transmission cycle. In a specific embodiment, the data pulses condition a second flip flop to energize the DME transceiver. During the next negative excursion of a 96 microsecond reference clock, the second flip flop is toggled, and during the next period of the reference clock, the decoder is disabled, the transmitter-modulator is energized, the ranging timer is enabled, and the first flip flop is reset. Since the time between the decoded data pulses is variable, jitter is built into the commencement of each transmission cycle.

Abstract: In a DME system, the least significant decade of the present aircraft to ground station distance is maintained encoded in a memory, and an up-down counter maintains a variable count. The complement of the present distance is compared with the present count, and when a difference is detected, a logical pulse increments the counter and also indicates passage of the aircraft through another distance interval. The sense of the difference between the present distance and the count also is monitored, responsive to which the direction of the count is controlled.

Abstract: A voltage controlled oscillator provides a pulse signal which, when frequency scaled, is representative of aircraft velocity. Pulses representative of passage of the aircraft over distance intervals are coupled to one input of a comparator-integrator, and the VCO output pulses are further divided and coupled to the other input terminal of the comparator-integrator. The integration voltage controls the VCO. The VCO signal is frequency scaled and fed to a counter, the output count of which is strobed periodically and decoded to yield velocity.

Abstract: An apparatus for measuring and evaluating a subject's visual field presents a target image, consisting of a spot of light, at a series of selected locations within the subject's visual field. Means are provided to monitor his resulting eye movement and positions in response to each target presentation. A projection apparatus presents the target images at various locations and in a programmed sequence. The apparatus also includes means for making a photographic plot of those presented targets which the subject has seen or missed, as desired. Determination of whether subject has seen or missed a particular target is evaluated by logic systems which discriminate between eye movement and positions displaying characteristics indicative of whether the subject has seen or missed the target. The logic discriminates between blinks, hunting eye movements and other characteristic positions and movements which are indicative of the subject having seen the target.

Abstract: Each bin of a one-thousand stage shift register represents a two-tenth mile aircraft to ground station interval, and the register is shifted a full cycle corresponding to a two-hundred mile spacing. During a first shifting epic, all pulses returned from the ground station are inserted into the bins in timed relationship to each other and to transmitted pulses. In subsequent epics, stored pulses from the register are reinstated therein if there is time coincidence with another received signal. Once the register contains one-and-only-one signal, corresponding to the aircraft to station distance, that signal is automatically reinserted for the next three epics, regardless of signal receipt. Further coincidence of a receive signal, however, resets the automatic regeneration for three more periods, and so on. After three periods without a coincidence, all signals are passed to the register during the next epic.

Abstract: In a radio receiver, noise limiter apparatus specifically designed to clip impulse noise and to pass the audio signal undistorted up to about 80% carrier modulation. The noise limiter comprises a clipping circuit which is normally turned on by the audio signal to pass same, and a noise impulse amplifier branch containing an amplifier which is edgetriggered to cause clipping during the presence of noise impulses and to eliminate an output from the impulse amplifier when an audio signal is present.

Abstract: An apparatus for measuring and evaluating a subject's visual field includes a projector for presenting a target image, consisting of a spot of light, at a series of selected locations within the subject's visual field. A mirror is mounted for movement about a pair of axes and is rotated to a desired attitude by step motors which control the position of the mirror about the respective axes. A light beam is directed toward the mirror and is reflected in a direction dependent on the attitude of the mirror as controlled by the step motors.

Abstract: For use in a channel synthesizer utilizing a pulse swallowing phase locked loop, an eight bit code represents the megahertz component of the selected channel. An eight stage shift register is preloaded with the coded version of the selected megahertz component, and exclusive OR logic responsive selectively to the first, third, fifth, and eighth stages generates data for the first stage during the next shift. NAND logic responsive to the various stages detects presence of certain code combinations which are representative of terminal count states. Each terminal count pulse is utilized for comparison with the frequency reference in the phase locked loop, and also in a feedback arrangement to reset the registers to their preloaded states.

Abstract: In order to produce signals having a desired communication channel frequency, a phase locked loop is provided, along with appropriate frequency division. For channels in the megahertz range having bandwidth in the kilohertz range, a kilohertz reference is provided for comparison, to drive the voltage controlled oscillator. The oscillator output is divided by the megahertz quantity, and by optional division multiples in the kilohertz channel range. In particular, a first division ratio is utilized for a portion of a reference cycle, and a second division ratio for the remainder of this cycle. Preloaded logic controls the two division rates, and by adjusting the portions of the cycle, correspondingly regulates the effective division ratio for the loop, and yields the proper channel frequency for locking.

Abstract: A voltage controlled oscillator in a phase locked loop generates signals through the avionics communication band, and the VCO output is divided alternately by first and second factors corresponding to kilohertz range increments, and then by a third factor corresponding to the applicable megahertz increment. The relative time periods during which the respective KHz factors are utilized depends upon the count generated by a logical circuit, operating responsively to encoded representations of channels to be utilized. First and second preloaded counters operate for a predetermined time period, during which both factors are utilized alternatively; during the remainder of the counting cycle, only one factor is utilized.

Abstract: In a radio synthesizer adapted for use in an aircraft transceiver, an out of lock detector which enables or inhibits output from the synthesizer depending upon whether the synthesizer phase lock loop is in or out of lock. Under normal in lock operating conditions the oscillator output is coupled to the input of an output amplifier. When the loop is out of lock, pulse signals are generated at the loop phase detector and peak integrated to produce a signal which inhibits transmission of the oscillator output to the output amplifier, so that no output is produced while the synthesizer searches for a selected frequency.