Seiko Epson Corporation

Seiko Communications Holding N.v.

Seiko Corporation

Seiko Communications Systems Inc.

Epson Corporation

At&e Corporation

Seiko Telecommunication Systems, Inc.

Seko Corp.

Elko Corp.

Jeffrey R Owen

Daniel J Park

Bruce C Nepple

James D English

Garth Upshaw

A ripple counter becomes programmable by use of intervening circuitry selectively inhibiting state transitions according to an initial programming step. The illustrated embodiment of a programmable ripple counter includes a forward chain of count registers operating generally in the fashion of a ripple counter, but selectively inhibited by an intervening control signal originating from a reverse chain of control registers. By selectively controlling the number of state transitions inhibited and by selectively controlling the number of registers participating in the counting operation, a low power general purpose programmable ripple counter results.

Low power programmable ripple counter

A phase locked loop circuit employing a single phase detector provides limited maximum lock time by avoiding hang-up. The circuit first establishes a gross indication of phase relation sufficient to establish a direction of phase shift away from the unstable equilibrium point. The phase is then shifted by a predetermined value to establish a bounded phase relation exclusive of the unstable equilibrium point and inclusive of the stable equilibrium point. Conventional phase locking then provides the desired frequency and phase relation, but without potential for hang-up.

Phase locked loop with limited lock time

A small, high Q loop antenna configured on a printed circuit board as a planar structure receives a radio signal and shields its interior planar area against interfering electric field energy while concentrating therein radio signal magnetic flux. A magnetic pickup loop, coplanar to the antenna loop and magnetically coupled thereto, receives the radio signal power by virtue of its magnetic coupling to the loop antenna. The magnetic pickup loop couples to a receiving device and delivers the radio signal thereto. Illustrated embodiments include loop antennas tunable to a desired resonant frequency.

Loop antenna with reduced electrical field sensitivity

An FM signal or protocol analyzer (PA) system: The PA system is capable of analyzing the broadcast signal at many levels, from analysis of the physical RF link to comprehensive analysis of the subcarrier messaging. The PA system is built on a computer including special hardware and software. The custom hardware comprises at least one precision RF receiver and signal processing circuitry. The custom software includes data acquisition, data analysis and data presentation software. As a feature of the present invention, a PA system is designed to be 'user friendly.' As such, it operates in a windowing environment and makes extensive use of graphical displays. The PA system can operate in a networking environment so the receiver and signal processing circuitry can be physically distant from the user's display and keyboard, in another computer connected to the network. The look and feel of the PA system being operated over a network is similar to the look and feel of a PA system with all its components being local, except for any performance limitations that are imposed by network throughput.

Analyzer for frequency modulated signals

Integrated circuit components automatically establish or disable a level-pulling condition relative to a given input IC pin as a function of detected signal activity at such IC pin, A logic signal responsive to signal activity at the IC pin drives the gate of a field effect transistor (FET) to dynamically establish or disable level-pulling function at the IC pin. Alternative embodiments include a flop-flop register and an OR gate driving the gate of the FET.

Gatable level-pulling circuit

A paging device includes a cryptographic function and a password accessed cryptographic key look-up table associating each stored key with a password. When an cryptographic message is collected by the paging device, the user can select a relatively long cryptographic key by entering a relatively shorter password. The paging device then applies a cryptographic function to a received message using a selected relatively long cryptographic key, the selection being a function of user entry of a relatively short password. Overall, paging messages in transit, i.e., while broadcast by radio signal, enjoy a high level of security by encryption with a relatively long cryptographic key by a message source. As accessed by the user, however, the cryptographic messages are reviewed in readable form by use of a relatively short password designating a relatively long stored cryptographic key.

Paging device including password accessed stored cryptographic keys

A time keeping and display system, device, and method are shown and illustrated including radio signal broadcast of a time of day reference signal. Remote time keeping devices intermittently collect the time of day reference. Each remote device automatically captures a current state of a time keeping counter when capturing the time of day reference. The captured state of the time keeping counter is later compared to the received time of day reference to calculate an update relative to the time of day counter. The calculated update may be a calculated error later applied as an offset to the counter, or may be a sum of the received time of day and an elapsed time, later loaded into the counter. When the remote device has no pending higher priority tasks, a brief fixed execution time procedure modifies the time keeping counter as a function of the calculated update. Because the process of modifying the time keeping counter is brief, no perceivable discontinuity in device operation, i.e., time display updates or response to user interface activity, occurs while the processing element of the device is dedicated entirely, i.e., interrupts disabled, to the task of modifying the content of the time keeping counter.

Method and apparatus for accurate time maintenance and display

A highly accurate time keeping device and time keeping system are disclosed. Time of day information is periodically sent to a wristwatch via radio signal. The time of day as displayed by the watch is updated periodically using the radio signal data and maintained between such periodic updates according to an algorithm of the present invention. The disclosed time keeping system thereby maintains a plurality of time keeping devices in substantially exact synchronization over an extended period.

Digital frequency demodulation is accomplished by monitoring similar transitions in an FM radio signal to determine frequency. Time intervals between similar transitions in the FM signal are established by selecting anticipated transition times and accumulating error values relative to actual transition times. Accumulated error values provide a basis for further selecting anticipated transition times in such manner that a reported sequence of anticipated transition times provides a basis for inferring signal frequency. In one illustrated embodiment, the chosen transition times are positive transitions in the FM signal and the anticipated times of transition are taken from a set of two time periods, an early transition and a late transition relative to a valid transition window. In one embodiment of the invention, accumulated error is stored in an integrator device while in another embodiment accumulated error is stored in the phase of a bi-frequency oscillator. By reporting the selected anticipation times by associated values in a digital bit stream, frequency may be inferred by computing a ratio of given digital values in the bit stream relative to the total number of samples in the bit stream.

Sigma-delta FM demodulator

Digital frequency demodulation is accomplished by monitoring similar transitions in an FM radio signal to determine frequency. Time intervals between similar transitions in the FM signal are established by selecting anticipated transition times and accumulating error values relative to actual transition times. Accumulated error values provide a basis for further selecting anticipated transition times in such manner that a reported sequence of anticipated transition times provides a basis for inferring signal frequency. In one illustrated embodiment, the chosen transition times are positive transitions in the FM signal and the anticipated times of transition are taken from a set of two time periods, an early transition and a late transition relative to a valid transition window. By reporting the selected anticipation times by associated values in a digital bit stream, frequency may be inferred by computing a ratio of given digital values in the bit stream relative to the total number of samples in the bit stream.

Sigma-delta digital FM demodulator

Bit synchronization is achieved by identifying potential bit sample points and assigning corresponding weight values as a function of signal noise vulnerability. The greater the possibility of error due to signal noise, the smaller the assigned weight value. The bit sample points associated with the largest accumulated weight value are taken as the appropriate data sample points for extracting information from the data signal. For a duobinary signal, zero crossings are identified as potential bit sample points and assigned a weight value corresponding to signal slope thereat. The number of possible bit sample points associated with each actual bit sample point is limited to a finite set by phase locking the carrier signal to the data rate.

Data bit synchronization

The present invention provides an antenna or preselector tuning method and circuit that tunes an antenna or preselector in a very short period of time. The circuit of the present invention does not rely on measuring the magnitude of the signal strength at the output of the receiver as do many prior art antenna tuning techniques. With the present invention a radio frequency (RF) oscillator set to the desired receiver frequency generates an excitation signal which is lightly coupled to the antenna tuned circuit through a network. A phase detector then compares the phase of signal established in the antenna tuned circuit with the phase of the excitation signal to produce an 'error' signal indicative of the phase shift of the excitation signal as it passes through the network. Using this 'error' signal and locked loop (PLL) techniques, an antenna tuning voltage is created that results in a zero phase shift through the network.

Radio antenna tuning circuit

The present invention provides a technique and system for modifying the modulation of the 66.5 kHz subcarrier in such a way that its spectrum will not overlap that required by the 57 kHz subcarrier, while at the same time maintaining compatibility with existing subcarrier receivers. A special signal is created whose spectral shape is asymmetrical with respect to the 66.5 kHz subcarrier. In the frequency domain, the lowest frequency part of the symmetrical spectrum is cut off, flipped about the carrier frequency and then added to the highest frequency part of the spectrum. This technique and system takes advantage of the fact that the receiver, with which the system is designed to operate, uses a sampling process which products frequency aliasing. With the present invention, the spectral shape produced at the transmitter is such that the aliasing caused by sampling in the receiver results in the lower-than-carrier and higher-than-carrier portions of the spectrum being adding together, producing in the receiver a symmetrical spectrum.

Transmitting information with cut and flip spectrum

The present invention relates to a system which uses information in a certain band of frequencies, f.sub.b. The information of interest is contained in an analog signal that has noise at higher frequencies. The analog signal is sampled using an integrate and hold amplifier, hence, noise from higher frequencies is aliased into the region of interest f.sub.b. In accordance with the present invention, the integrated and hold amplifier has a frequency response which has a zero at a frequency, f.sub.n, which is one of the frequencies aliased into the band of frequencies f.sub.b. Thus, the effect of the noise that appears near the frequency f.sub.n has much less effect on the signal when it is aliased into the frequency band of interest, f.sub.b. The performance of the system is thereby improved.

Growing community of inventors

Portland, OR, United States of America

Jeffrey R Owen