Manual of U.S. Patent Classification
as of June 30, 2000

Class
375
PULSE OR DIGITAL COMMUNICATIONS

Class definitions may be accessed by clicking on the class title, above.
Subclass definitions may be accessed by clicking on the subclass number, below.

Patents classified in a subclass may be accessed by clicking on the " " icon following the subclass number, below.

( please note that links to definitions and classified patents may not be available for some classes and subclasses )

For search strategies, please refer to the Classification Index Explanation of Data web page.

Subclass		Title
ClassTitle		===> PULSE OR DIGITAL COMMUNICATIONS
130		SPREAD SPECTRUM
131		. Hybrid form
132		. Frequency hopping
133		. . End-to-end transmission system
134		. . . Having specific code acquisition or tracking
135		. . Transmitter
136		. . Receiver
137		. . . Having specific code acquisition or tracking
138		. Time hopping
139		. Chirp
140		. Direct sequence
141		. . End-to-end transmission system
142		. . . Having correlation-type receiver
143		. . . Having matched-filter-type receiver
144		. . . Having multi-receiver or interference cancellation
145		. . . Having specific signaling for code synchronization
146		. . Transmitter
147		. . Receiver
148		. . . Multi-receiver or interference cancellation
149		. . . Having specific code synchronization
150		. . . Correlation-type receiver
151		. . . . Having SAW or charge-transfer device
152		. . . Matched-filter-type receiver
153		. . . . Having SAW or charge-transfer device
211		REPEATERS
212		. Ring or star configuration
213		. Testing
214		. Including pulse regeneration or conversion
215		. . Phase locked loop
216		APPARATUS CONVERTIBLE TO ANALOG
217		. Muting circuit and squelch
218		EARTH OR WATER MEDIUM
219		TRANSCEIVERS
220		. Transmission interface between two stations or terminals
221		. Loopback mode
222		. Modems (data sets)
223		. . Angle modulation
224		TESTING
225		. Data rate
226		. Phase error or phase jitter
227		. Signal noise
228		. With indicator
229		EQUALIZERS
230		. Automatic
231		. . Training period or initial set up
232		. . Adaptive
233		. . . Decision feedback equalizer
234		. . . Fractionally spaced equalizer
235		. . . Quadrature channels
236		. . . Accumulator or up/down counter
237		PULSE NUMBER MODULATION
238		PULSE WIDTH MODULATION
239		PULSE POSITION, FREQUENCY, OR SPACING MODULATION
240		BANDWIDTH REDUCTION OR EXPANSION
240.01		. Television or motion video signal
240.02		. . Adaptive
240.03		. . . Quantization
240.04		. . . . Feed forward
240.05		. . . . Feed back
240.06		. . . Feed forward
240.07		. . . Feed back
240.08		. . Feature based
240.09		. . . Polygonal approximation
240.1		. . . Separate coders
240.11		. . . . Subband coding
240.12		. . Predictive
240.13		. . . Intra/inter selection
240.14		. . . Plural
240.15		. . . Bidirectional
240.16		. . . Motion vector
240.17		. . . . Half-pixel refinement
240.18		. . Transform
240.19		. . . Wavelet
240.2		. . . Discrete cosine
240.21		. . Subsampling
240.22		. . Vector quantization
240.23		. . Variable length coding
240.24		. . Block coding
240.25		. . Specific decompression process
240.26		. . Associated signal processing
240.27		. . . Error detection or correction
240.28		. . . Synchronization
240.29		. . . Pre/post filtering
241		. Pulse code modulation
242		PULSE CODE MODULATION
243		. Correcting or reducing quantizing errors
244		. Differential
245		. . Quantizer or inverse quantizer
246		. . Length coding
247		. . Single bit (delta)
248		. . . Nonamplitude delta (area, etc.)
249		. . . Compand (overload prevention)
250		. . . . Redundancy removal
251		. . . . Syllabic
252		. . . Plural feedback loops
253		. Length coding
254		. Noise or distortion reduction
256		PULSE TRANSMISSION VIA RADIATED BASEBAND
257		CABLE SYSTEMS AND COMPONENTS
258		. Transformer coupling
259		SYSTEMS USING ALTERNATING OR PULSATING CURRENT
260		. Plural channels for transmission of a single pulse train
261		. . Quadrature amplitude modulation
262		. . . Maximum likelihood decoder or viterbi decoder
263		. . . Partial response
264		. . . Multilevel
265		. . . Trellis encoder or Trellis decoder
267		. . Diversity
268		. Amplitude modulation
269		. . With phase or frequency shift keying
270		. . Vestigial or single sideband or suppressed carrier
271		. Angle modulation
272		. . Frequency shift keying
273		. . . Combined with phase shift keying
274		. . . Minimum shift keying
275		. . . More than two frequencies
276		. . . One cycle or less per bit
277		. . . Vestigial or single sideband, or suppressed carrier
278		. . . Antinoise or distortion
279		. . Phase shift keying
280		. . . More than two phases
281		. . . . Quaternary
282		. . . Biphase (manchester codes)
283		. . . Differential phase shift keying (diphase)
284		. . . Antinoise or distortion
285		. Antinoise or distortion
286		MULTILEVEL
287		. With threshold level
288		. Transmission line
289		. Bipolar signal
290		. Partial response
291		. . Duobinary
292		. Disparity reduction
293		. Synchronized
294		. . Phase locked loop
295		TRANSMITTERS
296		. Antinoise or distortion (includes predistortion)
297		. . Power amplifier
298		. Quadrature amplitude modulation
299		. Plural diversity
300		. Amplitude modulation
301		. . Single or vestigial sideband or suppressed carrier
302		. Angle modulation
303		. . Frequency shift keying
304		. . . Antenna tuning with frequency shift
305		. . . Minimum shift keying
306		. . . One oscillator
307		. . . Two or more oscillators
308		. . Phase shift keying
309		. Keying circuits
310		. . Remote controlled
311		. . Automatic
312		. . Power or bias voltage supply keying
313		. . Key shock or click prevention
314		. . Including auxiliary control tube
315		. . Modulation by absorption of signal, changing antenna dimension or changing antenna impedance
316		RECEIVERS
317		. Automatic baseline or threshold adjustment
318		. . Differential amplifier
319		. . Automatic bias circuit for DC restoration
320		. Amplitude modulation
321		. . Single or vestigial sideband or suppressed carrier
322		. Angle modulation
323		. . Combined phase shift keyed and frequency shift keyed
324		. . Particular demodulator
325		. . . Including coherent detector
326		. . . Carrier recovery circuit or carrier tracking
327		. . . Phase locked loop
328		. . . Including switching or gating (digital circuits)
329		. . Phase shift keying
330		. . . Differential (diphase)
331		. . . . More than two phases
332		. . . Plural phase (>2)
333		. . . Biphase (manchester code)
334		. . Frequency shift keying
335		. . . More than two frequencies
336		. . . Minimum shift keying
337		. . . Separate mark and space channels
338		. Interrupted carrier wave
339		. . Carrier controlling local generator
340		. Particular pulse demodulator or detector
341		. . Maximum likelihood decoder or viterbi decoder
342		. . Locating predetermined portion of pulse
343		. . Correlative or matched filter
344		. Automatic frequency control
345		. Automatic gain control
346		. Interference or noise reduction
347		. . Diversity (frequency or time)
348		. . Intersymbol interference
349		. . Plural signal paths in receiver
350		. . By filtering (e.g., digital)
351		. . Gating, blanking, etc.
352		. With electromagnetic relay or solenoid
353		PULSE AMPLITUDE MODULATION
354		SYNCHRONIZERS
355		. Synchronizing the sampling time of digital data
356		. Network synchronizing more than two stations
357		. Synchronization failure prevention
358		. Feedback, receiver to transmitter
359		. Self-synchronizing signal (self-clocking codes, etc.)
360		. . With transition detector
361		. . Manchester code or biphase code
362		. Frequency or phase control using synchronizing signal
363		. . Synchronization bit insertion into artificially created gaps
364		. . Synchronization signals with unique amplitude, polarity, length, or frequency
365		. . Synchronization word
366		. . . Plurality of synchronization words
367		. . . Pseudo noise
368		. . . Synchronizer pattern recognizers
369		. . Start - stop
370		. . . With asynchronous data
371		. Phase displacement, slip or jitter correction
372		. . Elastic buffer
373		. . Phase locking
374		. . . With charge pump or up and down counters
375		. . . With frequency detector and phase detector
376		. . . Phase locked loop
377		MISCELLANEOUS
		*********************************
		FOREIGN ART COLLECTIONS
		*********************************
		Any foreign patents or non-patent literature from subclasses that have been reclassified have been transferred directly to FOR Collection listed below. These collections contain ONLY foreign patents or nonpatent literature. The parenthetical references in the Collection titles refer to the abolished subclasses from which these Collections were derived.
FOR 100		SPREAD SPECTRUM (375/200)
FOR 101		. Hybrid forms (375/201)
FOR 102		. Frequency hopping (375/202)
FOR 103		. Time hopping (375/203)
FOR 104		. Pulsed FM or chirp (375/204)
FOR 105		. Direct sequence (375/206)
FOR 106		. Matched filter (375/207)
FOR 107		. Pseudo-noise correlation (375/208)
FOR 108		. . Auto-correlation (375/209)
FOR 109		. . Cross-correlation (375/210)

Information Products Division -- Contacts

Questions regarding this report should be directed to:

U.S. Patent and Trademark Office
Information Products Division
PK3- Suite 441
Washington, DC 20231

tel: (703) 306-2600
FAX: (703) 306-2737
email: oeip@uspto.gov

---

Last Modified: 6 October 2000