US Patent Class 455
TELECOMMUNICATIONS



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Current as of: June, 1999
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  DF  CLASS NOTES
1  DF  INTERFERENCE SIGNAL TRANSMISSION (E.G., JAMMING)
2  DF  AUDIENCE SURVEY OR PROGRAM DISTRIBUTION USE ACCOUNTING
3.1  DF  DISTRIBUTION SYSTEM (E.G., PLURAL CABLES, ETC.)
3.2  DF  .~ Receiver for satellite broadcast
3.3  DF  .~ Combined with power distribution network
4.1  DF  .~ Remote control of distribution
4.2  DF  .~.~ With subscriber selection or switching
5.1  DF  .~ Two-way
6.1  DF  .~ Common antenna or cable
6.2  DF  .~.~ With specific cable converter
6.3  DF  .~ Combined with diverse art device (e.g., audio/sound or entertainment systems)
400  DF  HAVING SINGLE-CHANNEL TELEPHONE CARRIER
401  DF  .~ Including call signaling (e.g., ringing, off-hook, dialing)
402  DF  .~ Over power line
403  DF  RADIOTELEPHONE SYSTEM
404  DF  .~ Emergency or alarm communication
405  DF  .~ Usage measurement
406  DF  .~.~ Billing
407  DF  .~.~.~ At subscriber unit
408  DF  .~.~.~ At remote station
409  DF  .~.~ Rental
410  DF  .~ Security or fraud prevention
411  DF  .~.~ Privacy, lock-out, or authentication
412  DF  .~ Message storage or retrieval
413  DF  .~.~ Voice mail
414  DF  .~ Special service
415  DF  .~.~ Caller identification
416  DF  .~.~ Call conferencing
417  DF  .~.~ Call diversion
418  DF  .~ Programming control
419  DF  .~.~ Remote programming control
420  DF  .~.~.~ Control of another apparatus
421  DF  .~ Out-of-range indication
422  DF  .~ Zoned or cellular telephone system
423  DF  .~.~ Diagnostic testing, malfunction indication, or electrical condition measurement
424  DF  .~.~.~ System equipment
425  DF  .~.~.~ Subscriber equipment
426  DF  .~.~ Including other radio communication system (e.g., cordless telephone, paging, trunking, etc.)
427  DF  .~.~ Space satellite
428  DF  .~.~.~ Switching or routing
429  DF  .~.~.~ Cell projection
430  DF  .~.~.~ Ground station control
431  DF  .~.~ Airborne or aircraft
432  DF  .~.~ Roaming
433  DF  .~.~.~ Home location registration (HLR) or visitor location registration (VLR) detail
434  DF  .~.~ Control or access channel scanning
435  DF  .~.~ Registration
436  DF  .~.~ Handoff
437  DF  .~.~.~ Mobile assisted or initiated
438  DF  .~.~.~ Serving site initiated
439  DF  .~.~.~ Handoff initiated by another source (e.g., target, user initiated, mobile switching center (MSC), or mobile telephone switching office (MTSO), etc.)
440  DF  .~.~.~ Based upon unit location
441  DF  .~.~.~ Based upon unit velocity
442  DF  .~.~.~ Soft handoff
443  DF  .~.~.~ Overlapping cells
444  DF  .~.~.~ Between macro and micro cells
445  DF  .~.~ Call routing (e.g., to prevent backhaul, routing efficiency, least cost, or alternate routing)
446  DF  .~.~ Including cell planning or layout
447  DF  .~.~.~ Frequency reuse scheme
448  DF  .~.~.~ Co-located systems
449  DF  .~.~.~ Hierarchical cell structure
450  DF  .~.~ Channel allocation
451  DF  .~.~.~ Hybrid allocation
452  DF  .~.~.~ Dynamic allocation
453  DF  .~.~.~ Load balancing
454  DF  .~.~.~ Spectrum sharing for different type of system (e.g., point-to-point microwave, television, etc.)
455  DF  .~.~ Channel seizing
456  DF  .~.~ Location monitoring
457  DF  .~.~.~ Location display
458  DF  .~.~ Specific paging technique
459  DF  .~.~.~ Meet-me system
460  DF  .~.~.~ Auto-dialing
461  DF  .~ Including personal numbering system (i.e., intelligent network for subscriber tracking or follow-me subscriber feature)
462  DF  .~ Including private cordless extension system
463  DF  .~.~ Multi-users
464  DF  .~.~ Channel selection or allocation
465  DF  .~ Including public cordless extension system
466  DF  .~ Auxiliary data signaling (e.g., short message service (SMS))
7  DF  CARRIER WAVE REPEATER OR RELAY SYSTEM (I.E., RETRANSMISSION OF SAME INFORMATION)
8  DF  .~ Failure compensation (e.g., spare channel)
9  DF  .~ Monitoring
10  DF  .~.~ Fading compensation
11.1  DF  .~ Portable or mobile repeater
12.1  DF  .~.~ Space satellite
13.1  DF  .~.~.~ With plural repeater or relay systems
13.2  DF  .~.~.~ With synchronizing of satellites or system
13.3  DF  .~.~.~ With antenna feed network or multiple antenna switching
13.4  DF  .~.~.~ Power control
14  DF  .~ With transmission line
15  DF  .~ Two separate way transmission
16  DF  .~.~ Simultaneous using plural repeaters at each location
17  DF  .~ Plural modulated carriers
18  DF  .~ With delay or recording
19  DF  .~ Common antenna
20  DF  .~ With frequency conversion
21  DF  .~.~ With demodulator
22  DF  .~.~ Plural conversion stages
23  DF  .~ Frequency or phase modulation
24  DF  .~ Transmitter/receiver feedback compensation
25  DF  .~ Directive antenna
26.1  DF  USE OR ACCESS BLOCKING (E.G., LOCKING SWITCH)
31.1  DF  SYSTEM WITH RECEIVER SELECTION
31.2  DF  .~ Control of selectively responsive paging arrangement over telephone line
31.3  DF  .~.~ Two-way paging system
32.1  DF  .~ Receiver scans for address signal
35.1  DF  .~ Tone coded squelch
36.1  DF  .~.~ Plural tones
37.1  DF  .~.~.~ Difference frequency
38.1  DF  .~ Coded sequence
38.2  DF  .~.~ With actuation (e.g., turn on/off or alarm indication, etc.)
38.3  DF  .~.~.~ Power control or battery saving
38.4  DF  .~.~.~ Visual indication
38.5  DF  .~.~.~ Tone sequence
39  DF  TRANSMITTER AND RECEIVER AT SEPARATE STATIONS
40  DF  .~ Earth or water medium
41  DF  .~ Near field (e.g., inductive or capacitive coupling)
42  DF  .~ Frequency or phase modulation
43  DF  .~.~ With modification of frequencies of analog signal passed (e.g., pre-emphasis and de-emphasis)
44  DF  .~.~ With stated modulation index
45  DF  .~.~ Via subcarrier
46  DF  .~ Suppressed carrier wave system
47  DF  .~ Single or vestigial sideband system
48  DF  .~ Inverted sideband
500  DF  .~ Plural transmitters or receivers (i.e., more than two stations)
501  DF  .~.~ Noise, distortion, or singing reduction
502  DF  .~.~.~ Synchronized stations
503  DF  .~.~.~.~ Simulcast system
504  DF  .~.~.~ Fading compensation
505  DF  .~.~.~.~ Due to weather
506  DF  .~.~.~.~ Rayleigh or multipath fading
507  DF  .~.~ Central station (e.g., master, etc.)
508  DF  .~.~.~ Having console
509  DF  .~.~.~ Channel allocation
510  DF  .~.~.~.~ Plural requests (e.g., retries)
511  DF  .~.~.~.~ Control channel/voice channel conversion
512  DF  .~.~.~.~ Based on priority
513  DF  .~.~.~.~ Ranking (e.g., based on signal strength, etc.)
514  DF  .~.~.~.~ Having storage detail
515  DF  .~.~.~ Control channel monitoring (i.e., paging or access channel signaling) for system access
516  DF  .~.~.~ Channel seizing
517  DF  .~.~.~ To or from mobile station
518  DF  .~.~.~.~ Having talk group
519  DF  .~.~.~.~.~ Talk group forming (e.g., dynamic regrouping, talk group assignment)
520  DF  .~.~.~.~.~ On-site or multi-site trunking
521  DF  .~.~.~.~ Emergency dispatch or response
522  DF  .~.~.~.~ Transmission power control technique
523  DF  .~.~.~.~ Using radiating transmission line
524  DF  .~.~.~.~ Multiple base stations
525  DF  .~.~.~.~.~ Base station selection
526  DF  .~.~.~ Plural receivers tuned to common frequency
527  DF  .~.~ Break-in or priority override
528  DF  .~.~ Lockout or busy-idle signaling
59  DF  .~ Single message via plural carrier wave transmission
60  DF  .~.~ Different phases of same frequency carrier
61  DF  .~ Single message via plural modulation of single carrier
62  DF  .~ Optimum frequency selection
63  DF  .~ Distortion, noise, or other interference prevention, reduction, or compensation
64  DF  .~.~ Plasma source or barrier
65  DF  .~.~ Anti-multipath
66  DF  .~ With diverse art device
67.1  DF  .~ With measuring, testing, or monitoring of system or part
67.2  DF  .~.~ Using a chamber (e.g., room testing or audio surveillance, etc.)
67.3  DF  .~.~ Noise, distortion or unwanted signal detection (e.g., quality control, etc.)
67.4  DF  .~.~ Using a test signal
67.5  DF  .~.~ Of a microwave link or system
67.6  DF  .~.~ Phase measuring (e.g., group delay, propagation effects, etc.)
67.7  DF  .~.~ With indication (e.g., visual or voice signalling, etc.)
68  DF  .~ With control signal
69  DF  .~.~ Transmitter controlled by signal feedback from receiver
70  DF  .~.~ Receiver control signal originates at message transmitter
71  DF  .~.~.~ Frequency control
72  DF  .~.~.~ For compression and expansion of message signal (i.e., companding)
73  DF  TRANSMITTER AND RECEIVER AT SAME STATION (E.G., TRANSCEIVER)
74  DF  .~ Convertible (e.g., to diverse art device)
74.1  DF  .~.~ Cordless/corded conversion
75  DF  .~ With frequency stabilization (e.g., automatic frequency control)
76  DF  .~.~ Synthesizer
77  DF  .~ With tuning
78  DF  .~ With transmitter-receiver switching or interaction prevention
79  DF  .~.~ Automatic (e.g., voice operated)
80  DF  .~.~.~ With distributed parameter coupling
81  DF  .~.~.~.~ Waveguide
82  DF  .~.~.~ Common antenna
83  DF  .~.~ Single antenna switched between transmitter and receiver
84  DF  .~ With a common signal processing stage
85  DF  .~.~ Transmitter oscillator used as detector
86  DF  .~.~ Transmitter oscillator used as local oscillator
87  DF  .~.~.~ Tunable or variable
88  DF  .~ Transceiver controlling a separate transceiver or receiver
550  DF  .~ Radiotelephone equipment detail
551  DF  .~.~ Number assignment module (NAM) detail
552  DF  .~.~ Operable on more than one system
553  DF  .~.~.~ Dual mode telephone (i.e., analog and digital)
554  DF  .~.~ Remote private branch exchange (PBX) with wireless link to landline
555  DF  .~.~ Wireless private branch exchange (PBX) (i.e., wireless link to extension unit)
556  DF  .~.~ Integrated with other device (e.g., electronic notebook, personal digital assistant, etc.)
557  DF  .~.~ Interface attached device (e.g., interface with modem, facsimile, computer, etc.)
558  DF  .~.~.~ Card control element
559  DF  .~.~.~ Smart cable
560  DF  .~.~ Switching unit detail (e.g., mobile telephone switching office (MTSO), base station controller (BSC), etc.)
561  DF  .~.~ Base station detail
562  DF  .~.~.~ Having specific antenna arrangement
563  DF  .~.~ Having voice recognition or synthesization
564  DF  .~.~ Auto-dialing or repertory dialing (e.g., using bar code, etc.)
565  DF  .~.~ Restrictive dialing circuitry
566  DF  .~.~ Having display
567  DF  .~.~ Call alerting
568  DF  .~.~ Headgear
569  DF  .~.~ Hands-free or loudspeaking arrangement
570  DF  .~.~.~ Noise suppression or echo cancellation
571  DF  .~.~ Power booster
572  DF  .~.~ Power supply
573  DF  .~.~.~ Battery charging
574  DF  .~.~.~ Power conservation
575  DF  .~ Portable or mobile
90  DF  .~ Housing or support
91  DF  TRANSMITTER
92  DF  .~ Remote control of a transmitter
93  DF  .~ Convertible to different type (e.g., AM to FM)
94  DF  .~ Alternator
95  DF  .~ Mobile or portable
96  DF  .~.~ Transmitter ejected from moving vehicle
97  DF  .~.~ With antenna ejection or external support
98  DF  .~.~ With aircraft, satellite, or projectile
99  DF  .~.~ With vehicle
100  DF  .~.~ Body attached or connected
101  DF  .~ Diversity
102  DF  .~ Plural modulation
103  DF  .~ Plural separate transmitters or channels
104  DF  .~.~ Carrier and sidebands separately transmitted
105  DF  .~.~ Common frequency
106  DF  .~ Modulation by absorption, shielding, or reflecting
107  DF  .~ With variation of antenna impedance or dimension for modulation
108  DF  .~ Amplitude modulation
109  DF  .~.~ Vestigial or single sideband or suppressed carrier
110  DF  .~ Angle modulation
111  DF  .~.~ Including distributed parameter structure
112  DF  .~.~ With frequency multiplication or division
113  DF  .~.~ With frequency control
114  DF  .~ With harmonic radiation suppression
115  DF  .~ Measuring, testing, or monitoring of transmitter
116  DF  .~ Carrier amplitude control (e.g., voice operated on/off)
117  DF  .~ With electrical protection of transmitter circuit or operator
118  DF  .~ Frequency conversion
119  DF  .~ Carrier frequency stabilization
120  DF  .~ Including tuning
121  DF  .~.~ In antenna circuit
122  DF  .~.~.~ With saturable reactor
123  DF  .~.~.~ Automatically controlled
124  DF  .~.~ Distributed parameter device
125  DF  .~.~ Automatic adjustment of tuning
126  DF  .~ With feedback of modulated output signal
127  DF  .~ Power or bias voltage supply
128  DF  .~ With casing or housing
129  DF  .~ With coupled antenna
130  DF  RECEIVER OR ANALOG MODULATED SIGNAL FREQUENCY CONVERTER
131  DF  .~ Frequency conversion between signal source (e.g., wave collector) and receiver
132  DF  .~ Plural receivers
133  DF  .~.~ With output selecting
134  DF  .~.~.~ By signal strength
135  DF  .~.~.~ By signal quality (e.g., signal to noise ratio)
136  DF  .~.~.~ With control (e.g., automatic gain control, automatic frequency control, etc.)
137  DF  .~.~ With output combining
138  DF  .~.~.~ With control (e.g., automatic gain control)
139  DF  .~.~.~.~ Frequency or phase control
140  DF  .~.~ Selectively actuated or controlled
141  DF  .~.~ Including common stage (e.g., local oscillator)
142  DF  .~ Convertible to different type (e.g., AM to FM)
143  DF  .~.~ With distinct signal path for each type
144  DF  .~.~ With dual purpose amplifying or other stage
145  DF  .~ Panoramic display
146  DF  .~.~ Plural separate paths or plural oscillators
147  DF  .~.~ Particular local oscillator control
148  DF  .~.~ With oscilloscope sweep signal derivation or control
149  DF  .~ Plural output (e.g., plural speakers) (not stereo)
150.1  DF  .~ Signal selection based on frequency (e.g., tuning)
151.1  DF  .~.~ Remote control of channel or station selection
151.2  DF  .~.~.~ Wireless link (sonic, RF, or infrared)
151.3  DF  .~.~.~ Remote oscillator tuned
151.4  DF  .~.~.~ Plural electronic devices controlled
152.1  DF  .~.~.~ Of or combined with vehicle receiver
153.1  DF  .~.~.~ Mechanical
153.2  DF  .~.~.~.~ With wired link
154.1  DF  .~.~ With indication of frequency, channel, or selector condition (e.g., tuning aid)
154.2  DF  .~.~.~ Scanning display
155.1  DF  .~.~.~ By meter
156.1  DF  .~.~.~ Audible indicator
157.1  DF  .~.~.~ Analog frequency indication (e.g., dial)
157.2  DF  .~.~.~.~ With light indication or bar type
158.1  DF  .~.~.~ Channel index indication
158.2  DF  .~.~.~.~ With electronic digital indication
158.3  DF  .~.~.~.~.~ Using a counter
158.4  DF  .~.~.~.~ With multiple display functions
158.5  DF  .~.~.~.~ Non-numeric display (e.g., call letters)
159.1  DF  .~.~.~ Variable light indication
159.2  DF  .~.~.~.~ Plural lamps
160.1  DF  .~.~ Plural tuning modes (e.g., manual and scanning, etc.)
161.1  DF  .~.~ Frequency scanning
161.2  DF  .~.~.~ With processor control
161.3  DF  .~.~.~ Using signal strength or quality
162.1  DF  .~.~.~ Motor activated
163.1  DF  .~.~.~.~ Reversible motor (e.g., end-stop control)
164.1  DF  .~.~.~ With automatic frequency control
164.2  DF  .~.~.~.~ Processor controlled (AFC)
165.1  DF  .~.~.~ With frequency synthesizer
166.1  DF  .~.~.~ With channel skipping selection
166.2  DF  .~.~.~.~ With priority channel selection
167.1  DF  .~.~.~ With dual sweeping
168.1  DF  .~.~.~ Multiband
169.1  DF  .~.~.~ With particular variable voltage or current tuning
169.2  DF  .~.~.~.~ With varactor diode
170.1  DF  .~.~ With mechanical or electromechanical selection
171.1  DF  .~.~.~ Time actuated
172.1  DF  .~.~.~.~ Including a motor
173.1  DF  .~.~.~ With automatic frequency control of fine tuning
174.1  DF  .~.~.~ With muting (e.g., silent tuning)
175.1  DF  .~.~.~ With carrier wave preset
176.1  DF  .~.~.~ Combined with band selection
177.1  DF  .~.~.~ Combined with other control (e.g., bandwidth, volume, gain, etc.)
178.1  DF  .~.~.~ With plurality of tunable circuits
179.1  DF  .~.~ Channel or station selection
180.1  DF  .~.~.~ Combined with band selection
180.2  DF  .~.~.~.~ UHF and VHF
180.3  DF  .~.~.~.~.~ With phase locked loop (PLL) tuning
180.4  DF  .~.~.~.~.~ Varactor tuned (e.g., varactor diode)
181.1  DF  .~.~.~ Time controlled
182.1  DF  .~.~.~ With frequency control
182.2  DF  .~.~.~.~ Automatic (AFC)
182.3  DF  .~.~.~ Fine tuning
183.1  DF  .~.~.~ With frequency synthesizer
183.2  DF  .~.~.~.~ Processor controlled
184.1  DF  .~.~.~ With comparing desired and existing tuning conditions
185.1  DF  .~.~.~ With channel information storage
186.1  DF  .~.~.~.~ With memory control or programming
186.2  DF  .~.~.~.~.~ Having a keyboard
187.1  DF  .~.~.~ Separate tuned circuits for each channel or station
188.1  DF  .~.~ Band selection
188.2  DF  .~.~.~ UHF and VHF
189.1  DF  .~.~.~ With plural separate mixer or converter circuits
190.1  DF  .~.~.~ With frequency conversion
191.1  DF  .~.~.~ With plurality of tuned circuits
191.2  DF  .~.~.~.~ Varactor tuned
191.3  DF  .~.~.~.~ With switching between stages
192.1  DF  .~.~ With frequency control
192.2  DF  .~.~.~ Automatic (AFC)
192.3  DF  .~.~.~ Fine tuning
193.1  DF  .~.~ With antenna circuit tuning
193.2  DF  .~.~.~ With plural resonant circuits
193.3  DF  .~.~.~ Including varactor diode
194.1  DF  .~.~ With muting (e.g., silent tuning)
194.2  DF  .~.~.~ Amplifier controlled
195.1  DF  .~.~ Variable voltage or current tuning
196.1  DF  .~.~ Including variation of local oscillator frequency
197.1  DF  .~.~.~ By simultaneous control with signal selection
197.2  DF  .~.~.~.~ Variable capacitor tuned
197.3  DF  .~.~.~.~.~ Including additional tuning circuit
198.1  DF  .~.~.~.~ Including distributed parameter control device
199.1  DF  .~.~.~.~ Discrete frequency types (e.g., channel switching)
200.1  DF  .~.~ With other control (e.g., volume, gain, bandwidth, etc.)
201  DF  .~ Exalted carrier
202  DF  .~ Suppressed carrier
203  DF  .~ Carrier and single sideband
204  DF  .~ Vestigial sideband
205  DF  .~ Frequency or phase modulation
206  DF  .~.~ Responsive to one of overlapping signals
207  DF  .~.~ With plural conversion
208  DF  .~.~ With synchronized or controlled local oscillator
209  DF  .~.~.~ Plural local oscillators or mixers
210  DF  .~.~ With carrier amplitude modulation elimination (e.g., specified limiter)
211  DF  .~.~.~ Combined with other function
212  DF  .~.~ With squelch or other audio output silencing
213  DF  .~.~.~ Using specified filter
214  DF  .~.~ With particular discriminator or detector
215  DF  .~.~.~ Superregenerative
216  DF  .~.~ With particular frequency division or multiplication
217  DF  .~ With protection circuit for receiver circuit
218  DF  .~ Squelch
219  DF  .~.~ With automatic gain or volume control
220  DF  .~.~ Adjustable
221  DF  .~.~ Audio responsive
222  DF  .~.~ Noise controlled
223  DF  .~.~.~ Short duration (noise blankers)
224  DF  .~.~.~.~ Separate broadband detector channel
225  DF  .~.~ Plural paths
226.1  DF  .~ Measuring or testing of receiver
226.2  DF  .~.~ Signal strength
226.3  DF  .~.~ Signal-to-noise ratio
226.4  DF  .~.~ With meter or indicator
227  DF  .~ Responsive to an input signal of particular predetermined frequency
228  DF  .~.~ Responsive to specified modulation (e.g., call alarm, Conelrad)
229  DF  .~.~ Responsive to carrier absence or presence
230  DF  .~ Local control of receiver operation
231  DF  .~.~ Applied at or for specific intervals or periods of time
232.1  DF  .~.~ Gain control
233.1  DF  .~.~.~ With diverse control (tone, etc.)
234.1  DF  .~.~.~ Automatic
234.2  DF  .~.~.~.~ Processor controlled
235.1  DF  .~.~.~.~ Forward acting
236.1  DF  .~.~.~.~ Variable conversion efficiency (variable oscillator amplitude, etc.)
237.1  DF  .~.~.~.~ Responsive to locally injected pilot
238.1  DF  .~.~.~.~ Responsive to vehicle speed
239.1  DF  .~.~.~.~ Nonlinear automatic gain control
240.1  DF  .~.~.~.~.~ Variable automatic gain control loop gain
241.1  DF  .~.~.~.~.~ Different gain stages
242.1  DF  .~.~.~.~.~ Delayed
242.2  DF  .~.~.~.~.~.~ Different delay for different signal stages or thresholds
243.1  DF  .~.~.~.~.~.~ Radio frequency stage only delayed
244.1  DF  .~.~.~.~.~ Dual time constant
245.1  DF  .~.~.~.~ Automatic gain control signal derived from information signal
245.2  DF  .~.~.~.~.~ Plural stages controlled
246.1  DF  .~.~.~.~ Responsive to plural inputs
247.1  DF  .~.~.~.~.~ Separate automatic gain control signals
248.1  DF  .~.~.~.~ Constant or controlled input impedance
249.1  DF  .~.~.~.~ Variable attenuator type
250.1  DF  .~.~.~.~ Automatic gain control to improve strong signal handling
251.1  DF  .~.~.~.~ Plural stages with different levels or bias to each stage (e.g., partial automatic gain control)
252.1  DF  .~.~.~.~ Semiconductor
253.1  DF  .~.~.~.~ Plural stages controlled with plates, screen grids, or cathodes connected in parallel
253.2  DF  .~.~.~.~ Plural amplifier stages
254  DF  .~.~ Sensitivity control
255  DF  .~.~ Local oscillator frequency control
256  DF  .~.~.~ Combined with other control
257  DF  .~.~.~ Automatic
258  DF  .~.~.~.~ Utilizing particular local oscillator control
259  DF  .~.~.~.~.~ Reference oscillator or source
260  DF  .~.~.~.~.~.~ Phase lock loop or frequency synthesizer
261  DF  .~.~.~.~.~ Variable reactance (e.g., reactance tube)
262  DF  .~.~.~.~.~.~ Voltage controlled capacitor
263  DF  .~.~.~.~.~ Discriminator or detector
264  DF  .~.~.~.~.~ Voltage control of oscillator
265  DF  .~.~.~.~ With local oscillator synchronization or locking
266  DF  .~.~ Selectivity or bandwidth control
267  DF  .~.~ Tone control
268  DF  .~.~ Fidelity control
269  DF  .~ With wave collector (e.g., antenna)
270  DF  .~.~ Power-line or receiver element used as wave collector
271  DF  .~.~ Suppression of radiation from receiver via wave collector
272  DF  .~.~ Plural separate collectors
273  DF  .~.~.~ With particular output combining
274  DF  .~.~.~.~ Loop or coil antenna
275  DF  .~.~.~ With frequency changing or selecting in the output path of one or more collectors
276.1  DF  .~.~.~ With phase shifting, correcting, or regulating in the output path of one or more collectors
277.1  DF  .~.~.~ Selectively or alternately connected to receiver
277.2  DF  .~.~.~.~ By signal quality (e.g., noise)
278.1  DF  .~.~.~ Combined with noise or interference elimination
279.1  DF  .~.~.~.~ Plural antenna currents entering single transformer
280  DF  .~.~ With coupling to a stage of the receiver
281  DF  .~.~.~ Having distributed parameters
282  DF  .~.~.~.~ Transmission line
283  DF  .~.~.~ Undesired signal or noise control (e.g., antistatic)
284  DF  .~.~.~.~ Balancing or cancelling
285  DF  .~.~.~.~ With image frequency suppression
286  DF  .~.~.~.~ Wave filter, coil, or wave trap
287  DF  .~.~.~.~ Shunt or bypass
288  DF  .~.~.~.~ Particular composition (e.g., of cell or element)
289  DF  .~.~.~ With coupling varying, regulating, or control
290  DF  .~.~.~ Including passive tuned circuit
291  DF  .~.~.~ Using active device (e.g., as preamplifier or reactance)
292  DF  .~.~.~ Transformer or other passive inductance
293  DF  .~.~.~ Specified stage (e.g., mixer, amplifier, or demodulator)
294  DF  .~.~.~.~ With particular electron tube structure
295  DF  .~ Modulation distortion or cross talk correction or elimination
296  DF  .~ Noise or interference elimination
297  DF  .~.~ In vehicle
298  DF  .~.~ Originating in power supply
299  DF  .~.~.~ Filter or rectification in power supply energized by fluctuating or a.c. source
300  DF  .~.~ By shielding
301  DF  .~.~.~ Plural or compartmented shielding structure
302  DF  .~.~ Image frequency suppression
303  DF  .~.~ Using plural separate signal paths
304  DF  .~.~.~ Phase shift in at least one path
305  DF  .~.~.~ With balancing or neutralizing
306  DF  .~.~.~.~ Filter in at least one path
307  DF  .~.~ With specific filter structure
308  DF  .~.~ With amplitude limiter
309  DF  .~.~.~ In demodulator or low frequency (audio amplifier circuit)
310  DF  .~.~ Internally generated noise or oscillations
311  DF  .~.~ In radio frequency amplifier, intermediate frequency amplifier or converter circuit
312  DF  .~.~ In demodulator or low frequency (e.g., audio frequency)
313  DF  .~ Frequency modifying or conversion
314  DF  .~.~ Plural separate successive conversions
315  DF  .~.~.~ With plural separate local oscillators
316  DF  .~.~.~.~ With frequency stabilization for at least one local oscillator
317  DF  .~.~ Unwanted oscillation or radiation prevention
318  DF  .~.~ With specified local oscillator structure or coupling
319  DF  .~.~.~ With particular coupling
320  DF  .~.~.~.~ Lumped impedance
321  DF  .~.~.~ In a single envelope or with common active element (e.g., autodyne)
322  DF  .~.~.~.~ Plural common electrode
323  DF  .~.~ Particular frequency conversion structure or circuitry
324  DF  .~.~.~ Homodyne (i.e., zero beat or synchrodyne reception)
325  DF  .~.~.~ Including distributed electrical parameter structure
326  DF  .~.~.~.~ With balanced mixer
327  DF  .~.~.~.~.~ Stripline
328  DF  .~.~.~.~.~ Hollow waveguide
329  DF  .~.~.~.~ Electron beam tube
330  DF  .~.~.~.~ With nonlinear impedance (e.g., diode)
331  DF  .~.~.~ Crystal or electron tube diode
332  DF  .~.~.~ Push-pull
333  DF  .~.~.~ Transistor or integrated circuit
334  DF  .~ With particular receiver circuit
335  DF  .~.~ Plural diverse function tube or stage (performs plural functions alternately or concurrently)
336  DF  .~.~ Superregenerative detector or discriminator
337  DF  .~.~ Discriminator or demodulator
338  DF  .~.~ Coupling or decoupling between stages
339  DF  .~.~.~ Band pass filter
340  DF  .~.~.~ Variably tunable or adjustable
341  DF  .~.~ Amplifier
342  DF  .~.~.~ Reflex type
343  DF  .~.~ With particular power or bias supply (includes battery saving means and includes self-powered)
344  DF  .~ Combined with diverse art device
345  DF  .~.~ With vehicle
346  DF  .~.~.~ Detachable for portability
347  DF  .~ Cabinet, housing, or chassis structure
348  DF  .~.~ With retractable or readily detachable chassis
349  DF  .~.~ Sectional or interconnectable (e.g., modules)
350  DF  .~.~ With particular speaker mounting
351  DF  .~.~ Transportable
352  DF  .~ Remote control of receiver
353  DF  .~.~ Plural conditions from remote station
354  DF  .~.~.~ Mechanical
355  DF  .~.~ Amplitude, volume, or gain control
899  DF  MISCELLANEOUS
**********************************
FOREIGN ART COLLECTIONS
*******************************
FOR 100  DF  .~ Zoned or cellular (455/33.1)
FOR 101  DF  .~.~ Hand-off control (455/33.2)
FOR 102  DF  .~.~.~ Using plural antennas (455/33.3)
FOR 103  DF  .~.~ With overlapping zones (455/33.4)
FOR 104  DF  .~ Exclusive assigned channel (455/34.1)
FOR 105  DF  .~ Seized channel (455/34.2)
FOR 106  DF  .~ Plural transmitters or receivers (i.e., more than two stations) (455/49.1)
FOR 107  DF  .~.~ Noise, distortion, or singing reduction (455/50.1)
FOR 108  DF  .~.~.~ Synchronized stations (455/51.1)
FOR 109  DF  .~.~.~.~ Simulcast system (455/51.2)
FOR 110  DF  .~.~.~ Fading compensation (455/52.1)
FOR 111  DF  .~.~.~.~ Due to weather attenuation (455/52.2)
FOR 112  DF  .~.~.~.~ Rayleigh or multipath fading (455/52.3)
FOR 113  DF  .~.~ With central station (e.g., master, etc.) (455/53.1)
FOR 114  DF  .~.~.~ To or from mobile station (455/54.1)
FOR 115  DF  .~.~.~.~ With service request and response (455/54.2)
FOR 116  DF  .~.~.~.~ Using radiating transmission line (455/55.1)
FOR 117  DF  .~.~.~.~ Multiple base stations (455/56.1)
FOR 118  DF  .~.~.~ Plural receivers tuned to common frequency (455/57.1)
FOR 119  DF  .~.~ Break-in or priority override (455/58.1)
FOR 120  DF  .~.~ Lockout or busy-idle signalling (455/58.2)
FOR 121  DF  .~ Portable or mobile (455/89)