EP0102225A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Improved communications interface
Assignee: Computer Automation Inc
•
Filing: 1983-08-18
•
Granted: —
•
Expires: 2003-08-18
Abstract
Abstract There is disclosed an improved modem (78) for a single frequency, modulated RF carrier local data network for a distributed data processing system (Figure 4) and a method (Figure 7A and B) for line (64) acquisition and contention resolution. The protocol established for line acquisition and contention resolution is implemented by a modem controller (104). The controller (104) causes the receiver section (82) to listen for foreign carriers to determine when the line is busy. When the client device (66,70,72,74,68) of the modem (78) desires to send a data packet to another unit, the modem controller (104) causes the receiver (82) to listen for a certain pre-burst period and then causes the transmitter to send a burst of RF carrier out on the line and simultaneously causes the receiver (82) to listen to the line for interference beating i.e. changes in amplitude on the line which indicates another unit is requesting the line. To insure beat patterns, the frequency of the burst carrier is swept over a range during the burst. If a contention is found, a resolution thereof is made utilizing a random delay and retry protocol. After the burst, the controller causes the receiver (82) to listen to the line for other carriers. If none are found, the controller (104) causes the transmitter (78) to transmit a data packet preceded by a preamble (115) of 100% modulation level RF carrier. During the preamble period, all receivers (82) in the system set their respective automatic gain control levels to a level for comfortable reception. The gain level so established depends upon the strength of the received signal. This amplification level is maintained throughout the entire data packet. There is also disclosed herein a data link controller (530) and an interface specification for a generic class of network interface modems (78), one of which is disclosed herein for a client data processing unit for use in a data communications network. The specific modem (78) described herein is for use in a broadband local area data network with collision avoidance protocol. The data link controller (530) features hardware acknowledge circuitry (Figure 19) that acknowledges the receipt of a perfect data packet immediately upon receipt thereof without request to or assistance by the client data processing unit. The DLC (530) prepares the acknowledgment packet from the incoming data packet and places it on the data link without going through a line acquisition protocol. Each received acknowledgment packet is placed in a transmit buffer (571) at a known location relative to the data packet which was just transmitted, for which it is an acknowledgment so that each acknowledgment packet may be located in less time by the client data processing unit. The acknowledgment packets are logically part of the transmit process and are therefore placed in the transmit buffer.
Inventors
- 👤 Michael S. Friedman
- 👤 Kenneth D. Thomas
- 👤 Philip T. Chan
- 👤 Royce Earle Slick
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 08:17
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/12; H04L1/16; H04L1/18; H04L1/1867; H04L1/1874; H04L12/00; H04L12/28; H04L12/2801; H04L1/1829; H04L1/1848
Claims Analysis
Total Claims: 75
Claim 1
Independent Claim
99 words
A communications interface for a client data processing unit (51'6,514) that sends and receives data packets to and from other data processing units over a common data link ('64) comprising: a data link controller (530) for generating an acknowledgment packet from each incoming data packet directed to said client data processing unit (516,514); and a modem (78,104) for receiving said incoming data packet and for transmitting outgoing data packets after performing a link acquisition protocol and for transmitting said acknowledgment packet within a predetermined period after the end of said incoming data packet without performing said line acquisition protocol.
Claim 2
Dependent Claim
99 words
A communications interface for a client data processing unit (51'6,514) that sends and receives data packets to and from other data processing units over a common data link ('64) comprising: a data link controller (530) for generating an acknowledgment packet from each incoming data packet directed to said client data processing unit (516,514); and a modem (78,104) for receiving said incoming data packet and for transmitting outgoing data packets after performing a link acquisition protocol and for transmitting said acknowledgment packet within a predetermined period after the end of said incoming data packet without performing said line acquisition protocol.
Claim 3
Dependent Claim
75 words
A communications interface for a client data processing unit (51'6,514) that sends and receives data packets to and from other data processing units over a common data link (64) comprising: Acknowledgment circuits (Fig. 19) in said communications interface for generating an acknowledgment packet from incoming data packets directed to said client data processing unit (516,514); and a modem (78,104) for transmitting said acknowledgment packet to the data processing unit which sent said incoming data packet.
Claim 4
Dependent Claim
75 words
A communications interface for a client data processing unit (51'6,514) that sends and receives data packets to and from other data processing units over a common data link (64) comprising: Acknowledgment circuits (Fig. 19) in said communications interface for generating an acknowledgment packet from incoming data packets directed to said client data processing unit (516,514); and a modem (78,104) for transmitting said acknowledgment packet to the data processing unit which sent said incoming data packet.
Claim 5
Dependent Claim
61 words
An apparatus as defined in Claim 2 wherein said acknowledgment circuits (Fig. 19) include an acknowledgment and data sequencer (654), a transmit executive machine (650), a status register (670), a control register (668) and a modem control interface (68'6) for causing said transmitting means to send said acknowledgment packet within a predetermined time after the end of said incoming data packet.
Claim 6
Dependent Claim
46 words
An apparatus as defined in Claim 1 or 2 or 3 wherein said acknowledgment circuits (Fig. 19) includes circuits ( 72'6, 738,'654) to cause said modem (78,104) to transmit delimiting flags on both ends of data packets supplied by said client data processing unit for transmission.
Claim 7
Dependent Claim
29 words
An apparatus as defined in Claim 1 or 2 or 3 wherein said data link controller (530) includes circuits (784) for checking the accuracy of said incoming data packet.
Claim 8
Dependent Claim
39 words
'6. An apparatus as defined in Claim 5 wherein said data link controller (530) includes circuits (900,670,994) to signal said client data processing unit when a perfect data packet directed to said client data processing unit has been received.
Claim 9
Dependent Claim
41 words
An apparatus as defined in Claim 1 or 2 or 3 wherein said data link controller (530) includes circuits ( ' 650, ' 654, 726,738) to cause said model (78,104) to transmit delimiting flags on both ends of said acknowledgment packet.
Claim 10
Dependent Claim
43 words
An apparatus as defined in Claim 1 or 2 or 3 wherein said data link controller (530) includes a transmit buffer (571) for storing data packets to be transmitted in a queue and a FIFO receive buffer (571) for storing incoming data packets.
Claim 11
Dependent Claim
67 words
An apparatus as defined in Claim 8 wherein said data link controller (530) includes circuits (640,644,546,686,682,644) for taking a data packet from said transmit buffer (571) for transmission to another data processing unit and for placing the acknowledgment packet received in response to this data packet transmission in said transmit buffer (571) at a known location relative to the data packet to which the acknowledgment packet corresponds.
Claim 12
Dependent Claim
39 words
An apparatus as defined in Claim 5 wherein said data link controller (530) includes circuits (670,900,784) responsive to said checking circuits (784) to prevent the transmission of said acknowledgment packet if said incoming data packet is not received perfectly.
Claim 13
Dependent Claim
54 words
An apparatus as defined in Claim 5 wherein said data link controller (530) includes circuits ('654,830, 722,836,942) for generating an acknowledgment code for transmission in said acknowledgment packet which indicates in a first state that said data packet was perfectly received and in a second state that the sending unit must retry the transmission.
Claim 14
Dependent Claim
43 words
An apparatus as defined in Claim 11 wherein said acknowledgment code generating circuits ('654,830,722,836,942) generates different acknowledgment codes for indicating that a retry is necessary, each said code indicating that a different predetermined delay period should be imposed prior to retrying the transmission.
Claim 15
Dependent Claim
45 words
An apparatus as defined in Claim 1 or 2 or 3 wherein said data link controller (530) generates error check data from the data packets to be transmitted and transmits said error check data (542) with the data packet (524) from which it was generated.
Claim 16
Dependent Claim
106 words
A communications interface for a client data processing unit (514) that sends and receives data packets to and from other data processing units (515) over a common data link (64) comprising: circuits (571) for storing data packets to be sent to other units on said common link (64); circuits (530,78,104) for transmitting said stored data packets to said other units on said common link (64); circuits (530,78,104) for receiving an acknowledgment packet for a data packet sent to another unit; circuits ('640,'664,54'6,'68'6,'682,'6'64) for storing said received acknowledgment packet in said storing means (571) in a known location relative to the data packet to which it corresponds.
Claim 17
Dependent Claim
106 words
A communications interface for a client data processing unit (514) that sends and receives data packets to and from other data processing units (515) over a common data link (64) comprising: circuits (571) for storing data packets to be sent to other units on said common link (64); circuits (530,78,104) for transmitting said stored data packets to said other units on said common link (64); circuits (530,78,104) for receiving an acknowledgment packet for a data packet sent to another unit; circuits ('640,'664,54'6,'68'6,'682,'6'64) for storing said received acknowledgment packet in said storing means (571) in a known location relative to the data packet to which it corresponds.
Claim 18
Dependent Claim
121 words
A communications interface for a client data processing unit that sends and receives data packets to and from other data processing units over a common data link comprising: circuits for receiving incoming data packets addressed to said client data processing unit; circuits for checking the accuracy of said incoming data packets; circuits for signalling said client data processor that a data packet addressed to it has arrived when said incoming data packet has been received perfectly; and circuits for reserving said common data link for a time after reception of said data packet such that an acknowledgment packet can be prepared and transmitted to the sending unit without the need for acquiring said common data link through a line acquisition protocol.
Claim 19
Dependent Claim
121 words
A communications interface for a client data processing unit that sends and receives data packets to and from other data processing units over a common data link comprising: circuits for receiving incoming data packets addressed to said client data processing unit; circuits for checking the accuracy of said incoming data packets; circuits for signalling said client data processor that a data packet addressed to it has arrived when said incoming data packet has been received perfectly; and circuits for reserving said common data link for a time after reception of said data packet such that an acknowledgment packet can be prepared and transmitted to the sending unit without the need for acquiring said common data link through a line acquisition protocol.
Claim 20
Dependent Claim
109 words
1 ' 6. A method for transmitting and receiving data on a data network comprised of a plurality of data processing units, each with a communications interface coupled to a data link, said method comprising the steps of: obtaining exclusive use of said data network for one of said data processing units needing to send data to another of said data processing units by performing a link acquisition protocol; transmitting a data packet to said other data processing unit on said network; transmitting acknowledgment data from said other data processing unit to said transmitting unit immediately after receipt of said data packet without going through said link acquisition protocol.
Claim 21
Dependent Claim
109 words
1 ' 6. A method for transmitting and receiving data on a data network comprised of a plurality of data processing units, each with a communications interface coupled to a data link, said method comprising the steps of: obtaining exclusive use of said data network for one of said data processing units needing to send data to another of said data processing units by performing a link acquisition protocol; transmitting a data packet to said other data processing unit on said network; transmitting acknowledgment data from said other data processing unit to said transmitting unit immediately after receipt of said data packet without going through said link acquisition protocol.
Claim 22
Dependent Claim
30 words
The method of Claim 1'6 wherein the step of sending acknowledgment data further comprises the step of preparing the acknowledgment data in said communications interface from the received data packet.
Claim 23
Dependent Claim
39 words
The method of Claim 17 wherein the step of preparing said acknowledgment data includes the steps of: checking the incoming data packet to determine if it was perfectly received; and sending said acknowledgment data if it was perfectly received.
Claim 24
Dependent Claim
88 words
The method of Claim 17 wherein the step of preparing said acknowledgment data includes the steps of: checking the incoming data packet to determine if it was perfectly received; checking to determine whether said communications interface was able to successfully store the incoming data packet for use by the receiving data processing unit; and generating and sending a code in said acknowledgment packet so as to indicate either that the incoming data was perfectly received and successfully stored or that the sending communications interface should retry the transmission.
Claim 25
Dependent Claim
32 words
The method of Claim 16 or 17 or 18 or 19 wherein the step of transmitting said data packet includes the step of transmitting unique flag data to delimit said data packet.
Claim 26
Dependent Claim
31 words
The method of Claim 1'6 or 17 or 18 or 19 wherein the step of transmitting acknowledgment data includes the step of transmitting unique flag data to delimit said acknowledgment data.
Claim 27
Dependent Claim
53 words
The method of Claim 1'6 or 17 or 18 or 19, further comprising the step of placing the acknowledgment packet received by the data processing unit which transmitted the data packet in a transmit buffer at a known location relative to the location of said data packet to which said acknowledgment packet corresponds.
Claim 28
Dependent Claim
52 words
A method as described in Claim 1'6 or 17 or 18 or 19 wherein said acknowledgment data includes as a source address the address of the data processing unit that received the data packet and includes as a destination address the address of the data processing unit which transmitted the data packet.
Claim 29
Dependent Claim
27 words
A method as described in Claim 23 wherein said acknowledgment data includes error check data which allows the accuracy of the acknowledgment data itself to be checked.
Claim 30
Dependent Claim
83 words
A data link controller for a communications interface of a client data processing unit coupled to a data communications network coupled to other data processing units, comprising: means for detecting properly addressed incoming data and acknowledgment packets and for storing them for the use of said data processing unit; means for automatically preparing acknowledgment data from said incoming data packet for transmission to the source unit which sent the incoming data packet without interaction with or request by said client data processing unit.
Claim 31
Dependent Claim
83 words
A data link controller for a communications interface of a client data processing unit coupled to a data communications network coupled to other data processing units, comprising: means for detecting properly addressed incoming data and acknowledgment packets and for storing them for the use of said data processing unit; means for automatically preparing acknowledgment data from said incoming data packet for transmission to the source unit which sent the incoming data packet without interaction with or request by said client data processing unit.
Claim 32
Dependent Claim
59 words
2'6. An apparatus as defined in Claim 25 wherein said means for automatically preparing acknowledgment data includes means for selecting the destination address of the incoming data packet for use as the source address of the acknowledgment data and for selecting the source address of the incoming data packet for use as the destination address of the acknowledgment data.
Claim 33
Dependent Claim
58 words
An apparatus as defined in Claim 25 wherein said means for automatically preparing acknowledgment data includes means to generate error check data for said acknowledgment data and include said error check data with said acknowledgment data for use by the data link controller that transmitted the data pakcet to determine whether it has properly received the acknowledgment data.
Claim 34
Dependent Claim
78 words
An apparatus as defined in Claim 25 wherein said means for automatically preparing acknowledgment data includes means for detecting when said data packet has not been correctly received, and when the data packet has been properly received but there has not been enough storage capacity in said data link controller to store said incoming data packet, and to generate a code indicating when either of these conditions has occurred, and to include said code in said acknowledgment data.
Claim 35
Dependent Claim
39 words
An apparatus as defined in Claim 28 further comprising means for detecting when the data has been received properly but is not to be stored, and for generating a code so indicating and including it in said acknowledgment data.
Claim 36
Dependent Claim
68 words
An apparatus as defined in Claim 25, further comprising: means for storing said incoming data packets addressed to said client data processing unit for first-in/first-out utilization by said client data processing unit; means for determining the status of said storage means; and means for generating a code indicating when said storage means is full; and means for preventing storage of incoming data when said storage means is full.
Claim 37
Dependent Claim
18 words
An apparatus as defined in Claim 30, further comprising means for including said code in said acknowledgment data.
Claim 38
Dependent Claim
39 words
An apparatus as defined in Claim 25 or 2'6 or 27 or 28 or 29 or 30 or 31 further comprising: means for preventing the transmission of said acknowledgment data if said incoming data packet was not received perfectly.
Claim 39
Dependent Claim
71 words
An apparatus as defined in Claim 25 or 2'6 or 27 or 28 or 29 or 30 or 31 or 32, further comprising: transmission buffer means for storing data packets from said client data processing unit for transmission to other data processing units in said local area data network; and means for preparing said data packets for transmission by adding unique flag data which delimits the boundaries of said data packets.
Claim 40
Dependent Claim
41 words
An apparatus as defined in Claim 25 or 26 or 27 or 28 or 29 or 30 or 31, further comprising means for preparing said acknowledgment data for transmission by adding flag data to delimit the boundaries of said acknowledgment data.
Claim 41
Dependent Claim
47 words
An apparatus as defined in Claim 33, further comprising means for placing incoming acknowledgment data from other data processing units to which data packets have been sent in said transmission buffer means at a known location relative to said data packet to which said acknowledgment data corresponds.
Claim 42
Dependent Claim
79 words
3'6. A communication interface for interfacing a client data processing unit to a data network comprising: means for performing a link acquisition protocol for establishing a communication data link between said client data processing unit and another data processing unit on said network; and means for reserving said data network for use by said other data processing unit in sending a communication back to said client data processing unit without the need to go through another link acquisition protocol.
Claim 43
Dependent Claim
79 words
3'6. A communication interface for interfacing a client data processing unit to a data network comprising: means for performing a link acquisition protocol for establishing a communication data link between said client data processing unit and another data processing unit on said network; and means for reserving said data network for use by said other data processing unit in sending a communication back to said client data processing unit without the need to go through another link acquisition protocol.
Claim 44
Independent Claim
68 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: a circuit for transmitting a non data bearing burst of energy; a circuit for receiving signals on said transmission medium; and a circuit for preventing data transmission in response to detection by said receiving means of energy from any other modem.
Claim 45
Independent Claim
68 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: a circuit for transmitting a non data bearing burst of energy; a circuit for receiving signals on said transmission medium; and a circuit for preventing data transmission in response to detection by said receiving means of energy from any other modem.
Claim 46
Dependent Claim
17 words
An apparatus as defined in Claim 37 further comprising means for varying the frequency of said burst.
Claim 47
Independent Claim
99 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems comprising: a circuit for transmitting a non data bearing burst of waveform with a frequency that varies during the burst; a circuit for receiving signals on said transmission medium and detecting amplitude changes on said transmission media caused by interference beating between the signals from two or more transmitters contending for the transmission media; and a circuit for detecting the presence of any signal on said transmission medium during a predetermined post burst listening period.
Claim 48
Independent Claim
99 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems comprising: a circuit for transmitting a non data bearing burst of waveform with a frequency that varies during the burst; a circuit for receiving signals on said transmission medium and detecting amplitude changes on said transmission media caused by interference beating between the signals from two or more transmitters contending for the transmission media; and a circuit for detecting the presence of any signal on said transmission medium during a predetermined post burst listening period.
Claim 49
Dependent Claim
27 words
An apparatus as defined in Claim 37 or 38 or 39 wherein said non data bearing burst is a sinusoidal radio frequency carrier having a fixed amplitude.
Claim 50
Dependent Claim
143 words
An apparatus as defined in Claim 40 wherein said receiving a circuit include: a variable gain receiver coupled to said transmission medium to receive carrier energy and amplify it in accordance with said variable gain; a demodulator for converting the received signal into a D.C. signal which has an amplitude which varies with the amplitude of the output from said variable gain receiver; a comparator for comparing the output signal of said demodulator to a reference signal during said burst and for generating a contention signal when said D.C, signal achieves a predetermined relationship to said reference signal; and a circuit for setting the gain of said variable gain receiver to a predetermined level during bursting such that said comparator means will not generate said contention signal unless interference beating with another carrier is causing the amplitude of the received signal to vary.
Claim 51
Dependent Claim
57 words
An apparatus as defined in Claim 41 further including a controller coupled to said transmitting circuit and said detecting circuit to cause said transmitting circuit to transmit said burst while simultaneously causing said gain setting circuit to set the gain of said variable gain receiver at the predetermined level to detect interference beating on said transmission medium.
Claim 52
Dependent Claim
59 words
An apparatus as defined in Claim 42 wherein said controller also is coupled to said comparator and causes said gain setting circuit to set the gain of said receiver circuit to a second predetermined level during said post burst listening period and monitors the output of said comparator to determine if a signal is present on said transmission media.
Claim 53
Dependent Claim
51 words
An apparatus as defined in Claim 37 or 38 or 39 further comprising a circuit for controlling the delay imposed before a retry to transmit is initiated by generation of a random number which determines the delay, said randum number being generated by the randomness of the interference beat pattern itself.
Claim 54
Dependent Claim
41 words
An apparatus as defined in Claim 37 or 38 or 39 or 40 wherein each transmitter and receiver modem in the data network both transmits data to the other modems and receives data from the other modems on a single frequency.
Claim 55
Dependent Claim
24 words
4'6. An apparatus as defined in Claim 45 wherein each section of each modem receives data from the transmitter circuit in its own modem.
Claim 56
Dependent Claim
53 words
An apparatus as defined in Claim 46 further comprising a circuit for automatically adjusting the gain of the receiver circuit of each modem in the data network to a predetermined level during an unmodulated preamble signal preceding each transmitted data packet and holding that level constant during receipt of the entire data packet.
Claim 57
Dependent Claim
53 words
A local data network comprising: a transmission medium; and a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said freqency being the same for each transceiver.
Claim 58
Dependent Claim
53 words
A local data network comprising: a transmission medium; and a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said freqency being the same for each transceiver.
Claim 59
Dependent Claim
69 words
An apparatus as defined in Claim 48 further comprising a circuit in each transceiver for avoiding contentions for said transmission medium by two or more transceivers attempting to simultaneously transmit, comprising: a circuit for transmitting a non data bearing burst of carrier by each transceiver desiring to send data prior to sending said data; and a circuit for listening for interference with any other signal on said transmission medium.
Claim 60
Dependent Claim
32 words
An apparatus as defined in Claim 49 further comprising a circuit in each transceiver for detecting contentions for said transmission medium by listening for any signal on said medium after said burst.
Claim 61
Dependent Claim
45 words
Apparatus as defined in Claim 49 or 50 further comprising a circuit for controlling the time delay before another attempt to transmit is made by generating a random number and using said randum number to determine the amount of delay before again attempting to transmit.
Claim 62
Dependent Claim
52 words
An apparatus as defined in Claim 51 further comprising a circuit for transmitting a non data bearing preamble preceding each data packet and means for adjusting the gain of each transceiver for effective reception during said preamble and holding said gain for each transceiver constant during reception of the corresponding data packet.
Claim 63
Dependent Claim
41 words
An apparatus as defined in Claim 49 or 50 further comprising a circuit for altering the frequency of said burst carrier during said burst and means for detecting contentions by detecting amplitude changes on said transmission medium caused by interference beating.
Claim 64
Independent Claim
178 words
A method of transmitting packets of digital data using a plurality of transmitters each of which outputs an amplitude modulated radio frequency carrier having the same frequency on a single transmission medium coupled to a plurality of receivers which each have passbands encompassing the frequency of carrier said transmitters output, said method comprising the steps of: (a) listening to said transmission medium in order to detect the presence of conflicting carrier thereon for a predetermined period after the termination of the previous packet; (b) transmitting an access burst of carrier on said transmission medium for a predetermined period after said previous listening period; (c) listening to said bus line during the transmission of said access burst in order to detect the presence of conflicting carriers on said transmission medium during said access burst; (d) listening to said transmission medium in order to detect the presence of carrier thereon for a predetermined period after said access burst; and (e) transmitting a data packet on said transmission medium if no conflicting carrier was detected during steps (a), (c), and (d).
Claim 65
Independent Claim
178 words
A method of transmitting packets of digital data using a plurality of transmitters each of which outputs an amplitude modulated radio frequency carrier having the same frequency on a single transmission medium coupled to a plurality of receivers which each have passbands encompassing the frequency of carrier said transmitters output, said method comprising the steps of: (a) listening to said transmission medium in order to detect the presence of conflicting carrier thereon for a predetermined period after the termination of the previous packet; (b) transmitting an access burst of carrier on said transmission medium for a predetermined period after said previous listening period; (c) listening to said bus line during the transmission of said access burst in order to detect the presence of conflicting carriers on said transmission medium during said access burst; (d) listening to said transmission medium in order to detect the presence of carrier thereon for a predetermined period after said access burst; and (e) transmitting a data packet on said transmission medium if no conflicting carrier was detected during steps (a), (c), and (d).
Claim 66
Dependent Claim
55 words
The method of claim 54 further including the step of: (f) delaying another. attempt to transmit a data packet for a random time period after step (d) if (a) conflicting carrier was detected during steps (a), (c) and (d), said transmission access being retried by repeating the method steps by beginning again with step (a).
Claim 67
Dependent Claim
41 words
The method of claim 55 wherein step (b) includes changing the frequency of carrier during said access burst so that if two or more carriers are present on the bus line simultaneously, interference beating will be produced between the conflicting carriers.
Claim 68
Dependent Claim
54 words
The method of claim 5'6 further comprising the step: (g) detecting the presence of amplitude pulses produced due to said interference beating during step (b), so that the time of occurrence of said amplitude pulses provides a randomizing function for controlling the minimum time delay before transmission of an access burst may be retried.
Claim 69
Independent Claim
74 words
A method of receiving packets of digital data on an amplitude modulated radio frequency carrier bus line, said method comprising the steps of: (a) listening to the transmission medium for a packet preamble in order to sample the preamble and establish a receive amplification level corresponding to the strength of the preamble signal; and (b) listening to the transmission medium after said preamble and holding the receive amplification level established during said preamble constant.
Claim 70
Independent Claim
74 words
A method of receiving packets of digital data on an amplitude modulated radio frequency carrier bus line, said method comprising the steps of: (a) listening to the transmission medium for a packet preamble in order to sample the preamble and establish a receive amplification level corresponding to the strength of the preamble signal; and (b) listening to the transmission medium after said preamble and holding the receive amplification level established during said preamble constant.
Claim 71
Independent Claim
51 words
A method of avoiding contentions in transmitting packets of digital data on a broadband local data network comprising: transmitting a non data bearing burst of waveform; varying the frequency of the waveform during the burst; and listening for amplitude changes caused by interference beating between the transmitted burst and other signals.
Claim 72
Independent Claim
51 words
A method of avoiding contentions in transmitting packets of digital data on a broadband local data network comprising: transmitting a non data bearing burst of waveform; varying the frequency of the waveform during the burst; and listening for amplitude changes caused by interference beating between the transmitted burst and other signals.
Claim 73
Dependent Claim
27 words
' 60. The method of Claim 59 further comprising listening during a post burst period for the presence of any other signal present on the transmission media.
Claim 74
Dependent Claim
39 words
'61. A method as defined in Claim '60 further comprising generating a random number from the randomness of the interference beat pattern itself and waiting a time determined by the random number so generated before attempting to transmit again.
Claim 75
Dependent Claim
63 words
A method as defined in Claim 61 further comprising transmitting a data packet with an unmodulated preamble portion prior to transmitting each data packet and automatically adjusting the gain of each receiver in the system during said preamble according to the strength of its incoming signal and holding the gain levels so established constant during receipt of the data packet following the preamble.
References Cited (Backward Citations)
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