US5327581A — Method and apparatus for maintaining synchronizat…

Claim 1

Independent Claim 242 words

A simulcast system having a transmitter controller capable of synchronizing and maintaining synchronization of a plurality of base sites coupled to the transmitter controller, the plurality of base sites having transmitters capable of transmitting data as radio frequency transmission at substantially the same time, said transmitter controller comprising: means for generating time marks at predetermined time periods; means, coupled to the means for generating, for dividing the data into predetermined packets to be interposed between at least a pair of time marks; means, coupled to the means for dividing, for transmitting the data packets and time marks to the plurality of base sites; the base sites comprising: means for receiving the data packets and time marks; means, coupled to the means for receiving, for measuring the time between pairs of time marks; means, coupled to the means for measuring, for determining when there are variations in time between pairs of time marks and the predetermined time periods; means, coupled to the means for determining, for adjusting a delay time at each of the plurality of base sites in response to variation in time between time marks at the corresponding base site; and means, coupled to the means for adjusting, for delaying retransmission of data from a receipt of a start command by a predetermined delay time determined for each of the plurality of base sites to enable a retransmission of data at substantially the same time by the plurality of base sites.

Claim 2

Dependent Claim 242 words

A simulcast system having a transmitter controller capable of synchronizing and maintaining synchronization of a plurality of base sites coupled to the transmitter controller, the plurality of base sites having transmitters capable of transmitting data as radio frequency transmission at substantially the same time, said transmitter controller comprising: means for generating time marks at predetermined time periods; means, coupled to the means for generating, for dividing the data into predetermined packets to be interposed between at least a pair of time marks; means, coupled to the means for dividing, for transmitting the data packets and time marks to the plurality of base sites; the base sites comprising: means for receiving the data packets and time marks; means, coupled to the means for receiving, for measuring the time between pairs of time marks; means, coupled to the means for measuring, for determining when there are variations in time between pairs of time marks and the predetermined time periods; means, coupled to the means for determining, for adjusting a delay time at each of the plurality of base sites in response to variation in time between time marks at the corresponding base site; and means, coupled to the means for adjusting, for delaying retransmission of data from a receipt of a start command by a predetermined delay time determined for each of the plurality of base sites to enable a retransmission of data at substantially the same time by the plurality of base sites.

Claim 3

Dependent Claim 37 words

The simulcast system according to claim 1 wherein the means for transmitting the data comprises a modem capable transmitting the data at a speed faster than the transmission speed capable on a narrow band radio frequency channel.

Claim 4

Dependent Claim 38 words

The simulcast system according to claim 2 wherein the modem time-compresses the data before transmitting the data to the plurality of base sites and the plurality of base sites further including modems for decompressing the time-compressed received data.

Claim 5

Dependent Claim 40 words

The simulcast system according to claim 1 wherein the transmitting means includes a means for sorting a plurality of delay times to ensure that each of the plurality of base sites receives the delay time calculated for that base site.

Claim 6

Dependent Claim 40 words

The simulcast system according to claim 1 wherein a first time mark comprises a start-to-receive command for receiving data packets and a final time mark comprises the start command for initiating simulcast data transmission at the plurality of base sites.

Claim 7

Dependent Claim 18 words

The simulcast system according to claim 1 wherein a start-to-receive and the start command comprise predetermined time marks.

Claim 8

Dependent Claim 23 words

The simulcast system according to claim 1 wherein the transmitter controller comprises means for interposing the data packets between pairs of time marks.

Claim 9

Dependent Claim 33 words

The simulcast system according to claim 1 further comprising a means, coupled to the means for transmitting, for signifying when the last data packet is being transmitted to the plurality of base sites.

Claim 10

Dependent Claim 239 words

A simulcast system having a transmitter controller capable of synchronizing and maintaining synchronization of a plurality of base sites coupled to the transmitter controller, the plurality of base sites having transmitters capable of transmitting data as radio frequency transmission at substantially the same time, said transmitter controller comprising: generator for generating time marks at predetermined time periods; data divider, coupled to the generator, for dividing the data into predetermined packets to be interposed between at least a pair of time marks; transmitter, coupled to the data divider, for transmitting the data packets and time marks to the plurality of base sites; the base sites comprising: base site receivers for receiving the data packets and time marks; clocks, coupled to the base site receivers, for measuring the time between pairs of time marks; base sites controller, coupled to the clocks, for determining when there are variations in time between any pairs of time marks and the predetermined time periods; timer, coupled to the base sites controller, for adjusting a delay time at each of the plurality of base sites in response to a variation in time between time marks at the corresponding base site; and said timer for delaying retransmission of data from a receipt of a start command by a predetermined delay time determined for each of the plurality of base sites to enable a retransmission of data at substantially the same time by the plurality of base sites.

Claim 11

Dependent Claim 239 words

A simulcast system having a transmitter controller capable of synchronizing and maintaining synchronization of a plurality of base sites coupled to the transmitter controller, the plurality of base sites having transmitters capable of transmitting data as radio frequency transmission at substantially the same time, said transmitter controller comprising: generator for generating time marks at predetermined time periods; data divider, coupled to the generator, for dividing the data into predetermined packets to be interposed between at least a pair of time marks; transmitter, coupled to the data divider, for transmitting the data packets and time marks to the plurality of base sites; the base sites comprising: base site receivers for receiving the data packets and time marks; clocks, coupled to the base site receivers, for measuring the time between pairs of time marks; base sites controller, coupled to the clocks, for determining when there are variations in time between any pairs of time marks and the predetermined time periods; timer, coupled to the base sites controller, for adjusting a delay time at each of the plurality of base sites in response to a variation in time between time marks at the corresponding base site; and said timer for delaying retransmission of data from a receipt of a start command by a predetermined delay time determined for each of the plurality of base sites to enable a retransmission of data at substantially the same time by the plurality of base sites.

Claim 12

Independent Claim 205 words

A method for maintaining synchronization of data transmissions in a simulcast system, the simulcast system having a transmitter controller capable of synchronizing and maintaining synchronization of a plurality of base sites coupled to the transmitter controller, the plurality of base sites having transmitters capable of transmitting data as radio frequency transmission at substantially the same time, said method comprising the steps of: (a) generating time marks at a predetermined time periods; (b) dividing the data into predetermined packets to be interposed between at least a pair of time marks; (c) transmitting the data packets and time marks to the plurality of base sites; (d) periodically transmitting the data packets including the time marks to the plurality of base sites for determining variations in time to the plurality of base sites; (e) receiving the data packets and time marks by the plurality of base sites; (f) measuring the time between each consecutive pair of time marks; (g) determining when there are variations in time between pairs of time marks and the predetermined time period; and (h) adjusting for the difference in propagation delay of the respective base sites responsive to step (g) to compensate for variations in the propagation delays to the plurality of base sites.

Claim 13

Independent Claim 205 words

A method for maintaining synchronization of data transmissions in a simulcast system, the simulcast system having a transmitter controller capable of synchronizing and maintaining synchronization of a plurality of base sites coupled to the transmitter controller, the plurality of base sites having transmitters capable of transmitting data as radio frequency transmission at substantially the same time, said method comprising the steps of: (a) generating time marks at a predetermined time periods; (b) dividing the data into predetermined packets to be interposed between at least a pair of time marks; (c) transmitting the data packets and time marks to the plurality of base sites; (d) periodically transmitting the data packets including the time marks to the plurality of base sites for determining variations in time to the plurality of base sites; (e) receiving the data packets and time marks by the plurality of base sites; (f) measuring the time between each consecutive pair of time marks; (g) determining when there are variations in time between pairs of time marks and the predetermined time period; and (h) adjusting for the difference in propagation delay of the respective base sites responsive to step (g) to compensate for variations in the propagation delays to the plurality of base sites.

Claim 14

Dependent Claim 56 words

The method for maintaining synchronization according to claim 10 further including the step of delaying retransmission of data from the receipt of a start command by a predetermined delay time determined for each of the plurality of base sites to enable the retransmission of data at substantially the same time by the plurality of base sites.

Claim 15

Dependent Claim 33 words

The method for maintaining synchronization according to claim 10 wherein the step of transmitting transmits the data at a speed faster than the transmission speed capable on a narrow band radio frequency channel.

Claim 16

Dependent Claim 39 words

The method for maintaining synchronization according to claim 10 further comprises a step of compressing the data before transmitting to the plurality of base sites and the step of decompressing the received data at the plurality of base sites.

Claim 17

Dependent Claim 43 words

The method for maintaining synchronization according to claim 10 wherein the step of transmitting including a step of sorting a plurality of delay time to ensure that each of the plurality of base sites receives the delay time calculated for that base site.

Claim 18

Dependent Claim 46 words

The method for maintaining synchronization according to claim 10 wherein the step of transmitting transmits a first time marks a start-to-receive command for receiving data packets and a final time mark as a start command for initiating simulcast data transmission at the plurality of base sites.

Claim 19

Dependent Claim 35 words

The method for maintaining synchronization according to claim 10 wherein the step of determining further includes the step of averaging the delay time for adjusting the difference in time variations between pairs of time marks.

Claim 20

Dependent Claim 29 words

The method for maintaining synchronization according to claim 16 wherein the step of averaging includes the step of tracking the difference in time variations between pairs of time marks.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-07-04	1998-01-03	1998-07-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-07-04	2002-01-03	2002-07-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-07-04	2006-01-03	2006-07-05	$7700.00	Window Closed / Lapsed

Method and apparatus for maintaining synchronization in a simulcast system

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