DIGITAL RECEIVER PERFORMANCE IN THE PRESENCE OF IMAGE FREQUENCIES
First Claim
1. A method for receiving a message transmitted on one of a plurality of channels of a hop sequence of a multi-hop communication system, each channel having an associated frequency, and wherein when a message is transmitted on one channel of the hop sequence other channels of the sequence may exhibit images of the message, the method comprising the steps of:
- scanning the plurality of channels in the hop sequence;
determining for each of the scanned channels a value indicative of signal strength on the channel;
selecting one of the channels having a signal strength value that satisfies a threshold;
evaluating the selected channel in an attempt to detect a preamble of a message on that channel;
if the preamble is detected on the selected channel, tuning a receiver to a second channel in the hop sequence and evaluating the second channel in an attempt to detect the preamble on that second channel;
if no preamble is detected on the second channel, tuning the receiver back to the selected channel and receiving a remainder of the message on that selected channel; and
if the preamble is detected on the second channel, then maintaining the receiver tuned to the second channel and receiving the remainder of the message on that second channel.
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Accused Products
Abstract
A digital Radio Frequency (RF) receiver may exhibit image frequencies and these image frequencies may be mathematically related to the intermediate frequency (IF) that is utilized for transmission and reception. In accordance with an embodiment, channel switching may be performed to identify an appropriate receive frequency in the presence of image frequencies on other channels. In accordance with another embodiment, data on a receive channel is evaluated to determine whether the data is inverted, and then appropriate correction may be performed on subsequently received data.
9 Citations
18 Claims
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1. A method for receiving a message transmitted on one of a plurality of channels of a hop sequence of a multi-hop communication system, each channel having an associated frequency, and wherein when a message is transmitted on one channel of the hop sequence other channels of the sequence may exhibit images of the message, the method comprising the steps of:
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scanning the plurality of channels in the hop sequence; determining for each of the scanned channels a value indicative of signal strength on the channel; selecting one of the channels having a signal strength value that satisfies a threshold; evaluating the selected channel in an attempt to detect a preamble of a message on that channel; if the preamble is detected on the selected channel, tuning a receiver to a second channel in the hop sequence and evaluating the second channel in an attempt to detect the preamble on that second channel; if no preamble is detected on the second channel, tuning the receiver back to the selected channel and receiving a remainder of the message on that selected channel; and if the preamble is detected on the second channel, then maintaining the receiver tuned to the second channel and receiving the remainder of the message on that second channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for receiving a message transmitted on one of a plurality of channels of a hop sequence of a multi-hop communication system, wherein when a message is transmitted on one channel of the hop sequence other channels of the sequence may exhibit images of the message in which the bits of the message may be inverted, the method comprising the steps of:
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selecting one of the channels; detecting a preamble of a message on the selected channel; determining from a characteristic of the preamble that data of the message is inverted on the selected channel; and continuing to receive the data of the message on the selected channel but inverting the received data to recover the message. - View Dependent Claims (10)
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11. A receiver comprising:
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a processor; and memory coupled to the processor, the memory having stored thereon executable instructions that when executed by the processor cause the processor to effectuate operations comprising; scanning a plurality of channels in a hop sequence; determining for each of the scanned channels a value indicative of signal strength on the channel; selecting one of the channels having a signal strength value that satisfies a threshold; evaluating the selected channel in an attempt to detect a preamble of a message on that channel; if the preamble is detected on the selected channel, tuning the receiver to a second channel in the hop sequence and evaluating the second channel in an attempt to detect the preamble on that second channel; if no preamble is detected on the second channel, tuning the receiver back to the selected channel and receiving a remainder of the message on that selected channel; and if the preamble is detected on the second channel, then maintaining the receiver tuned to the second channel and receiving the remainder of the message on that second channel. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification