Systems and method for frequency based satellite channel scanning
First Claim
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1. A method for frequency based channel scanning comprising:
- placing a demodulator in a power scanning mode;
scanning a frequency spectrum to obtain power samples at a plurality of frequencies;
comparing the power samples to a threshold power to detect a channel, wherein the detected channel comprises a flat area, a left point of inflection, and a right point of inflection;
performing channel extraction once the channel is detected; and
obtaining a coarse estimate of the channel parameters associated with the detected channel, wherein obtaining the coarse estimate comprises measuring power at three separate frequencies for the left point of inflection for the channel.
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Abstract
A satellite signal demodulator is configured to use frequency-based channel scanning to sense the presence of a channel and to obtain the frequency profile of the channel. Once the channel is identified and the profile is obtained, channel extraction is used to identify the frequency parameters for a given channel. A coarse parameter estimation is performed to obtain a coarse estimate of the symbol rate (SR) and the center frequency (fc) of the channel. The coarse estimation can then be followed by a fine estimation of the symbol rate and center frequency (fc), using a bit tracking loop (BTL) lock indicator.
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Citations
18 Claims
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1. A method for frequency based channel scanning comprising:
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placing a demodulator in a power scanning mode; scanning a frequency spectrum to obtain power samples at a plurality of frequencies; comparing the power samples to a threshold power to detect a channel, wherein the detected channel comprises a flat area, a left point of inflection, and a right point of inflection; performing channel extraction once the channel is detected; and obtaining a coarse estimate of the channel parameters associated with the detected channel, wherein obtaining the coarse estimate comprises measuring power at three separate frequencies for the left point of inflection for the channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A receiver configured to act in a power scanning mode, comprising:
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a demodulator configured to receive a satellite signal; a power measurement circuit configured to determine frequency and power information for signals received by the demodulator and to compare the power information to a threshold power; and a processor configured to control the demodulator and the power measurement circuit and to determine signal rate and channel center frequency parameters based on the frequency and power information determined by the power measurement circuit if the power information is equal to or greater than the threshold power, to place the demodulator in a power scanning mode, to scan a frequency spectrum to obtain power samples at a plurality of frequencies until a channel is detected by comparing the power samples to the threshold power, to perform channel extraction once the channel is detected, and to obtain a coarse estimate of the channel parameters associated with the detected channel, wherein the detected channel comprise a flat area, a left point of inflection, and a right point of inflection, and wherein obtaining the coarse estimate comprises measuring power at three separate frequencies for the left point of inflection for the channel.
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13. The receiver of
FIG. 12 , wherein the demodulator comprises a matched filter, and wherein the processor is configured to place the demodulator in the power scanning mode by controlling the operation of the matched filter.
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18. A receiver configured to act in a power scanning mode, comprising:
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a demodulator configured to receive a satellite signal; a power measurement circuit configured to determine frequency and power information for signals received by the demodulator; and a processor configured to place the demodulator in a power scanning mode, to scan the frequency spectrum to obtain power samples at a plurality of frequencies, until a channel is detected by comparing the power samples to a threshold power, to perform channel extraction once a channel is detected, and to obtain a coarse estimate of the channel parameters associated with the detected channel, wherein the detected channel comprises a flat area, a left point of inflection, and a right point of inflection, and wherein obtaining the coarse estimate comprises measuring power at three separate frequencies for the left point of inflection for the channel.
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Specification