Channelized binary-level radiometer

Claim 2

A detector for sensing the presence of a frequency-hopped signal comprising in combination: (a) means for channelizing a frequency-hopped input signal into a plurality of channels having separate and individual frequency bands; (b) amplification-quantization means, connected in each channel for detecting the power level of the frequency signals present in that band and quantizing said power level to a binary signal; (c) first connection means for connecting the outputs of one-half of the channels into a first totalizing circuit means; (d) second connection means for connecting the second half of said channels into a second totalizing circuit means; (e) combining means for subtracting the totalized output of said second totalizing means from the output of said first totalizing means; (f) means for providing a DC output voltage which indicates the presence of a frequency-hopped signal being transmitted.

Claim 3

The detector of claim 1 wherein said means for channelizing includes: (2a1) a plurality of band pass filters wherein each filter passes a sub-band W/L of frequencies where L is the number of sub-bands and W is the total band width utilized; said band pass filters providing separate signal channels which are divided into an upper group and a lower group of channels.

Claim 4

The detector of claim 1 wherein said amplification-quantization means includes: (3b2) squaring circuit means in each channel for multiplying the signal in that individual channel by itself to estimate the power value in each channel to provide an output to a first threshold detector unit; (3b2) quantization means which includes a plurality of threshold detectors wherein a threshold detector unit for each channel compares the signal in that channel to a present threshold voltage value, V x , so that when the signal value exceeds V x , a positive voltage is generated.

Claim 5

The detector of claim 1 wherein said first and second totalizing means respectively includes: (4c1) said first totalizing circuit means for adding together the signal outputs from said upper one-half of channels; (4d2) said second totalizing circuit means for adding together the signal outputs from said lower one-half of channels.

Claim 6

The detector of claim 1 wherein said combining means includes: (5e1) a differential amplifier for receiving the totalized added signal outputs from said first and second totalizing circuit means and for providing a first stage output signal representing the difference between said first and second totalized signal outputs.

Claim 7

The detector of claim 1 wherein said means for providing said DC output voltage, indicating the presence of the frequency hopped signal, includes: (6f1) a first low-pass filter having a band width B equal to 1/T h where T h is the hop-dwell time period; (6f2) a power squaring circuit for multiplying the output of said first low-pass filter; (6f3) a second low-pass filter for filtering the output of said power squaring circuit to develop a discrete DC voltage output signifying the presence of, or a zero voltage signifying the absence of the frequency-hopped signal.

Claim 8

The combination of claim 1 wherein said means for providing a DC output voltage includes: (a) a first low-pass filter means having a band width approximately equal to 1/T h where T h represents the hop dwell period of the frequency-hopped input signal; (b) a magnitude squaring circuit for power detecting the output of said first low pass filter means and providing an output to a second low pass filter means; (c) said second low pass filter means for matching the DC output voltage signal from said magnitude squaring circuit in order to compare it against a second preset threshold to determine whether a frequency-hopped signal transmission is present rather than mere noise.

Claim 9

Apparatus for sensing presence/absence of a frequency-hopped signal comprising in combination: (a) means for receiving a wide band of frequencies covering a transmitted frequency-hopped sequence of signals; (b) means for channelizing said wide band into a plurality of sub-bands; (c) means for squaring, in power magnitude, the output signals of each of said sub-bands; (d) means for quantizing the varying signals of each sub-band in order to provide a binary level representation for each channel, wherein presence of the frequency-hopped signal produces a positive voltage output, and absence of the frequency-hopped signal produces a zero voltage output; (e) means for connecting said channelizing means into an upper set of sub-bands and a lower set of sub-bands; (f) means for totalizing the sum of the first group of sub-bands and the sum of the second group of sub-bands using first and second totalized sums; (g) means for subtracting the said second totalized sum from the first totalized sum to provide a first stage output; (h) means for conditioning the said first stage output of said totalizing means to provide a DC voltage output signal signifying the presence of a frequency-hopped input signal, or a zero output signifying absence of the frequency-hopped signal.

Claim 10

Apparatus for sensing presence/absence of a frequency-hopped signal comprising in combination: (a) means for receiving a wide band of frequencies covering a transmitted frequency-hopped sequence of signals; (b) means for channelizing said wide band into a plurality of sub-bands; (c) means for squaring, in power magnitude, the output signals of each of said sub-bands; (d) means for quantizing the varying signals of each sub-band in order to provide a binary level representation for each channel, wherein presence of the frequency-hopped signal produces a positive voltage output, and absence of the frequency-hopped signal produces a zero voltage output; (e) means for connecting said channelizing means into an upper set of sub-bands and a lower set of sub-bands; (f) means for totalizing the sum of the first group of sub-bands and the sum of the second group of sub-bands using first and second totalized sums; (g) means for subtracting the said second totalized sum from the first totalized sum to provide a first stage output; (h) means for conditioning the said first stage output of said totalizing means to provide a DC voltage output signal signifying the presence of a frequency-hopped input signal, or a zero output signifying absence of the frequency-hopped signal.

Claim 11

The apparatus of claim 8 wherein said means for channelizing includes: (8b1) a plurality of L band-pass filters which span the utilized frequency band W and which function to apportion sub-bands of frequency into each of channels.

Claim 14

A detector for sensing the presence of a frequency-hopped signal comprising in combination: (a) means for sorting said frequency-hopped signal through a plurality of channels having separate ranges of frequency bands; (b) means for detecting the power level of the sub-signal in each channel and quantifying it to a binary level signal to generate a channel output signal; (c) means for totalizing said channel output signals of the upper half of said channels to generate a first totalized sum; (d) means for totalizing said channel output signals of the lower half of said channels to generate a second totalized sum; (e) means for deriving a final output signal, from said first and second totalized sums, which indicates the presence or absence of said frequency-hopped signal.

Claim 15

A detector for sensing the presence of a frequency-hopped signal comprising in combination: (a) means for sorting said frequency-hopped signal through a plurality of channels having separate ranges of frequency bands; (b) means for detecting the power level of the sub-signal in each channel and quantifying it to a binary level signal to generate a channel output signal; (c) means for totalizing said channel output signals of the upper half of said channels to generate a first totalized sum; (d) means for totalizing said channel output signals of the lower half of said channels to generate a second totalized sum; (e) means for deriving a final output signal, from said first and second totalized sums, which indicates the presence or absence of said frequency-hopped signal.