Reduction of aliasing distortion in sampled signals

Claim 3

The method of claim 1 in which said combining step comprises the steps of independently storing each new sample as it is taken and combining all of said samples upon taking the last one.

Claim 4

The method of claim 1 in which said combining step comprises the step of sequentially accumulating said samples.

Claim 5

In an apparatus for generating, at rate f, pulse amplitude modulation (PAM) samples corresponding to a continuous wave signal having a highest frequency of interest not exceeding f/2 said apparatus including a plurality of storage capacitors, the method of reducing aliasing distortion comprising the steps of: sampling said signal nf times per second where n is an integer greater than 1, and combining the n most recently taken samples f times per second to produce by each of such sample combinations one of the PAM samples.

Claim 6

In an apparatus for generating, at rate f, pulse amplitude modulation (PAM) samples corresponding to a continuous wave signal having a highest frequency of interest not exceeding f/2 said apparatus including a plurality of storage capacitors, the method of reducing aliasing distortion comprising the steps of: sampling said signal nf times per second where n is an integer greater than 1, and combining the n most recently taken samples f times per second to produce by each of such sample combinations one of the PAM samples.

Claim 7

The method of claim 4 in which said combining step comprises the steps of: storing each of n samples on a different one of said capacitors, and momentarily connecting all of said capacitors in shunt f times per second to produce a composite sample having an amplitude which is the average of the samples stored on said capacitors.

Claim 8

The method of claim 4 in which said combining step comprises the steps of: discharging a first of said capacitors f times per second, and performing the following sequence of steps n times between successive discharging steps: coupling one of said samples to a second of said capacitors through said first capacitor, thereby storing on said second capacitor a voltage equal to the sum of the voltage stored on said first capacitor and said sample, and storing on said first capacitor the voltage stored on said second capacitor; the voltage appearing across said second capacitor just prior to a discharging step corresponding to a composite sample equal to the sum of all samples taken since the prior discharging step.

Claim 9

The method of claim 4 in which said combining step comprises the steps of: discharging a first of said capacitors f times per second, and performing the following sequence of steps n times between successive discharging steps: storing one of said samples on a second of said capacitors; and transferring at least part of the charge from said second capacitor to said first capacitor; the voltage appearing across said first capacitor just prior to a discharging step corresponding to a composite sample having an amplitude proportional to the sum of all samples taken since the prior discharging step.

Claim 10

The method of claim 4 further comprising the steps of sampling each of said composite samples just after it is produced and holding same until the next composite sample is produced.

Claim 11

In an apparatus for producing samples of a continuous wave signal, said apparatus including first and second terminals for receiving said signal, the improvement comprising: a source of a plurality of control signals, a third terminal, a first switch normally connecting said first and third terminals and responsive to a first one of said control signals to disconnect said terminals, at least one storage network connected between said second and third terminals, each storage network comprising a capacitor and a normally open switch, in series with said capacitor, operative to close in response to a second one of said control signals, and a storage capacitor connected between said second and third terminals.

Claim 12

In an apparatus for producing samples of a continuous wave signal, said apparatus including first and second terminals for receiving said signal, the improvement comprising: a source of a plurality of control signals, a third terminal, a first switch normally connecting said first and third terminals and responsive to a first one of said control signals to disconnect said terminals, at least one storage network connected between said second and third terminals, each storage network comprising a capacitor and a normally open switch, in series with said capacitor, operative to close in response to a second one of said control signals, and a storage capacitor connected between said second and third terminals.

Claim 13

The apparatus of claim 9 further comprising means for sampling and holding the signal appearing between said second and third terminals.

Claim 14

In an apparatus for producing f samples per second of a continuous wave input signal having a highest frequency of interest not exceeding f/2, the improvement comprising: means for taking nf samples per second of said signal, where n is an integer greater than 1, and means for adding n sequential ones of said samples.

Claim 15

In an apparatus for producing f samples per second of a continuous wave input signal having a highest frequency of interest not exceeding f/2, the improvement comprising: means for taking nf samples per second of said signal, where n is an integer greater than 1, and means for adding n sequential ones of said samples.

Claim 16

The apparatus of claim 11 further comprising means for sampling and holding the sum produced by said adding means f times per second.

Claim 17

The apparatus of claim 11 in which said adding means comprises: a plurality of capacitors, means, incorporating said sampling means, for storing each of n sequential ones of said samples on a different one of said capacitors, and means, included in said storing means, for connecting all of said capacitors in shunt.

Claim 18

The apparatus of claim 11 in which said adding means comprises: first and second storage means, means for providing to said first storage means the sum of the most recent one of said samples and the contents of said second storage means, means for applying to said second storage means the contents of said first storage means, and means for emptying said second storage means f times per second.

Claim 19

The apparatus of claim 11 in which said adding means comprises: a first capacitor for storing the most recent one of said samples, a second capacitor, means for transferring charge from said first to said second capacitor, and means for discharging said second capacitor after n new samples have been taken.

Claim 20

The apparatus of claim 15 in which said transferring means comprises: means for connecting first ends of said first and second capacitors after each of said samples is taken, and an inverting amplifier having its input and output connected, respectively, to the first and second ends of said second capacitor.