Sample rate coordinator and data handling system

• US 3,919,526 A
• Filed: 08/21/1974
• Issued: 11/11/1975
• Est. Priority Date: 08/21/1974
• Status: Expired due to Term

• Current Assignee: Cae-Link Corporation
• Original Assignee: Ansis Pommers, Robert W. Lotz
• Inventors: Pommers, Ansis, Lotz, Robert W.
• Primary Examiner(s): Cook, Daryl W.
• Application Number:
  US05/499,273
• Time in Patent Office: 447 Days
• Field of Search: 235/61.6A,61.6B,61.11E 250/555,566 340/347AD,347P
• US Class Current: 341/151
• CPC Class Codes: G06K 7/016 Synchronisation of sensing process

Abstract

A data sample rate is selected for a data base on a rotating drum. The sample rate determines the distance between samples on the data base. The sample distance is set into an adderaccumulator. As the data base is scanned, scanning pulses clock the accumulator to add the distance scanned between clock pulses to an intermediate sum held in the accumulator. The scanned distances are accumulated, causing the intermediate sum to increase by steps. Each time the intermediate sum exceeds the desired distance between samples, the accumulator activates a data sampling device for reading the data base. A remainder exists in the accumulator because the distance between sampled points is generally not a simple multiple of the distance between clocked points on the data base. That is, the encoding or timing capability of the convertor is fixed, defining fixed multiple thereof while the distance between data sampling points is selected independently of convertor capability. This mismatch or fundamental error remains in the accumulator and is added to the scan distance at the next scan pulse. The remainder or accumulating error changes by one multiple of the fundamental error at each subsequent sampling until the remainder exceeds one scan distance-the value of one step increase of the accumulator. The accumulator then activates the data sampling device one step sooner or later than usual depending on whether the accumulating error is increasing or decreasing with each overflow.

Claims

1. An apparatus for converting existing data into digital form, cOmprising:

annular rotating display means adapted to display the existing data;

sampling means for reading the existing data when activated;

scanning means for establishing relative motion between the existing data on the annular display means and the sampling means; and

an accumulator for holding an intermediate number which changes in magnitude by steps in response to the scanning means, each time the intermediate number changes by a required amount the accumulator activates the sampling means.

2. The apparatus of claim 1, wherein the intermediate number increases in magnitude by steps in response to the scanning means and is reduced at each sampling means activation by the amount required to activate the sampling means leaving a remainder which forms the initial magnitude of a new intermediate number which continues to increase by steps in response to the scanning means.

3. The apparatus of claim 2, wherein the accumulator has a COMPARE circuit which compares the intermediate number with a predetermined number, and which activates the sampling means each time the intermediate number equals or exceeds the predetermined number.

4. The apparatus of claim 2, wherein the accumulator overflows to activate the sampling means each time the intermediate number exceeds the capacity of the accumulator.

5. The apparatus of claim 2, further comprising a step controller for determining the magnitude of each step increase of the intermediate sum.

6. The apparatus of claim 2, wherein the magnitude of the step increase of the intermediate sum is fixed and corresponds to the distance on the original data medium which is scanned between each step increase.

7. The apparatus of claim 2, wherein the scanning means provides clock signals to the accumulator to cause the step changes in the magnitude of the intermediate number.

8. The apparatus of claim 7, wherein the scanning means comprises stepping motor means responsive to the clock signals for establishing the relative motion between the sampling means and the annular display means.

9. The apparatus of claim 2, wherein the scanning means comprises an encoder responsive to the distance scanned for providing signals to the accumulator to cause the step increases in the intermediate number.

10. The apparatus of claim 9, wherein a phase locked loop circuit is provided responsive to the encoder for providing signals to the accumulator to cause the step increases in the intermediate number.