Communications: electrical – Selective – Having electron beam device
Patent
1975-02-10
1976-03-30
Tubbesing, T. H.
Communications: electrical
Selective
Having electron beam device
235154, 330 86, 330144, 330124R, G01V 116, H03F 368, H03G 1104
Patent
active
039478068
ABSTRACT:
This is a seismic digital recording system for use where the seismic amplifiers are placed near the geophone locations and their outputs transmitted by common cable to the recording truck or recorded on magnetic tape at the geophone location. In such a digital recording system, it is impractical to use a high-speed, high gain-ranging amplifier of 15 or 16 bits range. In our design the gain-ranging amplifier is high-speed but employs fewer bits total range. The extra range is made up in a preamplifier which has a variable range of gain, which can be automatically set, but at slower speed. The invention involves a control system which is responsive to the output of an A/D converter which is connected to the output of the gain-ranging amplifier. This control examines the bit output of the A/D converter throughout the whole record and, depending on whether the most significant bit is a 0 or 1, and whether the less significant bits are 0 or 1, it acts to control the gain of the preamplifier on the suceeding record by increasing the gain, decreasing the gain, or leaving the gain set at its instant value. The gain of the preamplifier can be adjusted by 6-db steps for each succeeding record until it reaches a value for which the operation of the gain-ranging amplifier is optimum.
REFERENCES:
patent: 3392370 (1968-07-01), Neitzel
patent: 3436723 (1969-04-01), Savit
patent: 3466596 (1969-09-01), Siems et al.
patent: 3525948 (1970-08-01), Sherer et al.
patent: 3699325 (1972-10-01), Montgomery, Jr. et al.
patent: 3806864 (1974-04-01), Broding et al.
patent: 3813609 (1974-05-01), Wilkes et al.
Corkhill David P.
Freeman Francis R.
Birmiel H. A.
Pottorf Newell
Standard Oil Company
Tubbesing T. H.
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