Quadrature modulation arrangement with enhanced dynamic amplification range

Claim 2

A quadrature modulation transmission system with extended dynamic amplification range including in-phase and quadrature-phase modulators supplied with orthogonal carrier waves from a common source and a line mixer combining in-phase and quadrature-phase components into a composite signal for application to a transmission line CHARACTERIZED IN THAT a first relatively high-gain amplifier is provided in series with the in-phase modulator for low-level broadband components, a second amplifier with lesser gain than said first amplifier is provided in series with the quadrature-phase modulator for high-level discrete-frequency components and a common analog signal source furnishes an input to said first and second amplifiers in parallel.

Claim 3

The quadrature modulation system defined in claim 1 further CHARACTERIZED IN THAT a limiter is provided in the path of said first high-gain amplifier to preclude saturating such amplifier with high-level signals.

Claim 4

The quadrature modulation system defined in claim 1 further CHARACTERIZED IN THAT a remotely located receiver responds to said composite signal traversing said system.

Claim 5

The quadrature modulation system defined in claim 1 further CHARACTERIZED IN THAT a preamplifier furnishes an input in series with said common signal source and said first and second amplifiers in parallel.

Claim 6

In combination with a submarine acoustic survey system, (a) a hydrophone responsive to acoustic signals of wide dynamic range; (b) a preamplifier for signals incident at said hydrophone; (c) a first transmission channel connected to said preamplifier comprising in series (1) a first amplifier of relatively high gain for low-level signal components, (2) a limiter for prevention of saturation in said first amplifier, (3) a first low-pass filter, and (4) a first modulator; (d) a second transmission channel also connected to said preamplifier comprising in series, (1) a second amplifier of relatively low-gain for high level signal components, (2) a second low-pass filter, and (3) a second modulator; (e) a carrier wave source supplying orthogonally related phases of a common frequency to said first and second modulators, respectively; (f) a mixer for combining modulated signals from said first and second modulators into a composite signal; and (g) a transmission line for conveying said composite signal to a remote monitoring terminal.

Claim 7

In combination with a submarine acoustic survey system, (a) a hydrophone responsive to acoustic signals of wide dynamic range; (b) a preamplifier for signals incident at said hydrophone; (c) a first transmission channel connected to said preamplifier comprising in series (1) a first amplifier of relatively high gain for low-level signal components, (2) a limiter for prevention of saturation in said first amplifier, (3) a first low-pass filter, and (4) a first modulator; (d) a second transmission channel also connected to said preamplifier comprising in series, (1) a second amplifier of relatively low-gain for high level signal components, (2) a second low-pass filter, and (3) a second modulator; (e) a carrier wave source supplying orthogonally related phases of a common frequency to said first and second modulators, respectively; (f) a mixer for combining modulated signals from said first and second modulators into a composite signal; and (g) a transmission line for conveying said composite signal to a remote monitoring terminal.