Dual mode transmission system with switched linear amplifier

A dual mode signal transmission system wherein modulated signals are transmitted in a digital or analog mode comprising a first amplification means having controllable amplification gain responsive to a modulated signal transmission;

• a mode control means responsive to a mode selection signal for selectively providing an analog mode control signal specifying a non-linear transmission mode and a digital mode control signal specifying a linear transmission mode;
• said first amplification means including an amplification-adjustable, high frequency transmitter control amplifier and a non-linear high-power amplifier connected in series wherein said first amplification means is adjustable to a high power level to cause said first amplification means to operate in a non-linear mode in response to a differential control signal and
• wherein said first amplification means is adjustable to a low power level to cause said first amplification means to operate in a linear mode in response to a differential control signal;
• a power measuring means connected to the output of said non-linear, high-power amplifier of said first amplification means for providing a signal representative of a system actual transmission power level;
• means for providing a signal representative of a desired transmission power level;
• power level control means connected to said analog mode control signal and said digital mode control signal of said mode control means and to the output signal of said power measuring means representative of said system actual transmission power level and to said means for providing a signal representative of a desired transmission power level for comparing said actual and desired level signals for producing a differential control signal representative of their difference;
• and
• means for connecting said differential control signal from said power level control means to said amplification-adjustable, high frequency transmitter control amplifier and to said non-linear high-power amplifier of said first amplification means for controlling the output power of said first amplification means to provide an actual transmission power level equal to said desired transmission power level;
• wherein said signal from said power level control means adjusts the gain of both said high frequency transmitter control amplifier and said non-linear high power amplifier of said first amplification means to a high value to cause said first amplification means to operate in said non-linear mode in response to said analog mode control signal, and
• wherein the output from said power level control means adjusts the gain of only said high frequency transmitter control amplifier of said first amplification means to a low value to cause said first amplification means to operate in said linear mode in response to said digital mode control signal;
• an output means including a filter and antenna means for transmitting said modulated signals;
• a linear amplifier connected to said mode control means;
• and
• switch means connected to said mode control means for selectively disconnecting said non-linear high-power amplifier of said first amplification means from said power measuring means and for connecting said linear amplifier between said non-linear high-power amplifier of said first amplification means and said power measuring means in response to said digital mode control signal from said mode control means specifying said linear digital transmission mode and for disconnecting said linear amplifier from said non-linear high-power amplifier of said first amplification means and said power measuring means in response to said analog mode control signal from said mode control means specifying said non-linear analog transmission mode;
• and
• wherein said linear amplifier is connected between said non-linear high-power amplifier of said first amplification means and said power measuring means in response to said digital mode control signal specifying said linear digital transmission mode.