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AM/ASK/OOK Transmission at variable 140-160MHz

Question asked by UncleTom on Nov 13, 2010
Latest reply on Feb 1, 2011 by viantro

Key Information:
AM/ASK/OOK Transmission at 140-160MHz (variable, programmable)
Output: external Antenna 50 Ohm
Modulation (data rate): 0Hz to maximum 10kHz
Duty Cycle of modulating (data) input: 0% (power level always low) to 100% (power level always high).

Output: Sinus with 50mVss to 2.5Vss at 50 Ohm.

Power Control Accuracy: not critical, 5% or better.


1st question: which RF transmitters can be used with the a.m. frequencies for a simple Amplitude Modulation? Please suggest a device that suits.
Optionally a discrete approach is also welcome: VCO along with a VGA and an RF-Detector. The latter would be in the feedback loop to properly regulate the output signal envelope (block diagram enclosed). Which components would suit for VGA and an RF-Detector?

2nd question: I need to attach two antennas, one is mandatory, one is optional. Each antenna has its own SMA connector. Can this be done? Some sort of "divider" might be necessary? Is such  matching circuit built on discrete components?


3rd question: Is a low AM modulation speed of 0 to 1000Hz (10kHz max.) possible while adjusting the duty cycle of the modulating signal 0 to 100%? 100% means permanently full power level, 0% means permanently low (e.g. zero) power level.


4th question: is it correct to "translate" 50mVss at 50 Ohm to -20dBm and 2.5Vss at 50Ohm to +12dBm?


Kind regards and thanks in advance.