Answered: What constitutes Green Rx # Status

This is a two-part question.

  1. The easy part probably… What receiver output (a DC/digital signal or a signal pattern) is used by the Vex Microcontroller to decide whether or not to turn on the green Rx # LED on the front of the Microcontroller?

  2. The harder part perhaps… I believe that the Vex Transmitter sends user inputs to the Vex Receiver by encoding them in a series of what are nominally called “pulses” that vary in duration; and that the pulses are formed by shifting the transmitted signal’s frequency up and down about the center frequency of the channel the transmitter is operating on. Can you tell me what signal characteristics are detected and then used to declare that a valid transmitted signal exists (which in turn causes the receiver to turn on the receiver outputs that are the answer to question #1 above).

The big picture is that I am trying to understand what parts of the transmitted signal must be present and uncorrupted in order for the Receiver/Controller system to decide that a valid transmitter signal exists and to then begin trying to use that signal to control the a Vex Bot’s actions. In the absence of this “valid” signal, I am presuming that the microcontroller would do whatever it is programmed to do (of course), but in general would not (be programmed to) attempt to use any receiver outputs or react in any way to the state of the receiver outputs

Is it the brief presence of a strong enough single frequency signal at the right frequency?
Is it the presence of a strong enough single frequency signal for some non-trivial amount of time?
Is it the presence of the two expected frequencies at high enough power, regardless of whether the expected pulse train exists or is corrupted?
Is it the presence of a signal containing exactly 6 pulses? Is it the presence of a signal containing 6 pulses whose widths fall within certain bounds?
Is it the presence of a signal containing a 6-pulse pulse train every 18.5 ms?

Thanks in advance,

**1) The Vex Receiver looks at the received signal/pattern to determine whether it is a valid signal.

  1. Only the correct signal characteristics are used.

The entire signal protocol must be valid or it will not respond to the input signal.

See “Receiver Data Format” under Vex Transmitter & Receiver FAQs at**