Sending a trigger pulse by RF

[whit3rd]

On Dec 26, 11:39 pm, "Pimpom" <Pim...@invalid.net> wrote:

[about a remote RF timing signal]

Part of a system involving a timer. Max resolution 1ms. START
signal local to the RTC, STOP signal by the remote trigger.

If the remote is to be battery powered, it will go through
a few phases; first, the carrier is established (during this
phase, the receiver will have AGC fluctuations), then
a signal is sent (something like a tone burst) and received
(by a filter and trigger that rejects noise but not the signal).
The AGC needs settling time, and the tone decoder will
want a dozen or more cycles to detect (but can probably
drop its output quickly when the signal is interrupted),
so you'll actually get a 'receiver-end' time signal a
bit AFTER hitting the button on the remote. Be
prepared for this (and control that latency at all phases
of the design).

 

[Pimpom]

whit3rd wrote:

On Dec 26, 11:39 pm, "Pimpom" <Pim...@invalid.net> wrote:

[about a remote RF timing signal]
Part of a system involving a timer. Max resolution 1ms. START
signal local to the RTC, STOP signal by the remote trigger.

If the remote is to be battery powered, it will go through
a few phases; first, the carrier is established (during this
phase, the receiver will have AGC fluctuations), then
a signal is sent (something like a tone burst) and received
(by a filter and trigger that rejects noise but not the
signal).
The AGC needs settling time, and the tone decoder will
want a dozen or more cycles to detect (but can probably
drop its output quickly when the signal is interrupted),
so you'll actually get a 'receiver-end' time signal a
bit AFTER hitting the button on the remote. Be
prepared for this (and control that latency at all phases
of the design).

The remote trigger source, along with other things, will probably
be battery-powered (I haven't decided yet). But the battery will
be a car battery, so there's no need to worry too much about
conserving the charge.

I considered the AGC settling time and was thinking of making a
continuous carrier transmission, with the trigger signal inserted
at the proper time. Anyway, the tone burst method is just an
idea. I'm open to suggestions. Perhaps a pulse train with the
receiver accepting only a specified number of pulses within a
given period??