Hello All,
There is a notion of "detecting the signal" and "capturing the
signal" based on the received signal strength. The packet reception
success depends upon the noise on the channel too (SNR). For simplicity
of this discussion, let us ignore noise for the time being.

According to the best of my knowledge, the only physical entitiy
present(which impacts the discussion) in the data sheet of a wireless
receiver is the "receiver sensitivity". If the received signal level is
higher than this sensitivity (noise ~= 0), then the receiver is able to
successfully receive the packet.

However, in certain research work and simulators, "capture threshold"
and "reception threshold" variables are also introduced. Here is the
main point of this topic. Are these abstract entities? In a simple
scenario where a receiver is placed at some distance from transmitter.
Is there a possibility of sensing the packet but not being able to
decode it (assume noise ~= 0 again) ? If not, then the whole idea of
capture threshold is meaningless. If yes, then why doesnt the wireless
cards have it in their specs?

My thinking is that a signal can be captured properly if the
demodulation phase succeeds. There is always something on the channel.
If the demodulator can figure out the envelope wave (depending on the
modulation type), it should be able to demodulate the wave and capture
the digital content from the analog signal. Is there a possibility that
we detect the envelope wave but still not able to demodulate? (Again
assuming noise ~= 0). If this is so, then there can be carrier sensing
but incorrect reception.
Since the whole envelope wave is sent with the same power, is there any
reason of not decoding it after detecting it.

Wlog, I guess we can assume that this effect can be stated even when
any noise present on ths channel. There is still capture/detect effect,
but now we have to consider SNR ratio instead of just signal strength.

Any pointers to this topic is greatly appreciated. Sorry if the
question is very trivial to DSP/communication people! :)

Thanks and Regards,
Vinay