RF transceiver chips with low-kHz bandwidth?

[Joerg]

Thread read. Just the same, can you add (modulate with) some nice
predicable PRN thus using the extra bandwidth to your advantage?
Regulatory issues may make hash of this idea.

A good idea and most likely agencies won't have any beef with that if
you remain under the power limits. However, the chips are rather
restricted in terms of modulation. The buffet is usually limited to
on/off AM, bi-level AM, FSK and PSK. That's it :-(

 

[josephkk]

A good idea and most likely agencies won't have any beef with that if
you remain under the power limits. However, the chips are rather
restricted in terms of modulation. The buffet is usually limited to
on/off AM, bi-level AM, FSK and PSK. That's it :-(

The radio chip should just see the (bi-level or on/off) AM, the rest done
in a PIC or similar (at each end).

 

[Joerg]

The radio chip should just see the (bi-level or on/off) AM, the rest done
in a PIC or similar (at each end).

That's how people do correlation and it does improve range tremendously.
Until you get interference of the non-pure noise kind ...

 

[[email protected]]

That's how people do correlation and it does improve range tremendously.
Until you get interference of the non-pure noise kind ...

With AM, you really need a good AGC to feed the detector a proper
signal level compared to the detector threshold. The signal strength
can vary considerably due to multipath nulls, even when there is a
minor movement.

In order to generate a goof AGC signal, the data should not contain
long strings of 0's or 1's, thus, at least a scrambler or preferably a
suitable code should be used, to generate a more even distribution of
0 or 1 sequences.