CC1175: CC1175 turnaround timing

CC1175 is a High Performance RF Transmitter meaning that it doesn't have a RX part.

Yes, you're right that should explain it :) But we're not actually intending on using RX, so I should explain what we're trying to do :

We have an application where we need to switch a carrier ON or OFF to generate an OOK modulation. You might argue that the CC1175 has an embedded OOK modulator, but in our application it doesn't work because the spectrum generated by the CC1175 (again, in our application) isn't compliant with the ETSI standard (even when using spectrum shaping).

We've thought of a workaround and that involves using the chip in GFSK and switching the carrier ON/OFF manually by switching between IDLE and TX. Problem : going from IDLE state to TX (or the other way around is too long), more than 100µs. We wondered if there a way to avoid going into IDLE mode. If we could go into RX mode instead of IDLE on an OOK '0' (if we had a CC1120 for example), then we could be looking at 50µs which is fine for us. But on the CC1175, as you said, there is no RX.

Since the chip is from the same family as the CC1120 we thought that maybe the state machine would still accept it; the underlying goal being that we don't want to switch off the synthesizer when turning off the CW. We just want to kill the power, BUT we still need to benefit of the ramp-up and down shapes associated with GFSK, so we can’t just play on the output power to turn the CW on or off…

I don't know if I'm being very clear in my explanations^^

Yannish

I'm not completely following.
- Do you have some plot showing the non pass and which clause in the ETSI standard you are failing?
- How is using your method give a better spectrum than the power ramp built-in in CC1175?