Here's a bit more data. Looking at my readout my codes on the flight I referred to were receiver: 136 comprising of code 8 and code 128.

Rx code 8 is Rf link OK (bi or inidirectional)
Code 128 is Rx in unidirectional mode.

Add the two = 136.

Tx code is 160 consisting of codes 32 +128.
Code 32 is Tx is transmitting correct frames.
128 Tx is in Unidirectional mode.

Add the two=160

A Tx code of 168 comprises 8 + 32 + 128.
8 is rf link OK.
32 is Tx transmitting correct frames.
128 is Tx is in unidirectional mode.

Add the three= 168.

I have seen some brief 168 codes on earlier flights but always on the ground. In flight (judging by position of gear servo as the micro has no GPS) Tx stays on status 40 and rx on staus 8 showing all is solid.

For those not familiar with the codes, they double contunuosly (2,4,8,16 etc. ) so that a total code number can consist ONLY of specific numerical codes allowing a final code number to be broken down into individual numbers each of which refers to a specific code.

Regards, David.

PS Today the big DR 12-30 plus GPS plus 3 gyros goes into the PST reaction then into my FC Mig 29 for autostabs on all 3 axes.