The project has stalled some what as I test and become accustomed with the new RFD900 modems. Many problems have been discovered during the testing of these modems.
1. There seems to be issues at low bauds with TX (I want to use low baud rates so I have increased sensitivity
2. I’ve been getting RX, essentially corruptions in the incoming packets…losing packets.
3. I’ve found that X-Modem transfer of images just dies when it hits some problems.
It became obvious that I needed to look not only at my software, but also that of the radio modems. I decided that I would stick with the Open Source version of the software (rev 1.X) as I could go in at my leisure and look for issues in the code…and fix them…or atleast get a better understanding.
I managed to alleviate some of the RX issues by disabling USE_TICK_YIELD
I discovered that if I packed only one byte into the TX FIFO of the radio (rather than 4 bytes at a time), I removed my TX errors.
I discovered that the routines that determine how much data we can pack in, did not take into account that with ECC enabled, there are more trailer bytes.
I discovered that if I missed the start of the x-modem packet, the X-modem perl module would not wait for all the ‘bits’ of the failed packet…and so it would time out and end the transmission almost straight away.
In the end I decided to use:-
S0: FORMAT=25 S1: SERIAL_SPEED=57 S2: AIR_SPEED=16 S3: NETID=25 S4: TXPOWER=12 S5: ECC=1 S6: MAVLINK=0 S7: OPPRESEND=0 S8: MIN_FREQ=915000 S9: MAX_FREQ=928000 S10: NUM_CHANNELS=50 S11: DUTY_CYCLE=100 S12: LBT_RSSI=0 S13: MANCHESTER=0 S14: RTSCTS=0
It seems to work well with initial test around the house and up the street. It is also a bit faster then the 8kbits/second.
of course, things might change after I do a bit more testing.