Crosstalk between different netids

mantelt commented 7 years ago

Using the current master, I noticed that I get some of the (mavlink) packets sent from a device with different netid.

Having 3 radios A (netid = 25, plugged to pixhawk), B (netid = 25) and C (netid = 15) (see complete config below), communication between A and B seems to work fine. Plugging radio C, I receive quiet a few of the mavlink packets sent by A.

Using the old release-1-9, I didn't notice such a behavior.

Radio A

ATI
RFD SiK 2.0 on HM-TRP
ATI5
S0:FORMAT=26
S1:SERIAL_SPEED=57
S2:AIR_SPEED=64
S3:NETID=25
S4:TXPOWER=20
S5:ECC=1
S6:MAVLINK=1
S7:OPPRESEND=0
S8:MIN_FREQ=433050
S9:MAX_FREQ=434790
S10:NUM_CHANNELS=10
S11:DUTY_CYCLE=100
S12:LBT_RSSI=0
S13:MANCHESTER=0
S14:RTSCTS=0
S15:MAX_WINDOW=131

Radio B

ATI
RFD SiK 2.0 on HM-TRP
ATI5
S0:FORMAT=26
S1:SERIAL_SPEED=57
S2:AIR_SPEED=64
S3:NETID=25
S4:TXPOWER=20
S5:ECC=1
S6:MAVLINK=1
S7:OPPRESEND=1
S8:MIN_FREQ=433050
S9:MAX_FREQ=434790
S10:NUM_CHANNELS=10
S11:DUTY_CYCLE=100
S12:LBT_RSSI=0
S13:MANCHESTER=0
S14:RTSCTS=0
S15:MAX_WINDOW=131

Radio C

ATI
RFD SiK 2.0 on HM-TRP
ATI5
S0:FORMAT=26
S1:SERIAL_SPEED=57
S2:AIR_SPEED=64
S3:NETID=15
S4:TXPOWER=20
S5:ECC=1
S6:MAVLINK=1
S7:OPPRESEND=0
S8:MIN_FREQ=433050
S9:MAX_FREQ=434790
S10:NUM_CHANNELS=10
S11:DUTY_CYCLE=100
S12:LBT_RSSI=0
S13:MANCHESTER=0
S14:RTSCTS=0
S15:MAX_WINDOW=131

VigibotDev commented 7 years ago

Sorry for my english

Do you truly receive packets (or corrupted data) from other network ID on terminal or you just check the RX led on the radio ? With ECC enabled there is a software GOLAY function just check for ID and reject packet.

With a setup where you share same hopping frequency and speed you can get some packet loss You get the RX led ON when your 10 channel hopping collide. It's normal. but the packet must be discarded.

I can make tests with my fork because I can use all raw radio features from the last version of SiK without hopping/tdd and mavlink. (transparent serial single frequency modem). A very easy to do test tonight.

// setup a 16 bit network ID
//
void
radio_set_network_id(uint16_t id)
{
        netid[0] = id&0xFF;
        netid[1] = id>>8;
        if (!feature_golay) {
                // when not using golay encoding we use the hardware
                // headers for network ID
                register_write(EZRADIOPRO_TRANSMIT_HEADER_3, id >> 8);
                register_write(EZRADIOPRO_TRANSMIT_HEADER_2, id & 0xFF);
                register_write(EZRADIOPRO_CHECK_HEADER_3, id >> 8);
                register_write(EZRADIOPRO_CHECK_HEADER_2, id & 0xFF);
        }
}

        // decode the header
        errcount = golay_decode(6, buf, gout);
        if (gout[0] != netid[0] ||
            gout[1] != netid[1]) {
                // its not for our network ID 
                debug("netid %x %x\n",
                       (unsigned)gout[0],
                       (unsigned)gout[1]);
                goto failed;
        }

VigibotDev commented 7 years ago

You are right: there is no bad net id packet rejection with ECC (soft golay) enabled.

Without ECC the LED light up (radio_receive_in_progress) but is rejected.

I look if I can find the bug...

VigibotDev commented 7 years ago

I found the problem. The golay ECC code is never included because developpers added AES support on some board type, and disabled ECC on these boards.

golay23.h :

#ifndef INCLUDE_AES
#define INCLUDE_GOLAY
#endif

This is the only one "#define INCLUDE_GOLAY" from the code but it look NOT suffisient.

I just added this "#define INCLUDE_GOLAY" inside board.h to workaround for my HM_TRP board and it's work now: there is no more crosstalk:D

(root|~/SiK.Serveurperso/Firmware/radio) git diff
diff --git a/Firmware/include/board.h b/Firmware/include/board.h
index 7e29b32..8219bf1 100644
--- a/Firmware/include/board.h
+++ b/Firmware/include/board.h
@@ -97,6 +97,7 @@
 #if   defined(BOARD_rf50)
 # include "board_rf50.h"
 #elif defined(BOARD_hm_trp)
+#define INCLUDE_GOLAY
 # include "board_hm_trp.h"
 #elif defined(BOARD_rfd900)
 # include "board_rfd900.h"

This issue is now "Regression : Golay ECC code is never included on non-AES boards"

VigibotDev commented 7 years ago

The clean solution is just to add this inside radio.h like on golay23.h :

#ifndef INCLUDE_AES
#define INCLUDE_GOLAY
#endif

https://github.com/Serveurperso/SiK/commit/0f5f65c8848685bcf7ef5bb8915da3fc4c584d39

mantelt commented 7 years ago

Hey @Serveurperso Thanks a lot for debugging and fixing this so quickly! I will re-check your solution hopefully soon (I'm quite busy at the moment), but as you already checked it I'm positive that this will just work now.

VigibotDev commented 7 years ago

You must apply this patch https://github.com/Serveurperso/SiK/commit/0f5f65c8848685bcf7ef5bb8915da3fc4c584d39 or developers must add this commit (only) inside the official repo.

ArduPilot / SiK