MaxBotix Inc., has released the new XL-MaxSonar products. This product line should solver the problems above relate to noise and not enough acoustic output power. The XL-MaxSonar line has fully automatic real-time background calibration, much higher acoustic output power, greatly improved real-time noise rejection, centimeter resolution, longer distance range measurement, and for some models real-time analog envelope output and various analog hardware gains from 250 to 4000. These improvements result in virtually noise free distance readings for most users. The XL-MaxSonar is avaialbe in both indoor and ourdoor versions.
From my experiences ferrite beads just give nothing apart of its weight. Rings are better but only a bit. I experimented with rings with six turns on every servo cable (long cables). After a few flights I removed the rings - I am not sure if the glitch free distance is lnger or shorter ;). Anyway the airplane was much lighter and with better flying comfort.
Forgot to tell I indeed also have ferrite rings on each servo cable (2 turns for now) placed near the connector. I'll probably also add 3 such rings on the ArduPilot servo input cables.
Indeed I powered 2.4 video Tx, OSD and camera from one battery and engine, servos RC Rx and ArduPilot from another. After testing in this config I added grounded alumnium foil around OSD and ArduPilot. This has minimal impact on range I got.
Michal: I certainly won't forget range testing everything. I suspect that once the airframe and soft is ready, I'll move much more around the plane myself (by foot, bicylcle, car) than the plane!
One question to you: do you power the RF video from a separate source? In any case, I wouldn't otherwise. And maybe try to add some shielding from aluminium foil for testing?
Michal: I do not know it this helps in anyway, I am no electronician. I got a ultrasonic ange finder sensor from Maxbotix, so I went trough their web site and came across this. would such simple filtering (or similar) be of use for your setup? Maybe it's worth do some trying?
Excerpt from the Maxbotix site:
[...]
NEWS FLASH!
UAV and Mobile Robotic Users
(Simple fix for when electrical noise interferes with the MaxSonar sensors.)
When electrical noise is introduced on the line, it can cause the MaxSonar sensors to output unstable readings. Known items that cause excessive power supply noise are Sharp infrared range sensors, XBee radios, some wireless control systems, some switching power supplies, some servos, etc.
There is a simple solution that eliminates the effects of a dirty power supply to the sensor. By placing a resistor in series with the V+, along with a 100uF capacitor (Digi-Key part number: P803-ND or equivalent) to ground, you create an effective filter (i.e. almost a placebo battery) for the sensor. This ensures that almost any noise introduced onto the line is captured and only clean stable power is supplied to the sensor. For the circuit connections, please see the schematic below: [...]
My friend with o-scope measured RF noise in powerlines of my small FPV platform today. In particular one point (power cables from ArduPilot to GPS) there is huge noise - 13-15 kHz / 0.3-0.5 V. This could be my fault (too long cables or something else). Right now I am unable to put my OSD with ArduPilot in one frame. I tryed to do so but range check was a complete failure. I was able to move 3 meters away with colapsed anntena and about 100 meters with extended. I have to think about the solution, but I dont have a real plan how this should be done. The conclusion is that every device is like RF noise generator. There were filters in old analog/digital devices that somewhat could prevent such noise but I have no idea if they will work for us. I would try a few tricks like device separation or shielding whole areas.
Michal
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Please click this linkt to view more information about the XL-MaxSonar products. http://www.maxbotix.com/uploads/Small_Industrial_Ultrasonic_Sensors...
Best regards,
Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766 Ext. 2
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: www.maxbotix.com
MaxBotix, MaxSonar, EZ0, EZ1, EZ2, EZ3, EZ4 and WR1 are trademarks of MaxBotix Inc.
good job on nice and clean layout!
One question to you: do you power the RF video from a separate source? In any case, I wouldn't otherwise. And maybe try to add some shielding from aluminium foil for testing?
Good luck
Michal
Excerpt from the Maxbotix site:[...]
NEWS FLASH!
UAV and Mobile Robotic Users
(Simple fix for when electrical noise interferes with the MaxSonar sensors.)
When electrical noise is introduced on the line, it can cause the MaxSonar sensors to output unstable readings. Known items that cause excessive power supply noise are Sharp infrared range sensors, XBee radios, some wireless control systems, some switching power supplies, some servos, etc.
There is a simple solution that eliminates the effects of a dirty power supply to the sensor. By placing a resistor in series with the V+, along with a 100uF capacitor (Digi-Key part number: P803-ND or equivalent) to ground, you create an effective filter (i.e. almost a placebo battery) for the sensor. This ensures that almost any noise introduced onto the line is captured and only clean stable power is supplied to the sensor. For the circuit connections, please see the schematic below: [...]
Michal
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