Radio signal

Hi all,
my robot only works when i am less than 12ft away, anything over this distance its like it receives no signal. any suggestions on what i can do to improve the operating range.
thanks,
ROB....

buy a spektrum,

but a more serious answer, try moving the antenna more outside the robot. armour and reception arent real good friends

i have fitted an external aerial, before this it only worked when i stood next to it.

Got any pictures? Specification of the robot? what radio gear are you using?

receiver
http://i184.photobucket.com/albums/x44/robertlewis_98/DSC00057.jpghttp://i184.photobucket.com/albums/x...8/DSC00057.jpg

aerial
http://i184.photobucket.com/albums/x44/robertlewis_98/3611-001.jpghttp://i184.photobucket.com/albums/x...8/3611-001.jpg

robot
http://i184.photobucket.com/albums/x44/robertlewis_98/DSC00045.jpghttp://i184.photobucket.com/albums/x...8/DSC00045.jpg

the radio gear is the technobots skysport4

No sign of your external antenna on the photo (unless I am missing something). How is it fitted? Is it insulated from the metal armour?

yes its insulated
here is the pic

http://i184.photobucket.com/albums/x44/robertlewis_98/DSC00058.jpghttp://i184.photobucket.com/albums/x...8/DSC00058.jpg

Have you put capacitors across the terminals of your drill motors? They generate large amounts of noise

Is the total length of the aerial coming out the receiver the same as it was when brand new? ie did you cut the original aerial to take into account the addition of the metal aerial?

there is no capacitors on the drill motors and the i have not cut the original aerial.
what make or type of capacitor do i need all i know about them is that they have an ability store charge.

Hi Robert. As said before, the main thing that will cause you interfierance will be having no capacitors on your motors. Im not sure which ones you need but someone will have the answer on here. The other thing is that your receiver is really close to your speed controllers. Try and keep it as far away from any major current drawing wires or components. Another thing that helped me when i used to have these problems was to keep all the wiring as minimal and tidy as possible(it also helps when trying to fault find!)
Also, its been mentioned above but a spektrum DX6 is a VERY worthwhile solution to any of your transmitter problems - theyre so good that anything but 2.4ghz is now banned on the combat scene in America!

http://www.fightingrobots.co.uk/documents/emi.pdfhttp://www.fightingrobots.co.uk/documents/emi.pdf

10 nf max across between the motor terminals ...page 4 / 5

There is LOADS of other info in the document that should help you solve your problems.

Not quiet true Grant only for RoboGames and Combots.

try moving the antenna more outside the robot.

tried that and placed the receiver anywhere i could inside and out, the only place i have not tried is putting it where the sun dont shine:).
if i dont get no joy fitting a capacitor to the motors i will see if i can get a spektrum DX6
Thanks for all your replies
ROB....

What is the overall length of your ariel? If memory serves it should be about 40cm long.

its aprox 83cm long

BAD memory Ed.

The correct calculated length for a 1/8th wavelength 40Mhz R/C antenna is I believe 89cm ... 1/4 wave being 178.3cm.

Robert can you do a range check with the receiver OUT of the bot and working just a servo?

(Message edited by woody on August 05, 2007)

Well I was 1/2 right. Anyway 89cm is an impractical length.

89cms impractical? Try a full wavelength antenna, now thats impractical. :)

On the subject of reception in Roberts robot: Try
shielding of the antenna on the inside of the robot, the external antenna is fine, but if the antenna that is left on the inside picks up noise from everything in the robot that good signal has less a chance of coming through.

We shielded out antennas in the past (before we went to 2,4GHz) by using coax cable for ethernet (RG-58), the antenna in the middle, and a nice wiremesh shield around it to stop outside interference. It helped a lot.

also, shorten the distance between external antenna and reciever if possible, you antenna length is now effectivaly longer then its regular length because you need to add the length of the outside antenne with the inside. if the outside antenna is already tuned for 40MHz, you should only have something like 10 cm on the inside.

Robert can you do a range check with the receiver OUT of the bot and working just a servo?
yes woody and the range was 10 paces.

YUCK!
Theres summat VERY WRONG with your Transmitter or reciever!

Could you check that you have the same freq crystal in both your Transmitter and reciever.

Could you also check that the transmittter and reciever are both 40Mhz.

ive done that and tried 2 other sets of crystals

edit:
even fresh batteries

(Message edited by rob on August 06, 2007)

Seems that a Spektrum would indeed be your best bet.

BTW .... There has been one case reported on the Forum of a miss match in Transmitter and Reciever frequencies ...I.E. One being 40Mhz and the other 35Mhz.
Are you sure yours are both 40Mhz?

Robert, You have now tracked the problem down to the radio link between the transmitter and the receiver. Thats progress. Once you have eliminated mismatched crystals and the possibility suggested above that the tx and rcv might be on differnt bands, the next thing is to find someone with a 40 MHz tx and rcv that work well and use them to isolate the fault to either your tx or rcv. Once that is done you can take the offending equipment apart and look for loose wires or send it off for repair.

Robert as the second post says

buy a spektrum

i did not belive this i borrowed one and NEVER went back