Radio signal

[woody]

Radio signal

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)

[geeza]

Radio signal

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

[leorcc]

Radio signal

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-5, the antenna in the middle, and a nice wiremesh shield around it to stop outside interference. It helped a lot.

[leorcc]

Radio signal

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.

[rob]

Radio signal

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.

[woody]

Radio signal

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.

[rob]

Radio signal

ive done that and tried 2 other sets of crystals

edit:
even fresh batteries

(Message edited by rob on August 06, 2007)

[woody]

Radio signal

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?

[john_frizell]

Radio signal

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.

[beast]

Radio signal

Robert as the second post says

buy a spektrum

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