Re: [mowbot] A heavy mower

Dave Everett (deverett nospam at
Sat, 12 Jul 1997 22:48:13 +1000

At 04:23 PM 7/9/97 +0200, you wrote:

>Computer: PC-XT 1 MHz
>Command sender: 27 MHz 1/4 watt driven by serial computer output.
>Command receiver: serial decoder chip provides 8 discrete commands,
> five now in use.
>Location: 17 KHz pulse received by two mikes, delay measured
> by computer (using parallel port) allows
> triangulation.
>Sonar location repeatability ca. +/- one meter.
>Determination of actual direction with this poor accuracy is
>quite uncertain.

Have you considered using 4 mikes, like a doppler direction finding
array? The mikes would be spaced in a square.

>Motors interfering with radio reception is maddening, fixed by
>extensive shielding, bypassing, etc. 27 MHz is a rotten frequency,
>need much higher frequency for dependability and short antenna.

What are the chances of you mounting the XT on the robot to avoid the
comms transmission problems?
Dave Everett.