The Medway Handyman brought next idea :
Anyone have any specific knowledge/experience of ultrasonic measures?

I'm looking for a simple accurate way of measuring things like door frames,
alcoves, cupboard interiors etc rather than complete rooms.

Most seem to have a minimum range of 60cm which is fine, maximum range
whatever. Like one with a laser pointer to make life easier.

I have tried two or three and all have been reasonably accurate, given
the low resolution of the displays. They are fine for rough
measurements, but really not intended to replace a tape measure.

They can suffer errors if the surface they are aimed at isn't flat or
if it has things protruding from the surface.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk