Dave, thanks for the link. I had stumbled upon that site, and used the information there to be the basis for my own design. The guy uses an Atmel, which was another incentive for designing my own around a pic. But of course, the detail timings table he's given helped a lot.

In the page you pointed out, the writer uses a switch to control the Vdd itself; when I tried that my signal burst was not very clean. So my version has Vdd always connected to the battery and 2 separate momentary contact switches for the 2 functions.

My version is now working very well, functionally, so am now in the process of reducing the current consumption. Shutting off the watchdog, configuring the I/Os and using a nap in the loop has now reduced it to around 40 uA; I guess that means a single CR2032 should last for well over half a year of average use!

Again, thank you so much for the inputs.

Regards,

Anand