What are you wearing that measures cadence?
This heart rate strap measures cadence, vertical oscillation and stride length.
https://buy.garmin.com/en-US/US/shop-by-accessorie...
Also the newer garmin models (920XT, Fenix) measure stride length and cadence through the watch (with some loss of precision compared to the above HR strap)
I got a Garmin 220 not long ago. Seems just fine, smaller and more comfortable than my old 305. Not as many features, but seems to be all I need.
I haven't yet gotten the heart rate monitor out of the box, so the cadence number is coming from the watch itself. And I hadn't even noticed it on the map/data page.
Does show quite clearly where I was walking more. :-)