What is the range on the HRM chest strap transmitter?
How far does the signal from the HRM chest strap extend when it's being used? If my wife and I were to each get one of these watches and chest straps, will the signals from the chest straps interfere with each other's watch if we're side by side in a spin class or are riding our tandem bicycle? Also, my wife has an older Polar HRM watch that is maybe 7 or more years old. Would that older chest strap work with the M400, or would we need to buy a new, M400-specific chest strap? Thanks for whatever information you can provide.