It turns out that if you really want a device that can keep accurate time over a long period you must pay a significant amount of money. You would need a tempe

It turns out that if you really want a device that can keep accurate time over a long period you must pay a significant amount of money. You would need a temperature compensated crystal (TCXO) or ovenized crystal oscillator (OCXO). Both of these would cost tens to hundreds of dollars, which is orders of magnitude more than hardware makers are willing to spend. Not to mention these kinds of accurate oscillators tend to be power hungry.