Although they last mere milliseconds at any single frequency, their great distances from Earth — and large quantities of intervening plasma — delay their arrival at lower frequencies, spreading the signal out over a second or more and yielding a distinctive downward - swooping «whistle» across
the typical radio receiver band.
A
typical RFID system consists of a microchip programmed with identifying data — the «tag» — and a two - way
radio transmitter -
receiver, called an interrogator or a reader depending on its use.