A unique dual-frequency reference module (DFRM) from NEL Frequency Controls packs 10- and 100-MHz oven-controlled crystal oscillators (OCXOs) into a single compact housing. The oscillators can be locked with each other to gain the benefits of both reference sources.

Chuck Ulland, the companys Vice President of Sales and Marketing, explains: Our customers need both the 10 MHz and 100 MHz references to lock with each other. With the DFRM, customers now get the best performance features of both frequency references in one packageoutstanding close-in phase noise, stability, and aging of a 10-MHz OCXO coupled with the superior phase noise on the floor of a 100-MHz OCXO.

The two reference oscillators are characterized by outstanding phase noise: -115 dBc/Hz offset 1 Hz from the carrier and -145 dBc/Hz offset 10 kHz from the carrier. They feature excellent frequency stability with temperature, from 2 ppb peak to peak, and low aging rate as good as 0.25 ppb/day. The short-term stability is 1 x 10-12 for 1 s.