Dual protocol heart-rate monitor supports ANT+ and Bluetooth Smart wireless technologies and is designed to be worn on the arm instead of chest

Mar 17, 2015
Oslo, Norway 2015/03/17 - Nordic Semiconductor today announces that U.S. developer Scosche is employing Nordic nRF51422 Systems-on-Chip (SoCs) to provide both ANT+ and Bluetooth Smart (formerly known as Bluetooth low energy) wireless comms to smartphones, sports watches, bike computers, and gym equipment in the Scosche RHYTHM+ arm-band heart rate monitor.
In operation, the low-profile, one-size-fits-all RHYTHM+ is fastened to the forearm just below the user’s elbow and uses an optical sensor to measure blood flow in the arm and from that infers pulse rate and calories burned more accurately and comfortably, according to Scosche, than conventional chest-worn heart-rate (HR) monitors. In addition Scosche says that unlike a heart-rate strap, the RHYTHM+ does not require additional contact lubricants (electrode gel, saliva, water, or sweat across the electrodes) to get a reliable measurement.
By offering compatibility with both ANT+ and Bluetooth® Smart wireless technologies, Scosche says the RHYTHM+ will work with pretty much any third-party fitness hardware or app on the market.
The RHYTHM+ is powered by a 3.7 V lithium-polymer rechargeable battery that offers up to 8-hours of continuous use between re-charges. It has a wireless range of up to 100-ft / 30 meters, and is made from a silicone and polycarbonate hybrid with ‘breathable’ Lycra arm-strap that is sweatproof and waterproof (IP67-rated construction includes withstanding being submerged in up to 1m depth of water).
“Heart rate based training and exercise has yet to reach the mainstream population largely due to the price and inconvenient form factor of chest straps,” comments Joshua Duffy, Electrical Engineering Manager at Scosche. “The RHYTHM+ is designed to be low cost and comfortable to wear, and can work with pretty much any third-party fitness app or hardware the user wants regardless of whether it happens to employ ANT+ or Bluetooth Smart wireless technology.”
Duffy continues: “That said, we do recognize that ANT+ continues to have a certain dominance in the sports heart-rate monitoring market at present, possibly due to the proven robustness of the protocol in large, group training environments where multiple heart-rate measurements need to be collected simultaneously. But the ubiquity of Bluetooth Smart on modern smartphones, tablets, and computers also means this wireless technology cannot be ignored in sports.
“The Nordic nRF51422 is the only SoC on the market to support both ANT+ and Bluetooth Smart wireless technologies. It is also the only ultra low power Flash memory-based SoC to separate the application code from the wireless protocol stack which makes programing with the nRF51422 light-years easier and quicker than with competing devices.”
Duffy concludes: “Nordic is a clear leader in ULP wireless technology and their experience with ANT and ANT+ gives them an advantage over the competition. We have been very pleased with the level of technical support provided. On a sunny day here in southern California while performing range testing with the RHYTHM+ and an iPhone 5 we measured a successful line-of-sight HR transmission at 400 feet [121m] !”

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