BioNomadix Logger™ User Guide
Page 14 of 28
WWW.BIOPAC.COM
8.30.2018
Checking for RF Interference during an Acquisition
The Logger does not support the display of raw signals during an acquisition. It is recommended that the “Check
Data” option be used prior to the start of an acquisition to verify proper electrode and transducer connections and
check for any excess RF interference. Additionally, prior to sending a subject for a long-term acquisition a short-term
acquisition should be performed to check data integrity.
During an acquisition, the progress bar indicates both the amount of data acquired as well as the RF signal integrity.
Green indicates successful communication between the Logger and all transmitters. A red bar indicates there were
communication issues with at least one of the transmitters. Normally communication will be quickly re-established
between Loggers and transmitters. If the progress bar has prolonged periods of red indicating communication issues,
one of the transmitters may have been turned off, run out of battery, or shifted position to be too far away from the
Logger. Even if a single transmitter is unable to communicate data will still be recorded from remaining transmitters.
Communication issues may still occur for a variety of reasons including external RF noise, multiple Loggers in close
proximity, and non-optimal physical setup.
Using Multiple Loggers in Close Proximity
Multiple Loggers may be used in close proximity to each other, such as recording multiple subjects within a single
room or using multiple Loggers to record data from more than three transmitters on a single subject.
Each Logger should be set to a unique RF channel to avoid RF interference between the Loggers.
If two Loggers are set to the same RF channel, communications loss will occur. The RF channel may be set in the
Logger “Configure” menu. Use RF channels farther away from each other to minimize interference between
Loggers.
If a transmitter is paired to both a BioNomadix Logger and a BioNomadix Smart Center, note that only one of these
units should be powered on at a time. To use the paired transmitters with a Logger, the Smart Center should be
disconnected from the computer. Conversely, to use the transmitters with the Smart Center, the Logger should be
turned off.
Optimizing Physical Configuration for Best Recordings
Unlike the standard BioNomadix receivers, the Logger is a battery operated low power radio device designed for
“body area networks” where the Loggers and transmitters are attached to a subject. Loggers should always be
attached to the subject when possible to allow them to remain in close proximity to the transmitters. The maximum
recommended radio range between a Logger and an individual transmitter is approximately one meter. Even then,
minimizing the distance between the Logger and a transmitter will improve radio communications. When multiple
transmitters are in use, it is recommended to place the Logger physically as close as possible to the transmitter
operating at the highest sampling rate (e.g. EMG, ECG signals). If all transmitters are operating at the same rate,
attempt to position the Logger equidistant between all transmitters.
Avoid “body blocking” whenever possible. “Body blocking” is when a straight line drawn from a transmitter to the
Logger would intersect the human body. The human body absorbs RF energy at known rates (SAR). If portions of
the body are between the transmitter and a Logger, the reduction in signal strength will affect communications. To
achieve the best communications possible, keep an open “line of sight” between the Logger and transmitters that
does not intersect the body or intersects the least amount of body as possible. Keep the Logger and all transmitters on
the front (or back) of the body and, if possible, on the same side of the body. The optimal setup will depend on
transmitter placement and locations required for the various signal types.
Communications may also be affected by relative motion between the Logger and the transmitters. When possible,
keep the Logger and transmitter in close enough proximity to move roughly as a pair when the subject is in motion,
e.g. if transmitter is affixed to the torso, affix the Logger to the torso as well if possible.
The BioNomadix Shirt (BN-SHIRT) has many storage locations for transmitters and the Logger that can help
configure and maintain an optimal body area network on the upper torso.
