§  95.628   MedRadio transmitters.

   (a) Frequency monitoring. Except as provided in (b) of this section,
   all MedRadio programmer/control transmitters operating in the 401–406
   MHz band must operate under the control of a monitoring system that
   incorporates a mechanism for monitoring the channel or channels that
   the MedRadio system devices intend to occupy. The monitoring system
   antenna shall be the antenna normally used by the programmer/control
   transmitter for a communications session. Before the monitoring system
   of a MedRadio programmer/control transmitter initiates a MedRadio
   communications session, the following access criteria must be met:

   (1) The monitoring system bandwidth measured at its 20 dB down points
   must be equal to or greater than the emission bandwidth of the intended
   transmission.

   (2) Within 5 seconds prior to initiating a communications session,
   circuitry associated with a MedRadio programmer/control transmitter
   must monitor the channel or channels the system devices intend to
   occupy for a minimum of 10 milliseconds per channel.

   (3) Based on use of an isotropic monitoring system antenna, the
   monitoring threshold power level must not be more than 10logB(Hz) −150
   (dBm/Hz) + G(dBi), where B is the emission bandwidth of the MedRadio
   communications session transmitter having the widest emission and G is
   the MedRadio programmer/control transmitter monitoring system antenna
   gain relative to an isotropic antenna. For purposes of showing
   compliance with the above provision, the above calculated threshold
   power level must be increased or decreased by an amount equal to the
   monitoring system antenna gain above or below the gain of an isotropic
   antenna, respectively.

   (4) If no signal in a MedRadio channel above the monitoring threshold
   power level is detected, the MedRadio programmer/control transmitter
   may initiate a MedRadio communications session involving transmissions
   to and from a medical implant or medical body-worn device on that
   channel. The MedRadio communications session may continue as long as
   any silent period between consecutive data transmission bursts does not
   exceed 5 seconds. If a channel meeting the criteria in paragraph (a)(3)
   of this section is unavailable, the channel with the lowest ambient
   power level may be accessed.

   (5) When a channel is selected prior to a MedRadio communications
   session, it is permissible to select an alternate channel for use if
   communications are interrupted, provided that the alternate channel
   selected is the next best choice using the above criteria. The
   alternate channel may be accessed in the event a communications session
   is interrupted by interference. The following criteria must be met:

   (i) Before transmitting on the alternate channel, the channel must be
   monitored for a period of at least 10 milliseconds.

   (ii) The detected power level during this 10 millisecond or greater
   monitoring period must be no higher than 6dB above the power level
   detected when the channel was chosen as the alternate channel.

   (iii) In the event that this alternate channel provision is not used by
   the MedRadio system or if the criteria in paragraphs (a)(5)(i) and (ii)
   are not met, a channel must be selected using the access criteria
   specified in paragraphs (a)(1) through (a)(4) of this section.

   (6) As used in this section, the following definitions apply:

   (i) Emission bandwidth — Measured as the width of the signal between
   the points on either side of carrier center frequency that are 20 dB
   down relative to the maximum level of the modulated carrier. Compliance
   will be determined using instrumentation employing a peak detector
   function and a resolution bandwidth approximately equal to 1% of the
   emission bandwidth of the device under test.

   (ii) MedRadio channel —Any continuous segment of spectrum in the
   MedRadio band that is equal to the emission bandwidth of the device
   with the largest bandwidth that is to participate in a MedRadio
   communications session.

   Note to paragraph (a)(6)(ii): The rules do not specify a channeling
   scheme for use by MedRadio systems.

   (iii) MedRadio communications session —A collection of transmissions,
   that may or may not be continuous, between MedRadio system devices.

   (b) Exceptions to frequency monitoring criteria. MedRadio devices or
   communications sessions that meet any one of the following criteria are
   not required to use the access criteria set forth in paragraph (a) of
   this section:

   (1) MedRadio communications sessions initiated by a medical implant
   event.

   (2) MedRadio devices operating in either the 401–401.85 MHz or 405–406
   MHz bands, provided that the transmit power is not greater than 250
   nanowatts EIRP and the duty cycle for such transmissions does not
   exceed 0.1%, based on the total transmission time during a one-hour
   interval.

   (3) MedRadio devices operating in the 401.85–402 MHz band, provided
   that the transmit power is not greater than 25 microwatts EIRP and the
   duty cycle for such transmissions does not exceed 0.1%, based on the
   total transmission time during a one-hour interval.

   (4) MedRadio devices operating with a total emission bandwidth not
   exceeding 300 kHz centered at 403.65 MHz, provided that the transmit
   power is not greater than 100 nanowatts EIRP and the duty cycle for
   such transmissions does not exceed 0.01%, based on the total
   transmission time during a one-hour interval.

   (c) Operating frequency. MedRadio stations authorized under this part
   may operate on frequencies in the 401–406 MHz band as follows provided
   that the out-of-band emissions are attenuated in accordance with
   § 95.635:

   (1) MedRadio stations associated with medical implant devices, which
   incorporate a frequency monitoring system as set forth in paragraph (a)
   of this section, may operate on any of the frequencies in the 401–406
   MHz band.

   (2) MedRadio stations associated with medical implant devices, which do
   not incorporate a frequency monitoring system as set forth in paragraph
   (a) of this section, may operate on any frequency in 401–402 MHz or
   405–406 MHz bands, or at 403.65 MHz in the 402–405 MHz band.

   (3) MedRadio stations associated with medical body-worn devices,
   regardless of whether a frequency monitoring system as set forth in
   paragraph (a) of this section is employed, may operate on any of the
   frequencies in the 401–402 MHz or 405–406 MHz bands.

   (4) MedRadio stations that are used externally to evaluate the efficacy
   of a more permanent medical implant device, regardless of whether a
   frequency monitoring system as set forth in paragraph (a) of this
   section is employed, may operate on any of the frequencies in the
   402–405 MHz band, provided that:

   (i) Such external body-worn operation is limited solely to evaluating
   with a patient the efficacy of a fully implanted permanent medical
   device that is intended to replace the temporary body-worn device;

   (ii) RF transmissions from the external device must cease following the
   patient evaluation period, which may not exceed 30 days, except where a
   health care practitioner determines that additional time is necessary
   due to unforeseen circumstances;

   (iii) The maximum output power of the temporary body-worn device shall
   not exceed 200 nW EIRP; and

   (iv) The temporary body-worn device must comply fully with all other
   MedRadio rules applicable to medical implant device operation in the
   402–405 MHz band.

   (d) Authorized bandwidth. The authorized bandwidth of the emission from
   a MedRadio station operating between 402–405 MHz shall not exceed 300
   kHz, and no communications session involving MedRadio stations shall
   use more than a total of 300 kHz of bandwidth during such a session.
   The authorized bandwidth of the emission from a MedRadio station
   operating between 401–401.85 MHz or 405–406 MHz shall not exceed 100
   kHz, and no communications session involving MedRadio stations shall
   use more than a total of 100 kHz of bandwidth during such a session.
   The authorized bandwidth of the emission from a MedRadio station
   operating between 401.85–402 MHz shall not exceed 150 kHz, and no
   communications session involving MedRadio stations shall use more than
   a total of 150 kHz of bandwidth during such a session.

   Note to paragraph (d): This provision does not preclude full duplex or
   half duplex communications provided that the total amount of bandwidth
   utilized by all of the MedRadio channels employed in such a MedRadio
   communications session does not exceed 300 kHz in the 402–405 MHz band,
   or 100 kHz in the 401–402 MHz and 405–406 MHz bands.

   (e) Frequency stability. Each transmitter in the MedRadio service must
   maintain a frequency stability of ±100 ppm of the operating frequency
   over the range:

   (1) 25 °C to 45 °C in the case of medical implant transmitters; and

   (2) 0 °C to 55 °C in the case of MedRadio programmer/control
   transmitters and MedRadio body-worn transmitters.

   (f) Shared access. The provisions of this section shall not be used to
   extend the range of spectrum occupied over space or time for the
   purpose of denying fair access to spectrum for other MedRadio systems.

   (g) Measurement procedures. (1) MedRadio transmitters shall be tested
   for frequency stability, radiated emissions and EIRP limit compliance
   in accordance with paragraphs (g)(2) and (g)(3) of this section.

   (2) Frequency stability testing shall be performed over the temperature
   range set forth in (e) of this section.

   (3) Radiated emissions and EIRP limit measurements limit may be
   determined by measuring the radiated field from the equipment under
   test at 3 meters and calculating the EIRP. The equivalent radiated
   field strength at 3 meters for 25 microwatts, 250 nanowatts, and 100
   nanowatts EIRP is 18.2, 1.8, or 1.2 mV/meter, respectively, when
   measured on an open area test site; or 9.1, 0.9, or 0.6 mV/meter,
   respectively, when measured on a test site equivalent to free space
   such as a fully anechoic test chamber. Power measurements for
   transmissions by stations authorized under this section may be made
   either in accordance with a Commission-approved peak power technique,
   or the following. Peak transmit power must be measured over any
   interval of continuous transmission using instrumentation calibrated in
   terms of an rms-equivalent voltage. The measurement results shall be
   properly adjusted for any instrument limitations, such as detector
   response times, limited resolution bandwidth capability when compared
   to the emission bandwidth, sensitivity, etc., so as to obtain a true
   peak measurement for the emission in question over the full bandwidth
   of the channel.

   (i) For a transmitter intended to be implanted in a human body,
   radiated emissions and EIRP measurements for transmissions by stations
   authorized under this section may be made in accordance with a
   Commission-approved human body simulator and test technique. A formula
   for a suitable tissue substitute material is defined in OET Bulletin 65
   Supplement C (01–01).

   [ 74 FR 22705 , May 14, 2009]