47 CFR § 15.233 - Operation within the bands 43.71–44.49 MHz, 46.60–46.98 MHz, 48.75–49.51 MHz and 49.66–50.0 MHz.
(a) The provisions shown in this section are restricted to cordless telephones.
(b) An intentional radiator used as part of a cordless telephone system shall operate centered on one or more of the following frequency pairs, subject to the following conditions:
(1) Frequencies shall be paired as shown below, except that channel pairing for channels one through fifteen may be accomplished by pairing any of the fifteen base transmitter frequencies with any of the fifteen handset transmitter frequencies.
(2) Cordless telephones operating on channels one through fifteen must:
(i) Incorporate an automatic channel selection mechanism that will prevent establishment of a link on any occupied frequency; and
(ii) The box or an instruction manual which is included within the box which the individual cordless telephone is to be marketed shall contain information indicating that some cordless telephones operate at frequencies that may cause interference to nearby TVs and VCRs; to minimize or prevent such interference, the base of the cordless telephone should not be placed near or on top of a TV or VCR; and, if interference is experienced, moving the cordless telephone farther away from the TV or VCR will often reduce or eliminate the interference. A statement describing the means and procedures used to achieve automatic channel selection shall be provided in any application for equipment authorization of a cordless telephone operating on channels one through fifteen.
| Channel | Base transmitter (MHz) | Handset transmitter (MHz) |
|---|---|---|
| 1 | 43.720 | 48.760 |
| 2 | 43.740 | 48.840 |
| 3 | 43.820 | 48.860 |
| 4 | 43.840 | 48.920 |
| 5 | 43.920 | 49.020 |
| 6 | 43.960 | 49.080 |
| 7 | 44.120 | 49.100 |
| 8 | 44.160 | 49.160 |
| 9 | 44.180 | 49.200 |
| 10 | 44.200 | 49.240 |
| 11 | 44.320 | 49.280 |
| 12 | 44.360 | 49.360 |
| 13 | 44.400 | 49.400 |
| 14 | 44.460 | 49.460 |
| 15 | 44.480 | 49.500 |
| 16 | 46.610 | 49.670 |
| 17 | 46.630 | 49.845 |
| 18 | 46.670 | 49.860 |
| 19 | 46.710 | 49.770 |
| 20 | 46.730 | 49.875 |
| 21 | 46.770 | 49.830 |
| 22 | 46.830 | 49.890 |
| 23 | 46.870 | 49.930 |
| 24 | 46.930 | 49.990 |
| 25 | 46.970 | 49.970 |
(c) The field strength of the fundamental emission shall not exceed 10,000 microvolts/meter at 3 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. The provisions in § 15.35 for limiting peak emissions apply.
(d) The fundamental emission shall be confined within a 20 kHz band and shall be centered on a carrier frequency shown above, as adjusted by the frequency tolerance of the transmitter at the time testing is performed. Modulation products outside of this 20 kHz band shall be attenuated at least 26 dB below the level of the unmodulated carrier or to the general limits in § 15.209, whichever permits the higher emission levels. Emissions on any frequency more than 20 kHz removed from the center frequency shall consist solely of unwanted emissions and shall not exceed the general radiated emission limits in § 15.209. Tests to determine compliance with these requirements shall be performed using an appropriate input signal as prescribed in § 2.989 of this chapter.
(e) All emissions exceeding 20 microvolts/meter at 3 meters are to be reported in the application for certification.
(f) If the device provides for the connection of external accessories, including external electrical input signals, the device must be tested with the accessories attached. The emission tests shall be performed with the device and accessories configured in a manner which tends to produce the maximum level of emissions within the range of variations that can be expected under normal operating conditions.
(g) The frequency tolerance of the carrier signal shall be maintained within ±0.01% of the operating frequency. The tolerance shall be maintained for a temperature variation of −20 degrees C to + 50 degrees C at normal supply voltage, and for variation in the primary voltage from 85% to 115% of the rated supply voltage at a temperature of 20 degrees C. For battery operated equipment, the equipment tests shall be performed using a new battery.
(h) For cordless telephones that do not comply with § 15.214(d) of this part, the box or other package in which the individual cordless telephone is to be marketed shall carry a statement in a prominent location, visible to the buyer before purchase, which reads as follows:
Notice: The base units of some cordless telephones may respond to other nearby units or to radio noise resulting in telephone calls being dialed through this unit without your knowledge and possibly calls being misbilled. In order to protect against such occurrences, this cordless telephone is provided with the following features: (to be completed by the responsible party).
An application for certification of a cordless telephone shall specify the complete text of the statement that will be carried on the package and indicate where, specifically, it will be located on the carton.