LPD433 (low power device 433 MHz) is a UHF band in which licence free communication devices are allowed to operate. The frequencies correspond with the ITU region 1 ISM band of 433.050 MHz to 434.790 MHz, and operation is mainly limited to CEPT countries. The frequencies used are within the 70-centimeter band, which is traditionally reserved for higher power amateur radio operations in most nations worldwide.
LPD hand-held radios are authorized for license-free voice communications use in most of Europe using analog frequency modulation (FM) as part of short range device regulations, with 25 kHz channel spacing, for a total of 69 channels. In some countries, LPD devices may only be used with an integral and non-removable antenna with a maximum legal power output of 10 mW.
Voice communication in LPD band was introduced to reduce the burden on the eight PMR446 channels over shorter ranges (less than 1 km) . In some EU countries voice is not allowed over LPD.
LPD is also used by wireless instruments and digital devices such as car keylocks.
Usage by country
ITU Region 1 (Europe)
United Kingdom
In the UK, LPD433 equipment that meets the respective Ofcom Interface Requirement can be used for model control, analogue/digitised voice and remote keyless entry systems. There is significant scope for interference however, both on frequency and on adjacent frequencies, as the band is far from free. The frequencies from 430 to 440 MHz are allocated on a secondary basis to licensed radio amateurs who are allowed to use up to 40 W (16 dBW) between 430 and 432 MHz and 400 W (26 dBW) between 432 and 440 MHz. Channels 1 to 14 are UK amateur repeater outputs and channels 62 to 69 are UK amateur repeater inputs. This band is shared on a secondary basis for both licensed and licence exempt users, with the primary user being the Ministry of Defence.
Ofcom, together with the R.S.G.B. Emerging Technology Co-ordination Committee have produced guidelines to help mitigate the side effects of interference to an extent.
Other European countries
European remote keyless entry systems often use the 433 MHz band, although, as in all of Europe, these frequencies are within the 70-centimeter band allocated to amateur radio, and interference results. In Germany, before the end of 2008, radio control enthusiasts were able to use frequencies from channel 03 through 67 on the above chart for radio control of any form of model (air or ground-based), all with odd channel numbers (03, 05, etc. up to ch. 67) as read on the chart, with each sanctioned frequency having 50 kHz of bandwidth separation between each adjacent channel.
ITU Region 2 (America)
In ITU region 2 (the Americas), the frequencies that LPD433 uses are also within the 70-centimeter band allocated to amateur radio. In the United States LPD433 radios can only be used under FCC amateur regulations by properly licensed amateur radio operators.