HF pagers

From HFUnderground

Revision as of 19:22, 7 May 2020

List of known pager paging data link data systems remote control radio control in the 26-28 MHz CB or 11-meter frequency range.

See also the Remote Control FCC Part 95 Class C Page

History and Background Information

In the United States, Part 95 of the FCC rules allow use of the six 26 MHz/27 MHz RC frequencies for high power control, supervision, data link and "attention getting" devices. Mean (average) power limit is 4 watts on 26.995 MHz, 27.045 MHz, 27.095 MHz, 27.145 MHz, 27.195 MHz and 25 watts on 27.255 MHz. The majority of high power systems use 27.255 MHz - however some do transmit 4 watts on 26.995 MHz.

26.995, 27.045, 27.095, 27.145 and 27.195 MHz are all RC exclusive frequencies and voice transmissions are not allowed. However, these frequencies are often used as a "secret channel" or "A channel" by CBers and freeband operators. 27.255 MHz is CB channel 23 and data transmissions must co-exist with voice traffic on the same frequency. This likely explains the 25 watt power limit on 27.255 compared to the 4 watt power limit on the original 5 R/C channels.

The original five RC frequencies can trace their roots back to the origins of the CB radio service - when the band was first allocated as 26.96 MHz to 27.23 MHz the FCC band plan included five model control/data channels 35 kHz from the band edges with 50 kHz spacing between each RC channel. 26.995 MHz is 35 kHz above the bottom of the band (26.960 MHz) and 50 kHz away from the next R/C channel (27.045 MHz). 27.195 MHz is 35 kHz below the original edge of the band (27.230 MHz) as well. The 50 kHz spacing was in line with the capability of remote control systems in the 1950s. 27.255 MHz was originally used for paging and kept that use even after being designated as CB channel 23.

There is also extensive Part 15 usage of these frequencies for low-power R/C model control. Higher power levels are used by professional grade systems. Most higher-end remote control/radio control devices use the 72 MHz and 75 MHz frequencies (where 0.75 watts is the maximum power output) or the unlicensed 2.4 GHz band. However, there remains considerable use of 26-27 MHz for data link, remote sensor monitoring and other similar purposes due to the high power available for unlicensed users and excellent propagation characteristics for point-to-point data networks. Some vendors are now offering systems that operate on the 5 VHF MURS frequencies for data link purposes (although these are covered under the Part 95 rules as well, they are not part of the RCRS under FCC Part 95).

There appears to be extensive use of the 26 to 28 MHz band for paging, data link networks and other non-voice purposes in Europe and Russia.

Frequency List

Linear Pro Access XT-1 transmitter operating on 27.255 MHz with 10 watt transmit power, can be used as part of a long-range data link, remote sensor and remote system control systems along with companion receiver(s) and even other transmitters in the same network.

View of the PCB for the XT-1 27 MHz transmitter, note the crystal for frequency control. This device transmits a 10 watt FSK signal on 27.255 MHz (USA model) or a 4 watt FSK signal on 26.995 MHz (Canada model).

Keywords:

26 MHz pager 27MHz paging 27.255 MHz data link 27 MHz data transmitter 27007 kHz 27255 kHz FCC Part 15 Part 95 POCSAG 26.995MHz 27.045MHz 27.095MHz 27.145MHz 27.195MHz 27.225MHz 27.235MHz 27.245MHz 27.255MHz 27.270MHz 27.12 MHz ISM 27MHz band paging Long Range Systems 467.750 MHz RCRS Remote Control Radio Service 25 watt 27.255 data 27MHz data link 100mw low power data link IOT low frequency 900 MHz 151.820 MHz 151.880 MHz 151.940 MHz 154.570 MHz 154.600 MHz MURS data datalink 154MHz 151MHz license free long range 10 watt FSK signal Linear Systems WAVE lightning detector remote monitoring link 27MHz CB radio frequency list HFUnderground Community Audio Distribution Service CADS Wireless Public Address System WPAS 27.995 MHz 26.000 MHz 26MHz paging pager EU harmonized radio bands allocation 27.5 MHz 27500 kHz 27.905 MHz 10mw 1w 1 watt 27.915 MHz 27.965MHz 27.975 MHz 27.985 MHz 27.555 MHz international fixed service 26955 26.955 26,955 26,995 27,045 27,095 27,145 27,195, 27,225, 27,255 11_meter freeband 11 meter band 30 MHz band 29 MHz band 26 MHz band are 10 meter radios illegal freeband frequencies how do I use a CB radio police frequencies driftnet fishnet beacon radiobuoy buoy transmitter 1.6-4 MHz 26-28 MHz 26-30 MHz radio beacon 11m CB repeater 11 meter repeater MURS repeater 151.880 151.820 151.940 156.7 167.9 173.8 154.57 154.600 MHz crossband repeater 27.095 MHz 10mw 100mw 1km range IoT 27 MHz Part 95 Part 15 RCRS Radio Control Radio Service data link NTX0-27.095-5-100MW NTX0-27.095-5-10MW HF NBFM TRANSMITTER NARROW BAND TRANSMITTERS ETSI EN 300 220-3 (radio) EN 301 489-3 (EMC) and FCC 95.201-95.225