VHF low band DX
Via UK based SDR receiver
See below for the result of my research, 40.875 MHz, 40.900 MHz, 40.925 MHz and 40.950 MHz are allocated to on-site paging systems in Spain. Power output is limited to 5 watts. Channel bandwidth is 25 kHz.
40 MHz paging multitone paging activity noted at 1745 UTC, tuned in again at 1752 UTC and there are various paging (
sounds like POCSAG, likely narrower deviation variant...most signals are 8.5 kHz bandwidth, 9 kHz bandwidth...10 kHz at the most) signals.
40,875 MHz 40875kHz paging 40875 FM is apparently assigned to 5 watt on site paging services, including hospital paging pager systems. Internet searching resulted in me finding a Spanish language scanner forum focused on Spain itself and found this (machine-translated)
"Hello,
I am receiving a signal that seems to me to be POSAG at 40.875 Mhz, I do not usually scan these frequencies because I thought they had no activity, looking at CNAF I read: "Radio search in closed areas 5W", Could it be a search for a hospital or center nearby?. And I tried using the PDW program but without results, although I have never had results with this program, I may have it configured incorrectly. Let's see if someone can confirm that they also receive it and if they can decode it.
I am in the Mostoles area (Madrid).
Greetings
Santiago"
Original Spanish
"Buenas,
Estoy recibiendo una señal que me parece POSAG en 40,875 Mhz, no suelo escanear por estas frecuencias porque creia que no tenian actividad, mirando en CNAF leo: "Radio busqueda en recintos cerrados 5W", ¿Podrian ser buscas de algun hospital o centro cercano?. E intentado usar el programa PDW pero sin resultados, aunque no he optenido nunca resultados con este programa, puede que lo tenga mal configurado. Haber si alguien puede confirmar que tambien lo recibe y si lo puede decodificar.
Estoy en la zona de Mostoles (Madrid).
Saludos
Santiago"
Another reply to the same thread indicated that it is actually not POCSAG at all, not even POCSAG 512, but Multitone Paging:
https://www.sigidwiki.com/wiki/Multitone_PagingCNAF is almost certainly "Cuadro Nacional de Atribución de Frecuencias"
In Spanish:
UN-12 Radiobúsqueda en 40 MHz.
Los canales cuyas frecuencias se indican a continuación se destinan exclusivamente para el servicio de radiobúsqueda en recintos cerrados y en sus inmediaciones:
40,875 MHz 40,900 MHz
40,925 MHz 40,950 MHz
La potencia radiada aparente (p.r.a.) máxima será de 5 W y la anchura de banda de emisión máxima la correspondiente a una canalización de 25 kHz.
UN-13 Aplicaciones ICM en 40 MHz
And in English:
UN-12 40 MHz Paging.
The channels whose frequencies are indicated below are intended exclusively for paging services in enclosed areas and in their immediate vicinity:
40.875 MHz 40.900 MHz
40.925 MHz 40.950 MHz
The maximum apparent radiated power (e.r.p.) will be 5 W and the maximum emission bandwidth will be that corresponding to a 25 kHz channel.Source:
https://www.boe.es/buscar/act.php?id=BOE-A-2021-21346Also of interest is this:
UN-7 Land Mobile Service on 27 MHz.
The channels whose frequencies are indicated below are intended exclusively for the land mobile service. Power output limited to 20 watts.
27.505 MHz
27.515 MHz
27.525 MHz
27.535 MHz
27.545 MHz
27.555 MHz
27.565 MHz
27.575 MHz
27.585 MHz
27.595 MHz
27.845 MHz
27.855 MHz
The maximum apparent radiated power (ERP) will be 20 W and the maximum emission bandwidth will be that corresponding to a 10 kHz channel.
UN-8 Low power applications at 30 MHz.
Frequencies reserved for remote control and remote measurement outside the "ICM" bands under the consideration of common use:
29.710 MHz 29.900 MHz 30.125 MHz
29.720 MHz 29.910 MHz 30.135 MHz
29.730 MHz 29.920 MHz 30.145 MHz
29.740 MHz 29.930 MHz 30.155 MHz
29.750 MHz 29.940 MHz 30.165 MHz
29.760 MHz 29.950 MHz 30.175 MHz
29.770 MHz 29.960 MHz 30.185 MHz
29.780 MHz 29.970 MHz 30.195 MHz
29.790 MHz 29.980 MHz 30.205 MHz
29,800 MHz 29.990 MHz 30.215 MHz
29.810 MHz 30.035 MHz 30.225 MHz
29.820 MHz 30.045 MHz 30.235 MHz
29.830 MHz 30.055 MHz 30.245 MHz
29.840 MHz 30.065 MHz 30.255 MHz
29.850 MHz 30.075 MHz 30.265 MHz
29.860 MHz 30.085 MHz 30.275 MHz
29.870 MHz 30.095 MHz 30.285 MHz
29.880 MHz 30.105 MHz 30.295 MHz
29.890 MHz 30.115 MHz -
The first three channels, frequencies 29.710 MHz, 29.720 MHz, and 29.730 MHz, will be used primarily for leisure and recreational applications including voice transmissions, i.e., non-industrial uses and non-professional applications.
The separation between adjacent channels is 10 kHz. The maximum output power of the equipment will be 500 mW and the maximum authorized emission limit will be 100 mW.
UN-2 27 MHz Paging Radio.
The frequencies listed below are intended exclusively for paging services in enclosed areas and their immediate vicinity. Just like the 40.875 MHz, 40.900 MHz, 40.925 MHz and 40.950 MHz allocation, these frequencies are on site pager paging systems, including hospital pagers, 25 kHz bandwidth limit.
26.200 MHz
26.350 MHz
26.500 MHz
27.425 MHz
27.450 MHz
27.475 MHz
The maximum apparent radiated power will be 5 W and the maximum emission bandwidth will be that corresponding to a 25 kHz channel.
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