[RVRC] 70cm interference

[Marvin Bronstein]

Potential new interference to 70cm (420 ~ 450 MHZ) amateur* band.  Repeaters in Alabama, Georgia experiencing totally disabling conditions at some times.
Seems to be spreading around the world.




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Military radiolocation system to operate on 70 cm

As described in Schedule I of RBR-4, amateur usage of the 430-450 MHz (70 cm) band is on a no-protection, non-interference basis. Amateurs may not cause interference to nor be protected from interference from stations licensed in other services operating in that band. The same is true in the United States, and amateur operations on this band in a number of areas of the United States have power limits imposed on them in order to avoid interference to radiolocation services operated by the US military.

Industry Canada has informed Radio Amateurs of Canada (RAC) that it has authorized the Department of National Defence to use a digital system called Enhanced Position Location Reporting System (EPLRS) on these frequencies. The EPLRS system consists of mobile, fixed, transportable and airborne stations that use 5 MHz-wide spread spectrum channels to provide strategic telemetry information for military platforms. This authorization is on a no-protection, non-interference basis, which means that no new restrictions will be imposed on Canadian amateur operations in this band as a result.

Industry Canada has informed RAC that there is a slight potential for interference to amateur radio systems, typically in the form of a minor audible clicking noise. If Canadian amateurs encounter such interference, they are requested to report it to RAC at regulatory @ rac.ca. The information reported should include the geographical location, date, time, frequency and mode being used by the amateur station, and a description of the interference.

Questions or concerns regarding the planned implementation of EPLRS may be sent to regulatory @ rac.ca.

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 Tucson Arizona EPLIRS 

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We have experienced the spread sprectrum signal of this system in the repeater areas of the band. It is quite the irritant for analog 70cm repeater owners.

It does not seem to bother the D-STAR repeaters at all. 

The military has indicated nothing about any interference from the amateur side of the equation. The Tucson area has been "enjoying" this signal for about two-ish years now.

Tnx,
AK7AR 

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There's a similar system operating in the Washington DC area. Just as Industry Canada noted, the effect is a lot of frequent "clicking" in a typical FM passband. If you put a spectrum analyzer into peak hold mode over the 420 - 450 MHz band, it will build up a good picture of the individual wideband carriers after 15 minutes or so. The noise is definitely annoying when trying to monitor amateur satellites and other weak signals. Amateurs are secondary to military radiolocation in this band, but there's no allocation for military comm links, so if this system is being used for communications, then we may have some potential protection (in theory at least...).

73 de W4JE