[evlatests] Circularly polarized reflected lunar emission {External} {External} {External}

[Robert Minchin]

I think I sent this to Rick only yesterday:

The AMISR incoherent scatter radar operates over 430–450 MHz, so this would be pretty close to their band centre. They’re pretty powerful as well.

Robert

From: evlatests <evlatests-bounces at listmgr.nrao.edu> on behalf of Sergio Garza via evlatests <evlatests at listmgr.nrao.edu>
Date: Monday, November 13, 2023 at 7:36 PM
To: evlatests at listmgr.nrao.edu <evlatests at listmgr.nrao.edu>
Subject: Re: [evlatests] Circularly polarized reflected lunar emission {External} {External}
Would it be a possibility this is a lunar reflection of PAVE PAWS Radar
Systems and similar anti-ballistic missile early-warning systems?

Taiwan and China have their own versions but they're all based on and
similar to US military/Raytheon's system. Many of these systems have
frequency ranges between 420 - 450 MHz and pointed at the horizon and
higher.

Here's some specifications for PAVE PAWS:
https://spp.fas.org/military/program/track/pavepaws.htm

Here's the original environmental report with extra details although the
system (I believe) has since been upgraded:

https://apps.dtic.mil/sti/tr/pdf/ADA088320.pdf

There are several other and various systems around the world, all of
which always on. Presumably if this is the case, there are other
frequency ranges that reflect at different lunar orientations as well.

Sergio


On 11/13/23 6:08 PM, Ken Kellermann via evlatests wrote:
> Dave is correct.   At any given time it is not unlikely that some amateurs could be using this band for EME communication especially on a weekend and more especially when the moon is near perigee. However the BW for any individual signal would be only about 3 KHz for SSB and much less for CW or digital modes.  Amateur TV is allowed in this band but that would normally be line of sight.  I don’t think TV EME is feasible from any amateur station.
> Ken
>
> Sent from my iPad
>
>> On Nov 13, 2023, at 7:50 PM, David Schafer via evlatests <evlatests at listmgr.nrao.edu> wrote:
>>
>> The band 430MHz - 440MHz is allocated by the ITU for radio amateur operation and I recall this band being fairly popular for Earth-Moon-Earth (Moon Bounce) communication. I do not know about the possibility of these amateur stations being active most or all of the time. This type of communication certainly operates in a bandwidth << 1MHz.
>>
>> Dave
>>
>> -----Original Message-----
>> From: evlatests <evlatests-bounces at listmgr.nrao.edu> On Behalf Of Rick Perley via evlatests
>> Sent: Monday, November 13, 2023 5:02 PM
>> To: evlatests at listmgr.nrao.edu
>> Subject: [evlatests] Circularly polarized reflected lunar emission
>>
>> Our lunar observations often show reflected terrestrial RFI at certain times and frequencies.
>>
>> The data taken November 4 shows quite a spectacular example of this. I've looked, on a single ten-minute scan, for reflected circularly polarized emission in the frequency bands:  288 -- 352 MHz, and 384 --
>> 448 MHz.  The channelwidth was 1 MHz.
>>
>> Three channels showed remarkably strong emission (at about 1 Jy level):
>>
>> 437, 438, and 439 MHz.  No other frequencies showed anything. The typical rms noise is about 20 mJy.
>>
>> This is not local RFI -- it has to originate 'somewhere on earth'. Although I haven't yet checked every scan, the evidence strongly suggests it is on most of the time.
>>
>> Does anybody have any ideas?
>>
>> Rick
>>
>>
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