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Topics - alleycat

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31
HF Mystery Signals / Amateur mode 7040kHz PSK variant?
« on: March 30, 2021, 0143 UTC »
I'm seeing 2-minute long narrowband (roughly 75 Hz wide?) digital QSOs on 7040 kHz that I can't identify (apparently nothing similar at SigIdWiki). I think it might be some variant of PSK based on the resources at http://www.w1hkj.com/modes/index.htm, but I ran through all these modes in MultiPSK to no avail. Audio at https://www.lutins.org/temp/radio/7040_digi.mp3 waterfall as shown below. Thanks for any assistance!

32
I'm currently (24 March @ 0030z) monitoring 4300 kHz and hearing a series of very short pips at a 4-second interval. Folks on the UDXF discussion group at groups.io have reported this phenomenon on a large number of HF frequencies being audible around the world (including SDRs in North America, Austria and China). Audio clip at https://www.lutins.org/temp/radio/pips.mp3; waterfall as follows:

33
HF Mystery Signals / 7040 kHz - 5 second bursts, 150 kHz bandwidth
« on: March 14, 2021, 0207 UTC »
I'm familiar with most common amateur digital modes, but tonight I'm hearing (a new?) one on 40m from several stations that doesn't appear to be represented at SigIdWiki. Audio at https://www.lutins.org/temp/7042.mp3; waterfall thus:

34
HF Mystery Signals / Resources to ID VHF/UHF sigital signals?
« on: February 20, 2021, 1452 UTC »
Sorry if this is a bit off-topic. I recognize & respect that this is a forum for ID'ing HF signals. Can anyone point me to a similar forum for assistance in identifying unknown digital signals above 30 MHz not represented at SigIDWiki? Thanks!

P.S. If anyone *does* want to take a crack at it here, I'm hearing an approximately 15 kHz wide intermittent signal on 72.1 MHz that lasts roughly 2-10 seconds and sounds like a pager, but definitely is not POCSAG - waterfall at https://www.lutins.org/temp/701.jpg and audio at https://www.lutins.org/temp/701.m3. Promise I won't pester y'all with above-30 MHz signals again!

35
I just got ADS-B software up and running on my RPS1A. I notice route discrepancies between the software it uses (Virtual Radar Server) and other information sources. For example, for Jetblue flight 634 (7 Feb 2021), I observe the following:
 - Virtual Radar Server (Ver. 2.4.4.36598) identifies origin as San Francisco & Destination as Boston
 - FlightRadar iPhone app identifies origin as Port-Au-Prince & Destination as New York (JFK)
 - FlightAware.com identifies origin (Port-Au-Prince, Haiti) & Destination (Syracuse, NY) [these appear to be correct based on the flight track]

So why the discrepancies, and who do I believe? Thanks and happy monitoring!

36
Utility / Military? 6855 kHz USB (voice) starting 2323z 26 Jan 2021
« on: January 27, 2021, 0014 UTC »
I can find no record of 6855 kHz being an active mil freq, but heard what sounds like mil air traffic at 2323z and again at 2357z. Recordings of first message at https://www.lutins.org/temp/6855_1.mp3 and second message at https://www.lutins.org/temp/6855_2.mp3. Transcript (best as I can discern) of first message is as follows (M = male; F = female):

M: [Sevine ?] [Sevine ?] Speedair zero one, Speedair zero one
F: Speedair zero one [flight ?] forward go ahead
M: Charlie three five Charlie three five, Golf two three Golf two three, [chest ?] now zero two zero, zero two zero
F: Charlie three five Charlie three five, Golf two three Golf two three, zero two zero, zero two zero
[beep]
M: Roger Roger

37
Thanks Token for coming to my rescue last time - here's another one that doesn't bear any resemblance to anything on SigIDWiki: Every few minutes on 6961 kHz last night I observed two identical bursts in short succession of what appears to be a very brief 24 (?) tone signal. Audio at http://www.lutins.org/temp/6961.mp3 and waterfall at http://www.lutins.org/temp/6961.jpg. Thanks again in advance for your expertise!

38
HF Mystery Signals / LINK- not 11?
« on: January 24, 2021, 0134 UTC »
Are there other LINK- signals besides LINK-11? I hear a 2.8 kHz-wide signal booming in perennially on 6942 kHz (upstate NY, U.S.) that sounds like LINK-11, but the pulses are very regular. The example on SigIDWiki has long bursts between regular short pulses, while the recording on FirstToken's YouTube channel at https://www.youtube.com/watch?v=__-rtLRQUhg is characterized by a 'lilting' pulse. An audio example of what I'm hearing is posted to https://www.lutins.org/temp/6944_kHz.mp3, with a waterfall capture at https://www.lutins.org/temp/6944_kHz.jpg. Thanks for enlightening me!

39
Asian language talk show booming into upstate NY - nothing turns up in a search of this frequency, and this appears to be outside the standard broadcast bands. I'm using SDR Console, and judging by reception via networked radios, reception is strongest in northeastern North America. Can someone ID this? Thanks!

40
Decent signal with moderate fading in central New York State. "Growling voice" ID was unintelligible to me. Playing rock music (I don't recognize any of the tunes so far

Confirmed - ID @ 0258z. Steely Dan @ 0300z.

41
HF Mystery Signals / 6505 kHz digital signal - mixed modes
« on: December 31, 2020, 0355 UTC »
I can never seem to find a good match at SigIDWiki for the stuff I hear :P  Closest match appears to be "Saab Grintek MHF-50 MFSK Modem" but that's a South African mode and I don't think that's what I'm receiving loud & clear in NE North America. Going for a while not at 0350z on 6505 kHz - approximately 2.5 kHz-wide digital signal that cycles between several different modes; one sounds like RTTY, another has multiple tones. Audio sample at https://www.lutins.org/temp/6505.mp3 and waterfall at https://www.lutins.org/temp/6505.JPG. Any help appreciated!  73 de KC2KLC

42
...but I can't find anything that looks remotely close in the READ ME for this group nor at www.sigidwiki.com. Hear these all the time all over the HF band - waterfall at https://www.lutins.org/temp/waterfall.jpg  &  audio sample at https://www.lutins.org/temp/audio.mp3

43
Utility / GMDSS Station ID #s?
« on: November 29, 2020, 2332 UTC »
Are the station IDs for the GMDSS DSC stations on HF (2187.5, 4207.5, 6312.0, etc.) the same as the IDs used on longwave DGPS stations? I've been monitoring digital signals for decades, but recently discovered I'd missed the easy-to-log HF GMDSS signals - so I fired up DSCDecoder, and I'm seeing short "health" messages with Station IDs, but one of the IDs seem to be from an Asian station, which is unlikely given propagation at the time. Any advice regarding this mode is appreciated! 73 de KC2KLC

44
I just obtained a SDR-Kits patch antenna, and am decoding (using JAERO) a number of Inmarsat signals from 1545.015 through 1545.205 MHz. I see a lot of info online about these birtds, but none of the positions makes sense. I'm at roughly 75 degrees west, 42 degrees north, and the signals are strongest when I'm pointing south. (I'm on the west side of my house, so I have a clear shot south- west-north but anything at all east would presumably be blocked by the house.) Can anyone tell me for certain which Inmarsat I'm hearing? Thanks and 73 de KC2KLC!

45
HF Mystery Signals / Natural phenomenon?
« on: November 29, 2020, 0211 UTC »
I'm guessing this is a natural HF phenomenon (meteor?), but I suppose it could be a propagation check of some kind? When I used to monitor radio in the traditional fashion, I'd hear a "swoop" every once in a while - sounded like a carrier sweeping up (and I think it's always up) through the frequency I was monitoring - and once I started SDR'ing, I verified my hunch visually:

Anyone know for certain what this is? Thanks & 73 de KC2KLC

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