HFU HF Underground
Loggings => HF Beacons => Topic started by: Finman on August 15, 2021, 1411 UTC
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I'm hoping someone can shed some light on how HF beacon frequencies are chosen.
I see 4mhz, 6mhz and 8mhz freq's with some beacons grouped around a center freq, (4094, 4096, etc..). Just wondering about the how and why regarding freq selection.
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Hello,
An excellent question!
I can't answer for other operators, but when I have operated beacons in the past, frequency selection was determined by a number of factors...
- Availability of space for the antenna (determines the band used).
- Clear frequencies not listed as emergency or known to be critical for life, military or business communications.
- Geographical location.
- Will the signal be NVIS or not.
- Power used.
- Optimum times of operation for me vs. what the HAP charts determine.
I suspect there's two philosophies about this:
- Scientific (like I do) and
- Toss it up and see what happens ;D
73's
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I'm thinking "Clear frequencies" would be my first choice and after that, most likely, "there are other beacons near this freq, I'll put one up close by" or something like that.?
Hello,
An excellent question!
I can't answer for other operators, but when I have operated beacons in the past, frequency selection was determined by a number of factors...
- Availability of space for the antenna (determines the band used).
- Clear frequencies not listed as emergency or known to be critical for life, military or business communications.
- Geographical location.
- Will the signal be NVIS or not.
- Power used.
- Optimum times of operation for me vs. what the HAP charts determine.
I suspect there's two philosophies about this:
- Scientific (like I do) and
- Toss it up and see what happens ;D
73's
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Hi,
My list was not meant by order of importance, just a "checklist" ;)
Hobby beacon clusters can work; the Part-15 (RSS210 in .ca) HiFER's do this. The downside is it leads to "beacon cliques" where only a few-Hz-of-centre are scanned and beacons operating outside that area are "shunned". The cool thing about a PiFER beacons is they can appear anywhere at any time, so listeners keep scanning the entire band.
73's
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The 4.09565 KHz frequency for DW was selected to achieve good propagation with low power in a frequency band that is little used for maritime comms. Crystals are cheap and 4mhz is a popular frequency range for a number of beacons.
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Thanks for the replies and info. Very interesting. 8)
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I'd guess that originally they spring up where they are because of the availability of cheap crystals :-)
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I'd guess that originally they spring up where they are because of the availability of cheap crystals :-)
Agree!! Amazon sells 4.096 MHz and other crystals extremely cheap!
https://www.amazon.com/Glarks-Oscillator-Resonators-Assortment-11-0592MHz/dp/B07F63F6DR/ref=sr_1_2?dchild=1&keywords=4.096+crystal&qid=1629558706&sr=8-2
https://www.amazon.com/IIVVERR-4-096MHz-Crystal-Oscillators-osciladores/dp/B07LF95ZVW/ref=sr_1_1?dchild=1&keywords=4.096+MHz+quartz+crystal&qid=1629558972&sr=8-1
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Ahhhh, too easy when one can overthink the heck out of it like a good EE ;D ;D ;D
73's
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MY own 4096 cluster (it would become after 1997 with the implanting of the "Hexie" beacon in JTNP Dec. 1997: The original "Boondocks Beeper" in a canyon in middle MarinCounty just on a gel-cell bi-monthly replaced when possible... it was copied fine near San Diego in 1988. The ICM computer xtals were obtained at the Los Altos Hills Ham/Computer flea market in 1987
for $1 for a bag of ten, so began the first 4096 cluster which was designed for science and propagation monitoring as well as for its "musical wind-chime" ("artistic") thrust for it's sound - of course the ionosphere added a huge twist to its sound daily - mag. storms made the cluster go crazy with rapid fading, thus it could also indicate disturbed cx. on the Solar Maxx period of 2000-2001 and onward. (The Marin dashers on 4096 stopped about 1989 and no 4096 activity from myself occurred until Hexie JTNP -Dec. 1997 -- or some early testing of the Hexie beacon from near Lone Pine in Autumn 1997) ... and I did not know another neat dude was doing 4096 beacons until late 1995. (also responsible for Windy and maybe DW... ;-) ...).
So it was a cheap bag of 4096 crystals at a ham/computer flea market was the reason for my own 4096-cluster a long time ago now (those IC oscillators on 4096 available today did not exist back then, and the transmitters were usually NPN transistor based (2N2222A/2N3904/etc.) xtal oscillators.
Sometimes beacon implanters only listen to their own unit, or maybe another person's just for propagation checking, but indeed, there are un-told reasons for the existence of beacons - the sum-total power levels of transmission of all A1A beacons over time (and today) do not even exceed a the RF output of one 43m pir8 transmitter on any given weekend, and most ops. deem them harmless if not a bit naughty... oh well there are worse things in life that are naughty... in gov't too... MB
BTW -- note DW's freq. is near the former Wind beacon back long ago. good job! MB
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One other note: Just WHY was the first original "4096 Cluster" Hexie beacon (with 1 sec dash - 4011 keyer/xtal. osc. to a 2N4427 p.a. based xmtr.) NAMED Hexie? !) 4096 is a hexidecimal number or something like that (2 to the power of 12) 2,4,8,16,32,64,128,256,512,1024,2048,4096... seems familiar, right...
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and 2) !!! It was in lovely view of the HEXIE MOUNTAINS looming to the SW and south full of Pinyon Pines in contrast to our rocky bouldery high desert topography replete with lovely Joshua Trees and Creosote bushes in yellow bloom!
..."Let's name it 'Hexie' " said the inventor of the internet TCP/IP etc. etc. -- speaking to me in campfire light and good beer, on the evening after we had implanted Hexie on 4096.25 kHz (21 Dec. 1997) after going to a hardware store in 29Palms, CA and obtaining the antenna wire and parts the days beforehand... he brought the flexible panels and ASC charge controllers, and I had the tested xmtr. in the camper-van at White Tank CG/site 10/11... the third xmtr. made in Lone Pine of two others made in Marin County for the former Marin beepers near 4096 (ICM xtals, recall?).
God it was SO FUN! 73 de MB
oh yeah - approaching airliners to Palm Springs airport passing low overhead made the Hexie Beacon 2.5 miles distant do the Doppler-shift fading pattern familiar to FM DXers... plenty of short NVIS skip on those near solar max nights... at White Tank CG were we met many times to fix the darn thing... etc. - good history MB
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(also responsible for Windy and maybe DW... ;-) ...).
"inventor of the internet TCP/IP etc. etc. " told you this over the campfire too?
BTW -- note DW's freq. is near the former Wind beacon back long ago.
4096 is a decimal number.
Any transmitter's frequency on or near 4096 KHz is near some other beacon that is or was formerly transmitting on or near 4096 KHz. Your own Coxie drifts from 4095.8 to 4096.1 in the course of a day so we should assume it is also related to the former Wind beacon?
Digital devices used 4096 KHz as a clock frequency long before there were IC Oscillators; the common crystal frequency exists exactly because it is easily divisible by digital systems that will represent it in binary or hexidecimal formats.
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(also responsible for Windy and maybe DW... ;-) ...).
Terribly wrong old chap. DW is collecting temperature data for our Desert Weather group. We have no idea who owns Windy