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spankmeister posted:yeah eevblog owns my only problem is that the guy Dave likes to ramble a bit, stretching a 10 minute video into 40 minutes. i sort of gave up on dave's lab videos when he posted a rant about his ~ultra precision~ current source didn't work like in the datasheet when he built it on a loving solderless breadboard double sided copper clad board and a dremel or bust,
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# ? Feb 23, 2014 22:51 |
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# ? May 13, 2024 07:03 |
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good thing i hooked up an SWR meter this time around so I could see that i had !!!infinite SWR !!! and debugged it to not one but two broken conductors in the dual band mag mount i was using fixed, see if we can't find some more birds up there tonight turns out this Comet dual band antenna happens to have perfect SWR at 436, the satellite sub-band 2 meter kind of sucks tho =/ Next chance is about 20 minutes when VO-52 passes. This is a SSB/CW bird, so it is for the more hardcore fellas, but we have two decent passes this evening. Jonny 290 fucked around with this message at 00:06 on Feb 24, 2014 |
# ? Feb 24, 2014 00:03 |
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success again, receive only, but i brought out the 2 meter radio got a video of some signals from the satellite processing now
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# ? Feb 24, 2014 00:48 |
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i barely know what's going on in this thread but anyway
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# ? Feb 24, 2014 01:23 |
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Cold on a Cob posted:i barely know what's going on in this thread but anyway same
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# ? Feb 24, 2014 01:26 |
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Cold on a Cob posted:i barely know what's going on in this thread but anyway s a m e
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# ? Feb 24, 2014 01:26 |
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fun this afternoon: receiving the VO-52 downlink passband with my 2 meter radio now, one thing to understand about birds of this type is that they're transponders. They listen on a wide frequency range and retransmit everything they hear exactly as they hear it, in a little slice of another band. This means that A: there's a total power budget, so if you put out a stronger signal, you'll be retransmitted stronger and you're using more satellite power - this is rude B: several people can use the satellite at once, on different frequencies Transponders are usually inverting, which means that an upper sideband signal will come out as lower sideband and vice versa. The downlink is a mirror of the uplink, in a different band - shift your uplink frequency up and the downlink frequency will move down. transponders are more efficient and sensitive than FM style repeater satellites, because the signal stays as RF and is directly converted, whereas the other style receives it all the way to audio, then retransmits that audio. VO-52's transponder listens for earth stations between 435.225 and 435.275 MHz. It then shoves those down a 2-meter pipe back down to earth between 145.925 and 145.875 (not backwards, this nomenclature shows that it's an inverting transponder). In addition, there are beacon signals that the satellite continually transmits - the vid starts with us receiving one of those beacons' CW signal https://www.youtube.com/watch?v=qQbffGIwRyI
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# ? Feb 24, 2014 01:32 |
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i need to go get my ham license.
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# ? Feb 24, 2014 01:35 |
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Fax Sender posted:i need to go get my ham license.
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# ? Feb 24, 2014 07:23 |
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i dont mean to be rude or whatever but what or who stops you from just hammin' things up w/o taking some lame test from The Man?
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# ? Feb 24, 2014 08:24 |
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well I assume they have radio police that randomly listen in to make sure ppl aren't using ham for commercial purposes, also you have to register a call sign so if you broadcast with a fake one or without one you get hauled off to radio jail
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# ? Feb 24, 2014 08:38 |
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Nobody will talk to someone without a call sign anyway, it's the first thing you get asked for so you wouldn't get very far
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# ? Feb 24, 2014 08:43 |
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longview posted:Nobody will talk to someone without a call sign anyway, it's the first thing you get asked for so you wouldn't get very far can i just make one up?
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# ? Feb 24, 2014 08:44 |
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dibs on PU55Y
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# ? Feb 24, 2014 08:45 |
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Silver Alicorn posted:dibs on PU55Y SP3RG
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# ? Feb 24, 2014 08:48 |
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rotor posted:can i just make one up? Probably, there's always going to be somebody checking the lists to see if it's legit, this can be fun if your call sign isn't on the lists yet. Calling B0OB
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# ? Feb 24, 2014 11:58 |
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do you just have to take a test to get a ham radio license. basically i'm thinking of not actually messing with radios but getting a ham license and telling my wife that only licensed radio operators get to tune the car radio
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# ? Feb 24, 2014 15:07 |
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longview posted:Probably, there's always going to be somebody checking the lists to see if it's legit, this can be fun if your call sign isn't on the lists yet. steal one off someone major jokes when they start talking to you
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# ? Feb 24, 2014 15:09 |
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An SWR meter is pretty much just a directional wattmeter that can bet switched from forward to reverse. loled at iambic pentameter tho Kevin Mitnick P.E. posted:do you just have to take a test to get a ham radio license. basically i'm thinking of not actually messing with radios but getting a ham license and telling my wife that only licensed radio operators get to tune the car radio yeah theres no presentation or demo or essay questions, pass the multiple choice, get a thing in the mail
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# ? Feb 24, 2014 15:37 |
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Kevin Mitnick P.E. posted:do you just have to take a test to get a ham radio license. basically i'm thinking of not actually messing with radios but getting a ham license and telling my wife that only licensed radio operators get to tune the car radio i'm pretty sure that's what they call "a dad joke", but i giggled
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# ? Feb 24, 2014 15:40 |
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Kevin Mitnick P.E. posted:do you just have to take a test to get a ham radio license. basically i'm thinking of not actually messing with radios but getting a ham license and telling my wife that only licensed radio operators get to tune the car radio i loled
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# ? Feb 24, 2014 15:45 |
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dad jokes best jokes also i challenge anyone that says you can't make dad jokes if you're not a dad, you just have less people to torture with them e: nuff said, i don't want to derail this awesome thread
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# ? Feb 24, 2014 15:46 |
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Yall ask "what would happen if you just get on the air and started spamming poo poo" James R. Winstead, KD5OZY shares your curious nature http://www.arrl.org/news/view/fcc-proposes-to-fine-texas-radio-amateur-7000-for-malicious-interference quote:According to the NAL, released February 19, an agent from the Commission’s Dallas Office on January 21 used direction-finding techniques to positively identify the source of the interfering transmissions as Winstead’s address. After monitoring the transmissions from the station for about a half-hour, the agent heard Winstead, an Amateur Extra class licensee, “replay multiple times short sentences or conversations that had just been transmitted, and occasionally speak the word ‘George.’”
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# ? Feb 24, 2014 15:52 |
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there's an shall we say "unlicensed amateur radio enthusiast" near my moms place and whenever he's transmitting i can hear it over my moms DECT phone. e: thinking about reporting his rear end, i really could not give a poo poo about radio pirates if they have their poo poo together but this dude clearly doesn't have his poo poo together e2: i occasionally pick him up on my phone's earbuds whenever there is no music playing. also when i was still living there i picked him up on my (very very crappy) desktop mic spankmeister fucked around with this message at 16:03 on Feb 24, 2014 |
# ? Feb 24, 2014 15:58 |
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This thread rules Johnny, What do you guys think about the antennas that pop out of genetic algorithms http://en.wikipedia.org/wiki/Evolved_antenna All of the examples in the article looked small and therefore were for short range communication I guess, has anyone tried to make crazy shaped short wave antenna with one of these algorithms? It would be pretty awesome to drive by some dudes rural property and see something that looks like a giant modern art sculpture but in reality its an antenna
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# ? Feb 24, 2014 16:13 |
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ADINSX posted:This thread rules Johnny, Short answer: very legit. I do a lot of antenna modeling and sort of use genetic algorithms to evolve and tune them. Take a couple parameters, wiggle them up and down programatically and test it at each iteration. When you find something good, move on to other variables. http://hamsoft.ca/pages/mmana-gal.php more greybeard software with ancient libraries and UI. works tho. wish it was threaded =/
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# ? Feb 24, 2014 16:17 |
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anybody know any good books on the history of this poo poo? after reading that big ol' PSK post now i wanna see how this poo poo evolved into cell phones
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# ? Feb 24, 2014 17:12 |
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psk31 came after cell phones
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# ? Feb 24, 2014 17:13 |
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Silver Alicorn posted:psk31 came after cell phones
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# ? Feb 24, 2014 17:16 |
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my stupid brain cant grok any of this but i its cool seeing people who know about it do stuff
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# ? Feb 24, 2014 17:37 |
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Werthog 95 posted:anybody know any good books on the history of this poo poo? after reading that big ol' PSK post now i wanna see how this poo poo evolved into cell phones cell phones (GSM) use a modulation form that's pretty similar to PSK, it's called GMSK and it's not a linear modulation so it's closer to FM it's basically frequency shift keying with a specially chosen ratio of 1 and 0 frequencies that changes frequency slowly instead of rapidly (fast frequency changes = wide bandwidth), the demodulator is more complicated than straight FSK but I don't think it's much more complicated than the PSK demodulator except it's harder to build because the carrier frequency is higher in addition to that, there's a channel equalizer system to prevent reflections from interfering too much (each packet contains a certain set of bits that can be analyzed in real time to correct for reflections), a very efficient vocoder, encryption, time division and frequency division multiplexing (mobiles communicate in time slots that are assigned by the base station and also change frequency several times a second) there's also the roaming system where cells listen to nearby cells channels to handle the handover D-Star radios use the same kind of GMSK modulation at similar bitrates, but in D-Star they simplified the modem design by making an audio-frequency GMSK signal and then wrapping that in a normal FM carrier, I think the main attraction is to make it cheaper and easier to retrofit older designs with a DV mode D-Star also doesn't have any of the channel equalization (it cant because it can't see the actual FM signal on the air), nor does it have time division to handle multiple users per channel E: to put it in ham radio terms, GSM is basically transmitted as an SSB signal, whereas in D-Star they use the same modulation but put it inside an FM carrier and rely on the FM capture effect to reject interference and multipath longview fucked around with this message at 19:21 on Feb 24, 2014 |
# ? Feb 24, 2014 19:13 |
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I really hope there's some d-star action in denver because I WANT TO MESS WITH IT SO BAD
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# ? Feb 24, 2014 19:15 |
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I'll try to write up something about D-Star later tonight, including the ways of making hotspots and repeaters, it's not necessarily that expensive to set up a hotspot with decent power DMR radio is also starting to become more popular but it kind of sucks because it's only the repeater admin that can decide where to link repeaters, whereas in dstar all valid users can link repeaters to reflectors and other repeaters, the actual air-interface and (I think) voice codec are better though
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# ? Feb 24, 2014 19:27 |
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here's some guys using d-star on win95 https://www.youtube.com/watch?v=q8dUJp0rc0g
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# ? Feb 24, 2014 19:31 |
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ur not allowed to send encrypted files over ham freqs tho right?
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# ? Feb 24, 2014 19:37 |
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I know you're not allowed to use encrypted modes, like DMR or TETRA with encryption, some people think any kind of encoding is also illegal but that's not the case. If you're on an ARES assignment and need to transfer patient data or something like that then I suspect encrypting that data and transferring it using D-RATS would probably not cause any problems. Another grey area is using DD mode to transfer aprs.fi for example, or running an amateur radio wifi link.
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# ? Feb 24, 2014 19:44 |
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longview posted:or running an amateur radio wifi link. thats kinda where i was going w/ this.... also if u use a repeater to make a voip call and the person u call starts speaking obscenities
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# ? Feb 24, 2014 19:57 |
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PuTTY riot posted:thats kinda where i was going w/ this.... back in the day a lot of repeaters had the autopatch into a POTS line for local calls. I will always remember, stars come up, then you pound them down - star to bring up the patch, dial the number, then pound to hang up "hi mom i'm on the radio"
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# ? Feb 24, 2014 20:01 |
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oh that reminds me of this http://www.metamesh.org/quote:Meta Mesh takes mesh networking technology and ideas from around the world and implements them in a way that makes mesh networking accessible to anyone, regardless of their technical abilities. three nodes so far. lol. i guess this has nothing to do with amateur radio but technically, radio signals are involved
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# ? Feb 24, 2014 20:02 |
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# ? May 13, 2024 07:03 |
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PuTTY riot posted:thats kinda where i was going w/ this.... almost a 100% chance that running a 1500W 2.4GHz link and taking out wifi for the surrounding county will get you into some kind of trouble, european limit is 300W on VHF and up but anything above ~1W will take out wifi over a pretty large area another fun use of ham radio is keying up a 70cm HT and taking out OTA TV for everyone nearby using indoor antennas doing this may be legal but it's a good way to make enemies there was a case here in norway last year where a guy got the authorities to confiscate his neighbors plasma TV because it interfered with his HF rig, this wasn't exactly good for PR but a lot of hams I talked to said it was a good thing going around acting like we own the radio waves and causing problems for normal people is a good way to lose frequencies, a large continuous span like the 70cm band is worth a lot of money on the free market
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# ? Feb 24, 2014 20:27 |