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longview
Dec 25, 2006

heh.

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.

mikeselectricstuff owns too my only gripe with that one is that he needs to post more

:justpost:

i saw his vid on the dummy load earlier, the idea is brilliant

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, :cmon:

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Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp
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

Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp
success
again, receive only, but i brought out the 2 meter radio got a video of some signals from the satellite
processing now

Cold on a Cob
Feb 6, 2006

i've seen so much, i'm going blind
and i'm brain dead virtually

College Slice
i barely know what's going on in this thread but :allears: anyway

PuTTY riot
Nov 16, 2002

Cold on a Cob posted:

i barely know what's going on in this thread but :allears: anyway

same

maniacdevnull
Apr 18, 2007

FOUR CUBIC FRAMES
DISPROVES SOFT G GOD
YOU ARE EDUCATED STUPID

Cold on a Cob posted:

i barely know what's going on in this thread but :allears: anyway

s a m e

Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp
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

Fax Sender
Aug 11, 2013

kiss my ass
i need to go get my ham license.

PuTTY riot
Nov 16, 2002

Fax Sender posted:

i need to go get my ham license.

rotor
Jun 11, 2001

classic case of pineapple derangement syndrome
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?

Silver Alicorn
Mar 30, 2008

𝓪 𝓻𝓮𝓭 𝓹𝓪𝓷𝓭𝓪 𝓲𝓼 𝓪 𝓬𝓾𝓻𝓲𝓸𝓾𝓼 𝓼𝓸𝓻𝓽 𝓸𝓯 𝓬𝓻𝓮𝓪𝓽𝓾𝓻𝓮
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

longview
Dec 25, 2006

heh.
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

rotor
Jun 11, 2001

classic case of pineapple derangement syndrome

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?

Silver Alicorn
Mar 30, 2008

𝓪 𝓻𝓮𝓭 𝓹𝓪𝓷𝓭𝓪 𝓲𝓼 𝓪 𝓬𝓾𝓻𝓲𝓸𝓾𝓼 𝓼𝓸𝓻𝓽 𝓸𝓯 𝓬𝓻𝓮𝓪𝓽𝓾𝓻𝓮
dibs on PU55Y

rotor
Jun 11, 2001

classic case of pineapple derangement syndrome

Silver Alicorn posted:

dibs on PU55Y

SP3RG

longview
Dec 25, 2006

heh.

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

Nomnom Cookie
Aug 30, 2009



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

oh no blimp issue
Feb 23, 2011

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.

Calling B0OB

steal one off someone
major jokes when they start talking to you

Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp



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

prefect
Sep 11, 2001

No one, Woodhouse.
No one.




Dead Man’s Band

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 :blush:

Cold on a Cob
Feb 6, 2006

i've seen so much, i'm going blind
and i'm brain dead virtually

College Slice

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

Cold on a Cob
Feb 6, 2006

i've seen so much, i'm going blind
and i'm brain dead virtually

College Slice
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

Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp
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.’”

spankmeister
Jun 15, 2008






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. :mad:


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

ADINSX
Sep 9, 2003

Wanna run with my crew huh? Rule cyberspace and crunch numbers like I do?

This thread rules Johnny,

What do you guys think about the :catdrugs: 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

Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp

ADINSX posted:

This thread rules Johnny,

What do you guys think about the :catdrug: 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

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 =/

GameCube
Nov 21, 2006

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

Silver Alicorn
Mar 30, 2008

𝓪 𝓻𝓮𝓭 𝓹𝓪𝓷𝓭𝓪 𝓲𝓼 𝓪 𝓬𝓾𝓻𝓲𝓸𝓾𝓼 𝓼𝓸𝓻𝓽 𝓸𝓯 𝓬𝓻𝓮𝓪𝓽𝓾𝓻𝓮
psk31 came after cell phones

GameCube
Nov 21, 2006

Silver Alicorn posted:

psk31 came after cell phones

:pwn:

graph
Nov 22, 2006

aaag peanuts
my stupid brain cant grok any of this but i its cool seeing people who know about it do stuff :allears:

longview
Dec 25, 2006

heh.

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

Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp
I really hope there's some d-star action in denver because I WANT TO MESS WITH IT SO BAD

longview
Dec 25, 2006

heh.
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

PuTTY riot
Nov 16, 2002
here's some guys using d-star on win95

https://www.youtube.com/watch?v=q8dUJp0rc0g

PuTTY riot
Nov 16, 2002
ur not allowed to send encrypted files over ham freqs tho right?

longview
Dec 25, 2006

heh.
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.

PuTTY riot
Nov 16, 2002

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

Jonny 290
May 5, 2005



[ASK] me about OS/2 Warp

PuTTY riot posted:

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

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"

GameCube
Nov 21, 2006

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.

Our company envisions a regional, publicly owned and operated network of inexpensive Wi-Fi nodes on or in residences and small businesses, creating a shared network that is open, secure, anonymous, and free to use.

Unlike regular ISPs’ networks, the PittMesh network has no central points of failure. As long as nodes are powered, no ISP, terrorist organization, weather event, hacker, or government institution can disrupt the entire PittMesh network.

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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longview
Dec 25, 2006

heh.

PuTTY riot posted:

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

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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