my call sign at aol.com if you want to talk or do something: yospos radio thread

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > YOSPOS > my call sign at aol.com if you want to talk or do something: yospos radio thread

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Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

longview posted:

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

This is my big thing. After the UPS debacle* I started viewing the FCC in a rather dim light, and am terrified that they're going to just razor shave down our bands one bit at a time if we don't say anything until they've destroyed all the ham bands for _very_ minor incremental advances in their own service

*in the early 90s, UPS started crying and crying about how they needed a dedicated radio band for their trucks and how about 220-222 MHz out of the 220-225 MHz ham band, FCC said naw, UPS said BUT WE WANT IT and then FCC said okay and took it away from hams and then UPS said "aw jokes, jokes. Looks like 220-222 won't work out for us. We're good though - cellular data is here! Peace out" and the FCC never gave it back to hams.

# ? Feb 24, 2014 20:33

Adbot: ADBOT LOVES YOU

# ? Apr 20, 2024 06:50

GameCube: Nov 21, 2006

so what happens if hams just start using that band again? if ups isn't using it anymore, does anybody even care

# ? Feb 24, 2014 20:35

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

afaik they resold it at much lower prices to other private services, so if you interfere with them, they call FCC, white van visits, Notice of Apparent Liability, five-figure check made payable to FCC

# ? Feb 24, 2014 20:38

GameCube: Nov 21, 2006

gently caress

# ? Feb 24, 2014 20:39

sinekumquat: Jun 12, 2005; the most dangerous philosopher in the west; College Slice

spankmeister posted:

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

i'm too stupid to understand how this works. is his signal so powerful that whatever wires used in his earbuds act as antennas?

# ? Feb 24, 2014 20:47

longview: Dec 25, 2006; heh.

Verdafolio posted:

i'm too stupid to understand how this works. is his signal so powerful that whatever wires used in his earbuds act as antennas?

in a word, yes

SSB and AM transmissions transmit information by varying signal strength in tune with the signal, semiconductors and other metal-metal junctions can act as the rectifier diode in the AM receiver I talked about a while ago, the effect would be that you get a receiver out of audio circuits, digital circuits can be affected but usually not enough to cause noticeable interference since they're usually shielded against external RF and to prevent the signal wires from generating interference as well

this was a huge problem with all 90s consumer audio equipment, and many cheap amplifiers today, when GSM phones are placed nearby the time division nature of the signal means it turns on and off the transmitter at a frequency you can hear when it's rectified in an inadvertent receiver

manufacturers eventually sorted out the GSM signals by shielding and using opamps with built-in RFI shielding (opamps with EMI shielding are like magic compared to ones without), the reason they did it was of course because people were noticing the problem

the only people who notice CB and Ham activity are people right near powerful transmitters, AM radio transmitters have the same problem but they can usually put the transmitter in a mountain somewhere and do a remote feed

FM signals have a continuous signal strength so when this rectification happens it'll just cause some DC to appear, often a bit of 100/120Hz hum from the power supplies on top of it but it's not as big a problem

TV transmitters might also cause problems, analog TV used a sort of SSB called VSB that varies with picture brightness and DVB-T transmitters use OFDM, a linear digital modulation form that can also cause this problem

to prevent this problem, you can direct the transmitter to direct power elsewhere or otherwise lower power, or try to work out what wires are causing problems and put clip on RF chokes on the wires, coiling up the wire for a few turns can help against higher frequency noise too
but usually if you're getting interference in there's either a very strong signal nearby exceeding the civilian EMC test spec(10V/m I think is the toughest civilian spec, mil-spec is about 200V/m of RF at different frequencies + often an EMP test) or the equipment designer or installer made a mistake

longview fucked around with this message at 21:06 on Feb 24, 2014

# ? Feb 24, 2014 21:03

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

longview posted:

in a word, yes

R E C T I F I C A T I O N

Yep. this is also why I personally do not 100% discount the "my filling made me hear radio signals" stories. I think it's possible to have a semiconducting junction inside a bad filling, which could pick up enough energy to fire audio nerves. it'd be a 1 out of 100 million thing, but i want to believe

# ? Feb 24, 2014 21:07

PuTTY riot: Nov 16, 2002

longview posted:

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

i guess im not good at this nomenclature thing. i was thinking of using ham freqs as like a P2P 'WAN' connection that u'd hook up to a wifi router on ur camping trip then VHF or w/e back to wherever u have an internet uplink

also jonny how common are the white vans? like... have i likely seen one in the past 6 months and not known it? gov't plates or just whatever plates?

# ? Feb 24, 2014 21:20

PuTTY riot: Nov 16, 2002

goog says the white vans are limo tint green suburbans lol

# ? Feb 24, 2014 21:29

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

PuTTY riot posted:

i guess im not good at this nomenclature thing. i was thinking of using ham freqs as like a P2P 'WAN' connection that u'd hook up to a wifi router on ur camping trip then VHF or w/e back to wherever u have an internet uplink

also jonny how common are the white vans? like... have i likely seen one in the past 6 months and not known it? gov't plates or just whatever plates?

It might or might not be permissible. If it a: violates any obscenity guidelines, or b: is of a commerical nature, it's verboten. If the traffic was encrypted at one time, it's fine as long as you pass it unencrypted over ham airwaves (TCP/IP and HTTP are both allowed and widely used on some packet networks).

The white vans are rare, I think they have some on each coast and then chicago/dallas, and they travel onsite based on complaints. you won't find one in oxford unless the cops' radios or university PD is getting interfered with

# ? Feb 24, 2014 21:30

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

coffeetable posted:

is amateur radio astronomy a thing

or are the wavelengths too long for anyone w/o $10k lying around to bother with

Coming back to this - didnt forget about you.

I don't really know! But last night I got so deep in the satellite books that I taught myself what Lagrangian points are and now I want to join AMSAT (the amateur radio satellite org) and hook them up with some 2.0 millionaires who want to get press. They need like 5 million bucks to launch Phase 3E (the next wave of high orbit satellite) and its been just loving sitting in project hell for literally ten years now. thing is huge, will require a big rocket and a boost up to a big orbit

of course any 2.0 millionaire is going to not be altruistic at all so it won't work. sorry we're not going to put streaming ads or your companys name on it

Anyways i'm going to see if anybody is doing amateur radioastronomy stuff. As long as you can get some sort of receiver set up for the proper frequencies theres no reason you cant point an old TVRO dish at the sky and see what you hear

# ? Feb 24, 2014 22:10

longview: Dec 25, 2006; heh.

~~D-Star~~

What is D-Star?
D-Star is a amateur radio standard for digital radio, it supports two modes, Digital Voice and Digital Data, DV is the only mode in any real use so I'll focus on that

D-Star was developed by the Japanese Amateur Radio League with government funding from the late 90s and standardized in the early 2000s, it is to my knowledge the only wide spread digital voice mode designed specifically for amateur radio requirements. it is an open sores protocol that is fairly well documented, it does use a proprietary voice codec that is the root of a lot of criticism
Additionally the only manufacturer to deliver working out of the box radios is Icom, they were part of the design process and worked out of lot of the bugs in the original system.

DD mode doesn't have a voice component (I think) and allows a 128 kbit data link, it's only supported in the 23cm band and only one radio, the Icom ID-1 supports it. this radio has an ethernet port and it's possible to use it to run normal TCP/IP traffic over this channel

At a technical level DV mode uses a 6.25 kHz channel as opposed to a 25 kHz FM Voice channel, and the more modern and lower quality 12.5 kHz narrow FM voice channel that is starting to be mandated
at the core it has a 4800 baud digital channel, of this a proprietary AMBE2020 codec is used to make a 2.4 kbit/s voice bitstream, 1.2 kbit/s is used for forward error correction and the other 1200 bauds are mostly left up to the implementer
in practice the 1200 baud channel supports digital data transfer at a glacial pace (D-RATS) and is also used to transfer a text message included with the callsign, and Icom supports D-PRS for position reporting over this channel too

the air interface is a GMSK signal encapsulated in an FM carrier, there is no time division or other multiplexing technique so only one person can talk per channel, this is an advantage because it means a lot of radios can technically support it as long as they have a 9600 baud data port or can be modified to have one, most radios with pure FM transmitters (not phase modulated) can be modified for D-Star support

D-Star originally only operated in the 23cm, 70cm and 2m bands, but the IC-7100 supports running D-Star on all HF band plus 6m, I think most use is restricted to 10m and higher since the bandwidth needed is big compared to SSB and it might not be the best protocol for HF propagation IMO

What can I do with it?
D-Star DV mode supports both slow data transfer (position reporting for example) and voice, the neat thing about D-Star is it's digital so it can be stuffed into the internet pretty easily
this allows multiple repeaters to be linked up to the same chat room, typically called reflectors or rooms, when anyone at any linked repeater starts talking, all the other repeaters transmit this signal
the most popular set of rooms right now is the DCS system, which has rooms for every country with more than a few users, each country usually has a set of rooms for regions, testing, emcomm and so on
DCS013 (Norway) and probably others now have Echolink (a similar system for linking FM repeaters) gateway rooms too, I tested this yesterday and it worked pretty well
another neat feature is basically SELCAL, this system allows you to automatically connect your repeater to another repeater using the callsign of the person you want to reach (technically the last repeater this person was registered at, this happens whenever they key the transmitter)
unfortunately it doesn't work that well in the original implementation because call-sign routing (that's what it's called) automatically disconnects anyone else using the target repeater and it requires that the answering party hit a button to reverse-route otherwise it won't be a two way link

fortunately the germans who built the DCS system also built what's called the CCS system, this implements call sign routing by handling the linking in a different way where the target repeater is still connected to the room it was in, AND the calling repeater, allowing the caller to listen to active QSOs before making a call

so basically you can chat all over the world or locally, using the internet

Some myths
D-Star is old - it is, but it's also the only standard with more than a handful of users, but then again most standards are old by the time they're in widespread use

D-Star is Icom only - it isn't, the AMBE2020 codec is proprietary but is also widely available, Icom is the only manufacturer to provide a set of radios and complete repeater stacks to run D-Star but several projects offer Icom-free D-Star repeaters and radios if you're willing to DIY a bit
Yaesu and Kenwood are playing a political game, all these manufacturers were able to make interoperable NEXEDGE/IDAS radios using very similar tech for example

I can't decode D-Star on my Baofeng/IC-02AT, it's clearly encrypted and illegal
Nope, the codec is available at a low cost and volume to anyone willing to buy the AMBE2020 chip, the rest of the standard is open source

Other modes are more efficient - not really, Yaesu being Yaesu has a competing standard but I've literally never heard of anyone using it for anything except testing it once, this mode supports 9600 kbit but it uses twice the bandwidth so not really a big win, it does support dedicated data links at 9600 kbit so it's much faster than DV at data transfer
DMR and MOTOTRBO is starting to gain traction, oddballs in the UK are starting to use TETRA radios
these standards have some very nice features, like DMR using a 12.5 kHz channel with TDMA to run two voice channels at the same time, typically channel 1 is international and channel 2 is local chat for example. the disadvantage is the radios for this mode are not designed for amateur radio use, they often aren't keypad programmable and the programming software is usually expensive as hell if you can get it (vertex standard/yaesu being the worst at this)
additionally repeaters are linked to whatever the sysop set it to whereas D-Star lets all valid users link the repeater to where they want it

as an aside, if DMR was designed for amateur radio it would use the TDMA system on the repeater side to eliminate the need for duplex filters and splits, but they didn't because pro users don't care about buying a duplex filters, TETRA apparently supports using mobile radios as repeaters for HTs though

D-Star has bad voice quality - well, ok maybe, it's good for being a 2400 baud link ok? people sometimes sound like they have a cold, and when signals are choppy the vocoder output turns into beep and bloops, but over all it's not bad

Internet linking isn't real DXing, when the internet goes down the whole system goes down!
I won't comment on DXing or not, depends on the definition you use. When the internet goes down so does systems like Echolink, but then it's not like the FM repeater will reach any farther than the D-Star one anyway
D-Star makes it easy to link up repeaters and hotspots across bands and distances when the internet does work, which is a big advantage for many emcomm operations.
using hotspot nodes it is also possible to run cross-band repeaters on HF bands (think 40 meters NVIS) without generation loss like you'd get on a long chain of analog cross bands

So what's a hotspot, how do I make a repeater?

To make a repeater you buy the ID-RP2C repeater controller, then you choose what bands you want, most users want a 70cm module, the ID-RP4000V, and many want the ID-RP2000V 2m module and at only the price of a cheap car it's a real bargain, don't forget duplex filters!

If Icom won't give you the repeater stack for free then you're not going to buy it, fortunately the germans really love D-Star and have made a repeater controller, the DV-RPTR. This is a GMSK modem, a powerful DSP and some interface hardware for keying radios, USB and Ethernet.
The DV-RPTRv2 is usually used as a node adapter, or a modem. To make a working hotspot (simplex internet gateway), you need a radio with a 9600 baud packet radio port and you have to make your own interface cable, after that's done it's plug and play.
If you're like most people you'll then get a raspberry pi running some obscure linux distro and some software called irddbgateway and dvrpt-controller, if you're a shaggarian �bermensch like me you get a windows server 2012r2 vm running in hyper-v and run it there instead.

To make a repeater you need two radios or a suitable repeater and duplex filters, but the same DV-RPTR can be used provided it has internet.
When we set up our local 70cm repeater we used two FT-7900s and then a second DV-RPTR configured as a hotspot to remotely feed the repeater the same way echolink is usually connected.

The DV-RPTR can also be bought with an AMBE codec and a display, the same setup then works as a normal D-Star radio only more clunky and about as expensive, but it does support directly connecting to the internet at the same time.

So to end this, here is what D-Star isn't:
Professional grade modern digital radio - it isn't, pro users have other requirements and would find D-Star massively confusing to operate, TETRA, DMR and P25 are far better options for pro users but are too limited for amateur radio
TDMA FDMA and CDMA packet oriented (except DD) high bandwidth true diversity roaming - it's none of those things except one radio supports diversity receive, it's an improved analog FM, not 4G LTE
Encrypted - there is no support for encryption except for what you put in the data-channel

# ? Feb 24, 2014 22:14

PuTTY riot: Nov 16, 2002

Jonny 290 posted:

Coming back to this - didnt forget about you.

I don't really know! But last night I got so deep in the satellite books that I taught myself what Lagrangian points are and now I want to join AMSAT (the amateur radio satellite org) and hook them up with some 2.0 millionaires who want to get press. They need like 5 million bucks to launch Phase 3E (the next wave of high orbit satellite) and its been just loving sitting in project hell for literally ten years now. thing is huge, will require a big rocket and a boost up to a big orbit

of course any 2.0 millionaire is going to not be altruistic at all so it won't work. sorry we're not going to put streaming ads or your companys name on it

Anyways i'm going to see if anybody is doing amateur radioastronomy stuff. As long as you can get some sort of receiver set up for the proper frequencies theres no reason you cant point an old TVRO dish at the sky and see what you hear

if you can somehow insert the words 'augmented reality' in there i could prob help u out on that funding

# ? Feb 24, 2014 22:14

PuTTY riot: Nov 16, 2002

my .01% cousin or w/e that's running for texas house has a older bro that constantly posts venturebeat articles about augmented reality and google glass and owners manuals for ur car that are on ur phone.

i dont think that would work tho so sorry for the derail

# ? Feb 24, 2014 22:21

syscall girl: Nov 7, 2009; by FactsAreUseless; Fun Shoe

Jonny 290 posted:

Coming back to this - didnt forget about you.

I don't really know! But last night I got so deep in the satellite books that I taught myself what Lagrangian points are and now I want to join AMSAT (the amateur radio satellite org) and hook them up with some 2.0 millionaires who want to get press. They need like 5 million bucks to launch Phase 3E (the next wave of high orbit satellite) and its been just loving sitting in project hell for literally ten years now. thing is huge, will require a big rocket and a boost up to a big orbit

of course any 2.0 millionaire is going to not be altruistic at all so it won't work. sorry we're not going to put streaming ads or your companys name on it

Anyways i'm going to see if anybody is doing amateur radioastronomy stuff. As long as you can get some sort of receiver set up for the proper frequencies theres no reason you cant point an old TVRO dish at the sky and see what you hear

convince them that you're going to put *famous dead science guy*'s ashes into a non decaying orbit

# ? Feb 24, 2014 22:21

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

Payloads:

-1 Molniya orbit satellite with transponders on five different band pairs, attitude thrusters, magnetorquers, deployable solar panels and redundant backup control systems
-10cc semen, preserved, from Bill Nye

# ? Feb 24, 2014 22:41

syscall girl: Nov 7, 2009; by FactsAreUseless; Fun Shoe

why do i always learn about science guys dying on this forum

:rip:

harold ramis

# ? Feb 24, 2014 22:55

spankmeister: Jun 15, 2008

syscall girl posted:

why do i always learn about science guys dying on this forum

harold ramis

busting ghosts up in heaven. :unsmith:

# ? Feb 24, 2014 22:57

PuTTY riot: Nov 16, 2002

consistently acing first half of tech exam.

to do:
memorize approximate band --> freqs
memorize all formulas
learn schematics

practice a lil dB math (haven't done calculus since B Cal 2 my soph year of college, ugh)

idk if im gonna have time to get comfortable w/ general much less extra before monday. we will see i guess, no harm in taking it either way i suppose.

# ? Feb 25, 2014 00:09

maniacdevnull: Apr 18, 2007; FOUR CUBIC FRAMES
DISPROVES SOFT G GOD
YOU ARE EDUCATED STUPID

syscall girl posted:

science guys...harold ramis

uh, bill?

# ? Feb 25, 2014 00:11

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

PuTTY riot posted:

consistently acing first half of tech exam.

to do:
memorize approximate band --> freqs
memorize all formulas
learn schematics

practice a lil dB math (haven't done calculus since B Cal 2 my soph year of college, ugh)

idk if im gonna have time to get comfortable w/ general much less extra before monday. we will see i guess, no harm in taking it either way i suppose.

if you have any Q's ask them here and if i miss it/dont answer, PM me
im excited for you! srs

# ? Feb 25, 2014 00:19

PuTTY riot: Nov 16, 2002

thanks, ur like my e-elmer

# ? Feb 25, 2014 00:24

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

PuTTY riot posted:

thanks, ur like my e-elmer

trufacts: I was my Dad's Elmer.

i'm a KC4 call and he jumped in the game about 4 years later, got a KD4.

TO AUDIENCE: "Elmer" is the hobby term for an experienced ham mentor that gets you into the hobby and shows you the ropes. No crazy grey cats here sorry

# ? Feb 25, 2014 00:25

SmokaDustbowl: Feb 12, 2001; by vyelkin; Fun Shoe

I've got a uniden BCD996XT and it's fun to listen to the police but it's so loving complicated

also a windstorm blew my shortwave antenna down so I haven't DXed in forever. you can get some wacky poo poo on shortwave

# ? Feb 25, 2014 00:51

PuTTY riot: Nov 16, 2002

are QSL cards dead or are they still A Thing? they seem kinda cool

# ? Feb 25, 2014 00:54

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

PuTTY riot posted:

are QSL cards dead or are they still A Thing? they seem kinda cool

very much still a thing. internet call databases mean its way easier to send cards out, and people are more likely to send a card if they get a card

i'll see if i can dig up some that ive gotten

# ? Feb 25, 2014 00:57

PuTTY riot: Nov 16, 2002

heres what seems to be a pretty good study website, i like that it tracks progress on each subelement so u know what to work on:

https://hamstudy.org

gonna finish up technician tmw and then rest of the week is gonna be general. i think extra is way too lofty @ this point maybe ill get it later.

# ? Feb 25, 2014 09:13

BONGHITZ: Jan 1, 1970

Jonny 290 posted:

in this thread we discuss everything involving those wonderful ways in which humanity hurls epithets at each other via the invisible magic of RADIO WAVES

you've got questions? we've got really wordy answers typed by a guy that probably likes radio stuff a little too much
focus on ham/scanning/shortwave but we cover all the waves in all the spectrums

"the spectrum?"

yep. the spectrum.

Electromagnetic waves (we'll call them radio waves) all have a period of oscillation which is inversely proportional to their frequency. They travel pretty much at the speed of light in a vacuum or air, so we often refer to a particular frequency range based on how long one wavelength is at nominal c.
300 Mhz is one meter. 50 Mhz is six meters. 440 Mhz is 70cm, you get the idea.

"what's this 'shortwave' stuff?"

The terms 'shortwave' and 'HF' or 'high frequency' are interchangeable.

reframe your context to like 1920 or so. everybody's starting to mess with radio, but the tech sucks so bad that they can only operate on a few hundred kilohertz. Wavelength here is long, on the order of miles sometimes. Then they got better equipment and could transmit on higher frequencies. Thus, 'shortwave'.

The shortwave band is the band that is most strongly affected by YE OLDE IONOSPHERE. These frequencies have wavelengths that treat the ionized layers of the ionosphere as a mirror, more or less. If you are on Earth, and send a signal to the horizon, it'll eventually bounce off that ionosphere and head back towards the Earth, pretty far away.

The ionosphere is almost 100% affected by our friendly little yellow nuclear fusion reaction in the sky. Specifically, sunspots. Basically, as the sun comes up over an area, lower layers of the ionosphere are 'activated' by solar energy, which basically brings your mirror closer to Earth, shortening propagation. As the sun sets, these layers dissipate and your mirror rises again. You can once again talk to Europe from the US!
The higher the number of sunspots, the stronger propagation gets. These ebb and flow on a roughly 22 year cycle. Right now we are right around the peak of a somewhat-lackluster solar cycle, but conditions are still pretty good. Around 2018, my shortwave radios will probably go into storage for five years during the solar minimum.

The main appeal of shortwave is: the ionosphere. You can bounce poo poo over the horizon, and if you're lucky it will bounce again off the earth and back up into the ionosphere. You can get allll the way around the world with this (and matter of fact, if conditions are right, you can briefly transmit and hear your echo about 90 mS later after its gone all the way around the world.)
The main disadvantage of these bands are that antennas are large, and propagation is inconsistent. Monday might be gangbusters, then the sun sneezes and the next day you can't hear a god drat thing.

Now, as you go up in frequency, the waves stop bouncing off the ionosphere. however, they start to become better and better at point to point transmission in free air. This goes allll the way up to visible light and beyond (yep, light is this same energy, just at really high frequencies. You got antennas in your head) Also, shorter wavelengths are attenuated less by obstructions, to an extent.

So, if you don't need the range boosts from shortwave propagation, or if you can't fit a big antenna, and you just need local coverage, you go up in frequency. 100 Mhz is your FM radio. 150-ish used to be the primary law enforcement band. Then for a while the cops moved to systems around 460 MHz, and now the most common systems run around 850 MHz or so.

Engineering challenges go up as your frequency does. It's really easy to build a 1 MHz transmitter - it's really hard to build a 1 Ghz transmitter. Tolerances are low, precision must be high.

"what the hell is an antenna, anyways"

A piece of metal. that's it. As radio waves pass through an antenna, they induce an alternating current between the 'halves' of the antenna. This voltage is transmitted by your feedline, which can take many forms, into your radio receiver. The exact opposite happens on transmission - your radio produces a voltage, it is presented to the antenna, and the antenna takes that energy and converts it into radio waves - the better tuned the antenna, the better it does its job.

If the piece of metal has dimensions such that it is 'resonant' at the frequency of the waves, its properties will reinforce and enhance the voltage presented at the feedline, giving you a stronger signal. If it's not a resonant length, it becomes more complex and could possibly work well, or possibly be awful.

"you talked about two halves. But my car antenna only has one piece!"

Not quite. Your car antenna uses the vehicle as a 'ground' reference. It's not actually connected to the earth, but it is a big enough piece of metal that it will also pick up the radio waves and be the 'other half' of the antenna. This concept is called a 'counterpoise'.
This translates to fixed antennas, too. Those big AM broadcast antennas use the earth as a counterpoise. In order to effectively do this, you usually lay down a network of ground wires, directly on or in the earth, and use that as your counterpoise. There is a LOT of copper in a broadcast antenna's field.

"What's HAM radio?"

First of all, not an acronym. it's just ham radio.

I will take a US-centric view, as I am a US amateur operator. Just to get this out of the way, I was first licensed 23 years ago at age 11, and held a Technician class license with limited HF privileges until 2007 until I upgraded to Extra, the terminal license class. These are on a ten-year renewal and do not require retests, so i will be an Extra until I die.

In the early 20th century, the vast majority of technical advances in the new radio field were by non-professional experimenters playing with spark gaps and big coils in their garages. The government realized that the 'amateurs' were contributing a lot of help to the new tech, and allocated them specific frequency ranges in which they could talk to each other. To preserve the economic appeal of official licensing and regulation, all commercial traffic was banned. This provided basically a safe area free of high-power commercial broadcasters where guys who just liked to tinker with radios could put them on the air and talk to other tinkerers.

Over the past 100 years, hams have provided a lot of technical advancements to the radio art, and this continues to this day. Hams brought the world single-sideband transmission (greatly enhances long distance shortwave), moonbounce (literally bounce a signal off of the moon), various digital modes of transmitting information, and so on. The trend continues, with a lot of software-defined-radio development being done in the ham radio world today.

To ensure we have the ability to be proficient in many styles of communication, hams are allocated a wide variety of allowed bands of operation across the spectrum. Here's a real quick breakdown of what each major band is really like:

160 meters (1.8-2.0 MHz) - HUGE antennas. A quarter wave antenna here is 131 feet tall. Only the finest gentlemen operate here, there is a high standard of conduct and the circles are tight-knit. Many old guys use converted decommissioned AM broadcast transmitters. Referred to as 'Top Band', again a nod to when we measured things in wavelength instead of Hertz.

75 and 80 meters (3.5-4.0 MHz) - Used to be two bands, now is one big one. Atmospheric noise is high but medium-range (500-2000 mi) propagation is great at night. PACKED TO THE BRIM WITH RACIST GRANDPAS. Antennas are still big here, so the biggest signals you hear are the retired engineers who could afford to buy 200 acres of Kansas farmland and put huge towers on it. They have the expected political views. Seriously, this is the new CB radio. Stay off 75 meters. It's a cesspool.

40 meters (7-7.3 MHz) - Propagation is farther but less consistent than 75/80 meters. The main problem here is that there is a major shortwave broadcast band that co-exists at the top end of this range, and Radio Moscow can wreck like 20-30 KHz of spectrum when it's coming in strong. This is also used for local communications to a certain extent.

30 meters (10-10.15 MHz) - My favorite shortwave band. Why? YOU CAN'T TALK ON IT. 30 meters is a digital-only band, across the world. You won't hear anything but beeps, boops, squawks and squeals on here. It's guys chatting! Hook your radio up to your soundcard and watch the conversations fill your screen.

20 meters (14-14.35 MHz) - This is a cool band, as atmospheric noise is lower and propagation actually develops during the morning and through the early afternoon. Antennas are starting to come down to a reasonable size, and you can get some good signal out. However, there are small slices of this that host some absolutely legendary abusive operators, and you can tune in to hear them scream about communism and Obama. Still, most operators are good guys, and 20 meters is worth getting set up for.

17, 15 and 12 meters (around 18.1 Mhz, 21 MHz and 25 MHz) - these are lesser-used these days but in times of solar maximums can give you both good local propagation and some good ionospheric 'skip'.

10 meters (28-29.7 MHz) - Pretty popular - it's right next door to CB so they share a lot of propagation aspects. Lots of local, lots of worldwide at solar maximums. Tons of spectrum, so it's easy to spread out - or easy to miss somebody transmitting.

6 meters (50-54 MHz) - the first "VHF" band. Has properties of both line-of-sight bands and the higher HF bands. Not really popular except among guys that specifically like 6 meters.

2 meters (144-148 MHz) the most popular amateur band of all time. Antenna is about 19" for a quarter wave. Used radio is 30 bucks. Here is where you start to see 'repeaters' which are just strategically located relay stations that listen on one frequency , and retransmit whatever they hear on another. Your radio listens to the repeater's transmit freq, and transmits on its listening freq. Some guys network repeaters using telephone lines or (more commonly now) VoIP links, enabling you to talk up to a couple hundred miles on your little handy-talkie (we don't call them walkie-talkies).

70cm (420-450 MHz) - Becoming more and more popular every day. We can make better radios now, and these bands have decent penetration in semi-urban areas, leading to less fading and dropouts. Repeaters here are heavily networked due to slightly shorter range, and 2 meter repeater networks often use 70cm backhauls to connect their machines.

Above here is still kind of experimental.

33cm (902-928) - kind of dead except in super urban areas like Boston. Nobody makes ham rigs for this band so everybody hacks up surplus 860 MHz cop radios. hacker poo poo.

23cm(1296 MHz) - Another urban band, more popular than 33cm but the issues of short wavelength start to rear their head here. You gotta keep your connections short and solid. Often used for satellite work.

13cm (2.4 Ghz) - yeah bitch, we got spectrum right below the Wifi band. Except we can use up to 1500 watts of power. Just can't transmit Goatse or Bitcoin.

there are a bunch of microwave bands, and last I checked, amateurs were actually given exclusive use of all frequencies above 300 GHz. Anybody using the 902 mhz bands or higher is a GUARANTEED NERD and is likely a much better RF engineer than you or I.

"You mentioned CB, how's that doing?"

Weirdly. it's kind of fun to hear truckers and such, but everybody runs illegal power now through dirty transmitters, so the band is full of distorted shouting rednecks hitting sound-effects boxes and trying to make their neighbor's TVs blow up. It's basically the fyad of radio. We'll get more into CB on some later posts.

OP is getting big and fat, so I will wrap this one up with a quick list of what I have done with radio so far:

-Been the fourth youngest licensed amateur in North Carolina at the time of my licensing
-Won an award for being a coordinator for a ham-radio based score reporting network at a national soccer tournament
-Talked to the bass player from .38 special and Ronnie Milsap (both famous hams) as they toured through my area
-Said hi to astronauts on the ISS and cosmonauts on Mir
-On a camping trip, hooked a laptop to a battery powered HF radio, threw a wire in a tree and basically IRC'ed with South Africans and Europeans
-Used VHF and UHF bands to speak to hams in Vancouver, California and Michigan - by using low-earth-orbit satellites

The last item is my current obsession, and we will be talking more about satellite communications soon.

this weekend i'll try to get a good camera setup and maybe we'll have a youtube or two of what you can listen to, who you can talk to and what it's all about. We'll also cover scanners, commercial shortwave and other common ways you can snoop on invisble energies to figure out what they're ordering at the nearest drive-thru.

lotta words here

# ? Feb 25, 2014 09:23

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

keep honking, i'm reloading

i can type for this poo poo until the end of time.
work week brings less radio fun, i am ordering a $20 SDR on thursday though

# ? Feb 25, 2014 15:11

Nomnom Cookie: Aug 30, 2009

is it possible to spy on people's cell phone calls. gsm, i figure cdma would be a total pita cause of the hashing thing and anyway only at&t has signal at my house in the sticks

# ? Feb 25, 2014 15:22

Bloody: Mar 3, 2013

Kevin Mitnick P.E. posted:

is it possible to spy on people's cell phone calls. gsm, i figure cdma would be a total pita cause of the hashing thing and anyway only at&t has signal at my house in the sticks

no (unless youre the nsa)

# ? Feb 25, 2014 15:27

Nomnom Cookie: Aug 30, 2009

my sister works for nsa do you think she could get me some gear

# ? Feb 25, 2014 15:30

Bloody: Mar 3, 2013

also gsm is dumpster garbage trash and cdma is much better

# ? Feb 25, 2014 15:30

Nomnom Cookie: Aug 30, 2009

if only cdma was on any networks that weren't dumpster garbage trash

# ? Feb 25, 2014 15:30

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

I possess no fewer than three radio receivers that can receive the AMPS cellular band

too bad analog's dead

used to listen to people's calls down in hot springs in like 2000.

BORING.

SO loving BORING.

"what do you want for dinner?" "i dunno. what are you feeling like"
forever

# ? Feb 25, 2014 15:32

Bloody: Mar 3, 2013

Kevin Mitnick P.E. posted:

if only cdma was on any networks that weren't dumpster garbage trash

3g but now everybody uses 4g which uses ofdma which is like cdma but better

# ? Feb 25, 2014 15:33

spankmeister: Jun 15, 2008

Kevin Mitnick P.E. posted:

is it possible to spy on people's cell phone calls. gsm, i figure cdma would be a total pita cause of the hashing thing and anyway only at&t has signal at my house in the sticks

yes it is but it's easier with a phone with custom fw

https://events.ccc.de/congress/2010/Fahrplan/attachments/1783_101228.27C3.GSM-Sniffing.Nohl_Munaut.pdf

# ? Feb 25, 2014 15:44

Shaggar: Apr 26, 2006

hey jonny. if i use tomato on my routers @ home and want to bridge them and set them 2 a non-us zone that allows like channel 14 on 2.4ghz how much trouble will that get me in and is it far enough away from normal wifi to get away from all the other aps on 2.4ghz?

# ? Feb 25, 2014 16:28

Jonny 290: May 5, 2005; [ASK] me about OS/2 Warp

Shaggar posted:

hey jonny. if i use tomato on my routers @ home and want to bridge them and set them 2 a non-us zone that allows like channel 14 on 2.4ghz how much trouble will that get me in and is it far enough away from normal wifi to get away from all the other aps on 2.4ghz?

set them to japan, you should get channel 14, nobody cares, go fuckin hog wild
14 is far enough from 11 that it should be pretty rock solid

# ? Feb 25, 2014 16:29

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# ? Apr 20, 2024 06:50

maniacdevnull: Apr 18, 2007; FOUR CUBIC FRAMES
DISPROVES SOFT G GOD
YOU ARE EDUCATED STUPID

Bloody posted:

also gsm is dumpster garbage trash and cdma is much better

wrongo. compatibility > everything else.

# ? Feb 25, 2014 16:29

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > YOSPOS > my call sign at aol.com if you want to talk or do something: yospos radio thread

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