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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Bloody: Mar 3, 2013

software defined radio is really cool but gnuradio is a steaming heap of poo poo (obvious from the "gnu" in the name, but)

thats my radio contribution, cya

# ¿ Feb 22, 2014 00:49

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# ¿ Apr 28, 2024 10:44

Bloody: Mar 3, 2013

chmods please posted:

my favorite radio story is the station which broadcasted coast-to-coast at 500kW and caused massive arcing and power grid failures locally, interference for pretty much everyone on either side of 700KHz, and could be tuned in by anything metallic:

http://jeff560.tripod.com/wlw.html

im the part of this thats a very inaccurate summary of the links content

no arcing, no power grid failures, 0/10 would not read any of again

# ¿ Feb 22, 2014 20:00

Bloody: Mar 3, 2013

longview posted:

I suppose there might be cordless phones around that use 2.4, over here all that stuff is at 800 MHz and will soon have to fight with 4G LTE transmitters.

SDR# is supposed to be fairly easy to write plugins for, if you want to receive multiple frequencies you might want to set it up as a scanner or just get some more dongles for $10 a piece and a T piece to connect the same antenna like I did (it's not perfect but it works just fine)

the connector on those TV dongles is usually a MCX connector, an adapter to SMA would let you connect a more standard antenna

you probably also want to adjust the gain in the settings to the point where the noise floor starts rising, as well as making sure the ppm adjustment (frequency correction) is somewhat reasonable, in the picture I posted of the UHF transmission it was pretty far off center

one of the dongles I have can actually be so far off it can't receive a narrow signal without adjustment

sdr# you mean i didnt have to do that work thing in loving gnuradio i could have used something civilized

# ¿ Feb 23, 2014 07:35

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

Bloody: Mar 3, 2013

also gsm is dumpster garbage trash and cdma is much better

# ¿ Feb 25, 2014 15:30

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

Bloody: Mar 3, 2013

maniacdevnull posted:

i need to go dumpster diving where you live

i want a sillyscope so bad, where can i get a good n cheap one that can let me spy on, lets say, 57600baud serial traffic?

57.6kbaud traffic you could spy on with a good sound card

# ¿ Feb 26, 2014 04:48

Bloody: Mar 3, 2013

technically yes

# ¿ Feb 26, 2014 05:28

Bloody: Mar 3, 2013

ive only once debugged a serial port with a sound card it was a funny and awful experience and i dont really recommend it

# ¿ Feb 26, 2014 05:30

Bloody: Mar 3, 2013

i dont understand the basic premise of wanting to talk to ham users

# ¿ Feb 27, 2014 21:34

Bloody: Mar 3, 2013

yeah but fundamentally like who cares

idk my understanding of hammers is limited to the notion that they say hi to each other and then mail each other signal strength reports or w/e but like... so what?

# ¿ Feb 27, 2014 22:45

Bloody: Mar 3, 2013

PuTTY riot posted:

my understanding of drag racers is that they drive 1/4 mile to see who goes faster then they go home.

my understanding of football is they run with a ball and see who runs faster but like...so what

drag racing is p dumb

football pays really well

talking to greybeards is not interesting, if i wanted to talk to them i would just talk to them at work

# ¿ Feb 27, 2014 22:50

Bloody: Mar 3, 2013

PuTTY riot posted:

https://www.youtube.com/watch?v=IWE7FrVY9T4

is this u irl bloody?

basically yes

# ¿ Feb 27, 2014 22:55

Bloody: Mar 3, 2013

can i listen to nasa satellites n poo poo

# ¿ Feb 28, 2014 01:25

Bloody: Mar 3, 2013

https://www.ettus.com/product/details/X310-KIT rule 36

# ¿ Feb 28, 2014 04:25

Bloody: Mar 3, 2013

number stations are neat + one of the things i would want to try and listen to if i did radio things

# ¿ Mar 3, 2014 16:39

Bloody: Mar 3, 2013

its one of the ISM bands so go hog wild below some power level

oh jk thats just in region 1 apparently america is region 2 lolol

# ¿ Mar 3, 2014 23:15

Bloody: Mar 3, 2013

atomicthumbs posted:

this all sdr stuff seems way easier than hooking up my T90A to my computer. what's the best dongle for radio performance

edit: or do selectivity and sensitivity and poo poo even apply when it's SDR

edit: can i decode p25 with an SDR

poo poo that matters: bandwidth and operating range. rule 36 answer: anything ettus makes

# ¿ Mar 5, 2014 15:56

Bloody: Mar 3, 2013

longview posted:

lol if you're not rolling all N and SMA with semi rigid coax loving everywhere and RG-316 (proest coax) for flexible jumpers

just lol

this unironically

# ¿ Mar 5, 2014 20:23

Bloody: Mar 3, 2013

Jimmy Carter posted:

so my new life goal is to have a place like out of cabinporn.com and have the only connection to the outside world be via ham radio. Maybe put a sunshine powered repeater up on a hillside somewhere if the winlink VHF doesn't reach far enough

that site has a surprising number of fuckin terrible cabins considering cabin porn should be really easy (eg take a picture of any cabin) seriously look @ this poo poo

# ¿ Mar 11, 2014 04:36

Bloody: Mar 3, 2013

whats a qrper

# ¿ Mar 11, 2014 15:21

Bloody: Mar 3, 2013

Crankit posted:

qrp is a morse code abbreviation that means reduce power, qrp guys use low power transmitters. <10W for voice <5W for morse

that sounds cool, guess im a hipster

# ¿ Mar 11, 2014 19:12

Bloody: Mar 3, 2013

i wanna know what your callsigns are but i understand the whole 'lol real name and address' aspect but still

if it contains anything awesome u must post it
like if its khailsatan or someth

# ¿ Mar 12, 2014 21:05

Bloody: Mar 3, 2013

build your own

# ¿ Mar 13, 2014 16:52

Bloody: Mar 3, 2013

Jonny 290 posted:

Also an option

(the last one is a kit you can buy)

this kinda poo poo makes me wanna be a radio nerd

# ¿ Mar 13, 2014 17:05

Bloody: Mar 3, 2013

Jonny 290 posted:

holy poo poo this is great

some of the tech deetz are amazing given their 1966 context

and then:

# ¿ Mar 13, 2014 20:24

Bloody: Mar 3, 2013

a radio

# ¿ Mar 18, 2014 20:21

Bloody: Mar 3, 2013

surface mount soldering is seriously not that tough. get good pcbs built (eg oshpark/dorkbotpdx), get some good flux (avoid the thick/resiny poo poo, its useless), and don't freak out. having any access to decent optics to inspect your work more thoroughly will be a huge ++. you don't really need stenciling, paste, etc. absolutely avoid BGA packages, try to avoid no-leads packages (eg QFN). TQFP/similar are easy with flux - just think of it as "im gonna solder down this entire side of the package". flux/surface tension magic will wick the solder to the pads/pins and hlep keep the chip aligned. get some solder wick for when you accidentally put on a shitload too much solder. 0805 and 0603 passives aren't too bad to do by hand. 0402 are borderline. 0201 are great if you're overwhelmed by self-loathing. lots of alcohol for cleaning when you're done (and then drinking when youre actually done) is recommended.

you don't need super steady hands or high end equipment to solder smd by hand. i think smd is actually easier than through-hole/leaded. the parts are small, but whatever, surface tension and flux are magic.

# ¿ Mar 20, 2014 19:10

Bloody: Mar 3, 2013

your SNR is worse :confused:

# ¿ Mar 21, 2014 18:35

Bloody: Mar 3, 2013

longview posted:

synthesizers and fm detectors (the good kind)
so pretty much all radios today use synths, and all your favourite pink floyd, genesis and yes tracks feature synths somewhere in the background
while the prog rock version is primarily designed for showing off your solo skills for 40 minutes at a time the synthesized receiver is designed to allow you to tune any frequency you want within the band
the alternative to a synth is a crystal based receiver, not the crystal receiver like 290 was working on, but rather a crystal oscillator based receiver
this works just like a digital logic oscillator, the crystal is resonant at a designed frequency, this directly corresponds to your receive and transmit frequency with very little push or pull range, a simple circuit allows it to generate a RF signal that is used directly or indirectly as a local oscillator in the superhet receiver we already covered
usually for VHF the crystal is in the area of 10-16 MHz and is then multiplied by a predetermined factor, for HF you can use the crystal as part of the receiver and transmitter directly

the synth is much better since it lets you choose whatever frequency you want, the only downside is that a synth based receiver has finite steps, it is usually less than trivial to change the step size in a discrete/medium integration synth receiver as we will see
here's a block schematic from wikipedia:

you'd better refresh your page now

so the principle here is we actually start with the VCO, a simple circuit to generate a frequency based on a voltage input, this is usually done with an LC filter where the C is a varicap-diode, a diode that changes capacitance based on voltage
this is basically what's inside the local oscillator block in a block schematic of a radio, to tune it simply attach a variable voltage supply like a pot-meter to the VCO input and tune
this will of course drift terribly and change with time, temperature, moon phase and so on
we need a system that can control this VCO to the frequency we want, to do this we do a loving TON of maths in school and boil it down to like three formulas in the end wtf
anyway, the core of the synth is the phase comparator, this is usually also a phase-frequency comparator, it will take two frequencies as inputs and give a digital output indicating which frequency is faster than the other
when the frequencies are the same, it will indicate which phase leads which as a +- output, when the phases are the same it won't change state at all and will instead go to a high impedance, this is important later, the output of the comparator is connected to the VCO, forming a closed loop

since we are using a phase comparator what we are building is actually a phase locked loop, the alternative would be a frequency locked loop but nobody uses that anymore, at least not for FM

we've covered the f_o is our local oscillator (receive frequency + or - our IF freq), the VCO is easy, the phase comparator makes sense i suppose
now we need to give it a frequency to compare, if we had the frequency we wanted somewhere we could feed that in except why wouldn't you just use that frequency directly? you wouldn't do that because it's stupid, what you can get for about $10 on ebay is a highly stable 10 MHz oscillator, and some other frequencies as well. if we buy one of these we can use that combined with a divider circuit, this will divide the frequency by a certain integer

at this point let's suppose we want to make a VHF receiver tuned to 144.000 MHz, tuning in 25 kHz steps and the VCO running at the output frequency, our IF is 16.9 MHz, meaning we need a local oscillator out out of this circuit at 127.1 MHz, and we need to be able to change it to 144.025-16.9 = 127.125 MHz and so on

what we are going to do now is to change our 10 MHz reference oscillator to 25 kHz by diving it by 400, this means our R value is 400 and f_r is 25 kHz
then what we need to do is to ensure that the desired output frequency is also 25 kHz by determining N, we want 127.1 MHz so we divide by 5084, if we wanted 127.125 we would divide by 5085 and so on.
when the frequency at the VCO is lower than the target, a low frequency will the output to the comparator, this will cause a rising voltage to the VCO until it reaches the target frequency!
what we've ensured now is that our channel step is 25 kHz, and by manipulating the N register of a simple digital divider circuit we can change the channel!

another nice thing is that we have slaved our LO frequency to the 10 MHz reference oscillator, and by virtue of the magic of feedback systems this ensures our frequency output has the same fractional stability (ppm, % etc) as the master, eliminating a lot of uncertainty in the system, as long as that oscillator is good the rest is guaranteed to be good by design

what becomes clear is that if your manager decides he wants to tune in 12.5 kHz steps for some stupid reason you'll have to change both the R and the N values, and you'll need twice as many possible N values to tune the same frequency range
this is probably a reason why HT designers don't want to add too narrow steps, it adds complexity and who needs those super narrow steps for FM anyway
in general it's desireable to use as high a frequency as feasible for the reference frequency, the reason for this is phase noise. phase noise is also known as jitter in digital circuits, jitter in an FM local oscillator will directly couple into the received or transmitted signal since it causes deviations between the rx signal and the reference, just like a genuine signal does

what we can do to prevent this is to design our loop filter with a higher bandwidth, see, the feedback nature of the system doesn't just affect frequency, it affects phase noise too, if the master oscillator is a high quality stable OCXO then within the bandwidth of the PLL, this noise will be the same as the reference phase noise, if we have a smaller bandwidth for the PLL than the deviation of the information signal we risk adding noise to the signal, this is bad

so anyway, discriminators for FM:
to detect FM there are several methods available, this is one way

this thing again, if our f_r signal happens to be a downmixed FM signal, we can tune our VCO to output the same frequency range as the FM signal input by changing N, when the FM signal changes frequency the PLL will follow this input, the output from the loop filter will contain a low frequency signal that tracks changes in input frequency, a demodulated FM signal

lol the transparency

# ¿ Mar 21, 2014 22:09

Bloody: Mar 3, 2013

get a metcal

# ¿ Mar 24, 2014 01:34

Bloody: Mar 3, 2013

i was going to offer suggestions but the ti website has this neat feature where it crashes chrome for me so lol

# ¿ Mar 28, 2014 15:54

Bloody: Mar 3, 2013

update: their site also crashes ie.

# ¿ Mar 28, 2014 16:19

Bloody: Mar 3, 2013

another update for u: firefox managed to get the pdf of the layout. easy solution is gonna be to deadbug it. gently caress doing no-lead parts by hand.

# ¿ Mar 28, 2014 16:23

Bloody: Mar 3, 2013

Gnuradio (lol) will Fart data over tcp or udp out of the box

# ¿ Mar 30, 2014 04:59

Bloody: Mar 3, 2013

more like raspberry poo

# ¿ Mar 30, 2014 05:54

Bloody: Mar 3, 2013

Jonny 290 posted:

QST magazine, 1927:

# ¿ Apr 7, 2014 04:53

Bloody: Mar 3, 2013

longview posted:

it doubles as an indicator

this does not appear to be a cap

# ¿ Apr 7, 2014 17:59

Bloody: Mar 3, 2013

atomicthumbs posted:

bounce everything off the moon

# ¿ Apr 10, 2014 03:50

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# ¿ Apr 28, 2024 10:44

Bloody: Mar 3, 2013

Jonny 290 posted:

yeeeeeeah go get a temp

also tbqh you need a big rear end antenna on the burb man, i say we pool funds and get you one of these and a 10 meter rig

quote:

PENETRATOR HAM SPARROW

mmmmmmmooooooodsss

# ¿ Apr 11, 2014 01:12

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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