Ham Radio

Sounds intersting!
Do you have more details on this?
Try this link: http://www.arrl.org/digital-modes It introduces RTTY, PSK-31 and others. RTTY is the old protocol and it just transmits to any radio listening in. PSK-31 is more like a computer modem in that a radio receiving the signal can check for transmission errors and ask for a re-transmit of portions of messages that do not come over cleanly.

As per the FCC, if you are in the US, you can make up your own protocol so long as the specs are "published" somewhere. So there are a number of other systems out there.
 
I've messed around with the SDR dongle a bit. Mostly I've used it for monitoring local analog ham conversations. I need a better antenna setup than the crappy mag mount I have running right now.

Good luck with that SDR trunk program. How'd you build the quarterwave, by the way?
@skullmask One of these bulkhead SMA connectors:

shopping.jpeg

and 5 pieces of copper wire cut to 3.3 inches. Solder the 4 radials into the 4 corner holes and the center mast into the center conductor. You'll want to measure and trim the center mast so that you get 3.3 inches from the flange to the tip (for 850MHz). Bend the radials down so they are at a 270 degree angle to the center mast. It should look like a pyramid with a spire on top. Plug your coax onto the mating side of the connector and you've got a quick and dirty antenna. You can crimp a ring terminal to the end of the center mast so you can hang the antenna up by a string. Just take the length of the ring terminal into account, as it will add to the effective length of the antenna. This works well for uhf and vhf too using a BNC instead of the SMA shown.

I'll get out to the building soon and snap a pic of mine & post it.
 
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@skullmask - Here ya go. Sorry for the delay. I did this with 26awg solid copper wire, but 14awg or so would work just fine. I'm just receiving, so nothing too precision here. If I were transmitting, I'd be a little more precise and avoid the splitter.

I've got the SDRs running with Unitrunker & DSDPlus and can monitor trunked systems from 45 miles away. Pretty cool.
 

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Sparrow
@skullmask - Here ya go. Sorry for the delay. I did this with 26awg solid copper wire, but 14awg or so would work just fine. I'm just receiving, so nothing too precision here. If I were transmitting, I'd be a little more precise and avoid the splitter.

I've got the SDRs running with Unitrunker & DSDPlus and can monitor trunked systems from 45 miles away. Pretty cool.
@Sargon2112 Neat setup. I guess the hook at the tip of the antenna makes for a convienient method of hanging it up. I haven't seen dual SDRs set up like that before though. Is that so you can continuously monitor the trunked system's control channel with one while listening on working channels with the other?

This weekend I resumed messing with the HF set again. I bought a USB cable and connected my PC to the USB port on the Icom IC-7200 which has a built in sound card. Using Hamlib and fldigi I was able to work some stations using a digital mode called PSK31. Some US, some Canadian. I even briefly saw a few Spanish and German stations, but they could not receive me.

I'm really liking the digital modes. The constant hiss of background noise of phone SSB grates on me after a while. And its super hard to reach anyone since the band conditions are so bad. But with PSK I can just pick out a signal on my PC's waterfall display and type out messages, and they often get through whereas my voice does not.
 
@Sargon2112 Neat setup. I guess the hook at the tip of the antenna makes for a convienient method of hanging it up. I haven't seen dual SDRs set up like that before though. Is that so you can continuously monitor the trunked system's control channel with one while listening on working channels with the other?

This weekend I resumed messing with the HF set again. I bought a USB cable and connected my PC to the USB port on the Icom IC-7200 which has a built in sound card. Using Hamlib and fldigi I was able to work some stations using a digital mode called PSK31. Some US, some Canadian. I even briefly saw a few Spanish and German stations, but they could not receive me.

I'm really liking the digital modes. The constant hiss of background noise of phone SSB grates on me after a while. And its super hard to reach anyone since the band conditions are so bad. But with PSK I can just pick out a signal on my PC's waterfall display and type out messages, and they often get through whereas my voice does not.
Yep, the purpose of the dual SDRs is as you said. One is parked on the control and the software decodes the data, pointing the second SDR to the working channel. It's technically not scanning anything, it's just being pointed to the working channel like any other radio in the system.

These RTL-SDR dongles run hot as hell, I haven't measured it, but they have to be over 85C internally, judging by the exterior temp. I'll be pulling them from those cases and potting them in a thermally conductive epoxy to a heatsink for the final rig. Will probably double the life, if not more than double it.

I intend to get my FCC license this fall, if any nearby testing is being held with Covid scaring everyone. I've been into this stuff too long not to have it and I would enjoy the PSK stuff you described, especially on HF.
Right up my alley. Not to mention having use of the multiple 440, 2 meter and 6 meter repeaters in the surrounding areas.

What antenna setup do you run on your HF rig? Are you running a pre-amp to hear those European stations or just a good beam?

Cheers.
 

skullmask

Sparrow
What antenna setup do you run on your HF rig? Are you running a pre-amp to hear those European stations or just a good beam?
I have a few different setups. I started out using a homebrew version of the Buddipole and Buddistick, which I based off the following video:


Written instructions are included in the video description. A few things I did different from this guy was that I made the balun like he did, but installed three eyelets on the sides, and a threaded base on the bottom so it could act as a guying point and platform for either the vertical or horizontal elements. I also built a dedicated vertical instead of reusing the horizontal elements since I could go longer with the whip and use a smaller coil, with the hope that it would be more efficient on the lower bands. The whip elements and other needed parts you can't find in a hardware store can be found at buddipole.com.

I haven't bothered messing around with beams yet, just standard dipoles. I also have another simple balun set up with terminals for wire dipoles, with elements cut for 40 and 80m that I can swap between. I put them all up using painters poles. I don't have a permanent setup, just portable stuff I can run a cable to from the kitchen window.

As for the pre-amp, I've messed with it before but didn't bother for PSK31. To be honest with as high as the noise floor on HF has been, all the preamp does is amplify the noise too so I haven't seen much use for it. On the other hand, I've seen an improvement in signal quality using the attenuator on occasion, especially on voice SSB.
 
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