Author Topic: PSK31 on the Cheap and on the Move  (Read 21201 times)

Offline Alan Georges

  • Survival Demonstrator
  • *******
  • Posts: 4589
  • Karma: 210
  • Still trying to reason with hurricane season.
PSK31 on the Cheap and on the Move
« on: January 16, 2014, 08:00:58 PM »
Short and Sweet Version:

PSK31 is a digital mode that, according to an article in last December’s QST magazine, punches through noise and bad band conditions significantly better than SSB voice, or even CW Morse code.  This can make up for the low power and minimal antennas usually associated with go-bag radios.  An iPhone (or iPad) has enough computing power to do PSK31 encoding & decoding.  There is a $3 app (PSKer) that works; there are other apps, and other platforms (Android, etc.) but these are not addressed here (input invited!).  No hardware link is needed, it is only necessary to hold the phone near the radio’s speaker, or to key and hold the mic near the phone.  No keyboard is needed, though it is convenient to use one through the phone’s Bluetooth connection.  For receive-only applications, an SSB-capable shortwave receiver can serve.  Basic starter instructions, examples, frequencies, and relevant links are given in the long version below.


The Long Version:

I had kind of dismissed digital modes for ham operation, because y’know, who needs to be hauling a computer and interface box around when the SHTF?  I mean, that radio’s already heavy enough.  But then this article in the December issue of QST got my attention: a +26 dB advantage over SSB can make up for a lot of compromise antenna and QRP-level power.  To save you the bother of pulling out the calculator, that’s a factor of 400 in relative power.  So over Christmas I was staring at my iPhone and thinking “there’s got to be an app for that...”  And there is.  PSKer is on the Apple store, and there’re a few others, some receive-only, I think there’s another one that transmits; there’s probably something similar for the Android side of the world, but I haven’t looked.  (Please post something below if you do Android and find something out there.)

If at this point you’re wondering what the heck is PSK31, here’s the Wikipedia link: http://en.wikipedia.org/wiki/Psk31

So I pulled the app, played around with it some.  The interface is kind of clunky, and at least on the iPhone 4S the control panel button is invisible (it’s on the upper right corner of the screen).  But it does work.  There are four programmable macro buttons for frequently used messages, like “CQ CQ CQ,” “My name is...”, “My radio is...”, etc.  It’s not horrible to use, but not super-slick either.  If you can link in a Bluetooth keyboard, it’s a lot faster than using the screen’s keypad, but in a pinch the keypad will serve.  (Yes, I had to get a 20-something kid to show me how to link the keyboard...)  There are interface boxes, and I am still researching these, but the whole thing can work by “air linking” to the radio by just holding the phone near the speaker, or by holding the mic near the phone’s speaker and keying as you press return on the keypad.  It’s not hard to sort out, but it is the kind of thing you want sorted ahead of SHTF.

About setting the radio, here’s a list of suggested contact frequencies:
http://aintel.bi.ehu.es/psk31.html
Set the radio on USB, to the nearest whole frequency (i.e., where it says “14070.15” just use “14070”).  And.... listen.  If you’re hearing any whistling noises, they’ll show up as vertical lines in the waterfall plot.  If that makes no sense and you’re not finding anything, dig around on youtube for some examples.  BTW, I’ve found the most contacts on 14.070 and 7.035.

To send, most knowledgeable people (and here that would not be me) recommend turning down the power to 1/4, no more than 1/3, of the RF amplifier’s output.  That does knock down the 26 dB advantage to a ‘mere’ 20 dB.  Oh well.  Of course, you can only legally send on ham digital sub-bands.  While I am sure this would all work on say CB, I can think of about 10,000 perfectly good reasons not to do so.

So, how well’s it work?  I’ve had a couple of brief conversations on 20 meters, one out at 850 miles.  The guy on the other end was surprised I was using an iPhone.  On the receive-only side, this works quite well with my Tecsun 660 shortwave.  On just 5’ of random wire for an antenna, I’ve pulled in signals as far away as Ontario and Arizona, and I’m down near New Orleans.  They both reported that they were running only 25 watts.  So for you non-hams out there, this whole thing can work great on a $125 radio plus a $3 app, assuming you already have the phone.  And even the phone can be dirt cheap, I got my 4S for $50 on a contract-renewal special.  Again, look on the Android side of things too, that stuff can be downright reasonable.

I’m still working on finding a decent small interface box.  I’m sure I’m losing something in the air link between the phone and the radio.  A few random characters leak into the text from background noises.  But it does all work as-is, just air linking things.

Those guys operating PSK31 are fast, many are racking up contacts for contests or awards.  The Bluetooth link to a keyboard is a big help.  I’ll probably pick up an inexpensive keyboard this weekend so that I don’t have to keep cannibalizing my computer whenever I want to transmit.  (Kind of makes looking up the other guy on qrz.com in mid-QSO tricky.)  But as I said, in a pinch or just to try things out, the phone screen’s keypad will serve.  Certainly in a SHTF situation, when it’s all about the content of the message and not racking up QSL cards, things can slow down a bit.

OK, I’m just getting started in all of this, but some interesting things are popping up already.  I’m pretty blown away at how well this works, for so little extra investment.  Anybody else doing PSK31?  Anybody want to try making contacts over the weekend?

ps: SCWolverine posted a link to some good tutorials at: http://thesurvivalpodcast.com/forum/index.php?topic=43191.msg483160#msg483160

Offline FreeLancer

  • Global Moderator
  • Survival Veteran
  • ******
  • Posts: 6116
  • Karma: 772
Re: PSK31 on the Cheap and on the Move
« Reply #1 on: January 16, 2014, 08:52:50 PM »
Bookmarked for closer read later.

Offline FreeLancer

  • Global Moderator
  • Survival Veteran
  • ******
  • Posts: 6116
  • Karma: 772
Re: PSK31 on the Cheap and on the Move
« Reply #2 on: January 17, 2014, 01:53:54 AM »
Great info AG.  Definitely something I want to try.

Offline doublehelix

  • Survivalist Mentor
  • *****
  • Posts: 449
  • Karma: 21
Re: PSK31 on the Cheap and on the Move
« Reply #3 on: January 17, 2014, 11:02:15 AM »
Nice find and something to also try on the VHF/UHF repeaters.

Offline Canadian Prepper

  • Survivalist Mentor
  • *****
  • Posts: 676
  • Karma: 54
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #4 on: January 17, 2014, 11:34:11 AM »
Thank you for a very informative and timely post!

I've just got a Yaesu FT-897D during a boxing week sale and have just started to listen on the air and try to figure out it's many functions, especially since I have to figure out how to get around controlling background noise, as any of the conversations I've come across on 20,40 and 75m have been mostly impossible to follow, and I haven't yet tried to CQ for anyone. The 20m band however seems most resonant on my MFJ portable vertical and I'm pretty sure that I'll figure out how to listen and subsequently transmit with voice.

Back to the topic of this thread, I'll also be searching for a cell phone in the next few weeks and will look into getting one that can take the PSK31 app. I'll be busy enough trying to figure out voice in the next few weeks and haven't yet decided whether I'll get a Signalink USB connector or Rigblaster sound card interface (if that's what it's even called) but if getting the phone that I need anyway will allow me to transmit and receive on PSK31, I'll be up for tying to connect some weekend after I've set it up.

@Alan Georges: Do you know if the phone can use the app when local cell phone service is disrupted? If the app is integral to the phone, so that it can work with it even when local cell towers are out, it might be much easier to keep it powered and in use during an outage than a laptop.

Offline SCWolverine

  • Survivalist Mentor
  • *****
  • Posts: 547
  • Karma: 66

Offline Alan Georges

  • Survival Demonstrator
  • *******
  • Posts: 4589
  • Karma: 210
  • Still trying to reason with hurricane season.
Re: PSK31 on the Cheap and on the Move
« Reply #6 on: January 17, 2014, 05:33:53 PM »
Very nice links, SCW.  Lots to dig around on there.  Ultimately I'd like to have something to, at the very least, eliminate the air link.  Even if I have to key the mic when sending.

As if on cue today, I stumbled across a PSKer-like app for Android: https://play.google.com/store/apps/details?id=com.wolphi.psk31&hl=en

@Alan Georges: Do you know if the phone can use the app when local cell phone service is disrupted? If the app is integral to the phone, so that it can work with it even when local cell towers are out, it might be much easier to keep it powered and in use during an outage than a laptop.
It's a self-contained app, independent of cell tower coverage.  In fact I demo'ed it with my shortwave at a friend's BOL last weekend, well out of cell phone range.

Offline SCWolverine

  • Survivalist Mentor
  • *****
  • Posts: 547
  • Karma: 66

Offline Canadian Prepper

  • Survivalist Mentor
  • *****
  • Posts: 676
  • Karma: 54
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #8 on: January 17, 2014, 11:03:43 PM »
Exciting stuff! I was listening for PSK31 signals for the first time today with my FT-987D on 40m, and used my desktop's speaker headphones to listen to them with Digipan. For my first serious evening on the air I managed a couple of contacts in Washington State, one in Montana, a few in Pennsylvania and Maine, plus individual HAMs in Vermont and New York State. It was much easier than trying to tune into and listen to voice contacts. 

I'll probably still get the sound card interface for a laptop, but being able to receive and send with the help of the phone app would be great for weekend trips to relatives, the cottage, etc. It would also be more efficient to recharge the phone with the cigarette charger in my Alinco power supply and an emergency deep cycle battery during a power outage than losing that valuable energy recharging a laptop battery. 

Offline Hootie

  • Written Word Wrangler
  • Dedicated Contributor
  • ******
  • Posts: 1189
  • Karma: 43
  • Just another day gardening in the heat of texas
    • Frozen Gardener
Re: PSK31 on the Cheap and on the Move
« Reply #9 on: January 18, 2014, 08:34:13 AM »
Anyone try to PSK31 using a Baofeng Uv 5R  ?

Offline iam4liberty

  • Survival Demonstrator
  • *******
  • Posts: 3767
  • Karma: 304
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #10 on: January 18, 2014, 12:00:38 PM »
Anyone try to PSK31 using a Baofeng Uv 5R  ?

Yes, several have experimented with it and it works.  But the distance advantages of PSK31 disappear when sent via FM.  So an FM only radio like the Baofeng UV 5R is not what is typically used for PSK31 even on 2 meters.  For 2 meter FM it is easier and just as effective to use APRS.

Offline armymars

  • Survivalist Mentor
  • *****
  • Posts: 819
  • Karma: 23
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #11 on: January 18, 2014, 12:57:26 PM »
OT sort of

I use MT63 on FM when I'm in an exercise. The local EOC sends me the traffic with MT63 over the local 2M repeater or by simplex. Then I cut and paste to M110A or just resend it on a MARS frequency.  It's a lot faster then writing it down then typing it into my computer. I've used acoustical coupling for years when I ran portable every Wednesday morning. I now have a SCI-6 interface that I built from a kit.  Now my wife doesn't have to listen to it  when I'm on the air. 73

Offline Alan Georges

  • Survival Demonstrator
  • *******
  • Posts: 4589
  • Karma: 210
  • Still trying to reason with hurricane season.
Re: PSK31 on the Cheap and on the Move
« Reply #12 on: January 18, 2014, 05:26:27 PM »
Had a short QSO with a guy in Venezuela today, 2000 miles away on 25 watts, 20 meter band.  Of course everyone's signal is always reported as 599...  but his signal really was a 599 on this end.  Looking at the radio's power output meter, it was only hitting about 5 watts when I had the power turned down to 25.  I'm guessing that some level's off over the airlink.  So I cranked it up to 90, and the meter was peaking around 25 watts when actually transmitting data.  (No visible smoke or detectable burning smell so far.)

Still shopping for an inexpensive Bluetooth keyboard that I can dedicate to the iPhone.  Had a salesdroid in Best Buy tell me today that "Apple uses a different kind of Bluetooth, so you can only use the $79 Apple keyboard."     I smiled faintly and thanked him, then walked.  Sooner or later the right deal will pop up.  (Amazon has a nice one for $15 through an allied retailer, but the shipping time is glacial.  Maybe when I don't have so much travel slated for the near future...)  Until then, I can keep borrowing the computer's keyboard.

Anyway, this stuff works great!

Offline iam4liberty

  • Survival Demonstrator
  • *******
  • Posts: 3767
  • Karma: 304
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #13 on: January 18, 2014, 06:10:42 PM »
I use MT63 on FM when I'm in an exercise. The local EOC sends me the traffic with MT63 over the local 2M repeater or by simplex. Then I cut and paste to M110A or just resend it on a MARS frequency.

Elegant!

Had a short QSO with a guy in Venezuela today, 2000 miles away on 25 watts, 20 meter band.

Nice contact!  I like CW but I have a feeling within 10 years what you are doing will displace it, especially for contesting.

Sooner or later the right deal will pop up.  (Amazon has a nice one for $15 through an allied retailer, but the shipping time is glacial.  Maybe when I don't have so much travel slated for the near future...)  Until then, I can keep borrowing the computer's keyboard.

Have you checked newegg.com?  They usually have nice ones for $20 to $25.

Offline Alan Georges

  • Survival Demonstrator
  • *******
  • Posts: 4589
  • Karma: 210
  • Still trying to reason with hurricane season.
Re: PSK31 on the Cheap and on the Move
« Reply #14 on: January 18, 2014, 06:26:35 PM »
Have you checked newegg.com?  They usually have nice ones for $20 to $25.
Aw man, shoulda though of that.  Thanks.  One more place to check locally; if no joy, then newegg it is.  Nice selection of sub-$35 stuff, much of it very bugoutable looking.

Offline backwoods_engineer

  • Survivalist Mentor
  • *****
  • Posts: 978
  • Karma: 43
  • An engineer trying to get back to the woods
    • Backwoods Engineer's Blog
Re: PSK31 on the Cheap and on the Move
« Reply #15 on: January 19, 2014, 08:00:32 AM »
Anyone try to PSK31 using a Baofeng Uv 5R  ?

Not capable of it.  You need more rig than a $30 Chinese VHF/UHF rig for PSK-31.  It has to be SSB capable in order to perform the upconversion from baseband.

Oh, and those who say they've tried it using FM?  You're just putting tones in one end of a wideband radio, and getting them out the other end.  You're getting NONE of the SNR improvement that comes from the narrow bandwidth of PSK31 on HF.

Offline backwoods_engineer

  • Survivalist Mentor
  • *****
  • Posts: 978
  • Karma: 43
  • An engineer trying to get back to the woods
    • Backwoods Engineer's Blog
Re: PSK31 on the Cheap and on the Move
« Reply #16 on: January 19, 2014, 08:07:02 AM »
Alan,

I am PSK-31 capable in my truck.  I used a laptop and the Tigertronics Signalink USB interface, although I too have been experimenting with PSK apps on my iPhone.

I made a contact with a station in Quebec while sitting in a drive-thru.  I have made multiple contacts to other states and the Carribean while going down the road at 70+ MPH, by using the "canned" message capability of FLDigi, and a small handheld trackball for clicking the next frequency (FLDigi can show the conversations on the entire band at once).  Not recommended for perfect road safety, but I needed to know I could do it.

It's a great mode for a bug-out vehicle, especially one configured with an NVIS antenna.

Offline backwoods_engineer

  • Survivalist Mentor
  • *****
  • Posts: 978
  • Karma: 43
  • An engineer trying to get back to the woods
    • Backwoods Engineer's Blog
Re: PSK31 on the Cheap and on the Move
« Reply #17 on: January 19, 2014, 08:16:54 AM »
Had a salesdroid in Best Buy tell me today that "Apple uses a different kind of Bluetooth, so you can only use the $79 Apple keyboard."     I smiled faintly and thanked him, then walked. 

Salesdroid is WRONG, of course.  I use a cheap Chinese Bluetooth Keyboard I got from dx.com.  Don't the URL, but it's small, about half-again bigger than the iPhone.  Works fine on the iPhone4.

Offline Alan Georges

  • Survival Demonstrator
  • *******
  • Posts: 4589
  • Karma: 210
  • Still trying to reason with hurricane season.
Re: PSK31 on the Cheap and on the Move
« Reply #18 on: January 19, 2014, 04:22:07 PM »
Salesdroid is WRONG, of course.
Yeah, where the heck do they dig up guys like that?
Quote
I use a cheap Chinese Bluetooth Keyboard I got from dx.com.  Don't the URL, but it's small, about half-again bigger than the iPhone.  Works fine on the iPhone4.
Must be the *right* kind of Bluetooth then! :D

Made some 5000 mile hops on 10 meters to Uruguay and Brazil today – 25 watts.  This is stuff is like magic.

Offline armymars

  • Survivalist Mentor
  • *****
  • Posts: 819
  • Karma: 23
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #19 on: January 19, 2014, 06:06:18 PM »
I know I don't get any of the S/N advantage with it on FM. I just use it for the cut and paste advantage when passing traffic from the EOC to my Mars station. It saves time on both ends. 73

Offline iam4liberty

  • Survival Demonstrator
  • *******
  • Posts: 3767
  • Karma: 304
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #20 on: January 19, 2014, 08:27:32 PM »
I know I don't get any of the S/N advantage with it on FM.

But more importantly for FM you are getting robust error checking.  That should translate into speed and reliability.

Offline SCWolverine

  • Survivalist Mentor
  • *****
  • Posts: 547
  • Karma: 66
Re: PSK31 on the Cheap and on the Move
« Reply #21 on: January 20, 2014, 08:19:42 PM »
I hear MT63 is the Go-to Digi for 2m FM.....I'm almost there (well I'm there but need someone on the other end to receive  ;) )

http://www.qsl.net/wm2u/mt63.html

http://www.navymars.org/central/reg4/al/MT63.htm

some youtube stuff avail to view if interested as well!

Offline Carl

  • Mr HamTastic!
  • Forum Veteran
  • *********
  • Posts: 13105
  • Karma: 714
  • COW?...No ,I haven't seen your cow.
Re: PSK31 on the Cheap and on the Move
« Reply #22 on: May 18, 2014, 01:16:34 PM »
PSK is cool. With a 31 HZ wide signal and a computer listening compared to SSB voice 3000 HZ bandwidth and my old ears...a 20 watt PSK signal is equivalent to about 2000 watts voice AND the PC hears thing BELOW THE NOISE ...and that can't be done with human ears.

As to VHF  FM...yes , it will work,but no real advantage...besides some opsec.

But with SSB it really comes into it's own.

Offline TiredOldGrunt

  • Senior Survivalist
  • ****
  • Posts: 298
  • Karma: 15
  • Tabbed: "Regular Guy"
Re: PSK31 on the Cheap and on the Move
« Reply #23 on: May 18, 2014, 03:25:24 PM »
One of my longest recorded contact was with PSK on 20m with DJ5(XX) at a distance of 4,127 miles with less than 25w.   

:-)

Offline armymars

  • Survivalist Mentor
  • *****
  • Posts: 819
  • Karma: 23
  • New TSP Forum member
Re: PSK31 on the Cheap and on the Move
« Reply #24 on: May 18, 2014, 07:58:36 PM »
  PSK31 is cool. I've printed out more then one goust signal.

Offline Chemsoldier

  • Pot Stirrer
  • Moderator On Leave
  • Survival Veteran
  • *
  • Posts: 5722
  • Karma: 544
Re: PSK31 on the Cheap and on the Move
« Reply #25 on: May 18, 2014, 08:18:41 PM »
Thanks to all who have posted, I am definitely going to try this one day.

Offline Smurf Hunter

  • Survival Veteran
  • ********
  • Posts: 7172
  • Karma: 334
Re: PSK31 on the Cheap and on the Move
« Reply #26 on: May 22, 2014, 02:00:39 PM »
For complete newbies, this is an excellent intro:

https://www.youtube.com/watch?v=jQpBGh9RMEQ&list=PL8D7C6EBD6E2081E2

The radio is really not the important part, as the video demonstrates how you can playback the recorded PSK31 audio and have it decoded.  For anyone old enough to remember, this is very analogous to computer phone modems, or even FAX machines.  In theory you could do this with a cassette tape recorder from 1982 - though that's obviously not useful or convenient :)

You can try out the software with static audio recordings and see how well it works, or if you like the interface.

Offline backwoods_engineer

  • Survivalist Mentor
  • *****
  • Posts: 978
  • Karma: 43
  • An engineer trying to get back to the woods
    • Backwoods Engineer's Blog
Re: PSK31 on the Cheap and on the Move
« Reply #27 on: May 23, 2014, 01:37:11 PM »
One of my longest recorded contact was with PSK on 20m with DJ5(XX) at a distance of 4,127 miles with less than 25w.   

:-)

I also run <25W, and have Kiev, Ukraine in the log at 5,095 statute miles.

Offline bkt

  • Prepper
  • **
  • Posts: 43
  • Karma: 2
Re: PSK31 on the Cheap and on the Move
« Reply #28 on: June 26, 2014, 10:50:10 AM »
For those who might be interested in trying APRS, here's an inexpensive solution: http://www.mobilinkd.com/. It's tiny, cheap, works with a bunch of radios and smart phones/tablets, and it gets you sending and receiving digital data over radio.

I have one on order and it should be here in a few days. I'll write up a report after a round of testing.

Also, thanks for the info in this thread - I'm working on getting into packet radio and there's lots of good stuff here. :)

Offline Sailor

  • Senior Survivalist
  • ****
  • Posts: 205
  • Karma: 15
Re: PSK31 on the Cheap and on the Move
« Reply #29 on: November 25, 2014, 09:12:21 AM »
FT-857, droid, and that Wolfie link for psk-31 in the field.  Skip to 2m in the video. 

https://www.youtube.com/watch?v=CnCE9JKl44Y