GySgt D
January 07, 2006, 14:58
This was originally posted in 2002 on AWRM, frugals, arfcom, and Assaultweb. Since then, I have used PSK (phase shift keying) in Iraq, Japan, the Philippines, and elsewhere.
The post may seem a bit disjointed, as I've cut and pasted from several running threads. Over the years, it has evolved from a PSK-specific thread, to a PSK/RTTY/SSTV thread. Hopefully it is complete enough to be useful. I think that over-the-horizon communications will be very desirable after TSHTF, just as it is now. Amateur radio digital communications may come in quite handy, and I feel is worthy of any would-be survivalist's consideration.
************************************************** ****
Finally got all the stuff together AND working, for a one-man portable PSK station. Everything, minus the laptop, fits inside of a Camelback (and not one of those huge ones, either).
I field tested it a couple days ago, and received an answer on my very first call. It just happened to be a SgtMaj with the III Marine Expeditionary Force (on Okinawa island) who answered (he had intel on what I was up to beforehand, and he had set up a "radio ambush" for me). The second reply to my CQ calls was from California, and the third was from (Russian) Sakhalin Island. This was all with only 5 watts of power and a ground mounted vertical antenna.
Since I struggled with figuring this out the hard way, I'll tell y'all exactly what was required to make this happen. It seems as if every reference to digital communications that can be found on the internet is written as if the reader already knows everything they need to know beforehand. This was not the case with me. Every time I asked a question, I was given an answer that assumed a level of knowledge that I didn't always have. With that in mind, here is a brief description (in layman's terms) of what psk31 is and does, and my list of stuff that I personally used to get my operation on the air:
PSK31 is a type of digital communication. Instead of sending your voice over the airwaves, you send text. The benefits of text versus voice communication is beyond the scope of this simple explanation. PSK is suitable for low power use, and oftentimes does not require any extra $$$ to get on the air, unlike some other digital modes. It uses the sound card on your computer, which if you are reading this, you probably already own one. Getting on the air with PSK31 is almost entirely a matter of hooking up your computer to your ham radio. This can be accomplished using expensive store bought interface devices, or you can do what I did (and it works just fine), which is to simply purchase a $4 audio dubbing cable from your local wally world, along with a $7 mouse extension cord. You quite simply cut the dubbing cable in half, cut off the jack-side of the mouse cable, and splice the three of them together. http://www.packetradio.com/bbbb.htm has the diagrams that you need in order to do this. It is NOT rocket science. One end of what was once a dubbing cable goes into the microphone/audio-in jack on your computer, and the other goes to the headphone jack on your computer. The mouse cord end is what is hooked up to your radio (assuming that your particular radio requires the six-pin mini DIN connecter that I am describing here). Using readily available (and free) PSK31 software, you pretty much just follow the directions that came with the software, and quite literally type your message into your radio. Received signals are converted to text, and show up on your screen. Easy as pie.
Specifically what I used to put this together:
Yaesu FT-817 transceiver, HP Pavillion laptop computer (you don't need an expensive computer for this, a $200 garage sale special will work just fine in most cases), a $24 Ham Stick vertical antenna, six feet of RG-8 coax with (SO-239?) connector on each end, a LDG Electronics Z-11 autotuner (not always required), the aforementioned cables, a short RG-8 jumper cable (if you are going to use a tuner), PSK Commander software- http://groups.yahoo.com/group/FT817-Commander/ , and an external battery pack if you so desire.
BTW, one of the members of the Palomar Amateur Radio Club, of which I am a member, has an excellent website which has links to just about anything that you could possibly want to know about amateur radio. Give http://www.ac6v.com a try.
************************************************** *****snip comments*******
I won't comment on the legal aspects of encrypting amateur radio communications <snicker>, but it should work in theory.
Since PSK31 is not an "error-correcting" digital mode, you would need to have an error free transmission. This is quite possible with a good connection, but you can work around this problem by not attempting to communicate across the ocean with only 5 watts, and by sending your message two or three times consecutively (one of them is bound to work). ALTHOUGH I HAVE NOT TRIED IT, PGP would be my mode of choice. Less secure modes (which might not require as much transmitted data) might be appropriate for stuff that isn't of earth shattering importance.
BTW, last night I received signals from as far away as Paraguay. That is 12,160 away from me here in Okinawa. He didn't copy down my callsign correctly, but indications are that he at least heard me. My farthest QSO that I can PROVE on PSK was one with Oregon the other night, which is about 6,000 miles away from me. And I've already made a couple contacts with russian stations since starting this stuff a few days ago.
************************************************** ****snip comments*****
What he said.....
In the past couple of days, I have logged Buenos Aires, Argentina twice (12,000 miles away), and in the past couple weeks I've logged qso's with Russian, Australian, Japanese, and others quite a few times on PSK. Finally got a European station last week with Belarus, and an African station(or is it considered an Indian Ocean contact?)which was FR5HA on Reunion Island. All on only 5 watts and a dipole. Having a blast.
*************************** 1 Oct 2005 update**********
Here is a crummy pic of the aforementioned equipment. I have since made a nicer interface cable; shown here all tangled up on the table is my original cable which took all of ten minutes to build from scrounged components. This was taken on a FTX in Sept 2004; location=Laguna Mountain, San Diego County, California.
http://img.photobucket.com/albums/v521/GySgtD/100_0093.jpg
Here is a pic showing the gear neatly stowed in a SpecOps Brand PackRat bag. Haven't figured out a good way to pack a laptop into my ALICE pack yet, so I just carry it in an ordinary laptop case. The interface cables, dipole antenna with coax, and a length of 550 cord (for stringing up the antenna between a couple trees), all fit neatly into the laptop case. The PackRat bag easily fits inside of a backpack, or can be slung over your shoulder.
http://img.photobucket.com/albums/v521/GySgtD/817casea.jpg
It should be mentioned that I wrote this during the peak of the sunspot cycle, and that current atmospheric conditions do not support 11,000 mile contacts on only 5 watts. You can, however, still easily go across the continental United States. Also, I had only a few days of experience with digital communications when this was first written. I have since branched out into SSTV (slow scan television) and RTTY (radio teletype), which all use the exact same equipment and all use free internet software.
The links above may no longer be in operation; the software is still freely available. Google is your friend.
The post may seem a bit disjointed, as I've cut and pasted from several running threads. Over the years, it has evolved from a PSK-specific thread, to a PSK/RTTY/SSTV thread. Hopefully it is complete enough to be useful. I think that over-the-horizon communications will be very desirable after TSHTF, just as it is now. Amateur radio digital communications may come in quite handy, and I feel is worthy of any would-be survivalist's consideration.
************************************************** ****
Finally got all the stuff together AND working, for a one-man portable PSK station. Everything, minus the laptop, fits inside of a Camelback (and not one of those huge ones, either).
I field tested it a couple days ago, and received an answer on my very first call. It just happened to be a SgtMaj with the III Marine Expeditionary Force (on Okinawa island) who answered (he had intel on what I was up to beforehand, and he had set up a "radio ambush" for me). The second reply to my CQ calls was from California, and the third was from (Russian) Sakhalin Island. This was all with only 5 watts of power and a ground mounted vertical antenna.
Since I struggled with figuring this out the hard way, I'll tell y'all exactly what was required to make this happen. It seems as if every reference to digital communications that can be found on the internet is written as if the reader already knows everything they need to know beforehand. This was not the case with me. Every time I asked a question, I was given an answer that assumed a level of knowledge that I didn't always have. With that in mind, here is a brief description (in layman's terms) of what psk31 is and does, and my list of stuff that I personally used to get my operation on the air:
PSK31 is a type of digital communication. Instead of sending your voice over the airwaves, you send text. The benefits of text versus voice communication is beyond the scope of this simple explanation. PSK is suitable for low power use, and oftentimes does not require any extra $$$ to get on the air, unlike some other digital modes. It uses the sound card on your computer, which if you are reading this, you probably already own one. Getting on the air with PSK31 is almost entirely a matter of hooking up your computer to your ham radio. This can be accomplished using expensive store bought interface devices, or you can do what I did (and it works just fine), which is to simply purchase a $4 audio dubbing cable from your local wally world, along with a $7 mouse extension cord. You quite simply cut the dubbing cable in half, cut off the jack-side of the mouse cable, and splice the three of them together. http://www.packetradio.com/bbbb.htm has the diagrams that you need in order to do this. It is NOT rocket science. One end of what was once a dubbing cable goes into the microphone/audio-in jack on your computer, and the other goes to the headphone jack on your computer. The mouse cord end is what is hooked up to your radio (assuming that your particular radio requires the six-pin mini DIN connecter that I am describing here). Using readily available (and free) PSK31 software, you pretty much just follow the directions that came with the software, and quite literally type your message into your radio. Received signals are converted to text, and show up on your screen. Easy as pie.
Specifically what I used to put this together:
Yaesu FT-817 transceiver, HP Pavillion laptop computer (you don't need an expensive computer for this, a $200 garage sale special will work just fine in most cases), a $24 Ham Stick vertical antenna, six feet of RG-8 coax with (SO-239?) connector on each end, a LDG Electronics Z-11 autotuner (not always required), the aforementioned cables, a short RG-8 jumper cable (if you are going to use a tuner), PSK Commander software- http://groups.yahoo.com/group/FT817-Commander/ , and an external battery pack if you so desire.
BTW, one of the members of the Palomar Amateur Radio Club, of which I am a member, has an excellent website which has links to just about anything that you could possibly want to know about amateur radio. Give http://www.ac6v.com a try.
************************************************** *****snip comments*******
I won't comment on the legal aspects of encrypting amateur radio communications <snicker>, but it should work in theory.
Since PSK31 is not an "error-correcting" digital mode, you would need to have an error free transmission. This is quite possible with a good connection, but you can work around this problem by not attempting to communicate across the ocean with only 5 watts, and by sending your message two or three times consecutively (one of them is bound to work). ALTHOUGH I HAVE NOT TRIED IT, PGP would be my mode of choice. Less secure modes (which might not require as much transmitted data) might be appropriate for stuff that isn't of earth shattering importance.
BTW, last night I received signals from as far away as Paraguay. That is 12,160 away from me here in Okinawa. He didn't copy down my callsign correctly, but indications are that he at least heard me. My farthest QSO that I can PROVE on PSK was one with Oregon the other night, which is about 6,000 miles away from me. And I've already made a couple contacts with russian stations since starting this stuff a few days ago.
************************************************** ****snip comments*****
What he said.....
In the past couple of days, I have logged Buenos Aires, Argentina twice (12,000 miles away), and in the past couple weeks I've logged qso's with Russian, Australian, Japanese, and others quite a few times on PSK. Finally got a European station last week with Belarus, and an African station(or is it considered an Indian Ocean contact?)which was FR5HA on Reunion Island. All on only 5 watts and a dipole. Having a blast.
*************************** 1 Oct 2005 update**********
Here is a crummy pic of the aforementioned equipment. I have since made a nicer interface cable; shown here all tangled up on the table is my original cable which took all of ten minutes to build from scrounged components. This was taken on a FTX in Sept 2004; location=Laguna Mountain, San Diego County, California.
http://img.photobucket.com/albums/v521/GySgtD/100_0093.jpg
Here is a pic showing the gear neatly stowed in a SpecOps Brand PackRat bag. Haven't figured out a good way to pack a laptop into my ALICE pack yet, so I just carry it in an ordinary laptop case. The interface cables, dipole antenna with coax, and a length of 550 cord (for stringing up the antenna between a couple trees), all fit neatly into the laptop case. The PackRat bag easily fits inside of a backpack, or can be slung over your shoulder.
http://img.photobucket.com/albums/v521/GySgtD/817casea.jpg
It should be mentioned that I wrote this during the peak of the sunspot cycle, and that current atmospheric conditions do not support 11,000 mile contacts on only 5 watts. You can, however, still easily go across the continental United States. Also, I had only a few days of experience with digital communications when this was first written. I have since branched out into SSTV (slow scan television) and RTTY (radio teletype), which all use the exact same equipment and all use free internet software.
The links above may no longer be in operation; the software is still freely available. Google is your friend.