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Author Topic: PSK-31  (Read 13464 times)
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« Reply #15 on: August 13, 2000, 02:33:31 AM »

   Yes, indeed PSK31 on VHF works just great using FM rigs.  Because of the fact that the digital signal processing in PSK31 takes place at audio (baseband) the 20db of gain achieved by narrowing the bandwidth to 31 Hz as compared to the 3100 Hz of the audio signal the performance becomes outstanding.  Paths that are impossible using voice can often be bridged by using PSK31.  A path I tested that took a 13B2 Yagi pointed at mountains about 10 miles away to get through on voice was bridged by using PSK31 and the same power (40 watts FM) was good copy on PSK31 using just a mag mount whip on 147.440 MHz.  There is 12 dbd right there.  I then dropped the power to 5 watts and was still good copy.  There is another 8 db so overall I got 20 db improvement as advertised.  Same could be done using SSB but one Hz accuracy of tuneing might be tough. Also 2 meter FM rigs outnumber 2 meter SSB rigs by a wide margin.  They are cheaper,too.  They are also designed for 100% duty cycle.  The wider bandwidth of FM vs SSB has nothing to do with the case because the bandwidth reduction takes place at AUDIO. The big secret is to run the FM rigs UNSQUELCHED.  I figure a practical antenna on 2 meters which would produce 20 dbd gain might be an array of 8 13B2's.  Just think of the possibilities.

Aloha  --  Butch  --  W6KAG --  Molokai, HI
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KC8HNZ
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« Reply #16 on: August 13, 2000, 10:23:49 PM »

I might give it a try. If there is any one in the Northeast part of Ohio, look for me around 144.50(May change if its already set asidefor something.) after 8pm. 73's
Jason KC8HNZ
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N2FZ
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« Reply #17 on: August 14, 2000, 07:55:47 AM »

I also lose the audio when I plug into the output jack of my laptop.  I just got used to not having any audio.  You dont really need it anyway.  Just make sure that you are getting audio to the xciever by watching the RF output meter on your rig or SWR meter.
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WA4CNG
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« Reply #18 on: August 19, 2000, 11:40:11 AM »

I looked around alot.  Got help at www.buxcommco.com
They have diagrams for connections to almost any rig on the market, diagrams are on-line, just print.  They also have kits for interfaces.

I used a straignt 3.5mm patch cord from speaker to sound card input.  Bought $15 of parts from RS and built TX side.
I listened alot first as my RX interface was first, 3 weeks later I built the TX side.

Using Digipan and Winwarbler (3 channels at one time).
Just remember on the TX side, turn compressor off and adjust TX audio from sound card to where you just hit the amount of power you want to run.  I run from 20-40 watts without much problem.
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K1HC
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« Reply #19 on: August 20, 2000, 10:23:16 AM »

Hi Jason-
I'd like to try to work you via PSK31 on 2 meters.  I'll listen for you after 8 PM in the evenings on 144.500.  I'm running at ICOM IC-706MKII with a 160 watt Mirage amp to a 17 ele yagi at 55 ft.  If this gets posted to the PSK31 forum as well, I'm like to hear from others who can work PSK31 on VHF (6 and 2 meters).  Thanks!

73,

Dick, K1HC
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K8OCN
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« Reply #20 on: August 21, 2000, 12:16:15 AM »

Well I set up the receive part in about 5 min.
Its unbelivable that all those seperate signals are mixed together in such a small space.

I have a question and I am sure its been covered but I am new to eham, How does one make sure he is not going to interfear with another station if we are all transmitting on the same frequency?

(I do miss the RTTY image on the scope)

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K9OHI
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« Reply #21 on: August 23, 2000, 04:30:34 PM »

Don't worry, you're not all transmitting on the same frequency.

Let's say you have your transceiver set to precisely 14.070 MHZ USB.  What you see on the waterfall display are signals spread up the band from 14.070 MHZ.  For example, if you see a PSK 31 signal at 2 KHZ on the waterfall, he's actually transmitting a signal on 14.072 MHZ; a signal you see at 3 KHZ on the waterfall is transmitting on 14.073 MHZ, and so forth.

When you are operating PSK31 and key your transceiver, you will be transmitting on the same frequency as the station you are copying (assuming you have "netted" your transmit and receive functions) .  So, if you have your transceiver set at 14.070 MHZ USB and are copying a station at 3KHZ on the waterfall, both you and he are actually transmitting on 14.073 MHZ.  

If this doesn't make sense, you might want to take a look at the ARRL Handbook and read the section on Single Sideband.  That will explain how a transceiver, set at 14.070 MHZ, will transmit a carrier on 14.071 MHZ if a 1 KHZ sine wave is injected into the mike connection.

I agree, nothing quite as pretty as that crossed-line display of a RTTY signal on the o-scope.

Purists take note:  In the interests of simplicity, I have made some assumptions (adequate carrier and unwanted sideband suppression, for example) and have not addressed the actual bandwidth of the PSK signal, so please don't flame me with  technical critiques.  Think I've answered his basic question without getting into a lot of minutia.  We can save that for a later discussion.

                                                  Tom
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K8OCN
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« Reply #22 on: August 25, 2000, 10:09:30 AM »

Thanks for your post and your "Simple" description did make sence. I will also check out the ARRL handbook, I did not think this mode would be in there because it was so new. I think that even if its not in there I will find more info under the SSB Section.

I have made some contacts, I am still waiting for my interface I ordered so I use my IC-735 with its desk mike and feed the audio in from the computer speakers.

It seems to work fine (YL is not crazy about it) I transmitted into a dummy load and connected my 706 to a computer and the signal does not apeer to be any wider than others on the bank and I looks clean.

Thanks again for your reply.

Delbert McCord
KA8OCN
dmccord@usol.com
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N8XMS
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« Reply #23 on: September 03, 2000, 08:17:48 AM »

Is there a "preferred" way for reporting the "mode" on a QSL card for a PSK31 QSO?  Is "PSK" enough or should I indicate "PSK31" or even "BPSK"?
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KB2SMS
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« Reply #24 on: October 12, 2000, 11:10:27 PM »

 I just write PSK31 in the mode box. 73 de Tom


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"My best advice to anyone who wants to raise a happy, mentally healthy child is: Keep him or her as far away from a church as you can." - Frank Zappa
N8PKN
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Posts: 11




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« Reply #25 on: May 14, 2001, 02:52:07 AM »

I bought a RigBlaster at Dayton last year, finally got around to hooking it up a month ago. Tried using Digipan to do PSK-31, and was able to detect signals, recover copy, however when I placed the rig in transmit mode it stayed keyed up, wouldn't un-key unless I hit the ESC key on the computer keyboard. I never was able to make a contact with it. So much for the plug and play easy PSK-31.
It's now back in the box, gathering dust, I'll chase some good DX and (maybe) play with it later.  
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