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Author Topic: PSK31  (Read 460 times)
KJ4PKO
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Posts: 53




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« on: November 09, 2009, 06:40:37 PM »

I have a Yaesu ft-530 and can't get it to key when I send a psk31 transmission. If I turn VOX on it will transmitt a soon as I plug it in to the computer.  Please help me!
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AB9TA
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Posts: 20




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« Reply #1 on: November 09, 2009, 07:36:04 PM »

It sounds like you only have audio connections from the sound card to the radio. There is no PTT generated in the soundcard.
Do you have any kind of an interface that connects the computer's USB or serial port to the PTT contacts on your radio?
If not, then VOX or manual PTT will be the only way to transmit.
(If you use VOX, ensure that you don't transmit Windows sounds over the air.)

73's,
Bill AB9TA
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KJ4PKO
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Posts: 53




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« Reply #2 on: November 09, 2009, 08:10:29 PM »

No, I don't have an interface.  I guess I will manually push the PTT to transmit. Thanks!
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VA7CPC
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« Reply #3 on: November 09, 2009, 10:00:43 PM »

Something is screwy.

You don't say what software you're using, and I don't know the details of the FT-530's mic jack.

But if you're:

a) turning on the rig's VOX switch;

b) connecting the soundcard output (headphone jack) to the rig's mic input,

c) _not_ connecting the "PTT" pin on the rig's mic jack to anything,
 
the rig _should not_ go into XMIT mode unless the soundcard is generating sound.

And it should only be generating sound if the software is in "Transmit" mode.

So I suspect (only a suspicion) that your connections to the mic jack aren't what you think they are.

Transformer-coupled interfaces are really useful.  I urge you to put ferrites at _both ends_ of the cables from rig to computer.   "RF in the shack" can be a real problem with direct rig-to-computer cables.  

             Charles
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N5LRZ
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« Reply #4 on: November 10, 2009, 05:44:10 AM »

Do a google...

Sound Card Interface


You will get several items listed.

Look for the keying interfact that uses an optoisolator for the keying circuit.  I find that the opto is far easier to construct (just 1 resistor and the chip).  

You will also see many circuits uning a transistor as the heart of the keyer.  I have made these as well.  It just takes a few more parts and a little more time.

Once you have built your interface, plugging the input into your 9 pin serial jack on the back of yur computer and the output into your key circuit of your radio your computer will then auto key your radio when you click the transmit button on your computer screen.

IF you have only USB ports, well then you probably will have to acquire one of those commercial made interface units.  

Either way you want your computer to auto key your radio when you click on the computer prrograms transmit button.
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N4CQR
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Posts: 566




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« Reply #5 on: November 10, 2009, 05:47:17 AM »

PSK on FM?
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N7NBB
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« Reply #6 on: November 10, 2009, 06:35:54 AM »

I'm with N4CQR.  I guess you COULD do PSK 31 on FM (hopefully simplex) but I don't know how you would control the gain of the audio (deviation) I would think given the nature of the beast (FM) it would be pretty touchy to try and get all the controls set correctly so that your signal is not too wide... causing distortion, etc. It will be a neat experiment with you and a friend trying this.. let us know the results. As I said, I guess it "COULD" be done, just never heard of PSK31 using an FM handheld.
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AA4PB
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« Reply #7 on: November 10, 2009, 08:31:52 AM »

PSK31 works with FM but it is still FM and the signal is not narrow as it is when running PSK31 into a SSB transmitter. On the receive side, the SNR must still be good enough for the discriminator capture effect. The result is that you loose most of the benefit of PSK31 for weak signal work.

If you want the same benefits from PSK31 on VHF that you get on HF then you must use a SSB VHF transmitter and receiver.
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N5LRZ
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« Reply #8 on: November 10, 2009, 08:53:59 AM »

Re CQR...

Why not on FM...

I have hooked up an old 2 meter radio to my secondary computr to transmit SSTV, and other digital communications thru FM mode using a locl repeater.  

The computer sound card just sends out an audio just like a mic that the radio transmits just like voice.

Those who have an old VHF radio might want to try hooking it up to send SSTV pictures.  They quality is equal to the quality of digi Image.

Admittedly its not long range but its great for local contacts as long as one remembers to get the permission of the repeater owner and send short transmissions so as not to time out the repeater.
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N5LRZ
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« Reply #9 on: November 10, 2009, 08:57:13 AM »

Your first sentence is absoluely true without any doubt.  

But then again if one is running it thru a repeater the signal is not going to be narrow any way unless the repeater itself is configured as such.

And thermo ducting adds that bit of potential distance possibility of contacts into surrounding states.
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N5LRZ
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« Reply #10 on: November 10, 2009, 08:59:42 AM »

Re PB...

Try Olivia Mode..

I have not used it myself but several pieces I have read have stated that Olivia is great for weak signal work.

Worth a try?
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N4CQR
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Posts: 566




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« Reply #11 on: November 10, 2009, 09:19:48 AM »

Re: LRZ

Here (Kentucky) FM repeaters are typically used for voice communications. FM is typically used for voice.
However there are (and were) repeaters for ATV and other modes; ie Packet. (Wide mode-modes)

I normally adhere to the conventional gentleman's agreement on modes and their respective bands and segments.

But folks can certainly do as they choose...

73 Craig
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AI7RR
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Posts: 164




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« Reply #12 on: November 10, 2009, 10:06:14 AM »

PSK on VHF FM....wouldn't that be PSK25K or PSK12.5K if using narrowband?

My shallow attempt at a little humor this morning.

73,,Roger
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AA4PB
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Posts: 12891




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« Reply #13 on: November 10, 2009, 10:48:26 AM »

Unlike SSB, the bandwidth of an FM signal does not get narrow because you transmit a single tone. The FM bandwidth is determined primarily by the deviation. The deviation is the same whether you transmit voice or MCW or PSK31 or RTTY or any other sound card mode.

I doubt that even Olivia would see the normal performance advantage when transmitted thru an FM system because the FM system sets the limits. If the FM discriminator doesn't capture the FM signal then no Olivia tones get through.

Use a single tone as an example. If I send a single tone into a SSB transmitter I get one, narrow, RF signal output. If I send that same single tone into an FM transmitter set for +/-5kHz deviation then the RF signal is about 10kHz wide.
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N5LRZ
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« Reply #14 on: November 10, 2009, 03:03:57 PM »

RE PB...

When using a repeater as the relay efficiency and band width are not a major concern.  There are only three things you have to worry about:

Will the repeater control person get pizzed off because you used a digital mode on his repeater.

Will the repeater time out, not a good thing.

Will the mode work thru the repeater on FM.

And I guess a 4th, concern is it legal per the rules and regs.

Now of course the repeater owner may ask one to refrain from using their repeater system as ones 'booster' and he would of course be within their rights to ask one to stop.  But other than that I have no problem using the all tooooo many unused and underused repeaters in my area for pictures.
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