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Author Topic: I want to do digital, I am an idiot on computers  (Read 6702 times)
AD9DX
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« on: August 19, 2012, 12:54:02 PM »

Ok, I really want to get in to digital, mostly PSK RTTY and JT65HF.  The main reason I want to do digital, is that I am addicted to 6m and 160m, and want to start doing weak signal work on top and the magic band.  I see where JT65HF is a good method to getting new QSO's when conditions are not the best.  I am trying to get better with computers, I have a computer that will do anything I need.  It has an Intel i7 processor, so I am fairly sure I am good with that.  I need to have some sort of interface, which is where I really need help.  My rig is a Yaesu ft-2000D.  ANy help would be greatly appreciated.  I really don't have a price limit, I want the most capable easy to use interface I can get. 

Last question, I know you can run power with JT65 on bands I have a good amp that will allow me to do key down on 160 and will probably get a good 6m amp in the near future (if the need arises).  Does higher power on JT65 increase bandwidth like PSK??

Thank you all for reading and answering my questions. 
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EX, KC9TRM, KB9IRZ
STAYVERTICAL
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« Reply #1 on: August 19, 2012, 02:47:45 PM »

Hi, and nice to see another prospective digital user.

1.
First, if you are an idiot on computers as your heading states (I bet you are not really), you need the simplest solution.
I would suggest you investigate the USB-Signalink interface by Tigertronics.
There are dozens of solutions out there, all equally effective in putting out a signal in digital modes, but there are basically two camps.

The first camp is where you use the internal soundcard of the PC to produce digital audio to modulate your transmitter.
Audio from the receiver is processed by the onboard soundcard as well.
In some cases these interfaces may have a built in Push to Talk circuit which is activated by the audio coming from the PC.
Other ones in this camp may need a serial port to provide Push to Talk support.
And some may have a USB port to provide Push to Talk.
But the main element in these interfaces is that they use the onboard PC soundcard.

The second camp is where a second soundcard is hooked up to the PC to provide digital support.
This camp generally uses a USB connection from the PC to the interface box where the second soundcard is housed.
Within this interface is the soundcard, and frequently a Push to Talk circuit which is activated when sound is produced by this card.

The first method has leads from the PC headphone, microphone and either a serial or USB port.
The second method has only one USB lead from the PC.

Advantages of the first method are basically you can make an inexpensive interface and if it has a Push to Talk circuit - it can be quick.
Disadvantages of the first method is that you have more leads from the PC, and sounds from the PC can end up on the air (dings etc).
Also, the control of the audio volume is done on the PC screen, so you have more controls to adjust (although some interfaces have volume controls).
You also lose the use of your PC soundcard while using digimodes.

Advantages of the second method (external soundcard) is simplicity of leads (one from the USB port) and good R.F. shielding, as well as simplicity.
Disadvantages of the second method is that the onboard audio activated Push to Talk may be a bit slow for ack/nack modes such as packet.
For the vast majority of digital modes however, the Push to Talk is certainly fast enough.

Again, if you want a simple setup, which has worked well for many users (see eHam reviews), I would suggest the USB-Signalink.


2.
On the question of power and digital modes, this is one where you have probably opened a hornets nest.
PSK31 does not increase in bandwidth with high power, nor does any other digital mode.
A clean 1KW PSK31 signal is exactly as wide as a clean 10W PSK31 signal.
The problem comes about because of the IMD performance of some transmitters as you push them higher in power.
Because higher power in some transceivers/amplifiers comes with higher IMD, the PSK31 signal gets wider by producing modulation products with itself.

This is purely because of the design of the amplifier, not caused by the level of power being used.

Where the matter becomes complicated and confused is that the typical PSK31 user is looking at a waterfall with many signals co-existing.
His receiver AGC is adjusting itself to the aggregate signal level of all the signals in his passband.
Now, while all the signals are about the same level, everyone is happy, and copy is easy.

But, now comes the big signal on the scene.
He may not be running high power, just close, or have a good antenna or propagation path.
His signal, being much stronger than the others, sends the AGC into defensive mode and it drops the gain of the receiver.
The big signal remains, but all the others disappear - the so called digital whiteout.

The solution is to do what CW ops do.
Use the IF filters, IF DSP, IF shift etc to remove the big signal from your passband.
But note that it should be done in the I.F. stages to stop AGC pumping from him.
Audio filtering can help to some extent, but it does nothing to keep him from your I.F. stages.

Most digital modes operators use around the 30 to 40 watt range of power in practice.
This is mainly because most guys use 100 watt transceivers, and many digital modes are high duty cycle, like key down.
So a safe operating point for operation is around 30 watts to keep the finals cool.

I hope this helps,

73 - Rob
 
« Last Edit: August 19, 2012, 02:53:51 PM by STAYVERTICAL » Logged
AD9DX
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« Reply #2 on: August 19, 2012, 05:08:50 PM »

Rob, that helped immensely.  In theory that all makes sense. I am hoping that getting everything set up with the signal link USB is easy like you say.  I completely understand the CW analogy.  I know those tricks, and am glad to hear those work on digi too. 
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EX, KC9TRM, KB9IRZ
AD9DX
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« Reply #3 on: August 19, 2012, 05:21:17 PM »

So, if the Signallink USB is a FB interface and costs $100, why do people spend megabucks on others?
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EX, KC9TRM, KB9IRZ
VE3FMC
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« Reply #4 on: August 19, 2012, 05:53:47 PM »

So, if the Signallink USB is a FB interface and costs $100, why do people spend megabucks on others?

Good question. I have been using a SignaLink USB since September 2007 and have never had any problems with mine. I use it daily for JT65 contacts and other digital modes.

Friend of mine has been using his about the same length of time and never had any issues with his.

Solid interface as far as I am concerned.
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W5DQ
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« Reply #5 on: August 19, 2012, 07:56:49 PM »

So, if the Signallink USB is a FB interface and costs $100, why do people spend megabucks on others?

I use a homebrew interface I designed and built myself and it cost a whole whopping $20, if that much. It interfaces to one of my computer sound cards (I run 4 of them) and it supports PSK31, RTTY, JT65, SSTV with PTT and CW keying via a serial port. It really isn't that hard to build one yourself and you can save a many bucks doing it.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
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« Reply #6 on: August 20, 2012, 01:10:51 AM »

So, if the Signallink USB is a FB interface and costs $100, why do people spend megabucks on others?

I will add my voice to the chorus of happy USB-Signalink customers.
I have two, and they both have worked well for years.

There is nothing wrong with the other types, but pricing is a matter for the manufacturers.

If you go with the USB-signalink, here are some things which may trip you up, but are easily avoided.

1. If you want to use the USB-Signalink be careful when buying not to get the Signalink SL or SL 1+
   These are versions which use the PC soundcard, but give you PTT and volume control.
   They do not contain an onboard soundcard.
   You want the USB-Signalink.

2. When you plug in the USB-signalink into your USB2 port, it will install (under windows) as an extra soundcard.
    The extra soundcard is normally named "USB-Audio-Codec"  in windows, which you will need to know to select it in a digimodes program.

3. The USB-Signalink (like any extra soundcard), appears to load as the default PC soundcard, so you may find after plugging it in that
    you can't hear any sounds from your PC anymore.
    This is because windows has made the external soundcard your default soundcard.
    If you unplug it, the normal PC soundcard will be used, but if it is plugged in you need to re-assign the default soundcard to
    the PC onboard one. Once you have re-assigned it once, it should not have to be done every time.

4. To make the onboard Push To Talk circuit work, you will need to find the volume sliders in windows and set the master one
    to maximum. This ensures the Push To Talk activates when you send.

5. You will need to get a cable (or make one up) which goes to your radio from the USB-Signalink.
    Check the tigertronics site and find the appropriate cable for your radio.
    
6.  When you get the USB-Signalink, you will need to open it and either jumper a DIL header with some jumper wires, or fit a
     preconfigured header for your radio.
     The Tigertronics site has a manual for download which shows how to configure the jumper.

By this time you have probably given away any ideas of going digital, but it sounds more complex than it really is.
I only provided the above points to give you a heads up to things which are commonly asked about by people setting one up.
None of these things may bother you at all, but at least you will have some foreknowledge of what is required.

73 - Rob
« Last Edit: August 20, 2012, 01:55:25 AM by STAYVERTICAL » Logged
KC4MOP
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« Reply #7 on: August 20, 2012, 03:55:17 AM »

Looks like the Signalink wins hands down. It really is a nice interface between computer and radio, I have one.
Order the cable and the "plug-in" for your model radio.

Power levels for both digital modes seem to be under 50 watts. Some operators like full power on RTTY, I don't understand that part, but remember that these digital modes are almost like 100% duty cycle and you better make sure your antenna and amplifier are up to the task.
Keep PSK 31 and JT65HF under 50 watts and you'll be fine. It is really a courtesy to others on the band. Being the BOSS will not make too many operators happy with your legal limit signal. You will hear the many many signals in the digital subands and then you will understand. Actually you will be tuning the transceiver observing the computer and the software.
JT65HF gets a little involved and requires precise timing, when to receive and when to send.Once you have the timing issues resolved and you see all of the stations calling CQ, you highlight the station of interest and select how you want to respond and the software takes over from there. It is not always the first time that you will make contact. The timing and possible 5 other stations in there trying to complete a "QSO" will take several cycles. QSO's is something scripted by convention for JT65HF. You can enter minor extra info through some computer short cuts (macros) a little extra chatter but it is extremely limited.
I think RTTY and PSK 31 are the chatter modes. JT65HF is something fairly new and kinda neat using only 20 watts
There are a lot of great tutorial links and threads on eHam about these modes and how to set up your station and computer.
Let us know when you are on the air.
Fred
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AD9DX
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« Reply #8 on: August 20, 2012, 05:13:00 AM »

I am also going to be adding an LP Pan to my station. Is all of this going to require 2 computers? I am already planning on using 2 monitors.
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EX, KC9TRM, KB9IRZ
AA4PB
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« Reply #9 on: August 20, 2012, 05:19:52 AM »

So, if the Signallink USB is a FB interface and costs $100, why do people spend megabucks on others?

It's mostly a matter of what features the interface has. I've built interfaces using nothing more than a few resistors and an NPN transistor for PTT that worked perfectly well for PSK31 and cost under $1. Add a couple of transformers and you reduce the possibility of hum due to grounding issues or RFI if the antenna is close by or not properly balanced. Add an internal sound card (ala Signalink-usb) and you reduce the number of connecting cables. For additional $$$ you can add a rig control interface, CW key output, direct FSK output, and even a TNC for amtor and pactor ARQ.

I finally ended up with a SignaLink-USB myself. Got it back when you had to wait 2-3 months for the order to be filled. Remember that the SignaLink-USB is only a USB audio device. The PTT is done via an internal VOX-like circuit. It doesn't provide interfaces for direct PTT control by the software, direct CW keying, direct FSK keying, or rig control.
« Last Edit: August 20, 2012, 06:08:29 AM by AA4PB » Logged
N4CR
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« Reply #10 on: August 20, 2012, 05:56:03 AM »

I ran a number of different sound cards and homebrew interfaces. For the last several years I've been using a SignaLink USB. I did take it apart to make several modifications to make it better than factory, but it worked very good right out of the box. I'm just a tinkerer at heart.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
W5DQ
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« Reply #11 on: August 20, 2012, 08:38:08 AM »

Regardless of what you use, don't forget to turn OFF Windows sounds because you don't want transmit "Boinnngggggg! You got mail" or other Windows 'noise'. Lots of folks drop in an interface and forget about the fact that Windows uses whatever is available to output sounds and if it happens to be your digital interface, out she goes to the world via HF.  Embarrassed

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
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« Reply #12 on: August 20, 2012, 02:26:33 PM »

Regardless of what you use, don't forget to turn OFF Windows sounds because you don't want transmit "Boinnngggggg! You got mail" or other Windows 'noise'. Lots of folks drop in an interface and forget about the fact that Windows uses whatever is available to output sounds and if it happens to be your digital interface, out she goes to the world via HF.  Embarrassed

Gene W5DQ

Quite right Gene,

If you use an external soundcard type of interface like the USB Signalink, you can leave windows sounds enabled, and still play music or whatever else while using digimodes.
But you do need to ensure that the player program does not use the external soundcard to stream its output.

For example, on Skype, I believe one option is to "ring on all devices".
So if you have your rig on, and you receive a skype call, you may find the ringtone being broadcast.
Also, beware when using other audio programs - look at what soundcard they configure themselves to use.
Some programs may decide to use the signalink (or other external soundcard) just for fun.

It's not a big problem, just something to remember if you are trying to figure out why you can't hear the person on the other end of your skype call, but your rig is mysteriously sending!

73 - Rob
« Last Edit: August 20, 2012, 02:28:32 PM by STAYVERTICAL » Logged
KC3JV
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« Reply #13 on: August 31, 2012, 08:09:39 PM »

I didn't like all of the crap I had to do to use my computer.   So I bought an NUE-PSK modem.   Very small with a self contained display.  Just buy the correct cable for you radio hitch up a 12V supply or use use batteries and hitch up a keyboard and your on the air.   Review here before you buy.

Mark KC3JV
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K5TED
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« Reply #14 on: September 18, 2012, 08:50:22 AM »

Signalink USB is the easiest digi interface I've used. I bought my first one a few years ago, and just got another one right here on eHam for $50. I've built my own isolation transformer scheme interfaces, cobbled them together from patch cords and  Radio Shack ground loop isolators, and also have used the MFJ Soundcard Interface. Signalink is King so far. There are others out there that are essentially the same sort of device, i.e. usb soundcard with rig cable, but the form factor alone sold me on the Signalink. Plug in two cables, load drivers, config digi software and you are on the air.

I also use a NUE-PSK, but for me it is in an entirely different league of devices. It's my field terminal. One radio, One device, A Keyboard. Thrilling.
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